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• Compare images to find differences

  - by _simon_

  Task: I have a camera mounted on the end of our assembly line, which captures images of produced items. Let's for example say, that we produce tickets (with some text and pictures on them). So every produced ticket is photographed and saved to disk as image. Now I would like to check these saved images for anomalies (i.e. compare them to an image (a template), which is OK). So if there is a problem with a ticket on our assembly line (missing picture, a stain,...), my application should find it (because its image differs too much from my template). Question: What is the easiest way to compare pictures and find differences between them? Do I need to write my own methods, or can I use existing ones? It would be great if I just set a tolerance value (i.e. images can differ for 1%), put both images in a function and get a return value of true or false :) Tools: C# or VB.NET, Emgu.CV (.NET wrapper for OpenCV) or something similar

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• c# class design - what can I use instead of "static abstract"?

  - by Ryan

  I want to do the following public abstract class MyAbstractClass { public static abstract int MagicId { get; } public static void DoSomeMagic() { // Need to get the MagicId value defined in the concrete implementation } } public class MyConcreteClass : MyAbstractClass { public static override int MagicId { get { return 123; } } } However I can't because you can't have static abstract members. I understand why I can't do this - any recommendations for a design that will achieve much the same result? (For clarity - what I am trying to do is provide a library with an abstract base class but the concrete versions MUST implement a few properties/methods themselves and yes, there are good reasons for keeping it static.)

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• GCC compiler -- bug or unspecified behavior?

  - by Jared P

  When I have conflicting definitions of the ivars of a class in objective-c (not redeclaring the class in the same file, but rather naming the same class with diff ivars, no warnings or better yet errors are issued by the compiler. However, both sets of ivars are useable by the appropriate methods in the respective files. For instance Foo.m: @interface foo { int a; } - (int)method; @end @implementation foo - (int)method { return a; } @end Bar.m: @interface foo { float baz; } @end @implementation foo (category) - (float)blah { return baz; } @end compiles without warnings or errors. Is this intentional? Is this an unchecked error? (for the record, a and baz are actually the same memory location.)

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• How to Print reports in Silvelright 4

  - by lightmeetsdark

  I am wondering if there is anything built in to Silverlight, or possibly c# to allow for printing reports? I'd be happy with any number of methods: exporting files to a pdf format and printing from there, exporting as a text document of some sort and printing from there, or just simply showing the print dialog from the web application itself. I know there are ways to do this in C#, but the c# code-behind is different for many things in Silverlight applications and I can't seem to find anything that will work. So if anyone has any ideas on things I could try it would be very much appreciated! Thank you!

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• Drawing a waveform in C#

  - by user488792

  Hi! I want to be able to display a WaveForm in C#, along with some simple features such as zooming and selection. I already have the data as a short[] of amplitude values. However, I am an amateur when it comes to hardcoding GUI. I have already found a possible helper class WaveFormClass that may help me achieve this but as a backup, I want to learn how to manually do it. So may I ask for some methods and possibly some links that will help? Thanks!

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• What is the right way to implement communication between java objects?

  - by imoschak

  I'm working on an academic project which simulates a rather large queuing procedure in java. The core of the simulator rests within one package where there exist 8 classes, each one implementing a single concept. Every class in the project follows SRP. These classes encapsulate the behavior of the simulator and inter-connect every other class in the project. The problem that has arisen is that most of these 8 classes are, as is logical i think, tightly coupled and each one has to have working knowledge of every other class in this package in order to be able to call methods from it when needed. The application needs only one instance of each class so it might be better to create static fields for each class in a new class and use that to make calls -instead of preserving a reference in each class for every other class in the package (which I'm certain that is incorrect)-, but is this considered a correct design solution? or is there a design pattern maybe that better suits my needs?

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• Mongodb, simple IN problem

  - by afvasd

  Hi everyone I am new to mongo, this is my db design: product := { name: str group: ref, comments: [ ref, ref, ref, ref ] } comments := { ... a bunch of comments stuff } tag := { _id: int, #Need this for online requests tag: str, products: [ {product: ref, score: float}, ... ], comments: [ {comment: ref, score: float}, ...], } So my usage pattern is: GIVEN a product, find comments that have certain tag and sort them accordingly. My current approach involves: Look for that tag object that has tag=myTag pull all the comments out, sorted look for that product where product.name=myProduct pull all the comments out (which are dbrefs by the way) loop through the result of 2, and checking if they are in 4, (this I can do a limit 10) etc. It's pretty inefficient. Any better methods?

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• Keeping object in memory (iPhone SDK)

  - by Chris

  I am trying to create a UIImageView called theImageView in the touchesBegan method that I can then then move to a new location in touchesMoved. Currently I am receiving an "undeclared" error in touchesMoved where I set the new location for theImageView. What can I do to keep theImageView in memory between these two methods? - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { ... UIImageView *theImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image.png"]]; theImageView.frame = CGRectMake(263, 228, 193, 300); [theImageView retain]; ... } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { ... theImageView.frame = CGRectMake(300, 300, 193, 300); ... }

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• Flipping an image using a one dimensional array of characters.

  - by Jeff

  I have the data of an image loaded into memory as a one dimensional array. Since I'm trying to use OpenGL to draw it, and since it reads from the bottom up, I want to try and flip the elements of the array before they're sent to OpenGL. Maybe there's a way to tell OpenGL to read from the top to the bottom? Anyways, I tried using a few methods of sorting arrays and they also flip the image horizontally, which is very much like the original problem. So can I flip the data only one way?

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• Generate service layer with Hibernate

  - by gmate

  Hi all! I generate *.hbm.xml mapping files and *.java file from the DB schema, with Hibernate tools. My question is, that is there any option, to generate service classes also? These are the classes where I implement the store(), find(), delete(), etc... methods. I know that for C# there are many solutions to generate almost everything. I'm looking for the same, but with Hibernate. Is there any? Thanks for every reply in advance!

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• What are the differences in performance between synchronous and asynchronous JavaScript script loading?

  - by jasdeepkhalsa

  My question is simply: what are the differences in performance between synchronous and asynchronous JavaScript script loading? From what I've gathered synchronous code blocks the loading of a page and/or rest of the code from executing. This happens at two levels. First, at the level of the script actually loading, and secondly, within the JavaScript code itself. For example, on the page: Synchronous: <script src="demo_async.js" type="text/javascript"></script> Asynchronous: <script async src="demo_async.js" type="text/javascript"></script> And within a script: Synchronous: function a() {alert("a"); function b() {alert("b");}} Asynchronous (and self-executing): (function(a, function(b){ alert(b); }) { alert(a); }))(); So what really is the difference in performance from using these different loading methods and JavaScript patterns?

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• How can I Find out what BCL types a custom type is using its method?

  - by dotnetdev

  If I have a class, eg T1, and I want to know what classes in the BCL it is using, how could I do this? I came up with this: T1.GetType().GetMethods().Where(x => x.DeclaringType.Namespace == "System"); But this will get all methods in my custom type, but I want to look inside each Method, so I was hoping I could do something like: T1.GetType().GetMethods().BodyTypesUsed; to check if my method uses a type like Streamwriter. How could I achieve this?

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• Freezing a listboxitem while items are being added

  - by siz

  We have a ListBox that has a number of items. Items are inserted into the ListBox via an ObservableCollection. Some of these items can be edited right in the ListBox. However, if an item is added at an index < the edited item's index, the entire content of the ListBox moves down. What we'd like to do is the following: if an item is in edit mode, we'd like to freeze its position on the screen. It is fine if items are added to the collection and the UI around the item changes. But the position of the item should remain constant on the screen. The only thing I've been able to do so far is attach to the ScrollChanged event and, at most, use either BringIntoView or ScrollIntoView methods to ensure that the item is always displayed somewhere in the UI, but I am unable to lock down its position. Has anyone done something like this and help out?

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• How to change a particular element of a C++ STL vector

  - by cambr

  vector<int> l; for(int i=1;i<=10;i++){ l.push_back(i); } Now, for example, how do I change the 5th element of the vector to -1? I tried l.assign(4, -1); It is not behaving as expected. None of the other vector methods seem to fit. I have used vector as I need random access functionality in my code (using l.at(i)).

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• Return an opaque object to the caller without violating type-safety

  - by JS Bangs

  I have a method which should return a snapshot of the current state, and another method which restores that state. public class MachineModel { public Snapshot CurrentSnapshot { get; } public void RestoreSnapshot (Snapshot saved) { /* etc */ }; } The state Snapshot class should be completely opaque to the caller--no visible methods or properties--but its properties have to be visible within the MachineModel class. I could obviously do this by downcasting, i.e. have CurrentSnapshot return an object, and have RestoreSnapshot accept an object argument which it casts back to a Snapshot. But forced casting like that makes me feel dirty. What's the best alternate design that allows me to be both type-safe and opaque?

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• Validate authenticity of website owner

  - by Cyber Junkie

  Hello all! I'm planning to develop a web app where users will list their site/blog. When people submit their sites, how can I confirm that they are the owners of it? So for instance there is a user Mark who wants to submit someone else's website without their approval. I want to restrict Mark from doing so unless he is the actual owner. My idea was to do a comparison between the user's email domain and the website domain she/he wants to submit. If they match allow the user to submit the website. However most people don't register with their website domain address.. or perhaps I'll implement a Facebook connect in the future. What other methods would you suggest?

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• Nesting arrays into NSDictionary object (Objective-C)

  - by antalbud

  I would like to define tasks using NSDictionary, which I'd like to save in a plist file (I didn't have much luck with Core Data so far), but got stuck at two points: -- When using initWithObjectsAndKeys: I can change the data type to number or boolean, using NSDate's numberWithInt: and numberWithBool: methods, respectively. I can't seem to find the method to change the type to date though. I couldn't find anything like that in the documentation. -- The second problem I ran into was with the nested arrays. How can I add them to the dictionary? I have uploaded a picture to here of what I am trying to achieve. Thank you in advance!

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• How do I get a Type[] with arguments from a MethodCallExpression?

  - by Tomas Lycken

  I'm reflecting over a class (in a unit test of said class) to make sure its members have all the required attributes. To do so, I've constructed a couple of helpers, that take an Expression as an argument. I do some checks for it, and take slightly different actions depending on what type of Expression it is, but it's basically the same. Now, my problem is that I have several methods with the same name (but different signatures), and the following code throws an AmbiguousMatchException: // TOnType is a type argument for the type where the method is declared // mce is the MethodCallExpression var m = typeof(TOnType).GetMethod(mce.Method.Name); Now, if I could add an array of Type[] with the types of the arguments to this method as a second parameter to .GetMethod(), the problem would be solved. But how do I find this Type[] array that I need? I have cast the Expression<Func<...>> to an Expression, and then to a MethodCallExpression, and in this method the contents of <...> is not known.

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• Optimal way to initialize varying objects

  - by John Smith

  I have to initialize a lot of different types of objects based on an integer parameter. They all have the same overall initialization methods. At the moment I have the following code #def APPLE 1 #def PEAR 2 switch (t) { case APPLE: newobj = [[FApple alloc] init]; break; case PEAR: newobj = [[FPear] alloc] init]; break; default: retobj = nil; } I believe there must be a better way to do this. When I add FOrange I have to go and add another line here. What would be a better way?

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• "modal" in apple documentation

  - by Crystal

  Apple uses "modal" often in their documentation. Like dismissModalViewController in their titles of methods, or documentation like: "The UIViewController class provides the fundamental view-management model for iPhone applications. The basic view controller class supports the presentation of an associated view in addition to basic support for managing modal views and rotating views in response to device orientation changes. Subclasses such as UINavigationController and UITabBarController provide additional behavior for managing complex hierarchies of view controllers and views." I'm not sure as to what context I should think of when I see modal in the names and documentation. Any thoughts? Thanks.

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• QuickTime movie disappearing from Javascript when scrolled offscreen in Firefox?

  - by c-had

  I have a web page I'm creating that uses Javascript to control an embedded QuickTime player. I add the QuickTime movie to the page using the AC_QuickTime.js file from Apple (as described here - http://developer.apple.com/mac/library/documentation/QuickTime/Conceptual/QTScripting_HTML/QTScripting_HTML_Document/ScriptingHTML.html#//apple_ref/doc/uid/TP40001525-2-SW1 ). Everything seems to be working fine - I can call methods on the QuickTime movie and control its playback (as well as get the current timestamp). The problem is that in Firefox, when I scroll down such that the QuickTime player is no longer visible, I get the following error every time I try to call a method on the QuickTime movie: Error calling method on NPObject! This does not occur in Safari. Why is this happening, and is there any way to work around this?

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• Extendable accessing of sqlite database on android platform

  - by mscriven

  Hi, I am fairly new to the android sdk and databases and have been searching for an answer to this quite some time. I am trying to build an app which has multiple tables within a database. e.g. one for weapons, armours etc. However, my DatabaseManager class which handles all of my table creating, DatabaseHelper inner class and populating of data is creating for an extremely large class requiring high maintenance. Every time I would like to add or remove a table column I need to change quite a few areas of code, - Every reference to the addition of a row in that table with data - The method that the above calls - The method returning all of the database rows - The code in the helper class creating the table - Any specific update methods My question is this: Surely there must be some better way of coding this system, maybe using a database isn't the best way to go, or am i just not used to such large classes having only learned java at university and my largest class consisting of a mere 400-600 lines of code. Thanks for any help!

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• Delegate Example From C# In Depth Confusion

  - by ChloeRadshaw

  I am looking at this example: List<Product> products = Product. GetSampleProducts() ; products.Sort( (first, second) => first.Name.CompareTo(second. Name) ) ; foreach (Product product in products) { Console. WriteLine(product) ; } What function is actually called in the API when you do that? Does the compiler create a class which implemnents the IComparer interface? I thought delegates were anonymous methods - Here it seems to be an anonymous interface implementation which is casuing confusion

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• Write a tree class in Java where each level has a unique object type

  - by user479576

  I need to write a tree class in Java where each level has a unique object type. The way it is written below does not take advantage of generics and causes alot of duplicate code. Is there a way to write this with Generics ? public class NodeB { private String nodeValue; //private List<NodeB> childNodes; // constructors // getters/setters } public class NodeA { private String value; private List<NodeB> childNodes; // constructors // getters/setters } public class Tree { private String value; private List<NodeA> childNodes; // constructors // tree methods }

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• Windows Service on NetworkService account can't access remote (shared) directory

  - by Aetius

  I'm trying to remotely access a shared folder with a Windows Service set to NetworkService account permissions. However, I get errors when I try to do this, e.g. Directory.Exists(servicePath) returns false, FileSystemWatcher doesn't recognize activity in the directory. If I change the service's account to LocalSystem, these methods work. I don't want to give the service root-level access, though. It seems to be a permissions problem, so how can I give the service permission to access the directory and monitor it?

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