Search Results

Search found 8219 results on 329 pages for 'less'.

Page 319/329 | < Previous Page | 315 316 317 318 319 320 321 322 323 324 325 326  | Next Page >

• LINQ to Twitter Maintenance Feedback

  - by Joe Mayo

  Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/06/16/linq-to-twitter-maintenance-feedback.aspxIt’s always fun to receive positive feedback on your work. If you receive a sufficient amount of positive feedback, you know you’re doing something right. Sometimes, people provide negative feedback too. There are a couple ways to handle it: come back fighting or engage for clarification. The way you handle the negative feedback depends on what your goals are. Feedback Approaches If you know the feedback is incorrect and you need to promote your idea or product, you might want to come back fighting. The feedback might just be comments by a troll or competitor wanting to spread FUD. However, this could be the totally wrong approach if you misjudge the source and intentions of the feedback. In a lot of cases, feedback is a golden opportunity. Sometimes, a problem exists that you either don’t know about or don’t realize the true impact of the problem. If you decide to come back fighting, you might loose the opportunity to learn something new. However, if you engage the person providing the feedback, looking for clarification, you might learn something very important. Negative feedback and it’s clarification can lead to the collection of useful and actionable data. In my case, something that prompted this blog post, I noticed someone who tweeted a negative comment about LINQ to Twitter. Normally, any less than stellar comments are usually from folks that need help – so I help if I can. This was different. I was like “Don’t use LINQ to Twitter”. This is an open source project, the comment didn’t come from a competing project, and  sounded more like an expression of frustration. So I engaged. Not only did the person respond, but I got some decent quality feedback. What’s also interesting is a couple other side conversations sprouted on the subject, which gave me more useful data. LINQ to Twitter Thread Actions Essentially, this particular issue centered around maintenance. There are actually several sub-issues at play here: dependencies, error handling, debugging, and visibility. I’ll describe each one and my interpretation. Dependencies Dependencies are where a library has references to other libraries. This means that when you build your application, you need DLLs for the entire dependency graph for your application. There are several potential problems with this that include more libraries for configuration management, potential versioning mismatches, and lack of cross-platform support. In the early days of LINQ to Twitter, I allowed developers to contribute and add dependencies, but it became very problematic (for reasons stated). It was like a ball and chain that kept me from moving forward. So, I refactored and pulled other open-source into my project to eliminate external dependencies. This lets me fix the code in my project without relying on someone else to upgrade or fix their DLL. The motivation for this was from early negative feedback that translated as important data and acted on it. Today, LINQ to Twitter has zero dependencies. Note: Rejecting good code from community members who worked hard to make your project better is a painful experience in itself. I have to point out that any contribution was not in vain because they had a positive influence on my subsequent refactoring that resulted in a better developer experience. Error Handling Error handling has been a problem in the past. I have this combination of supporting both synchronous and asynchronous (APM) processing that can be complex at times. Within the last 6 months, I did a fair amount of refactoring to detect errors and process them properly. I also refactored TwitterQueryException so it includes important data from Twitter. During this refactoring, I’ve made breaking changes that I felt would improve the development experience (small things like renaming a callback property to Exception, rather than Error). I think the async error handling is much better than it was a year ago. For all the work I’ve done, there is more to do. I think that a combination of more error handling support, e.g. improving semantics, and education through documentation and samples will improve the error handling story. Because of what I’ve done so far, it isn’t bad, but I see opportunities for improvement. Debugging Debugging can be painful. Here’s why: you have multiple layers of technology to navigate and figure out where the real problem is – Twitter API, Security, HTTP, LINQ to Twitter, and application. You can probably add your own nuances to that list, but the point is that debugging in this environment can be complex. I think that my plans for error handling will contribute to making the debugging process easier. However, there’s more I can do in the way of documentation and guidance. Some of the questions to be answered revolve around when something goes wrong, how does the developer figure out that there is a problem, what the problem is, and what to do about it. One example that has gone a long way to helping LINQ to Twitter developers is the 401 FAQ. A 401 Unauthorized is the error that the Twitter API returns when a use isn’t able to authenticate and is one of the most difficult problems faced by LINQ to Twitter developers. What I did was read guidance from Twitter and collect techniques from my own development and actions helping other developers to compile an extensive list of reasons for the 401 and ways to fix the problem. At one time, over half of the questions I answered in the forums were to help solve 401 issues. After publishing the 401 FAQ, I rarely get a 401 question and it’s because the person didn’t know about the FAQ. If the person is too lazy to read the FAQ, that’s not my issue, but the results in support issues have been dramatic. I think debugging can benefit from the education and documentation approach, but I’m always open to suggestions on whatever else I can do. Visibility Visibility is a nuance of the error handling/debugging discussion but is deeply rooted in comfort and control. The questions to ask in this area are what is happening as my code runs and how testable is the code. In support of these areas, LINQ to Twitter does have logging and TwitterContext properties that help see what’s happening on requests. The logging functionality allows any developer to connect a TextWriter to the Log property of TwitterContext to see what’s happening. Further, TwitterContext has a Headers property to see the headers Twitter returns and a RawResults property to show the Json string Twitter returns. From a testing perspective, I’ve been able to write hundreds of unit tests, over 600 when this post is published, and growing. If you write your own library, you have full control over all of these aspects. The tradeoff here is that while you have access to the LINQ to Twitter source code and modify it for all the visibility, LINQ to Twitter *will* change (which is good) and you will have to figure out how to merge that with your changes (which is hard). The fact is that this is a limitation of any 3rd party library, not just LINQ to Twitter. So, it’s a design decision where the tradeoff is between control and productivity. That said, there are things I can do with LINQ to Twitter to make the visibility story more compelling. I think there are opportunities to improve diagnostics. This would be a ton of work because it would need to provide multi-level logging that can be tuned for production and support any logging provider you want to attach. I’ve considered approaches such as how the new Semantic Logging application block connects to Windows Error Reporting as a potential target. Whatever I do would need to be extensible without creating native external dependencies. e.g. how many 3rd party libraries force a dependency on a logging framework that you don’t use. So, this won’t be an easy feat, but I believe it can be part of the roadmap. I think that a lot of developers are unaware of existing visibility features, so the first step would be to provide more documentation and guidance. My thought are that this would lead to more feedback that will help improve this area. Summary Recent feedback highlights some of items that are important to LINQ to Twitter developers, such as dependencies, error handling, debugging, and visibility. I know that there are maintenance issues that have been problems for LINQ to Twitter developers in the past. I’ve done a lot of work in this area, such as improving error handling, adding visibility features, and providing extensive API documentation. That said, there is more to be done to make LINQ to Twitter the best Twitter API experience available for .NET developers and I welcome anyone’s thoughts on what I’ve written here or new improvements. @JoeMayo

  Read the article

• Stumbling Through: Visual Studio 2010 (Part III)

  The last post ended with us just getting started on stumbling into text template file customization, a task that required a Visual Studio extension (Tangible T4 Editor) to even have a chance at completing.  Despite the benefits of the Tangible T4 Editor, I still had a hard time putting together a solid text template that would be easy to explain.  This is mostly due to the way the files allow you to mix code (encapsulated in <# #>) with straight-up text to generate.  It is effective to be sure, but not very readable.  Nevertheless, I will try and explain what was accomplished in my custom tt file, though the details of which are not really the point of this article (my way of saying dont criticize my crappy code, and certainly dont use it in any somewhat real application.  You may become dumber just by looking at this code.  You have been warned really the footnote I should put at the end of all of my blog posts). To begin with, there were two basic requirements that I needed the code generator to satisfy:  Reading one to many entity framework files, and using the entities that were found to write one to many class files.  Thankfully, using the Entity Object Generator as a starting point gave us an example on how to do exactly that by using the MetadataLoader and EntityFrameworkTemplateFileManager you include references to these items and use them like so: // Instantiate an entity framework file reader and file writer MetadataLoader loader = new MetadataLoader(this); EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this); // Load the entity model metadata workspace MetadataWorkspace metadataWorkspace = null; bool allMetadataLoaded =loader.TryLoadAllMetadata("MFL.tt", out metadataWorkspace); EdmItemCollection ItemCollection = (EdmItemCollection)metadataWorkspace.GetItemCollection(DataSpace.CSpace); // Create an IO class to contain the 'get' methods for all entities in the model fileManager.StartNewFile("MFL.IO.gen.cs"); Next, we want to be able to loop through all of the entities found in the model, and then each property for each entity so we can generate classes and methods for each.  The code for that is blissfully simple: // Iterate through each entity in the model foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name)) {     // Iterate through each primitive property of the entity     foreach (EdmProperty edmProperty in entity.Properties.Where(p => p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))     {         // TODO:  Create properties     }     // Iterate through each relationship of the entity     foreach (NavigationProperty navProperty in entity.NavigationProperties.Where(np => np.DeclaringType == entity))     {         // TODO:  Create associations     } } There really isnt anything more advanced than that going on in the text template the only thing I had to blunder through was realizing that if you want the generator to interpret a line of code (such as our iterations above), you need to enclose the code in <# and #> while if you want the generator to interpret the VALUE of code, such as putting the entity name into the class name, you need to enclose the code in <#= and #> like so: public partial class <#=entity.Name#> To make a long story short, I did a lot of repetition of the above to come up with a text template that generates a class for each entity based on its properties, and a set of IO methods for each entity based on its relationships.  The two work together to provide lazy-loading for hierarchical data (such getting Team.Players) so it should be pretty intuitive to use on a front-end.  This text template is available here you can tweak the inputFiles array to load one or many different edmx models and generate the basic xml IO and class files, though it will probably only work correctly in the simplest of cases, like our MFL model described in the previous post.  Additionally, there is no validation, logging or error handling which is something I want to handle later by stumbling through the enterprise library 5.0. The code that gets generated isnt anything special, though using the LINQ to XML feature was something very new and exciting for me I had only worked with XML in the past using the DOM or XML Reader objects along with XPath, and the LINQ to XML model is just so much more elegant and supposedly efficient (something to test later).  For example, the following code was generated to create a Player object for each Player node in the XML:         return from element in GetXmlData(_PlayerDataFile).Descendants("Player")             select new Player             {                 Id = int.Parse(element.Attribute("Id").Value)                 ,ParentName = element.Parent.Name.LocalName                 ,ParentId = long.Parse(element.Parent.Attribute("Id").Value)                 ,Name = element.Attribute("Name").Value                 ,PositionId = int.Parse(element.Attribute("PositionId").Value)             }; It is all done in one line of code, no looping needed.  Even though GetXmlData loads the entire xml file just like the old XML DOM approach would have, it is supposed to be much less resource intensive.  I will definitely put that to the test after we develop a user interface for getting at this data.  Speaking of the data where IS the data?  Weve put together a pretty model and a bunch of code around it, but we dont have any data to speak of.  We can certainly drop to our favorite XML editor and crank out some data, but if it doesnt totally match our model, it will not load correctly.  To help with this, Ive built in a method to generate xml at any given layer in the hierarchy.  So for us to get the closest possible thing to real data, wed need to invoke MFL.IO.GenerateTeamXML and save the results to file.  Doing so should get us something that looks like this: <Team Id="0" Name="0">   <Player Id="0" Name="0" PositionId="0">     <Statistic Id="0" PassYards="0" RushYards="0" Year="0" />   </Player> </Team> Sadly, it is missing the Positions node (havent thought of a way to generate lookup xml yet) and the data itself isnt quite realistic (well, as realistic as MFL data can be anyway).  Lets manually remedy that for now to give us a decent starter set of data.  Note that this is TWO xml files Lookups.xml and Teams.xml: <Lookups Id=0>   <Position Id="0" Name="Quarterback"/>   <Position Id="1" Name="Runningback"/> </Lookups> <Teams Id=0>   <Team Id="0" Name="Chicago">     <Player Id="0" Name="QB Bears" PositionId="0">       <Statistic Id="0" PassYards="4000" RushYards="120" Year="2008" />       <Statistic Id="1" PassYards="4200" RushYards="180" Year="2009" />     </Player>     <Player Id="1" Name="RB Bears" PositionId="1">       <Statistic Id="2" PassYards="0" RushYards="800" Year="2007" />       <Statistic Id="3" PassYards="0" RushYards="1200" Year="2008" />       <Statistic Id="4" PassYards="3" RushYards="1450" Year="2009" />     </Player>   </Team> </Teams> Ok, so we have some data, we have a way to read/write that data and we have a friendly way of representing that data.  Now, what remains is the part that I have been looking forward to the most: present the data to the user and give them the ability to add/update/delete, and doing so in a way that is very intuitive (easy) from a development standpoint.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

  Read the article

• Stumbling Through: Visual Studio 2010 (Part III)

  The last post ended with us just getting started on stumbling into text template file customization, a task that required a Visual Studio extension (Tangible T4 Editor) to even have a chance at completing.  Despite the benefits of the Tangible T4 Editor, I still had a hard time putting together a solid text template that would be easy to explain.  This is mostly due to the way the files allow you to mix code (encapsulated in <# #>) with straight-up text to generate.  It is effective to be sure, but not very readable.  Nevertheless, I will try and explain what was accomplished in my custom tt file, though the details of which are not really the point of this article (my way of saying dont criticize my crappy code, and certainly dont use it in any somewhat real application.  You may become dumber just by looking at this code.  You have been warned really the footnote I should put at the end of all of my blog posts). To begin with, there were two basic requirements that I needed the code generator to satisfy:  Reading one to many entity framework files, and using the entities that were found to write one to many class files.  Thankfully, using the Entity Object Generator as a starting point gave us an example on how to do exactly that by using the MetadataLoader and EntityFrameworkTemplateFileManager you include references to these items and use them like so: // Instantiate an entity framework file reader and file writer MetadataLoader loader = new MetadataLoader(this); EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this); // Load the entity model metadata workspace MetadataWorkspace metadataWorkspace = null; bool allMetadataLoaded =loader.TryLoadAllMetadata("MFL.tt", out metadataWorkspace); EdmItemCollection ItemCollection = (EdmItemCollection)metadataWorkspace.GetItemCollection(DataSpace.CSpace); // Create an IO class to contain the 'get' methods for all entities in the model fileManager.StartNewFile("MFL.IO.gen.cs"); Next, we want to be able to loop through all of the entities found in the model, and then each property for each entity so we can generate classes and methods for each.  The code for that is blissfully simple: // Iterate through each entity in the model foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name)) {     // Iterate through each primitive property of the entity     foreach (EdmProperty edmProperty in entity.Properties.Where(p => p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))     {         // TODO:  Create properties     }     // Iterate through each relationship of the entity     foreach (NavigationProperty navProperty in entity.NavigationProperties.Where(np => np.DeclaringType == entity))     {         // TODO:  Create associations     } } There really isnt anything more advanced than that going on in the text template the only thing I had to blunder through was realizing that if you want the generator to interpret a line of code (such as our iterations above), you need to enclose the code in <# and #> while if you want the generator to interpret the VALUE of code, such as putting the entity name into the class name, you need to enclose the code in <#= and #> like so: public partial class <#=entity.Name#> To make a long story short, I did a lot of repetition of the above to come up with a text template that generates a class for each entity based on its properties, and a set of IO methods for each entity based on its relationships.  The two work together to provide lazy-loading for hierarchical data (such getting Team.Players) so it should be pretty intuitive to use on a front-end.  This text template is available here you can tweak the inputFiles array to load one or many different edmx models and generate the basic xml IO and class files, though it will probably only work correctly in the simplest of cases, like our MFL model described in the previous post.  Additionally, there is no validation, logging or error handling which is something I want to handle later by stumbling through the enterprise library 5.0. The code that gets generated isnt anything special, though using the LINQ to XML feature was something very new and exciting for me I had only worked with XML in the past using the DOM or XML Reader objects along with XPath, and the LINQ to XML model is just so much more elegant and supposedly efficient (something to test later).  For example, the following code was generated to create a Player object for each Player node in the XML:         return from element in GetXmlData(_PlayerDataFile).Descendants("Player")             select new Player             {                 Id = int.Parse(element.Attribute("Id").Value)                 ,ParentName = element.Parent.Name.LocalName                 ,ParentId = long.Parse(element.Parent.Attribute("Id").Value)                 ,Name = element.Attribute("Name").Value                 ,PositionId = int.Parse(element.Attribute("PositionId").Value)             }; It is all done in one line of code, no looping needed.  Even though GetXmlData loads the entire xml file just like the old XML DOM approach would have, it is supposed to be much less resource intensive.  I will definitely put that to the test after we develop a user interface for getting at this data.  Speaking of the data where IS the data?  Weve put together a pretty model and a bunch of code around it, but we dont have any data to speak of.  We can certainly drop to our favorite XML editor and crank out some data, but if it doesnt totally match our model, it will not load correctly.  To help with this, Ive built in a method to generate xml at any given layer in the hierarchy.  So for us to get the closest possible thing to real data, wed need to invoke MFL.IO.GenerateTeamXML and save the results to file.  Doing so should get us something that looks like this: <Team Id="0" Name="0">   <Player Id="0" Name="0" PositionId="0">     <Statistic Id="0" PassYards="0" RushYards="0" Year="0" />   </Player> </Team> Sadly, it is missing the Positions node (havent thought of a way to generate lookup xml yet) and the data itself isnt quite realistic (well, as realistic as MFL data can be anyway).  Lets manually remedy that for now to give us a decent starter set of data.  Note that this is TWO xml files Lookups.xml and Teams.xml: <Lookups Id=0>   <Position Id="0" Name="Quarterback"/>   <Position Id="1" Name="Runningback"/> </Lookups> <Teams Id=0>   <Team Id="0" Name="Chicago">     <Player Id="0" Name="QB Bears" PositionId="0">       <Statistic Id="0" PassYards="4000" RushYards="120" Year="2008" />       <Statistic Id="1" PassYards="4200" RushYards="180" Year="2009" />     </Player>     <Player Id="1" Name="RB Bears" PositionId="1">       <Statistic Id="2" PassYards="0" RushYards="800" Year="2007" />       <Statistic Id="3" PassYards="0" RushYards="1200" Year="2008" />       <Statistic Id="4" PassYards="3" RushYards="1450" Year="2009" />     </Player>   </Team> </Teams> Ok, so we have some data, we have a way to read/write that data and we have a friendly way of representing that data.  Now, what remains is the part that I have been looking forward to the most: present the data to the user and give them the ability to add/update/delete, and doing so in a way that is very intuitive (easy) from a development standpoint.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

  Read the article

• Hibernate unable to instantiate default tuplizer - cannot find getter

  - by ZeldaPinwheel

  I'm trying to use Hibernate to persist a class that looks like this: public class Item implements Serializable, Comparable<Item> { // Item id private Integer id; // Description of item in inventory private String description; // Number of items described by this inventory item private int count; //Category item belongs to private String category; // Date item was purchased private GregorianCalendar purchaseDate; public Item() { } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public int getCount() { return count; } public void setCount(int count) { this.count = count; } public String getCategory() { return category; } public void setCategory(String category) { this.category = category; } public GregorianCalendar getPurchaseDate() { return purchaseDate; } public void setPurchasedate(GregorianCalendar purchaseDate) { this.purchaseDate = purchaseDate; } My Hibernate mapping file contains the following: <property name="puchaseDate" type="java.util.GregorianCalendar"> <column name="purchase_date"></column> </property> When I try to run, I get error messages indicating there is no getter function for the purchaseDate attribute: 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!) 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 20 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost:3306/home_inventory 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=root, password=****} 1078 [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: MySQL, version: 5.1.45 1078 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.12 ( Revision: ${bzr.revision-id} ) 1103 [main] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.MySQLDialect 1107 [main] INFO org.hibernate.engine.jdbc.JdbcSupportLoader - Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 1109 [main] INFO org.hibernate.transaction.TransactionFactoryFactory - Using default transaction strategy (direct JDBC transactions) 1110 [main] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Maximum outer join fetch depth: 2 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled 1112 [main] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {} 1113 [main] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.NoCachingRegionFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled 1114 [main] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled 1117 [main] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Check Nullability in Core (should be disabled when Bean Validation is on): enabled 1151 [main] INFO org.hibernate.impl.SessionFactoryImpl - building session factory org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer] at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:110) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:135) at org.hibernate.tuple.entity.EntityEntityModeToTuplizerMapping.<init>(EntityEntityModeToTuplizerMapping.java:80) at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:323) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:475) at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:133) at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84) at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:295) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1385) at service.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:53) at service.ItemSvcHibImpl.generateReport(ItemSvcHibImpl.java:78) at service.test.ItemSvcTest.testGenerateReport(ItemSvcTest.java:226) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:164) at junit.framework.TestCase.runBare(TestCase.java:130) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:120) at junit.framework.TestSuite.runTest(TestSuite.java:230) at junit.framework.TestSuite.run(TestSuite.java:225) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:107) ... 29 more Caused by: org.hibernate.PropertyNotFoundException: Could not find a getter for puchaseDate in class domain.Item at org.hibernate.property.BasicPropertyAccessor.createGetter(BasicPropertyAccessor.java:328) at org.hibernate.property.BasicPropertyAccessor.getGetter(BasicPropertyAccessor.java:321) at org.hibernate.mapping.Property.getGetter(Property.java:304) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildPropertyGetter(PojoEntityTuplizer.java:299) at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:158) at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:77) ... 34 more I'm new to Hibernate, so I don't know all the ins and outs, but I do have the getter and setter for the purchaseDate attribute. I don't know what I'm missing here - does anyone else? Thanks!

  Read the article

• Having trouble binding a ksoap object to an ArrayList in Android

  - by Maskau

  I'm working on an app that calls a web service, then the webservice returns an array list. My problem is I am having trouble getting the data into the ArrayList and then displaying in a ListView. Any ideas what I am doing wrong? I know for a fact the web service returns an ArrayList. Everything seems to be working fine, just no data in the ListView or the ArrayList.....Thanks in advance! EDIT: So I added more code to the catch block of run() and now it's returning "org.ksoap2.serialization.SoapObject".....no more no less....and I am even more confused now... package com.maskau; import java.util.ArrayList; import org.ksoap2.SoapEnvelope; import org.ksoap2.serialization.PropertyInfo; import org.ksoap2.serialization.SoapObject; import org.ksoap2.serialization.SoapSerializationEnvelope; import org.ksoap2.transport.AndroidHttpTransport; import android.app.*; import android.os.*; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView; import android.view.View; import android.view.View.OnClickListener; public class Home extends Activity implements Runnable{ /** Called when the activity is first created. */ public static final String SOAP_ACTION = "http://bb.mcrcog.com/GetArtist"; public static final String METHOD_NAME = "GetArtist"; public static final String NAMESPACE = "http://bb.mcrcog.com"; public static final String URL = "http://bb.mcrcog.com/karaoke/service.asmx"; String wt; public static ProgressDialog pd; TextView text1; ListView lv; static EditText myEditText; static Button but; private ArrayList<String> Artist_Result = new ArrayList<String>(); @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main); myEditText = (EditText)findViewById(R.id.myEditText); text1 = (TextView)findViewById(R.id.text1); lv = (ListView)findViewById(R.id.lv); but = (Button)findViewById(R.id.but); but.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { wt = ("Searching for " + myEditText.getText().toString()); text1.setText(""); pd = ProgressDialog.show(Home.this, "Working...", wt , true, false); Thread thread = new Thread(Home.this); thread.start(); } } ); } public void run() { try { SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); PropertyInfo pi = new PropertyInfo(); pi.setName("ArtistQuery"); pi.setValue(Home.myEditText.getText().toString()); request.addProperty(pi); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.dotNet = true; envelope.setOutputSoapObject(request); AndroidHttpTransport at = new AndroidHttpTransport(URL); at.call(SOAP_ACTION, envelope); java.util.Vector<Object> rs = (java.util.Vector<Object>)envelope.getResponse(); if (rs != null) { for (Object cs : rs) { Artist_Result.add(cs.toString()); } } } catch (Exception e) { // Added this line, throws "org.ksoap2.serialization.SoapObject" when run Artist_Result.add(e.getMessage()); } handler.sendEmptyMessage(0); } private Handler handler = new Handler() { @Override public void handleMessage(Message msg) { ArrayAdapter<String> aa; aa = new ArrayAdapter<String>(Home.this, android.R.layout.simple_list_item_1, Artist_Result); lv.setAdapter(aa); try { if (Artist_Result.isEmpty()) { text1.setText("No Results"); } else { text1.setText("Complete"); myEditText.setText("Search Artist"); } } catch(Exception e) { text1.setText(e.getMessage()); } aa.notifyDataSetChanged(); pd.dismiss(); } }; }

  Read the article

• why is LZMA SDK (7-zip) so slow

  - by Tono Nam

  I found 7-zip great and I will like to use it on .net applications. I have a 10MB file (a.001) and it takes: 2 seconds to encode. Now it will be nice if I could do the same thing on c#. I have downloaded http://www.7-zip.org/sdk.html LZMA SDK c# source code. I basically copied the CS directory into a console application in visual studio: Then I compiled and eveything compiled smoothly. So on the output directory I placed the file a.001 which is 10MB of size. On the main method that came on the source code I placed: [STAThread] static int Main(string[] args) { // e stands for encode args = "e a.001 output.7z".Split(' '); // added this line for debug try { return Main2(args); } catch (Exception e) { Console.WriteLine("{0} Caught exception #1.", e); // throw e; return 1; } } when I execute the console application the application works great and I get the output a.7z on the working directory. The problem is that it takes so long. It takes about 15 seconds to execute! I have also tried http://stackoverflow.com/a/8775927/637142 approach and it also takes very long. Why is it 10 times slower than the actual program ? Also Even if I set to use only one thread: It still takes much less time (3 seconds vs 15): (Edit) Another Possibility Could it be because C# is slower than assembly or C ? I notice that the algorithm does a lot of heavy operations. For example compare these two blocks of code. They both do the same thing: C void main() { time_t now; int i,j,k,x; long counter ; counter = 0; now = time(NULL); /* LOOP */ for(x=0; x<10; x++) { counter = -1234567890 + x+2; for (j = 0; j < 10000; j++) for(i = 0; i< 1000; i++) for(k =0; k<1000; k++) { if(counter > 10000) counter = counter - 9999; else counter= counter +1; } printf (" %d \n", time(NULL) - now); // display elapsed time } printf("counter = %d\n\n",counter); // display result of counter printf ("Elapsed time = %d seconds ", time(NULL) - now); gets("Wait"); } output c# static void Main(string[] args) { DateTime now; int i, j, k, x; long counter; counter = 0; now = DateTime.Now; /* LOOP */ for (x = 0; x < 10; x++) { counter = -1234567890 + x + 2; for (j = 0; j < 10000; j++) for (i = 0; i < 1000; i++) for (k = 0; k < 1000; k++) { if (counter > 10000) counter = counter - 9999; else counter = counter + 1; } Console.WriteLine((DateTime.Now - now).Seconds.ToString()); } Console.Write("counter = {0} \n", counter.ToString()); Console.Write("Elapsed time = {0} seconds", DateTime.Now - now); Console.Read(); } Output Note how much slower was c#. Both programs where run from outside visual studio on release mode. Maybe that is the reason why it takes so much longer in .net than on c++. Conclusion I cannot seem to know what is causing the problem. I guess I will use 7z.dll and invoke the necessary methods from c#. A library that does that is at: http://sevenzipsharp.codeplex.com/ and that way I am using the same library that 7zip is using as: // dont forget to add reference to SevenZipSharp located on the link I provided static void Main(string[] args) { // load the dll SevenZip.SevenZipCompressor.SetLibraryPath(@"C:\Program Files (x86)\7-Zip\7z.dll"); SevenZip.SevenZipCompressor compress = new SevenZip.SevenZipCompressor(); compress.CompressDirectory("MyFolderToArchive", "output.7z"); }

  Read the article

• Android text layout question: two textviews, side-by-side, with different layout alignments and weights

  - by thx1200

  I'm still a bit of an Android noob, forgive me if this is simple and I'm just not seeing it. There are two portions of text in a view that spans the entire width horizontally, but is only as high as one line of text. The left side must always be displayed in full, but should take no more horizontal space than it needs. The right side should be pushed over by the left side and fill up the remainder of the screen width. If the right side text is smaller than this width, the text should be right-aligned horizontally. If the text is greater than the width, it should scroll horizontally. The text on the right side will be updated frequently and should slide up with new text when the app tells it (explaining the TextSwitcher in the layout). I have tried two different layout styles. In both situations, I can get the left side to "push" the layout, the right side to scroll, but I can't figure out how to get the right side to right align. It is always left aligned. Here is a picture showing what is happening... http://img10.imageshack.us/img10/5599/androidlayout.png In addition (but less important), in my layout code I have android:fadingEdge="none" on the TextViews, but it still has a faded edge on the left and right side when it scrolls. Why is that? Here are the two layouts I created, which yield the results shown, but not the results I want. Using a horizontal LinearLayout... <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/LinearLayoutStatusBar" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_margin="2px" android:background="#555555" > <TextView android:id="@+id/TextViewTimer" android:textSize="18px" android:textColor="#FFFFFF" android:layout_gravity="left" android:layout_weight="0" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="0px" android:layout_marginRight="3px" android:text="Left Side" > </TextView> <TextSwitcher android:id="@+id/TextSwitcherDetails" android:inAnimation="@anim/push_up_in" android:outAnimation="@anim/push_up_out" android:layout_weight="1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="right" android:layout_marginLeft="3px" android:layout_marginRight="0px" > <TextView android:id="@+id/TextViewDetails1" android:textSize="18px" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_gravity="right" android:singleLine="true" android:ellipsize="marquee" android:marqueeRepeatLimit="marquee_forever" android:scrollHorizontally="true" android:focusable="true" android:focusableInTouchMode="true" android:fadingEdge="none" android:text="Right Side 1" > </TextView> <TextView android:id="@+id/TextViewDetails2" android:textSize="18px" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_gravity="right" android:singleLine="true" android:ellipsize="marquee" android:marqueeRepeatLimit="marquee_forever" android:scrollHorizontally="true" android:focusable="true" android:focusableInTouchMode="true" android:fadingEdge="none" android:text="Right Side 2 - This is a really long text this is long and fun and fun and long" > </TextView> </TextSwitcher> </LinearLayout> And the RelativeLayout style... <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/LinearLayoutStatusBar" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_margin="2px" android:background="#555555" > <TextView android:id="@+id/TextViewTimer" android:textSize="18px" android:textColor="#FFFFFF" android:layout_gravity="left" android:layout_weight="0" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="0px" android:layout_marginRight="3px" android:layout_alignParentLeft="true" android:text="Left Side" > </TextView> <TextSwitcher android:id="@+id/TextSwitcherDetails" android:inAnimation="@anim/push_up_in" android:outAnimation="@anim/push_up_out" android:layout_weight="1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="3px" android:layout_marginRight="0px" android:layout_toRightOf="@+id/TextViewTimer" android:layout_alignParentRight="true" android:fadingEdge="none" android:fadingEdgeLength="0px" > <TextView android:id="@+id/TextViewDetails1" android:textSize="18px" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="right" android:singleLine="true" android:ellipsize="marquee" android:marqueeRepeatLimit="marquee_forever" android:scrollHorizontally="true" android:focusable="true" android:focusableInTouchMode="true" android:fadingEdge="none" android:fadingEdgeLength="0px" android:text="Right Side 1" > </TextView> <TextView android:id="@+id/TextViewDetails2" android:textSize="18px" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="right" android:singleLine="true" android:ellipsize="marquee" android:marqueeRepeatLimit="marquee_forever" android:scrollHorizontally="true" android:focusable="true" android:focusableInTouchMode="true" android:fadingEdge="none" android:fadingEdgeLength="0px" android:text="Right Side 2 - This is a really long text this is long and fun and fun and long" > </TextView> </TextSwitcher> </RelativeLayout> So how do I get that text on the right side to right-align. Thanks!

  Read the article

• Using AES encryption in .NET - CryptographicException saying the padding is invalid and cannot be removed

  - by Jake Petroules

  I wrote some AES encryption code in C# and I am having trouble getting it to encrypt and decrypt properly. If I enter "test" as the passphrase and "This data must be kept secret from everyone!" I receive the following exception: System.Security.Cryptography.CryptographicException: Padding is invalid and cannot be removed. at System.Security.Cryptography.RijndaelManagedTransform.DecryptData(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount, Byte[]& outputBuffer, Int32 outputOffset, PaddingMode paddingMode, Boolean fLast) at System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount) at System.Security.Cryptography.CryptoStream.FlushFinalBlock() at System.Security.Cryptography.CryptoStream.Dispose(Boolean disposing) at System.IO.Stream.Close() at System.IO.Stream.Dispose() ... And if I enter something less than 16 characters I get no output. I believe I need some special handling in the encryption since AES is a block cipher, but I'm not sure exactly what that is, and I wasn't able to find any examples on the web showing how. Here is my code: using System; using System.IO; using System.Security.Cryptography; using System.Text; public static class DatabaseCrypto { public static EncryptedData Encrypt(string password, string data) { return DatabaseCrypto.Transform(true, password, data, null, null) as EncryptedData; } public static string Decrypt(string password, EncryptedData data) { return DatabaseCrypto.Transform(false, password, data.DataString, data.SaltString, data.MACString) as string; } private static object Transform(bool encrypt, string password, string data, string saltString, string macString) { using (AesManaged aes = new AesManaged()) { aes.Mode = CipherMode.CBC; aes.Padding = PaddingMode.PKCS7; int key_len = aes.KeySize / 8; int iv_len = aes.BlockSize / 8; const int salt_size = 8; const int iterations = 8192; byte[] salt = encrypt ? new Rfc2898DeriveBytes(string.Empty, salt_size).Salt : Convert.FromBase64String(saltString); byte[] bc_key = new Rfc2898DeriveBytes("BLK" + password, salt, iterations).GetBytes(key_len); byte[] iv = new Rfc2898DeriveBytes("IV" + password, salt, iterations).GetBytes(iv_len); byte[] mac_key = new Rfc2898DeriveBytes("MAC" + password, salt, iterations).GetBytes(16); aes.Key = bc_key; aes.IV = iv; byte[] rawData = encrypt ? Encoding.UTF8.GetBytes(data) : Convert.FromBase64String(data); using (ICryptoTransform transform = encrypt ? aes.CreateEncryptor() : aes.CreateDecryptor()) using (MemoryStream memoryStream = encrypt ? new MemoryStream() : new MemoryStream(rawData)) using (CryptoStream cryptoStream = new CryptoStream(memoryStream, transform, encrypt ? CryptoStreamMode.Write : CryptoStreamMode.Read)) { if (encrypt) { cryptoStream.Write(rawData, 0, rawData.Length); return new EncryptedData(salt, mac_key, memoryStream.ToArray()); } else { byte[] originalData = new byte[rawData.Length]; int count = cryptoStream.Read(originalData, 0, originalData.Length); return Encoding.UTF8.GetString(originalData, 0, count); } } } } } public class EncryptedData { public EncryptedData() { } public EncryptedData(byte[] salt, byte[] mac, byte[] data) { this.Salt = salt; this.MAC = mac; this.Data = data; } public EncryptedData(string salt, string mac, string data) { this.SaltString = salt; this.MACString = mac; this.DataString = data; } public byte[] Salt { get; set; } public string SaltString { get { return Convert.ToBase64String(this.Salt); } set { this.Salt = Convert.FromBase64String(value); } } public byte[] MAC { get; set; } public string MACString { get { return Convert.ToBase64String(this.MAC); } set { this.MAC = Convert.FromBase64String(value); } } public byte[] Data { get; set; } public string DataString { get { return Convert.ToBase64String(this.Data); } set { this.Data = Convert.FromBase64String(value); } } } static void ReadTest() { Console.WriteLine("Enter password: "); string password = Console.ReadLine(); using (StreamReader reader = new StreamReader("aes.cs.txt")) { EncryptedData enc = new EncryptedData(); enc.SaltString = reader.ReadLine(); enc.MACString = reader.ReadLine(); enc.DataString = reader.ReadLine(); Console.WriteLine("The decrypted data was: " + DatabaseCrypto.Decrypt(password, enc)); } } static void WriteTest() { Console.WriteLine("Enter data: "); string data = Console.ReadLine(); Console.WriteLine("Enter password: "); string password = Console.ReadLine(); EncryptedData enc = DatabaseCrypto.Encrypt(password, data); using (StreamWriter stream = new StreamWriter("aes.cs.txt")) { stream.WriteLine(enc.SaltString); stream.WriteLine(enc.MACString); stream.WriteLine(enc.DataString); Console.WriteLine("The encrypted data was: " + enc.DataString); } }

  Read the article

• Optimized Image Loading in a UIScrollView

  - by Michael Gaylord

  I have a UIScrollView that has a set of images loaded side-by-side inside it. You can see an example of my app here: http://www.42restaurants.com. My problem comes in with memory usage. I want to lazy load the images as they are about to appear on the screen and unload images that aren't on screen. As you can see in the code I work out at a minimum which image I need to load and then assign the loading portion to an NSOperation and place it on an NSOperationQueue. Everything works great apart from a jerky scrolling experience. I don't know if anyone has any ideas as to how I can make this even more optimized, so that the loading time of each image is minimized or so that the scrolling is less jerky. - (void)scrollViewDidScroll:(UIScrollView *)scrollView{ [self manageThumbs]; } - (void) manageThumbs{ int centerIndex = [self centerThumbIndex]; if(lastCenterIndex == centerIndex){ return; } if(centerIndex >= totalThumbs){ return; } NSRange unloadRange; NSRange loadRange; int totalChange = lastCenterIndex - centerIndex; if(totalChange > 0){ //scrolling backwards loadRange.length = fabsf(totalChange); loadRange.location = centerIndex - 5; unloadRange.length = fabsf(totalChange); unloadRange.location = centerIndex + 6; }else if(totalChange < 0){ //scrolling forwards unloadRange.length = fabsf(totalChange); unloadRange.location = centerIndex - 6; loadRange.length = fabsf(totalChange); loadRange.location = centerIndex + 5; } [self unloadImages:unloadRange]; [self loadImages:loadRange]; lastCenterIndex = centerIndex; return; } - (void) unloadImages:(NSRange)range{ UIScrollView *scrollView = (UIScrollView *)[[self.view subviews] objectAtIndex:0]; for(int i = 0; i < range.length && range.location + i < [scrollView.subviews count]; i++){ UIView *subview = [scrollView.subviews objectAtIndex:(range.location + i)]; if(subview != nil && [subview isKindOfClass:[ThumbnailView class]]){ ThumbnailView *thumbView = (ThumbnailView *)subview; if(thumbView.loaded){ UnloadImageOperation *unloadOperation = [[UnloadImageOperation alloc] initWithOperableImage:thumbView]; [queue addOperation:unloadOperation]; [unloadOperation release]; } } } } - (void) loadImages:(NSRange)range{ UIScrollView *scrollView = (UIScrollView *)[[self.view subviews] objectAtIndex:0]; for(int i = 0; i < range.length && range.location + i < [scrollView.subviews count]; i++){ UIView *subview = [scrollView.subviews objectAtIndex:(range.location + i)]; if(subview != nil && [subview isKindOfClass:[ThumbnailView class]]){ ThumbnailView *thumbView = (ThumbnailView *)subview; if(!thumbView.loaded){ LoadImageOperation *loadOperation = [[LoadImageOperation alloc] initWithOperableImage:thumbView]; [queue addOperation:loadOperation]; [loadOperation release]; } } } } EDIT: Thanks for the really great responses. Here is my NSOperation code and ThumbnailView code. I tried a couple of things over the weekend but I only managed to improve performance by suspending the operation queue during scrolling and resuming it when scrolling is finished. Here are my code snippets: //In the init method queue = [[NSOperationQueue alloc] init]; [queue setMaxConcurrentOperationCount:4]; //In the thumbnail view the loadImage and unloadImage methods - (void) loadImage{ if(!loaded){ NSString *filename = [NSString stringWithFormat:@"%03d-cover-front", recipe.identifier, recipe.identifier]; NSString *directory = [NSString stringWithFormat:@"RestaurantContent/%03d", recipe.identifier]; NSString *path = [[NSBundle mainBundle] pathForResource:filename ofType:@"png" inDirectory:directory]; UIImage *image = [UIImage imageWithContentsOfFile:path]; imageView = [[ImageView alloc] initWithImage:image andFrame:CGRectMake(0.0f, 0.0f, 176.0f, 262.0f)]; [self addSubview:imageView]; [self sendSubviewToBack:imageView]; [imageView release]; loaded = YES; } } - (void) unloadImage{ if(loaded){ [imageView removeFromSuperview]; imageView = nil; loaded = NO; } } Then my load and unload operations: - (id) initWithOperableImage:(id<OperableImage>) anOperableImage{ self = [super init]; if (self != nil) { self.image = anOperableImage; } return self; } //This is the main method in the load image operation - (void)main { [image loadImage]; } //This is the main method in the unload image operation - (void)main { [image unloadImage]; }

  Read the article

• Using Image Source with big images in WPF

  - by xyzzer

  I am working on an application that allows users to manipulate multiple images by using ItemsControl. I started running some tests and found that the app has problems displaying some big images - ie. it did not work with the high resolution (21600x10800), 20MB images from http://earthobservatory.nasa.gov/Features/BlueMarble/BlueMarble_monthlies.php, though it displays the 6200x6200, 60MB Hubble telescope image from http://zebu.uoregon.edu/hudf/hudf.jpg just fine. The original solution just specified an Image control with a Source property pointing at a file on a disk (through a binding). With the Blue Marble file - the image would just not show up. Now this could be just a bug hidden somewhere deep in the funky MVVM + XAML implementation - the visual tree displayed by Snoop goes like: Window/Border/AdornerDecorator/ContentPresenter/Grid/Canvas/UserControl/Border/ContentPresenter/Grid/Grid/Grid/Grid/Border/Grid/ContentPresenter/UserControl/UserControl/Border/ContentPresenter/Grid/Grid/Grid/Grid/Viewbox/ContainerVisual/UserControl/Border/ContentPresenter/Grid/Grid/ItemsControl/Border/ItemsPresenter/Canvas/ContentPresenter/Grid/Grid/ContentPresenter/Image... Now debug this! WPF can be crazy like that... Anyway, it turned out that if I create a simple WPF application - the images load just fine. I tried finding out the root cause, but I don't want to spend weeks on it. I figured the right thing to do might be to use a converter to scale the images down - this is what I have done: ImagePath = @"F:\Astronomical\world.200402.3x21600x10800.jpg"; TargetWidth = 2800; TargetHeight = 1866; and <Image> <Image.Source> <MultiBinding Converter="{StaticResource imageResizingConverter}"> <MultiBinding.Bindings> <Binding Path="ImagePath"/> <Binding RelativeSource="{RelativeSource Self}" /> <Binding Path="TargetWidth"/> <Binding Path="TargetHeight"/> </MultiBinding.Bindings> </MultiBinding> </Image.Source> </Image> and public class ImageResizingConverter : MarkupExtension, IMultiValueConverter { public Image TargetImage { get; set; } public string SourcePath { get; set; } public int DecodeWidth { get; set; } public int DecodeHeight { get; set; } public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) { this.SourcePath = values[0].ToString(); this.TargetImage = (Image)values[1]; this.DecodeWidth = (int)values[2]; this.DecodeHeight = (int)values[3]; return DecodeImage(); } private BitmapImage DecodeImage() { BitmapImage bi = new BitmapImage(); bi.BeginInit(); bi.DecodePixelWidth = (int)DecodeWidth; bi.DecodePixelHeight = (int)DecodeHeight; bi.UriSource = new Uri(SourcePath); bi.EndInit(); return bi; } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) { throw new Exception("The method or operation is not implemented."); } public override object ProvideValue(IServiceProvider serviceProvider) { return this; } } Now this works fine, except for one "little" problem. When you just specify a file path in Image.Source - the application actually uses less memory and works faster than if you use BitmapImage.DecodePixelWidth. Plus with Image.Source if you have multiple Image controls that point to the same image - they only use as much memory as if only one image was loaded. With the BitmapImage.DecodePixelWidth solution - each additional Image control uses more memory and each of them uses more than when just specifying Image.Source. Perhaps WPF somehow caches these images in compressed form while if you specify the decoded dimensions - it feels like you get an uncompressed image in memory, plus it takes 6 times the time (perhaps without it the scaling is done on the GPU?), plus it feels like the original high resolution image also gets loaded and takes up space. If I just scale the image down, save it to a temporary file and then use Image.Source to point at the file - it will probably work, but it will be pretty slow and it will require handling cleanup of the temporary file. If I could detect an image that does not get loaded properly - maybe I could only scale it down if I need to, but Image.ImageFailed never gets triggered. Maybe it has something to do with the video memory and this app just using more of it with the deep visual tree, opacity masks etc. Actual question: How can I load big images as quickly as Image.Source option does it, without using more memory for additional copies and additional memory for the scaled down image if I only need them at a certain resolution lower than original? Also, I don't want to keep them in memory if no Image control is using them anymore.

  Read the article

• Scheduling runtime-specified Activity in Workflow 4 RC

  - by johnny g

  Hi, so I have this requirement to kick off Activities provided to me at run-time. To facilitate this, I have set up a WorkflowService that receives Activities as Xaml, hydrates them, and kicks them off. Sounds simple enough ... ... this is my WorkflowService in Xaml <Activity x:Class="Workflow.Services.WorkflowService.WorkflowService" ... xmlns:local1="clr-namespace:Workflow.Activities" > <Sequence sap:VirtualizedContainerService.HintSize="277,272"> <Sequence.Variables> <Variable x:TypeArguments="local:Workflow" Name="Workflow" /> </Sequence.Variables> <sap:WorkflowViewStateService.ViewState> <scg3:Dictionary x:TypeArguments="x:String, x:Object"> <x:Boolean x:Key="IsExpanded">True</x:Boolean> </scg3:Dictionary> </sap:WorkflowViewStateService.ViewState> <p:Receive CanCreateInstance="True" DisplayName="ReceiveSubmitWorkflow" sap:VirtualizedContainerService.HintSize="255,86" OperationName="SubmitWorkflow" ServiceContractName="IWorkflowService"> <p:ReceiveParametersContent> <OutArgument x:TypeArguments="local:Workflow" x:Key="workflow">[Workflow]</OutArgument> </p:ReceiveParametersContent> </p:Receive> <local1:InvokeActivity Activity="[ActivityXamlServices.Load(New System.IO.StringReader(Workflow.Xaml))]" sap:VirtualizedContainerService.HintSize="255,22" /> </Sequence> </Activity> ... which, except for repetitive use of "Workflow" is pretty straight forward. In fact, it's just a Sequence with a Receive and [currently] a custom Activity called InvokeActivity. Get to that in a bit. Receive Activity accepts a custom type, [DataContract] public class Workflow { [DataMember] public string Xaml { get; set; } } which contains a string whose contents are to be interpreted as Xaml. You can see the VB expression that then converts this Xaml to an Activity and passes it on. Now this second bit, the custom InvokeActivity is where I have questions. First question: 1) given an arbitrary task, provided at runtime [as described above] is it possible to kick off this Activity using Activities that ship with WF4RC, out of the box? I'm fairly new, and thought I did a good job going through the API and existing documentation, but may as well ask :) Second: 2) my first attempt at implementing a custom InvokeActivity looked like this public sealed class InvokeActivity : NativeActivity { private static readonly ILog _log = LogManager.GetLogger (typeof (InvokeActivity)); public InArgument<Activity> Activity { get; set; } public InvokeActivity () { _log.DebugFormat ("Instantiated."); } protected override void Execute (NativeActivityContext context) { Activity activity = Activity.Get (context); _log.DebugFormat ("Scheduling activity [{0}]...", activity.DisplayName); // throws exception to lack of metadata! :( ActivityInstance instance = context.ScheduleActivity (activity, OnComplete, OnFault); _log.DebugFormat ( "Scheduled activity [{0}] with instance id [{1}].", activity.DisplayName, instance.Id); } protected override void CacheMetadata (NativeActivityMetadata metadata) { // how does one add InArgument<T> to metadata? not easily // is my first guess base.CacheMetadata (metadata); } // private methods private void OnComplete ( NativeActivityContext context, ActivityInstance instance) { _log.DebugFormat ( "Scheduled activity [{0}] with instance id [{1}] has [{2}].", instance.Activity.DisplayName, instance.Id, instance.State); } private void OnFault ( NativeActivityFaultContext context, Exception exception, ActivityInstance instance) { _log.ErrorFormat ( @"Scheduled activity [{0}] with instance id [{1}] has faulted in state [{2}] {3}", instance.Activity.DisplayName, instance.Id, instance.State, exception.ToStringFullStackTrace ()); } } Which attempts to schedule the specified Activity within the current context. Unfortunately, however, this fails. When I attempt to schedule said Activity, the runtime returns with the following exception The provided activity was not part of this workflow definition when its metadata was being processed. The problematic activity named 'DynamicActivity' was provided by the activity named 'InvokeActivity'. Right, so the "dynamic" Activity provided at runtime is not a member of InvokeActivitys metadata. Googled and came across this. Couldn't sort out how to specify an InArgument<Activity> to metadata cache, so my second question is, naturally, how does one address this issue? Is it ill advised to use context.ScheduleActivity (...) in this manner? Third and final, 3) I have settled on this [simpler] solution for the time being, public sealed class InvokeActivity : NativeActivity { private static readonly ILog _log = LogManager.GetLogger (typeof (InvokeActivity)); public InArgument<Activity> Activity { get; set; } public InvokeActivity () { _log.DebugFormat ("Instantiated."); } protected override void Execute (NativeActivityContext context) { Activity activity = Activity.Get (context); _log.DebugFormat ("Invoking activity [{0}] ...", activity.DisplayName); // synchronous execution ... a little less than ideal, this // seems heavy handed, and not entirely semantic-equivalent // to what i want. i really want to invoke this runtime // activity as if it were one of my own, not a separate // process - wrong mentality? WorkflowInvoker.Invoke (activity); _log.DebugFormat ("Invoked activity [{0}].", activity.DisplayName); } } Which simply invokes specified task synchronously within its own runtime instance thingy [use of WF4 vernacular is certainly questionable]. Eventually, I would like to tap into WF's tracking and possibly persistance facilities. So my third and final question is, in terms of what I would like to do [ie kick off arbitrary workflows inbound from client applications] is this the preferred method? Alright, thanks in advance for your time and consideration :)

  Read the article

• How to count each digit in a range of integers?

  - by Carlos Gutiérrez

  Imagine you sell those metallic digits used to number houses, locker doors, hotel rooms, etc. You need to find how many of each digit to ship when your customer needs to number doors/houses: 1 to 100 51 to 300 1 to 2,000 with zeros to the left The obvious solution is to do a loop from the first to the last number, convert the counter to a string with or without zeros to the left, extract each digit and use it as an index to increment an array of 10 integers. I wonder if there is a better way to solve this, without having to loop through the entire integers range. Solutions in any language or pseudocode are welcome. Edit: Answers review John at CashCommons and Wayne Conrad comment that my current approach is good and fast enough. Let me use a silly analogy: If you were given the task of counting the squares in a chess board in less than 1 minute, you could finish the task by counting the squares one by one, but a better solution is to count the sides and do a multiplication, because you later may be asked to count the tiles in a building. Alex Reisner points to a very interesting mathematical law that, unfortunately, doesn’t seem to be relevant to this problem. Andres suggests the same algorithm I’m using, but extracting digits with %10 operations instead of substrings. John at CashCommons and phord propose pre-calculating the digits required and storing them in a lookup table or, for raw speed, an array. This could be a good solution if we had an absolute, unmovable, set in stone, maximum integer value. I’ve never seen one of those. High-Performance Mark and strainer computed the needed digits for various ranges. The result for one millon seems to indicate there is a proportion, but the results for other number show different proportions. strainer found some formulas that may be used to count digit for number which are a power of ten. Robert Harvey had a very interesting experience posting the question at MathOverflow. One of the math guys wrote a solution using mathematical notation. Aaronaught developed and tested a solution using mathematics. After posting it he reviewed the formulas originated from Math Overflow and found a flaw in it (point to Stackoverflow :). noahlavine developed an algorithm and presented it in pseudocode. A new solution After reading all the answers, and doing some experiments, I found that for a range of integer from 1 to 10n-1: For digits 1 to 9, n*10(n-1) pieces are needed For digit 0, if not using leading zeros, n*10n-1 - ((10n-1) / 9) are needed For digit 0, if using leading zeros, n*10n-1 - n are needed The first formula was found by strainer (and probably by others), and I found the other two by trial and error (but they may be included in other answers). For example, if n = 6, range is 1 to 999,999: For digits 1 to 9 we need 6*105 = 600,000 of each one For digit 0, without leading zeros, we need 6*105 – (106-1)/9 = 600,000 - 111,111 = 488,889 For digit 0, with leading zeros, we need 6*105 – 6 = 599,994 These numbers can be checked using High-Performance Mark results. Using these formulas, I improved the original algorithm. It still loops from the first to the last number in the range of integers, but, if it finds a number which is a power of ten, it uses the formulas to add to the digits count the quantity for a full range of 1 to 9 or 1 to 99 or 1 to 999 etc. Here's the algorithm in pseudocode: integer First,Last //First and last number in the range integer Number //Current number in the loop integer Power //Power is the n in 10^n in the formulas integer Nines //Nines is the resut of 10^n - 1, 10^5 - 1 = 99999 integer Prefix //First digits in a number. For 14,200, prefix is 142 array 0..9 Digits //Will hold the count for all the digits FOR Number = First TO Last CALL TallyDigitsForOneNumber WITH Number,1 //Tally the count of each digit //in the number, increment by 1 //Start of optimization. Comments are for Number = 1,000 and Last = 8,000. Power = Zeros at the end of number //For 1,000, Power = 3 IF Power 0 //The number ends in 0 00 000 etc Nines = 10^Power-1 //Nines = 10^3 - 1 = 1000 - 1 = 999 IF Number+Nines <= Last //If 1,000+999 < 8,000, add a full set Digits[0-9] += Power*10^(Power-1) //Add 3*10^(3-1) = 300 to digits 0 to 9 Digits[0] -= -Power //Adjust digit 0 (leading zeros formula) Prefix = First digits of Number //For 1000, prefix is 1 CALL TallyDigitsForOneNumber WITH Prefix,Nines //Tally the count of each //digit in prefix, //increment by 999 Number += Nines //Increment the loop counter 999 cycles ENDIF ENDIF //End of optimization ENDFOR SUBROUTINE TallyDigitsForOneNumber PARAMS Number,Count REPEAT Digits [ Number % 10 ] += Count Number = Number / 10 UNTIL Number = 0 For example, for range 786 to 3,021, the counter will be incremented: By 1 from 786 to 790 (5 cycles) By 9 from 790 to 799 (1 cycle) By 1 from 799 to 800 By 99 from 800 to 899 By 1 from 899 to 900 By 99 from 900 to 999 By 1 from 999 to 1000 By 999 from 1000 to 1999 By 1 from 1999 to 2000 By 999 from 2000 to 2999 By 1 from 2999 to 3000 By 1 from 3000 to 3010 (10 cycles) By 9 from 3010 to 3019 (1 cycle) By 1 from 3019 to 3021 (2 cycles) Total: 28 cycles Without optimization: 2,235 cycles Note that this algorithm solves the problem without leading zeros. To use it with leading zeros, I used a hack: If range 700 to 1,000 with leading zeros is needed, use the algorithm for 10,700 to 11,000 and then substract 1,000 - 700 = 300 from the count of digit 1. Benchmark and Source code I tested the original approach, the same approach using %10 and the new solution for some large ranges, with these results: Original 104.78 seconds With %10 83.66 With Powers of Ten 0.07 A screenshot of the benchmark application: If you would like to see the full source code or run the benchmark, use these links: Complete Source code (in Clarion): http://sca.mx/ftp/countdigits.txt Compilable project and win32 exe: http://sca.mx/ftp/countdigits.zip Accepted answer noahlavine solution may be correct, but l just couldn’t follow the pseudo code, I think there are some details missing or not completely explained. Aaronaught solution seems to be correct, but the code is just too complex for my taste. I accepted strainer’s answer, because his line of thought guided me to develop this new solution.

  Read the article

• Three ways to upload/post/convert iMovie to YouTube

  - by user351686

  For Mac users, iMovie is probably a convenient tool for making, editing their own home movies so as to upload to YouTube for sharing with more people. However, uploading iMovie files to YouTube can't be always a smooth run, I did notice many people complaining about it. This article is delivered for guiding those who are haunted by the nightmare by providing three common ways to upload iMovie files to YouTube. YouTube and iMovie YouTube is the most popular video sharing website for users to upload, share and view videos. It empowers anyone with an Internet connection the ability to upload video clips and share them with friends, family and the world. Users are invited to leave comments, pick favourites, send messages to each other and watch videos sorted into subjects and channels. YouTube accepts videos uploaded in most container formats, including WMV (Windows Media Video), 3GP (Cell Phones), AVI (Windows), MOV (Mac), MP4 (iPod/PSP), FLV (Adobe Flash), MKV (H.264). These include video codecs such as MP4, MPEG and WMV. iMovie is a common video editing software application comes with every Mac for users to edit their own home movies. It imports video footage to the Mac using either the Firewire interface on most MiniDV format digital video cameras, the USB port, or by importing the files from a hard drive where users can edit the video clips, add titles, and add music. Since 1999, eight versions of iMovie have been released by Apple, each with its own functions and characteristic, and each of them deal with videos in a way more or less different. But the most common formats handled with iMovie if specialty discarded as far as to my research are MOV, DV, HDV, MPEG-4. Three ways for successful upload iMovie files to YouTube Solution one and solution two suitable for those who are 100 certainty with their iMovie files which are fully compatible with YouTube. For smooth uploading, you are required to get a YouTube account first. Solution 1: Directly upload iMovie to YouTube Step 1: Launch iMovie, select the project you want to upload in YouTube. Step 2: Go to the file menu, click Share, select Export Movie Step 3: Specify the output file name and directory and then type the video type and video size. Solution 2: Post iMovie to YouTube straightly Step 1: Launch iMovie, choose the project you want to post in YouTube Step 2: From the Share menu, choose YouTube Step 3: In the pop-up YouTube windows, specify the name of your YouTube account, the password, choose the Category and fill in the description and tags of the project. Tick Make this movie more private on the bottom of the window, if possible, to limit those who can view the project. Click Next, and then click Publish. iMovie will automatically export and upload the movie to YouTube. Step 4: Click Tell a Friend to email friends and your family about your film. You are also allowed to copy the URL from Tell a Friend window and paste it into an email you created in your favourite email application if you like. Anyone you send to email to will be able to follow the URL directly to your movie. Note: Videos uploaded to YouTube are limited to ten minutes in length and a file size of 2GB. Solution 3: Upload to iMovie after conversion If neither of the above mentioned method works, there is still a third way to turn to. Sometimes, your iMovie files may not be recognized by YouTube due to the versions of iMovie (settings and functions may varies among versions), video itself (video format difference because of file extension, resolution, video size and length), compatibility (videos that are completely incompatible with YouTube). In this circumstance, the best and reliable method is to convert your iMovie files to YouTube accepted files, iMovie to YouTube converter will be inevitably the ideal choice. iMovie to YouTube converter is an elaborately designed tool for convert iMovie files to YouTube workable WMV, 3GP, AVI, MOV, MP4, FLV, MKV for smooth uploading with hard-to-believe conversion speed and second to none output quality. It can also convert between almost all popular popular file formats like AVI, WMV, MPG, MOV, VOB, DV, MP4, FLV, 3GP, RM, ASF, SWF, MP3, AAC, AC3, AIFF, AMR, WAV, WMA etc so as to put on various portable devices, import to video editing software or play on vast amount video players. iMovie to YouTube converter can also served as an excellent video editing tool to meet your specific program requirements. For example, you can cut your video files to a certain length, or split your video files to smaller ones and select the proper resolution suitable for demands of YouTube by Clip or Settings separately. Crop allows you to cut off unwanted black edges from your videos. Besides, you can also have a good command of the whole process or snapshot your favourite pictures from the preview window. More can be expected if you have a try.

  Read the article

• ASPX ajax form post help

  - by StealthRT

  Hey all, i have this peice of code that allows a user to select a jpg image, resize it and uploads it to the server driectory. The problem being is that it reloads the aspx page when it saves the image. My question is-is there any way to do this same thing but with ajax so that it doesn't leave the page after submitting it? I've done this pleanty of times with classic asp pages but never with a aspx page. Here is the code for the ASPX page: <%@ Page Trace="False" Language="vb" aspcompat="false" debug="true" validateRequest="false"%> <%@ Import Namespace=System.Drawing %> <%@ Import Namespace=System.Drawing.Imaging %> <%@ Import Namespace=System.Drawing.Text %> <%@ Import Namespace=System %> <%@ Import Namespace=System.IO %> <%@ Import Namespace=System.Web %> <%@ Import Namespace=System.ServiceProcess %> <%@ Import Namespace=Microsoft.Data.Odbc %> <%@ Import Namespace=System.Data.Odbc %> <%@ Import Namespace=MySql.Data.MySqlClient %> <%@ Import Namespace=MySql.Data %> <%@ Import Namespace=System.Drawing.Drawing2D %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.ADO" %> <%@ Import Namespace=ADODB %> <SCRIPT LANGUAGE="VBScript" runat="server"> const Lx = 200 const Ly = 60 const upload_dir = "/img/avatar/" const upload_original = "tmpAvatar" const upload_thumb = "thumb" const upload_max_size = 256 dim fileExt dim newWidth, newHeight as integer dim l2 dim fileFld as HTTPPostedFile Dim originalimg As System.Drawing.Image dim msg dim upload_ok as boolean </script> <% Dim theID, theEmail, maleOrFemale theID = Request.QueryString("ID") theEmail = Request.QueryString("eMail") maleOrFemale = Request.QueryString("MF") randomize() upload_ok = false if lcase(Request.ServerVariables("REQUEST_METHOD"))="post" then fileFld = request.files(0) if fileFld.ContentLength > upload_max_size * 1024 then msg = "Sorry, the image must be less than " & upload_max_size & "Kb" else try fileExt = System.IO.Path.GetExtension(fileFld.FileName).ToLower() if fileExt = ".jpg" then originalImg = System.Drawing.Image.FromStream(fileFld.InputStream) if originalImg.Height > Ly then newWidth = Ly * (originalImg.Width / originalImg.Height) newHeight = Ly end if Dim thumb As New Bitmap(newWidth, newHeight) Dim gr_dest As Graphics = Graphics.FromImage(thumb) dim sb = new SolidBrush(System.Drawing.Color.White) gr_dest.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality gr_dest.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality gr_dest.FillRectangle(sb, 0, 0, thumb.Width, thumb.Height) gr_dest.DrawImage(originalImg, 0, 0, thumb.Width, thumb.Height) try originalImg.save(Server.MapPath(upload_dir & upload_original & fileExt), originalImg.rawformat) thumb.save(Server.MapPath(upload_dir & theID & fileExt), originalImg.rawformat) msg = "Uploaded " & fileFld.FileName & " to " & Server.MapPath(upload_dir & upload_original & fileExt) upload_ok = true File.Delete(Server.MapPath(upload_dir & upload_original & fileExt)) catch msg = "Sorry, there was a problem saving your avatar. Please try again." end try if not thumb is nothing then thumb.Dispose() thumb = nothing end if else msg = "That image does not seem to be a JPG. Upload only JPG images." end if catch msg = "That image does not seem to be a JPG." end try end if if not originalImg is nothing then originalImg.Dispose() originalImg = nothing end if end if %><head> <meta http-equiv="pragma" content="no-cache" /> </head> <html> <script type="text/javascript" src="js/jquery-1.3.min.js"></script> <form enctype="multipart/form-data" method="post" runat="server" id="sendImg"> <input type="file" name="upload_file" id="upload_file" style="-moz-opacity: 0; opacity:0; filter: alpha(opacity=0); margin-top: 5px; float:left; cursor:pointer;" onChange="$('#sendImg').submit();" > <input type="submit" value="Upload" style="visibility:hidden; display:none;"> </form> </body> </html> Any help would be great! :o) David

  Read the article

• Ethernet Communication Error

  - by SivaKumar

  Hi, I wrote a program to query the status of the Ethernet printer for that i created a TCP Stream Socket and i send the query command to the printer.In case of Error less condition it returns No error status but in error case its getting hang at recv command.Even i used Non blocking now the recv command returns nothing and error set as Resource temporarily unavailable. code: #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <errno.h> #include <stdlib.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/socket.h> #include <signal.h> #include <termios.h> #include <poll.h> #include <netinet/tcp.h> #include <stdarg.h> int main() { int ConnectSocket,ConnectSocket1,select_err,err,nRet,nBytesRead; struct timeval waitTime = {10,30}; fd_set socket_set; unsigned char * dataBuf = NULL; unsigned char tempVar, tempVar1, tempVar2, tempVar3; char reset[] = "\033E 2\r"; char print[] = "\033A 1\r"; char buf[1024]={0}; ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); printf("The Socket ID is %d\n",ConnectSocket); if (ConnectSocket < 0) { perror("socket()"); return 0; } struct sockaddr_in clientService; clientService.sin_family = AF_INET; clientService.sin_addr.s_addr = inet_addr("192.168.0.129"); //Printer IP clientService.sin_port = htons( 9100); // Printer Port if ( connect( ConnectSocket, (struct sockaddr*) &clientService, sizeof(clientService) ) == -1) { perror("connect()"); close(ConnectSocket); return -1; } /* if((nRet = ioctl(ConnectSocket , FIONREAD, &nBytesRead) == -1)) { perror("ioctl()"); } perror("ioctl()"); */ FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { int optVal = 0; int optLen = sizeof(optVal); if(select_err == -1) { perror("select() write-side"); } else { //Timeout errno=0; err = getsockopt(ConnectSocket, SOL_SOCKET, SO_ERROR, (char*)&optVal, &optLen); printf("the return of the getsockopt is %d\n",err); printf("the opt val is %s\n",(char*)optVal); perror("getsockopt()"); if(err == -1) { perror("getsockopt() write-side"); } } printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); //close(ConnectSocket); return -1; } err = send(ConnectSocket,print,sizeof(print)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); return -1; } err = send(ConnectSocket,reset,sizeof(reset)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); printf("i am in reading \n"); select_err = select(ConnectSocket+1, &socket_set, NULL, NULL, &waitTime); printf("the retun of the read side select is %d \n",select_err); perror("select()"); if (-1 == select_err|| 0 == select_err) { printf("Read timeout; ConnectSocket: %d\n", ConnectSocket); close(ConnectSocket); perror("close()"); return -1; } printf("Before Recv\n"); nBytesRead = recv(ConnectSocket , buf, 1024, 0); printf("No of Bytes read is %d\n",nBytesRead); printf("%s\n",buf); if(nBytesRead == -1) { perror("recv()"); close(ConnectSocket); perror("clode()"); return -1; } close(ConnectSocket); return 1; }

  Read the article

• NerdDinner form validation DataAnnotations ERROR in MVC2 when a form field is left blank.

  - by Edward Burns

  Platform: Windows 7 Ultimate IDE: Visual Studio 2010 Ultimate Web Environment: ASP.NET MVC 2 Database: SQL Server 2008 R2 Express Data Access: Entity Framework 4 Form Validation: DataAnnotations Sample App: NerdDinner from Wrox Pro ASP.NET MVC 2 Book: Wrox Professional MVC 2 Problem with Chapter 1 - Section: "Integrating Validation and Business Rule Logic with Model Classes" (pages 33 to 35) ERROR Synopsis: NerdDinner form validation ERROR with DataAnnotations and db nulls. DataAnnotations in sample code does not work when the database fields are set to not allow nulls. ERROR occurs with the code from the book and with the sample code downloaded from codeplex. Help! I'm really frustrated by this!! I can't believe something so simple just doesn't work??? Steps to reproduce ERROR: Set Database fields to not allow NULLs (See Picture) Set NerdDinnerEntityModel Dinner class fields' Nullable property to false (See Picture) Add DataAnnotations for Dinner_Validation class (CODE A) Create Dinner repository class (CODE B) Add CREATE action to DinnerController (CODE C) This is blank form before posting (See Picture) This null ERROR occurs when posting a blank form which should be intercepted by the Dinner_Validation class DataAnnotations. Note ERROR message says that "This property cannot be set to a null value. WTH??? (See Picture) The next ERROR occurs during the edit process. Here is the Edit controller action (CODE D) This is the "Edit" form with intentionally wrong input to test Dinner Validation DataAnnotations (See Picture) The ERROR occurs again when posting the edit form with blank form fields. The post request should be intercepted by the Dinner_Validation class DataAnnotations. Same null entry error. WTH??? (See Picture) See screen shots at: http://www.intermedia4web.com/temp/nerdDinner/StackOverflowNerdDinnerQuestionshort.png CODE A: [MetadataType(typeof(Dinner_Validation))] public partial class Dinner { } [Bind(Include = "Title, EventDate, Description, Address, Country, ContactPhone, Latitude, Longitude")] public class Dinner_Validation { [Required(ErrorMessage = "Title is required")] [StringLength(50, ErrorMessage = "Title may not be longer than 50 characters")] public string Title { get; set; } [Required(ErrorMessage = "Description is required")] [StringLength(265, ErrorMessage = "Description must be 256 characters or less")] public string Description { get; set; } [Required(ErrorMessage="Event date is required")] public DateTime EventDate { get; set; } [Required(ErrorMessage = "Address is required")] public string Address { get; set; } [Required(ErrorMessage = "Country is required")] public string Country { get; set; } [Required(ErrorMessage = "Contact phone is required")] public string ContactPhone { get; set; } [Required(ErrorMessage = "Latitude is required")] public double Latitude { get; set; } [Required(ErrorMessage = "Longitude is required")] public double Longitude { get; set; } } CODE B: public class DinnerRepository { private NerdDinnerEntities _NerdDinnerEntity = new NerdDinnerEntities(); // Query Method public IQueryable<Dinner> FindAllDinners() { return _NerdDinnerEntity.Dinners; } // Query Method public IQueryable<Dinner> FindUpcomingDinners() { return from dinner in _NerdDinnerEntity.Dinners where dinner.EventDate > DateTime.Now orderby dinner.EventDate select dinner; } // Query Method public Dinner GetDinner(int id) { return _NerdDinnerEntity.Dinners.FirstOrDefault(d => d.DinnerID == id); } // Insert Method public void Add(Dinner dinner) { _NerdDinnerEntity.Dinners.AddObject(dinner); } // Delete Method public void Delete(Dinner dinner) { foreach (var rsvp in dinner.RSVPs) { _NerdDinnerEntity.RSVPs.DeleteObject(rsvp); } _NerdDinnerEntity.Dinners.DeleteObject(dinner); } // Persistence Method public void Save() { _NerdDinnerEntity.SaveChanges(); } } CODE C: // ************************************** // GET: /Dinners/Create/ // ************************************** public ActionResult Create() { Dinner dinner = new Dinner() { EventDate = DateTime.Now.AddDays(7) }; return View(dinner); } // ************************************** // POST: /Dinners/Create/ // ************************************** [HttpPost] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { dinner.HostedBy = "The Code Dude"; _dinnerRepository.Add(dinner); _dinnerRepository.Save(); return RedirectToAction("Details", new { id = dinner.DinnerID }); } else { return View(dinner); } } CODE D: // ************************************** // GET: /Dinners/Edit/{id} // ************************************** public ActionResult Edit(int id) { Dinner dinner = _dinnerRepository.GetDinner(id); return View(dinner); } // ************************************** // POST: /Dinners/Edit/{id} // ************************************** [HttpPost] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = _dinnerRepository.GetDinner(id); if (TryUpdateModel(dinner)){ _dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } return View(dinner); } I have sent Wrox and one of the authors a request for help but have not heard back from anyone. Readers of the book cannot even continue to finish the rest of chapter 1 because of these errors. Even if I download the latest build from Codeplex, it still has the same errors. Can someone please help me and tell me what needs to be fixed? Thanks - Ed.

  Read the article

• OpenGL basics: calling glDrawElements once per object

  - by Bethor

  Hi all, continuing on from my explorations of the basics of OpenGL (see this question), I'm trying to figure out the basic principles of drawing a scene with OpenGL. I am trying to render a simple cube repeated n times in every direction. My method appears to yield terrible performance : 1000 cubes brings performance below 50fps (on a QuadroFX 1800, roughly a GeForce 9600GT). My method for drawing these cubes is as follows: done once: set up a vertex buffer and array buffer containing my cube vertices in model space set up an array buffer indexing the cube for drawing as 12 triangles done for each frame: update uniform values used by the vertex shader to move all cubes at once done for each cube, for each frame: update uniform values used by the vertex shader to move each cube to its position call glDrawElements to draw the positioned cube Is this a sane method ? If not, how does one go about something like this ? I'm guessing I need to minimize calls to glUniform, glDrawElements, or both, but I'm not sure how to do that. Full code for my little test : (depends on gletools and pyglet) I'm aware that my init code (at least) is really ugly; I'm concerned with the rendering code for each frame right now, I'll move to something a little less insane for the creation of the vertex buffers and such later on. import pyglet from pyglet.gl import * from pyglet.window import key from numpy import deg2rad, tan from gletools import ShaderProgram, FragmentShader, VertexShader, GeometryShader vertexData = [-0.5, -0.5, -0.5, 1.0, -0.5, 0.5, -0.5, 1.0, 0.5, -0.5, -0.5, 1.0, 0.5, 0.5, -0.5, 1.0, -0.5, -0.5, 0.5, 1.0, -0.5, 0.5, 0.5, 1.0, 0.5, -0.5, 0.5, 1.0, 0.5, 0.5, 0.5, 1.0] elementArray = [2, 1, 0, 1, 2, 3,## back face 4, 7, 6, 4, 5, 7,## front face 1, 3, 5, 3, 7, 5,## top face 2, 0, 4, 2, 4, 6,## bottom face 1, 5, 4, 0, 1, 4,## left face 6, 7, 3, 6, 3, 2]## right face def toGLArray(input): return (GLfloat*len(input))(*input) def toGLushortArray(input): return (GLushort*len(input))(*input) def initPerspectiveMatrix(aspectRatio = 1.0, fov = 45): frustumScale = 1.0 / tan(deg2rad(fov) / 2.0) fzNear = 0.5 fzFar = 300.0 perspectiveMatrix = [frustumScale*aspectRatio, 0.0 , 0.0 , 0.0 , 0.0 , frustumScale, 0.0 , 0.0 , 0.0 , 0.0 , (fzFar+fzNear)/(fzNear-fzFar) , -1.0, 0.0 , 0.0 , (2*fzFar*fzNear)/(fzNear-fzFar), 0.0 ] return perspectiveMatrix class ModelObject(object): vbo = GLuint() vao = GLuint() eao = GLuint() initDone = False verticesPool = [] indexPool = [] def __init__(self, vertices, indexing): super(ModelObject, self).__init__() if not ModelObject.initDone: glGenVertexArrays(1, ModelObject.vao) glGenBuffers(1, ModelObject.vbo) glGenBuffers(1, ModelObject.eao) glBindVertexArray(ModelObject.vao) initDone = True self.numIndices = len(indexing) self.offsetIntoVerticesPool = len(ModelObject.verticesPool) ModelObject.verticesPool.extend(vertices) self.offsetIntoElementArray = len(ModelObject.indexPool) ModelObject.indexPool.extend(indexing) glBindBuffer(GL_ARRAY_BUFFER, ModelObject.vbo) glEnableVertexAttribArray(0) #position glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0) glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ModelObject.eao) glBufferData(GL_ARRAY_BUFFER, len(ModelObject.verticesPool)*4, toGLArray(ModelObject.verticesPool), GL_STREAM_DRAW) glBufferData(GL_ELEMENT_ARRAY_BUFFER, len(ModelObject.indexPool)*2, toGLushortArray(ModelObject.indexPool), GL_STREAM_DRAW) def draw(self): glDrawElements(GL_TRIANGLES, self.numIndices, GL_UNSIGNED_SHORT, self.offsetIntoElementArray) class PositionedObject(object): def __init__(self, mesh, pos, objOffsetUf): super(PositionedObject, self).__init__() self.mesh = mesh self.pos = pos self.objOffsetUf = objOffsetUf def draw(self): glUniform3f(self.objOffsetUf, self.pos[0], self.pos[1], self.pos[2]) self.mesh.draw() w = 800 h = 600 AR = float(h)/float(w) window = pyglet.window.Window(width=w, height=h, vsync=False) window.set_exclusive_mouse(True) pyglet.clock.set_fps_limit(None) ## input forward = [False] left = [False] back = [False] right = [False] up = [False] down = [False] inputs = {key.Z: forward, key.Q: left, key.S: back, key.D: right, key.UP: forward, key.LEFT: left, key.DOWN: back, key.RIGHT: right, key.PAGEUP: up, key.PAGEDOWN: down} ## camera camX = 0.0 camY = 0.0 camZ = -1.0 def simulate(delta): global camZ, camX, camY scale = 10.0 move = scale*delta if forward[0]: camZ += move if back[0]: camZ += -move if left[0]: camX += move if right[0]: camX += -move if up[0]: camY += move if down[0]: camY += -move pyglet.clock.schedule(simulate) @window.event def on_key_press(symbol, modifiers): global forward, back, left, right, up, down if symbol in inputs.keys(): inputs[symbol][0] = True @window.event def on_key_release(symbol, modifiers): global forward, back, left, right, up, down if symbol in inputs.keys(): inputs[symbol][0] = False ## uniforms for shaders camOffsetUf = GLuint() objOffsetUf = GLuint() perspectiveMatrixUf = GLuint() camRotationUf = GLuint() program = ShaderProgram( VertexShader(''' #version 330 layout(location = 0) in vec4 objCoord; uniform vec3 objOffset; uniform vec3 cameraOffset; uniform mat4 perspMx; void main() { mat4 translateCamera = mat4(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, cameraOffset.x, cameraOffset.y, cameraOffset.z, 1.0f); mat4 translateObject = mat4(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, objOffset.x, objOffset.y, objOffset.z, 1.0f); vec4 modelCoord = objCoord; vec4 positionedModel = translateObject*modelCoord; vec4 cameraPos = translateCamera*positionedModel; gl_Position = perspMx * cameraPos; }'''), FragmentShader(''' #version 330 out vec4 outputColor; const vec4 fillColor = vec4(1.0f, 1.0f, 1.0f, 1.0f); void main() { outputColor = fillColor; }''') ) shapes = [] def init(): global camOffsetUf, objOffsetUf with program: camOffsetUf = glGetUniformLocation(program.id, "cameraOffset") objOffsetUf = glGetUniformLocation(program.id, "objOffset") perspectiveMatrixUf = glGetUniformLocation(program.id, "perspMx") glUniformMatrix4fv(perspectiveMatrixUf, 1, GL_FALSE, toGLArray(initPerspectiveMatrix(AR))) obj = ModelObject(vertexData, elementArray) nb = 20 for i in range(nb): for j in range(nb): for k in range(nb): shapes.append(PositionedObject(obj, (float(i*2), float(j*2), float(k*2)), objOffsetUf)) glEnable(GL_CULL_FACE) glCullFace(GL_BACK) glFrontFace(GL_CW) glEnable(GL_DEPTH_TEST) glDepthMask(GL_TRUE) glDepthFunc(GL_LEQUAL) glDepthRange(0.0, 1.0) glClearDepth(1.0) def update(dt): print pyglet.clock.get_fps() pyglet.clock.schedule_interval(update, 1.0) @window.event def on_draw(): with program: pyglet.clock.tick() glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) glUniform3f(camOffsetUf, camX, camY, camZ) for shape in shapes: shape.draw() init() pyglet.app.run()

  Read the article

• Alpha Beta Search

  - by Becky

  I'm making a version of Martian Chess in java with AI and so far I THINK my move searching is semi-working, it seems to work alright for some depths but if I use a depth of 3 it returns a move for the opposite side...now the game is a bit weird because when a piece crosses half of the board, it becomes property of the other player so I think this is part of the problem. I'd be really greatful if someone could look over my code and point out any errors you think are there! (pls note that my evaluation function isn't nearly complete lol) MoveSearch.java public class MoveSearch { private Evaluation evaluate = new Evaluation(); private int blackPlayerScore, whitePlayerScore; public MoveContent bestMove; public MoveSearch(int blackScore, int whiteScore) { blackPlayerScore = blackScore; whitePlayerScore = whiteScore; } private Vector<Position> EvaluateMoves(Board board) { Vector<Position> positions = new Vector<Position>(); for (int i = 0; i < 32; i++) { Piece piece = null; if (!board.chessBoard[i].square.isEmpty()) { // store the piece piece = board.chessBoard[i].square.firstElement(); } // skip empty squares if (piece == null) { continue; } // skip the other players pieces if (piece.pieceColour != board.whosMove) { continue; } // generate valid moves for the piece PieceValidMoves validMoves = new PieceValidMoves(board.chessBoard, i, board.whosMove); validMoves.generateMoves(); // for each valid move for (int j = 0; j < piece.validMoves.size(); j++) { // store it as a position Position move = new Position(); move.startPosition = i; move.endPosition = piece.validMoves.elementAt(j); Piece pieceAttacked = null; if (!board.chessBoard[move.endPosition].square.isEmpty()) { // if the end position is not empty, store the attacked piece pieceAttacked = board.chessBoard[move.endPosition].square.firstElement(); } // if a piece is attacked if (pieceAttacked != null) { // append its value to the move score move.score += pieceAttacked.pieceValue; // if the moving pieces value is less than the value of the attacked piece if (piece.pieceValue < pieceAttacked.pieceValue) { // score extra points move.score += pieceAttacked.pieceValue - piece.pieceValue; } } // add the move to the set of positions positions.add(move); } } return positions; } // EvaluateMoves() private int SideToMoveScore(int score, PieceColour colour) { if (colour == PieceColour.Black){ return -score; } else { return score; } } public int AlphaBeta(Board board, int depth, int alpha, int beta) { //int best = -9999; // if the depth is 0, return the score of the current board if (depth <= 0) { board.printBoard(); System.out.println("Score: " + evaluate.EvaluateBoardScore(board)); System.out.println(""); int boardScore = evaluate.EvaluateBoardScore(board); return SideToMoveScore(boardScore, board.whosMove); } // fill the positions with valid moves Vector<Position> positions = EvaluateMoves(board); // if there are no available positions if (positions.size() == 0) { // and its blacks move if (board.whosMove == PieceColour.Black) { if (blackPlayerScore > whitePlayerScore) { // and they are winning, return a high number return 9999; } else if (whitePlayerScore == blackPlayerScore) { // if its a draw, lower number return 500; } else { // if they are losing, return a very low number return -9999; } } if (board.whosMove == PieceColour.White) { if (whitePlayerScore > blackPlayerScore) { return 9999; } else if (blackPlayerScore == whitePlayerScore) { return 500; } else { return -9999; } } } // for each position for (int i = 0; i < positions.size(); i++) { // store the position Position move = positions.elementAt(i); // temporarily copy the board Board temp = board.copyBoard(board); // make the move temp.makeMove(move.startPosition, move.endPosition); for (int x = 0; x < 32; x++) { if (!temp.chessBoard[x].square.isEmpty()) { PieceValidMoves validMoves = new PieceValidMoves(temp.chessBoard, x, temp.whosMove); validMoves.generateMoves(); } } // repeat the process recursively, decrementing the depth int val = -AlphaBeta(temp, depth - 1, -beta, -alpha); // if the value returned is better than the current best score, replace it if (val >= beta) { // beta cut-off return beta; } if (val > alpha) { alpha = val; bestMove = new MoveContent(alpha, move.startPosition, move.endPosition); } } // return the best score return alpha; } // AlphaBeta() } This is the makeMove method public void makeMove(int startPosition, int endPosition) { // quick reference to selected piece and attacked piece Piece selectedPiece = null; if (!(chessBoard[startPosition].square.isEmpty())) { selectedPiece = chessBoard[startPosition].square.firstElement(); } Piece attackedPiece = null; if (!(chessBoard[endPosition].square.isEmpty())) { attackedPiece = chessBoard[endPosition].square.firstElement(); } // if a piece is taken, amend score if (!(chessBoard[endPosition].square.isEmpty()) && attackedPiece != null) { if (attackedPiece.pieceColour == PieceColour.White) { blackScore = blackScore + attackedPiece.pieceValue; } if (attackedPiece.pieceColour == PieceColour.Black) { whiteScore = whiteScore + attackedPiece.pieceValue; } } // actually move the piece chessBoard[endPosition].square.removeAllElements(); chessBoard[endPosition].addPieceToSquare(selectedPiece); chessBoard[startPosition].square.removeAllElements(); // changing piece colour based on position if (endPosition > 15) { selectedPiece.pieceColour = PieceColour.White; } if (endPosition <= 15) { selectedPiece.pieceColour = PieceColour.Black; } //change to other player if (whosMove == PieceColour.Black) whosMove = PieceColour.White; else if (whosMove == PieceColour.White) whosMove = PieceColour.Black; } // makeMove()

  Read the article

• Qt - drag and drop with graphics view framework

  - by David Davidson

  I'm trying to make a simple draggable item using the graphics framework. Here's the code for what I did so far: Widget class: class Widget : public QWidget { Q_OBJECT public: Widget(QWidget *parent = 0); ~Widget(); }; Widget::Widget(QWidget *parent) : QWidget(parent) { DragScene *scene = new DragScene(); DragView *view = new DragView(); QHBoxLayout *layout = new QHBoxLayout(); DragItem *item = new DragItem(); view->setAcceptDrops(true); scene->addItem(item); view->setScene(scene); layout->addWidget(view); this->setLayout(layout); } Widget::~Widget() { } DragView class: class DragView : public QGraphicsView { public: DragView(QWidget *parent = 0); }; DragView::DragView(QWidget *parent) : QGraphicsView(parent) { setRenderHints(QPainter::Antialiasing); } DragScene class: class DragScene : public QGraphicsScene { public: DragScene(QObject* parent = 0); protected: void dragEnterEvent(QGraphicsSceneDragDropEvent *event); void dragMoveEvent(QGraphicsSceneDragDropEvent *event); void dragLeaveEvent(QGraphicsSceneDragDropEvent *event); void dropEvent(QGraphicsSceneDragDropEvent *event); }; DragScene::DragScene(QObject* parent) : QGraphicsScene(parent) { } void DragScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event){ } void DragScene::dragMoveEvent(QGraphicsSceneDragDropEvent *event){ } void DragScene::dragLeaveEvent(QGraphicsSceneDragDropEvent *event){ } void DragScene::dropEvent(QGraphicsSceneDragDropEvent *event){ qDebug() << event->pos(); event->acceptProposedAction(); DragItem *item = new DragItem(); this->addItem(item); item->setPos(event->pos()); } DragItem class: class DragItem : public QGraphicsItem { public: DragItem(QGraphicsItem *parent = 0); QRectF boundingRect() const; void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0); protected: void mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event); void mouseMoveEvent(QGraphicsSceneMouseEvent *event); void mousePressEvent(QGraphicsSceneMouseEvent *event); void mouseReleaseEvent(QGraphicsSceneMouseEvent *event); }; DragItem::DragItem(QGraphicsItem *parent) : QGraphicsItem(parent) { setFlag(QGraphicsItem::ItemIsMovable); } QRectF DragItem::boundingRect() const{ const QPointF *p0 = new QPointF(-10,-10); const QPointF *p1 = new QPointF(10,10); return QRectF(*p0,*p1); } void DragItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget){ if(painter == 0) painter = new QPainter(); painter->drawEllipse(QPoint(0,0),10,10); } void DragItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event){ } void DragItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event){ } void DragItem::mousePressEvent(QGraphicsSceneMouseEvent *event){ QMimeData* mime = new QMimeData(); QDrag* drag = new QDrag(event->widget()); drag->setMimeData(mime); drag->exec(); } void DragItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event){ } main.cpp instantiates a Widget and shows it. When I try to drag the circle, the app just creates another circle over the original one, regardless of where I release the drag. qDebug() in DragScene's dropEvent() shows QPointF(0,0) everytime the drag ends. I'm having a hard time trying to understand exactly what I have to do, which classes I should subclass, which methods needs to be overriden, to make this work. The documentation on this isn't very detailed. I'd like to know how to make this work, and if there's some other, more comprehensive resource to learn about the graphics view framework, besides the official documentation (which is excellent btw, but it would be great if there was a more detailed treatise on the subject). EDIT: Following badgerr's advice, I replaced item-pos() in DragScene::dropEvent() with item-scenePos(), now the drop event creates a new circle in the drop site, which is more or less what I wanted. But the original circle is still in place, and while the drag is in progress, the item doesn't follow the mouse cursor. The QGraphicsSceneDragDropEvent documentation says that pos() should return the cursor position in relation to the view that sent the event, which, unless I got it wrong, shouldn't be (0,0) all the time. Weird. I've read in a forum post that you can use QDrag::setPixMap() to show something during the drag, and in examples I've seen pictures being set as pixmaps, but how do I make the pixmap just like the graphics item I'm supposed to be dragging?

  Read the article

• Class member functions instantiated by traits

  - by Jive Dadson

  I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched Stack Overflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state information was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (VC++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice? UPDATE: Here's another try at explaining it. I want the user to be able to fill out an order (manifest) for a custom optimizer, something like ordering off of a Chinese menu - one from column A, one from column B, etc.. Waiter, from column A (updaters), I'll have the BFGS update with Cholesky-decompositon sauce. From column B (line-searchers), I'll have the cubic interpolation line-search with an eta of 0.4 and a rho of 1e-4, please. Etc... UPDATE: Okay, okay. Here's the playing-around that I've done. I offer it reluctantly, because I suspect it's a completely wrong-headed approach. It runs okay under vc++ 2008. #include <boost/utility.hpp> #include <boost/type_traits/integral_constant.hpp> namespace dj { struct CBFGS { void bar() {printf("CBFGS::bar %d\n", data);} CBFGS(): data(1234){} int data; }; template<class T> struct is_CBFGS: boost::false_type{}; template<> struct is_CBFGS<CBFGS>: boost::true_type{}; struct LMQN {LMQN(): data(54.321){} void bar() {printf("LMQN::bar %lf\n", data);} double data; }; template<class T> struct is_LMQN: boost::false_type{}; template<> struct is_LMQN<LMQN> : boost::true_type{}; struct default_optimizer_traits { typedef CBFGS update_type; }; template<class traits> class Optimizer; template<class traits> void foo(typename boost::enable_if<is_LMQN<typename traits::update_type>, Optimizer<traits> >::type& self) { printf(" LMQN %lf\n", self.data); } template<class traits> void foo(typename boost::enable_if<is_CBFGS<typename traits::update_type>, Optimizer<traits> >::type& self) { printf("CBFGS %d\n", self.data); } template<class traits = default_optimizer_traits> class Optimizer{ friend typename traits::update_type; //friend void dj::foo<traits>(typename Optimizer<traits> & self); // How? public: //void foo(void); // How??? void foo() { dj::foo<traits>(*this); } void bar() { data.bar(); } //protected: // How? typedef typename traits::update_type update_type; update_type data; }; } // namespace dj int main_() { dj::Optimizer<> opt; opt.foo(); opt.bar(); std::getchar(); return 0; }

  Read the article

• Fast block placement algorithm, advice needed?

  - by James Morris

  I need to emulate the window placement strategy of the Fluxbox window manager. As a rough guide, visualize randomly sized windows filling up the screen one at a time, where the rough size of each results in an average of 80 windows on screen without any window overlapping another. It is important to note that windows will close and the space that closed windows previously occupied becomes available once more for the placement of new windows. The window placement strategy has three binary options: Windows build horizontal rows or vertical columns (potentially) Windows are placed from left to right or right to left Windows are placed from top to bottom or bottom to top Why is the algorithm a problem? It needs to operate to the deadlines of a real time thread in an audio application. At this moment I am only concerned with getting a fast algorithm, don't concern yourself over the implications of real time threads and all the hurdles in programming that that brings. So far I have two choices which I have built loose prototypes for: 1) A port of the Fluxbox placement algorithm into my code. The problem with this is, the client (my program) gets kicked out of the audio server (JACK) when I try placing the worst case scenario of 256 blocks using the algorithm. This algorithm performs over 14000 full (linear) scans of the list of blocks already placed when placing the 256th window. 2) My alternative approach. Only partially implemented, this approach uses a data structure for each area of rectangular free unused space (the list of windows can be entirely separate, and is not required for testing of this algorithm). The data structure acts as a node in a doubly linked list (with sorted insertion), as well as containing the coordinates of the top-left corner, and the width and height. Furthermore, each block data structure also contains four links which connect to each immediately adjacent (touching) block on each of the four sides. IMPORTANT RULE: Each block may only touch with one block per side. The problem with this approach is, it's very complex. I have implemented the straightforward cases where 1) space is removed from one corner of a block, 2) splitting neighbouring blocks so that the IMPORTANT RULE is adhered to. The less straightforward case, where the space to be removed can only be found within a column or row of boxes, is only partially implemented - if one of the blocks to be removed is an exact fit for width (ie column) or height (ie row) then problems occur. And don't even mention the fact this only checks columns one box wide, and rows one box tall. I've implemented this algorithm in C - the language I am using for this project (I've not used C++ for a few years and am uncomfortable using it after having focused all my attention to C development, it's a hobby). The implementation is 700+ lines of code (including plenty of blank lines, brace lines, comments etc). The implementation only works for the horizontal-rows + left-right + top-bottom placement strategy. So I've either got to add some way of making this +700 lines of code work for the other 7 placement strategy options, or I'm going to have to duplicate those +700 lines of code for the other seven options. Neither of these is attractive, the first, because the existing code is complex enough, the second, because of bloat. The algorithm is not even at a stage where I can use it in the real time worst case scenario, because of missing functionality, so I still don't know if it actually performs better or worse than the first approach. What else is there? I've skimmed over and discounted: Bin Packing algorithms: their emphasis on optimal fit does not match the requirements of this algorithm. Recursive Bisection Placement algorithms: sounds promising, but these are for circuit design. Their emphasis is optimal wire length. Both of these, especially the latter, all elements to be placed/packs are known before the algorithm begins. I need an algorithm which works accumulatively with what it is given to do when it is told to do it. What are your thoughts on this? How would you approach it? What other algorithms should I look at? Or even what concepts should I research seeing as I've not studied computer science/software engineering? Please ask questions in comments if further information is needed. [edit] If it makes any difference, the units for the coordinates will not be pixels. The units are unimportant, but the grid where windows/blocks/whatever can be placed will be 127 x 127 units.

  Read the article

• Master Details and collectionViewSource in separate views cannot make it work.

  - by devnet247

  Hi all, I really cannot seem to make/understand how it works with separate views It all works fine if a bundle all together in a single window. I have a list of Countries-Cities-etc... When you select a country it should load it's cities. Works So I bind 3 listboxes successfully using collection sources and no codebehind more or less (just code to set the datacontext and selectionChanged). you can download the project here http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip <Window.Resources> <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCityList},Path=Hotels}" x:Key="cvsHotelList"/> </Window.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition/> </Grid.RowDefinitions> <TextBlock Grid.Column="0" Grid.Row="0" Text="Countries"/> <TextBlock Grid.Column="1" Grid.Row="0" Text="Cities"/> <TextBlock Grid.Column="2" Grid.Row="0" Text="Hotels"/> <ListBox Grid.Column="0" Grid.Row="1" Name="lstCountries" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCountryList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="1" Grid.Row="1" Name="lstCities" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCityList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="2" Grid.Row="1" Name="lstHotels" ItemsSource="{Binding Source={StaticResource cvsHotelList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> </Grid> Does not work I am trying to implement the same using a view for each eg(LeftSideMasterControl -RightSideDetailsControls) However I cannot seem to make them bind. Can you help? I would be very grateful so that I can understand how you communicate between userControls You can download the project here. http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip I have as follows LeftSideMasterControl.xaml <Grid> <ListBox Name="lstCountries" SelectionChanged="OnSelectionChanged" DisplayMemberPath="Name" ItemsSource="{Binding Countries}"/> </Grid> RightViewDetailsControl.xaml MainView.xaml <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> </UserControl.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition Width="3*"/> </Grid.ColumnDefinitions> <Views:LeftViewMasterControl x:Name="leftSide" Margin="5" Content="{Binding Source=}"/> <GridSplitter Grid.Column="0" Grid.Row="0" Background="LightGray"/> <Views:RightViewDetailsControl Grid.Column="1" x:Name="RightSide" Margin="5"/> </Grid> ViewModels public class CountryListVM : ViewModelBase { public CountryListVM() { Countries = new ObservableCollection<CountryVM>(); } public ObservableCollection<CountryVM> Countries { get; set; } private RelayCommand _loadCountriesCommand; public ICommand LoadCountriesCommand { get { return _loadCountriesCommand ?? (_loadCountriesCommand = new RelayCommand(x => LoadCountries(), x => CanLoadCountries)); } } private static bool CanLoadCountries { get { return true; } } private void LoadCountries() { var countryList = Repository.GetCountries(); foreach (var country in countryList) { Countries.Add(new CountryVM { Name = country.Name }); } } } public class CountryVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } public class CityListVM : ViewModelBase { private CountryVM _selectedCountry; public CityListVM(CountryVM country) { SelectedCountry = country; Cities = new ObservableCollection<CityVM>(); } public ObservableCollection<CityVM> Cities { get; set; } public CountryVM SelectedCountry { get { return _selectedCountry; } set { _selectedCountry = value; OnPropertyChanged("SelectedCountry"); } } private RelayCommand _loadCitiesCommand; public ICommand LoadCitiesCommand { get { return _loadCitiesCommand ?? (_loadCitiesCommand = new RelayCommand(x => LoadCities(), x => CanLoadCities)); } } private static bool CanLoadCities { get { return true; } } private void LoadCities() { var cities = Repository.GetCities(SelectedCountry.Name); foreach (var city in cities) { Cities.Add(new CityVM() { Name = city.Name }); } } } public class CityVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } Models ========= public class Country { public Country() { Cities = new ObservableCollection<City>(); } public string Name { get; set; } public ObservableCollection<City> Cities { get; set; } } public class City { public City() { Hotels = new ObservableCollection<Hotel>(); } public string Name { get; set; } public ObservableCollection<Hotel> Hotels { get; set; } } public class Hotel { public string Name { get; set; } }

  Read the article

• Where is the virtual function call overhead?

  - by Semen Semenych

  Hello everybody, I'm trying to benchmark the difference between a function pointer call and a virtual function call. To do this, I have written two pieces of code, that do the same mathematical computation over an array. One variant uses an array of pointers to functions and calls those in a loop. The other variant uses an array of pointers to a base class and calls its virtual function, which is overloaded in the derived classes to do absolutely the same thing as the functions in the first variant. Then I print the time elapsed and use a simple shell script to run the benchmark many times and compute the average run time. Here is the code: #include <iostream> #include <cstdlib> #include <ctime> #include <cmath> using namespace std; long long timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p) { return ((timeA_p->tv_sec * 1000000000) + timeA_p->tv_nsec) - ((timeB_p->tv_sec * 1000000000) + timeB_p->tv_nsec); } void function_not( double *d ) { *d = sin(*d); } void function_and( double *d ) { *d = cos(*d); } void function_or( double *d ) { *d = tan(*d); } void function_xor( double *d ) { *d = sqrt(*d); } void ( * const function_table[4] )( double* ) = { &function_not, &function_and, &function_or, &function_xor }; int main(void) { srand(time(0)); void ( * index_array[100000] )( double * ); double array[100000]; for ( long int i = 0; i < 100000; ++i ) { index_array[i] = function_table[ rand() % 4 ]; array[i] = ( double )( rand() / 1000 ); } struct timespec start, end; clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start); for ( long int i = 0; i < 100000; ++i ) { index_array[i]( &array[i] ); } clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end); unsigned long long time_elapsed = timespecDiff(&end, &start); cout << time_elapsed / 1000000000.0 << endl; } and here is the virtual function variant: #include <iostream> #include <cstdlib> #include <ctime> #include <cmath> using namespace std; long long timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p) { return ((timeA_p->tv_sec * 1000000000) + timeA_p->tv_nsec) - ((timeB_p->tv_sec * 1000000000) + timeB_p->tv_nsec); } class A { public: virtual void calculate( double *i ) = 0; }; class A1 : public A { public: void calculate( double *i ) { *i = sin(*i); } }; class A2 : public A { public: void calculate( double *i ) { *i = cos(*i); } }; class A3 : public A { public: void calculate( double *i ) { *i = tan(*i); } }; class A4 : public A { public: void calculate( double *i ) { *i = sqrt(*i); } }; int main(void) { srand(time(0)); A *base[100000]; double array[100000]; for ( long int i = 0; i < 100000; ++i ) { array[i] = ( double )( rand() / 1000 ); switch ( rand() % 4 ) { case 0: base[i] = new A1(); break; case 1: base[i] = new A2(); break; case 2: base[i] = new A3(); break; case 3: base[i] = new A4(); break; } } struct timespec start, end; clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start); for ( int i = 0; i < 100000; ++i ) { base[i]->calculate( &array[i] ); } clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end); unsigned long long time_elapsed = timespecDiff(&end, &start); cout << time_elapsed / 1000000000.0 << endl; } My system is LInux, Fedora 13, gcc 4.4.2. The code is compiled it with g++ -O3. The first one is test1, the second is test2. Now I see this in console: [Ignat@localhost circuit_testing]$ ./test2 && ./test2 0.0153142 0.0153166 Well, more or less, I think. And then, this: [Ignat@localhost circuit_testing]$ ./test2 && ./test2 0.01531 0.0152476 Where are the 25% which should be visible? How can the first executable be even slower than the second one? I'm asking this because I'm doing a project which involves calling a lot of small functions in a row like this in order to compute the values of an array, and the code I've inherited does a very complex manipulation to avoid the virtual function call overhead. Now where is this famous call overhead?

  Read the article

• How to Stich to Image objects in Java

  - by Imran

  Hi, I have a scenario in which i`m getting a number of tiles (e.g.12) from my mapping server. Now for buffering and offline functions I need to join them all back again so that we have to deal with 1 single image object instead of 12. I ve tried to do it without JAI my code is below. package imagemerge; import java.awt.*; import java.awt.image.*; import java.awt.event.*; public class ImageSticher extends WindowAdapter { Image tile1; Image tile2; Image result; ColorModel colorModel; int width,height,widthr,heightr; //int t1,t2; int t12[]; public ImageSticher() { } public ImageSticher (Image img1,Image img2,int w,int h) { tile1=img1; tile2=img2; width=w; height=h; colorModel=ColorModel.getRGBdefault(); } public Image horizontalStich() throws Exception { widthr=width*2; heightr=height; t12=new int[widthr * heightr]; int t1[]=new int[width*height]; PixelGrabber p1 =new PixelGrabber(tile1, 0, 0, width, height, t1, 0, width); p1.grabPixels(); int t2[]=new int[width*height]; PixelGrabber p2 =new PixelGrabber(tile2, 0, 0, width, height, t1, 0, width); p2.grabPixels(); int y, x, rp, rpi; int red1, red2, redr; int green1, green2, greenr; int blue1, blue2, bluer; int alpha1, alpha2, alphar; for(y=0;y<heightr;y++) { for(x=0;x<widthr;x++) { //System.out.println(x); rpi=y*widthr+x; // index of resulting pixel; rp=0; //initializing resulting pixel System.out.println(rpi); if(x<(widthr/2)) // x is less than width , copy first tile { //System.out.println("tile1="+x); blue1 = t1[rpi] & 0x00ff; // ERROR occurs here green1=(t1[rpi] >> 8) & 0x00ff; red1=(t1[rpi] >> 16) & 0x00ff; alpha1 = (t1[rpi] >> 24) & 0x00ff; redr = (int)(red1 * 1.0); // copying red band pixel into redresult,,,,1.0 is the alpha valye redr = (redr < 0)?(0):((redr>255)?(255):(redr)); greenr = (int)(green1 * 1.0); // redr = (int)(red1 * 1.0); // greenr = (greenr < 0)?(0):((greenr>255)?(255):(greenr)); bluer = (int)(blue1 * 1.0); bluer = (bluer < 0)?(0):((bluer>255)?(255):(bluer)); alphar = 255; //resulting pixel computed rp = (((((alphar << 8) + (redr & 0x0ff)) << 8) + (greenr & 0x0ff)) << 8) + (bluer & 0x0ff); } else // index is ahead of half way...copy second tile { blue2 = t2[rpi] & 0x00ff; // blue band bit of first tile green2=(t2[rpi] >> 8) & 0x00ff; red2=(t2[rpi] >> 16) & 0x00ff; alpha2 = (t2[rpi] >> 24) & 0x00ff; redr = (int)(red2 * 1.0); // copying red band pixel into redresult,,,,1.0 is the alpha valye redr = (redr < 0)?(0):((redr>255)?(255):(redr)); greenr = (int)(green2 * 1.0); // redr = (int)(red2 * 1.0); // greenr = (greenr < 0)?(0):((greenr>255)?(255):(greenr)); bluer = (int)(blue2 * 1.0); bluer = (bluer < 0)?(0):((bluer>255)?(255):(bluer)); alphar = 255; //resulting pixel computed rp = (((((alphar << 8) + (redr & 0x0ff)) << 8) + (greenr & 0x0ff)) << 8) + (bluer & 0x0ff); } t12[rpi] = rp; // copying resulting pixel in the result int array which will be converted to image } } MemoryImageSource mis; if (t12!=null) { mis = new MemoryImageSource(widthr, heightr, colorModel, t12, 0, widthr); result = Toolkit.getDefaultToolkit().createImage(mis); return result; } return null; } } now to check the my theory Im trying to join or stich two tiles horizontaly but im getting the error : java.lang.ArrayIndexOutOfBoundsException: 90000 at imagemerge.ImageSticher.horizontalStich(ImageSticher.java:69) at imageStream.ImageStream.getImage(ImageStream.java:75) at imageStream.ImageStream.main(ImageStream.java:28) is there some kind of limitation because when stiching two images of 300 x 300 horizontally it means the resulting image will be 600 x 300 ... that would make 180000 index size but its giving error at 90000, what am I doing wrong here

  Read the article

• Using WeakReference to resolve issue with .NET unregistered event handlers causing memory leaks.

  - by Eric

  The problem: Registered event handlers create a reference from the event to the event handler's instance. If that instance fails to unregister the event handler (via Dispose, presumably), then the instance memory will not be freed by the garbage collector. Example: class Foo { public event Action AnEvent; public void DoEvent() { if (AnEvent != null) AnEvent(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } If I instantiate a Foo, and pass this to a new Bar constructor, then let go of the Bar object, it will not be freed by the garbage collector because of the AnEvent registration. I consider this a memory leak, and seems just like my old C++ days. I can, of course, make Bar IDisposable, unregister the event in the Dispose() method, and make sure to call Dispose() on instances of it, but why should I have to do this? I first question why events are implemented with strong references? Why not use weak references? An event is used to abstractly notify an object of changes in another object. It seems to me that if the event handler's instance is no longer in use (i.e., there are no non-event references to the object), then any events that it is registered with should automatically be unregistered. What am I missing? I have looked at WeakEventManager. Wow, what a pain. Not only is it very difficult to use, but its documentation is inadequate (see http://msdn.microsoft.com/en-us/library/system.windows.weakeventmanager.aspx -- noticing the "Notes to Inheritors" section that has 6 vaguely described bullets). I have seen other discussions in various places, but nothing I felt I could use. I propose a simpler solution based on WeakReference, as described here. My question is: Does this not meet the requirements with significantly less complexity? To use the solution, the above code is modified as follows: class Foo { public WeakReferenceEvent AnEvent = new WeakReferenceEvent(); internal void DoEvent() { AnEvent.Invoke(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } Notice two things: 1. The Foo class is modified in two ways: The event is replaced with an instance of WeakReferenceEvent, shown below; and the invocation of the event is changed. 2. The Bar class is UNCHANGED. No need to subclass WeakEventManager, implement IWeakEventListener, etc. OK, so on to the implementation of WeakReferenceEvent. This is shown here. Note that it uses the generic WeakReference that I borrowed from here: http://damieng.com/blog/2006/08/01/implementingweakreferencet I had to add Equals() and GetHashCode() to his class, which I include below for reference. class WeakReferenceEvent { public static WeakReferenceEvent operator +(WeakReferenceEvent wre, Action handler) { wre._delegates.Add(new WeakReference<Action>(handler)); return wre; } public static WeakReferenceEvent operator -(WeakReferenceEvent wre, Action handler) { foreach (var del in wre._delegates) if (del.Target == handler) { wre._delegates.Remove(del); return wre; } return wre; } HashSet<WeakReference<Action>> _delegates = new HashSet<WeakReference<Action>>(); internal void Invoke() { HashSet<WeakReference<Action>> toRemove = null; foreach (var del in _delegates) { if (del.IsAlive) del.Target(); else { if (toRemove == null) toRemove = new HashSet<WeakReference<Action>>(); toRemove.Add(del); } } if (toRemove != null) foreach (var del in toRemove) _delegates.Remove(del); } } public class WeakReference<T> : IDisposable { private GCHandle handle; private bool trackResurrection; public WeakReference(T target) : this(target, false) { } public WeakReference(T target, bool trackResurrection) { this.trackResurrection = trackResurrection; this.Target = target; } ~WeakReference() { Dispose(); } public void Dispose() { handle.Free(); GC.SuppressFinalize(this); } public virtual bool IsAlive { get { return (handle.Target != null); } } public virtual bool TrackResurrection { get { return this.trackResurrection; } } public virtual T Target { get { object o = handle.Target; if ((o == null) || (!(o is T))) return default(T); else return (T)o; } set { handle = GCHandle.Alloc(value, this.trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak); } } public override bool Equals(object obj) { var other = obj as WeakReference<T>; return other != null && Target.Equals(other.Target); } public override int GetHashCode() { return Target.GetHashCode(); } } It's functionality is trivial. I override operator + and - to get the += and -= syntactic sugar matching events. These create WeakReferences to the Action delegate. This allows the garbage collector to free the event target object (Bar in this example) when nobody else is holding on to it. In the Invoke() method, simply run through the weak references and call their Target Action. If any dead (i.e., garbage collected) references are found, remove them from the list. Of course, this only works with delegates of type Action. I tried making this generic, but ran into the missing where T : delegate in C#! As an alternative, simply modify class WeakReferenceEvent to be a WeakReferenceEvent, and replace the Action with Action. Fix the compiler errors and you have a class that can be used like so: class Foo { public WeakReferenceEvent<int> AnEvent = new WeakReferenceEvent<int>(); internal void DoEvent() { AnEvent.Invoke(5); } } Hopefully this will help someone else when they run into the mystery .NET event memory leak!

  Read the article

< Previous Page | 315 316 317 318 319 320 321 322 323 324 325 326  | Next Page >