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Why must "stride" in the System.Drawing.Bitmap constructor be a multiple of 4?

- by Gorchestopher H

I am writing an application that requires me to take a proprietary bitmap format (an MVTec Halcon HImage) and convert it into a System.Drawing.Bitmap in C#. The only proprietary functions given to me to help me do this involve me writing to file, except for the use of a "get pointer" function. This function is great, it gives me a pointer to the pixel data, the width, the height, and the type of the image. My issue is that when I create my System.Drawing.Bitmap using the constructor: new System.Drawing.Bitmap(width, height, stride, format, scan) I need to specify a "stride" that is a multiple of 4. This may be a problem as I am unsure what size bitmap my function will be hit with. Supposing I end up with a bitmap that is 111x111 pixels, I have no way to run this function other than adding a bogus column to my image or subtracting 3 columns. Is there a way I can sneak around this limitation?

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Using free function as pseudo-constructors to exploit template parameter deduction

- by Poita_

Is it a common pattern/idiom to use free functions as pseudo-constructors to avoid having to explicitly specify template parameters? For example, everyone knows about std::make_pair, which uses its parameters to deduce the pair types: template <class A, class B> std::pair<A, B> make_pair(A a, B b) { return std::pair<A, B>(a, b); } // This allows you to call make_pair(1, 2), // instead of having to type pair<int, int>(1, 2) // as you can't get type deduction from the constructor. I find myself using this quite often, so I was just wondering if many other people use it, and if there is a name for this pattern?

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cannot access localhost using ip

- by Robert

I have done a small web development project using eclipse. It runs well when I try running it on browser with url localhost:8080/myproject/home.html. But if I want to access it on another machine (laptop, mobile, etc. using the same wifi) it is not possible; it is not able to connect. After Googling for a while found out that I have to use the IP address instead of 'localhost'. So I tried 10.0.0.4:8080/myproject/home.html, but still does not work. In fact i am unable to open that url on the same machine (where localhost:8080/myproject/home.html works fine). I also added a new Inbound rule in control panel firewall settings, allowing access to all ports for protocol TCP. Still have problem in running application with the url 10.0.0.4:8080/myproject/home.html (both on same machine as well as laptop and mobile). FYI i am using Eclipse Indigo, Apache tomcat 6.0 and server.xml file contents is as below: <?xml version="1.0" encoding="UTF-8"?> <Server port="8005" shutdown="SHUTDOWN">  <Listener SSLEngine="on" className="org.apache.catalina.core.AprLifecycleListener"/>  <Listener className="org.apache.catalina.core.JasperListener"/>  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener"/>  <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener"/> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener"/>  <GlobalNamingResources>  <Resource auth="Container" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" name="UserDatabase" pathname="conf/tomcat-users.xml" type="org.apache.catalina.UserDatabase"/> </GlobalNamingResources>  <Service name="Catalina">    <Connector port="8080" protocol="HTTP/1.1" address="10.0.0.4" connectionTimeout="20000" redirectPort="8443" />      <Connector port="8009" protocol="AJP/1.3" redirectPort="8443"/>   <Engine defaultHost="localhost" name="Catalina">      <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/>  <Host appBase="webapps" autoDeploy="true" name="localhost" unpackWARs="true" xmlNamespaceAware="false" xmlValidation="false">     <Context docBase="myproject" path="/myproject" reloadable="true" source="org.eclipse.jst.jee.server:myproject"/></Host> </Engine> </Service> </Server>

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NHibernate Overcoming NotSupportedException

- by Jordan Wallwork

Does anyone know of any way to overcome NotSupportedException? I have a method against a User: public virtual bool IsAbove(User otherUser) { return HeirarchyString.StartsWith(otherUser.HeirarchyString); } And I want to do: _session.Query<User>.Where(x => loggedInUser.IsAbove(x)); But this throws a NotSupportedException. The real pain though is that using _session.Query<User>.Where(x => loggedInUser.HeirarchyString.StartsWith(x.HeirarchyString)); works absolutely fine. I don't like this as a solution, however, because it means that if I change how the IsAbove method works, I have to remember all the places where I have duplicated the code whenever I want to update it

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Algorithm for Source Control System?

- by Michael Stum

I need to write a simple source control system and wonder what algorithm I would use for file differences? I don't want to look into existing source code due to license concerns. I need to have it licensed under MPL so I can't look at any of the existing systems like CVS or Mercurial as they are all GPL licensed. Just to give some background, I just need some really simple functions - binary files in a folder. no subfolders and every file behaves like it's own repository. No Metadata except for some permissions. Overall really simple stuff, my single concern really is how to store only the differences of a file from revision to revision without wasting too much space but also without being too inefficient (Maybe store a full version every X changes, a bit like Keyframes in Videos?)

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WPF Application - Role Management Recommendations

- by David Ward

I have a WPF application with a WCF service layer and a SQL database. I now want to restrict elements of the application so that certain functions are only available to those users with a particular role. For example, you will only be able to navigate to the settings screen if you are an administrator. I would like a user to be a member of 1 or more authorisation groups and each authorisation group to have 1 or more roles associated. A long time ago I used AzMan (Authorisation Manager) to do a similar thing. Does anyone think that there are better approaches? Is AzMan "old news"? Alternatives? Thanks.

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Apache 13 permission denied in user's home directory

- by Dave

Hi, My friend's website was working fine until he moved the document root from /var/www/xxx to /home/user/xxx Apache give 13 permission denied error messages when we try to access the site via a web browser. The site is configured as a virtual directory. All the Apache configurations were unchanged (except for the directory change). We tried to chmod 777 /home/user/xxx, chown apache /home/user/xxx. But they didn't work. Is there some kind of security feature set on the user's home directories? The server OS is CentOS (Godaddy VPS). Any help is appreciated! Thanks!

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In C, how do you capture a group with regex?

- by Sylvain

Hi, I'm trying to extract a string from another using regex. I'm using the POSIX regex functions (regcomp, regexec ...), and I fail at capturing a group ... For instance, let the pattern be something as simple as "MAIL FROM:<(.*)>" (with REG_EXTENDED cflags) I want to capture everything between '<' and '' My problem is that regmatch_t gives me the boundaries of the whole pattern (MAIL FROM:<...) instead of just what's between the parenthesis ... What am I missing ? Thanks in advance,

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Outputing resized animated gif to browser using imagick

- by Freeman

I intent to resize an animated gif and outputing it to the browser on-the-fly. My problem is that when I save the resized image it is of good quality, but if I echo it to the browser it is of poor quality and the animation is removed. Here is the code:` header("Content-type:image/gif"); try { /* Read in the animated gif */ $animation = new Imagick("images/nikks.gif"); /*** Loop through the frames ***/ foreach ($animation as $frame) { /*** Thumbnail each frame ***/ $frame->thumbnailImage(200, 200); /*** Set virtual canvas size to 100x100 ***/ $frame->setImagePage(200, 200, 0, 0); } /*** Write image to disk. Notice writeImages instead of writeImage ***/ //$animation->writeImages("images/nikkyo1.gif",true); echo $animation; } catch(Exception $e) { echo $e-getMessage(); } `

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Naming Optional Parameters in VSB

- by SteveNeedsSheetNames

In Visual Basic, I have Functions with a lot of Optional arguments. I would like to be able to pass just a few of these Optional arguments to a Function without having to use numerous commas and spaces to get to the ones I want. Somewhere I saw a way to name params such as OptVar:=val, but that does not seem to work. Just wondering if there is a way to do this. This would help readability. Thanks in advance for the replies.

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How do I combine an unmanaged dll and a managed assembly into one file?

- by Lasse V. Karlsen

SQLite from PHX Software has combined a managed assembly (System.Data.SQLite) with an unmanaged dll (the SQLite 32- or 64-bit dll) into one file, and managed to link them together. How do I do this? Do I need to embed the managed assembly into the unmanaged dll, or vice versa? ie. my questions are: In which order do I need to do this? What tools or knowledge do I need in order to do this? How (if different) do I link to the exported functions from the unmanaged dll in my managed code? The reason I ask this is that I want to build a managed zLib wrapper. I know there is managed classes in .NET but from experience they're a bit limited (and a bit boneheaded in that they don't do proper buffering), so I'd like to create my own copy, also because I want to learn how to do this. So does anyone know what I need to do and how?

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Implementing password hashing/salting algorithm from crackstation.net

- by Mason240

I am trying to implement a password hashing/salting algorithm from crackstation.net, but I am unsure how implement it. Storing the password upon user registration seems to be as simple as passing the password into create_hash(). $password = create_hash($_POST['Password']; I'm not following how to validate upon user login. validate_password($password, $good_hash) returns either true or false, and takes $password as parameter, so it seems like a no brainer except for the second parameter $good_hash. Where does this param come from? It is my understanding that password is turned into a hash value every time its used, and that the hash value is what is stored and compared. So why would I have both the $password and $good_hash values? Quick overview of the functions: function create_hash($password){ calls pbkdf2() } function validate_password($password, $good_hash){ calls pbkdf2() calls slow_equals() } function slow_equals($a, $b){ } function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false){ } Of course a different, better method for this would also be just as helpful. Thank you

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Django's manage.py shell won't indent

- by hora

I seem to have run into a strange bug or more likely some setting I am unfamiliar with on my system that is not allowing me to tab when I am in Django's shell (python manage.py shell is how I run it). For obvious reasons this is proving to be annoying since I can't do any loops or conditonals in the shell. If I hit tab it completes all functions that are available to me, like bash does in a terminal. I've tried just using spaces for my indents but I always get an indentation error. Does anyone know why this is happening and what I can do to get tab to work in my shell again? (It may be relevant to know that this is on a Ubuntu 9.04 system). Edit: tab works fine in the regular pythong shell, it's only in django's that it doesn't. Thanks.

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Pros and Cons of Different macro function / inline methods in C

- by Robert S. Barnes

According to the C FAQ, there are basically 3 practical methods for "inlining" code in C: #define MACRO(arg1, arg2) do { \ /* declarations */ \ stmt1; \ stmt2; \ /* ... */ \ } while(0) /* (no trailing ; ) */ or #define FUNC(arg1, arg2) (expr1, expr2, expr3) To clarify this one, the arguments are used in the expressions, and the comma operator returns the value of the last expression. or using the inline declaration which is supported as an extension to gcc and in the c99 standard. The do { ... } while (0) method is widely used in the Linux kernel, but I haven't encountered the other two methods very often if at all. I'm referring specifically to multi-statement "functions", not single statement ones like MAX or MIN. What are the pros and cons of each method, and why would you choose one over the other in various situations?

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Why is the 'if' statement considered evil?

- by Vadim

I just came from Simple Design and Testing Conference. In one of the session we were talking about evil keywords in programming languages. Corey Haines, who proposed the subject, was convinced that if statement is absolute evil. His alternative was to create functions with predicates. Can you please explain to me why if is evil. I understand that you can write very ugly code abusing if. But I don't believe that it's that bad.

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MIDI on Android: Libs and So Forth

- by yar

I've been contemplating (re)building an app on iPad for some time, where I would use objective-C and DSMI to send MIDI signals to a host computer. This is not bad (I mean, except for actually writing the app). Now I'm contemplating perhaps developing the app for Android tablets (TBA). In Java, what options are available for MIDI message communication? I'm quite familiar with javax.sound.midi, but then I would need a virtual MIDI port to send messages to the host. On the other hand, if the app were done in Adobe AIR, what options would I have available for communicating with MIDI? Obviously another option is to send/receive messages over a TCP/IP socket to a Java host, and talk that way, but it sounds a tad cumbersome... or perhaps not? DSMI does use a host program, after all.

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Interpolating 1D Gaussian into 2D Gaussian

- by Drazick

Let's say I have a 1D Gaussian function. Its length is 600 for that matter. I want to Interpolate it into 2D Gaussian of the size 600 X 600. This is the code I wrote (OTFx is the Gaussian Function, OTF - 2d Interpolated Function): [x, y] = meshgrid([-300:299], [-300:299]); r = sqrt((x .^ 2) + (y .^ 2)); OTF = interp1([-300:299], OTFx, r(:), 'spline'); OTF = reshape(OTF, [600, 600]); The problem is I get Overshoot at the end: How can I prevent it? Is there better Interpolating algorithm for Monotonic Descending Functions?

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is jQuery 1.4.2 compatible with Closure Compiler?

- by Mohammad

According to the official release statement version 1.4 has been re-written to be compressed with Closure Compiler yet when I use the online version of closure compiler I get 130 warnings. This is the code I use. // ==ClosureCompiler== // @compilation_level ADVANCED_OPTIMIZATIONS // @output_file_name default.js // @code_url http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.js // ==/ClosureCompiler== And as far as I know you get the real benefit of Closure Compiler if you include the library with your code also, so it removes the unused functions. Yet my testing show that I can't get any further than compressing the library itself.. What am I doing wrong? Any kind of insight will be much appreciated.

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SelfReferenceProperty vs. ListProperty Google App Engine

- by John

Hi All, I am experimenting with the Google App Engine and have a question. For the sake of simplicity, let's say my app is modeling a computer network (a fairly large corporate network with 10,000 nodes). I am trying to model my Node class as follows: class Node(db.Model): name = db.StringProperty() neighbors = db.SelfReferenceProperty() Let's suppose, for a minute, that I cannot use a ListProperty(). Based on my experiments to date, I can assign only a single entity to 'neighbors' - and I cannot use the "virtual" collection (node_set) to access the list of Node neighbors. So... my questions are: Does SelfReferenceProperty limit you to a single entity that you can reference? If I instead use a ListProperty, I believe I am limited to 5,000 keys, which I need to exceed. Thoughts? Thanks, John

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How to organize code using an optional assembly reference?

- by apoorv020

I am working on a project and want to optionally use an assembly if available. This assembly is only available on WS 2008 R2, and my ideal product whould be a common binary for both computers with and without the assembly. However, I'm primarily developing on a Windows 7 machine, where I cannot install the assembly. How can I organize my code so that I can (with minimum changes) build my code on a machine without the assembly and secondly, how do I ensure that I call the assembly functions only when it is present. (NOTE : The only use of the optional assembly is to instantiate a class in the library and repeatedly call a (single) function of the class, which returns a boolean. The assembly is fsrmlib, which exposes advanced file system management operations on WS08R2.) I'm currently thinking of writing a wrapper class, which will always return true if the assembly is not present. Is this the right way to go about doing this?

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Watching setTimeout loops so that only one is running at a time.

- by DA

I'm creating a content rotator in jQuery. 5 items total. Item 1 fades in, pauses 10 seconds, fades out, then item 2 fades in. Repeat. Simple enough. Using setTimeout I can call a set of functions that create a loop and will repeat the process indefinitely. I now want to add the ability to interrupt this rotator at any time by clicking on a navigation element to jump directly to one of the content items. I originally started going down the path of pinging a variable constantly (say every half second) that would check to see if a navigation element was clicked and, if so, abandon the loop, then restart the loop based on the item that was clicked. The challenge I ran into was how to actually ping a variable via a timer. The solution is to dive into JavaScript closures...which are a little over my head but definitely something I need to delve into more. However, in the process of that, I came up with an alternative option that actually seems to be better performance-wise (theoretically, at least). I have a sample running here: http://jsbin.com/uxupi/14 (It's using console.log so have fireBug running) Sample script: $(document).ready(function(){ var loopCount = 0; $('p#hello').click(function(){ loopCount++; doThatThing(loopCount); }) function doThatOtherThing(currentLoopCount) { console.log('doThatOtherThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatThing(currentLoopCount)},5000) } } function doThatThing(currentLoopCount) { console.log('doThatThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatOtherThing(currentLoopCount)},5000); } } }) The logic being that every click of the trigger element will kick off the loop passing into itself a variable equal to the current value of the global variable. That variable gets passed back and forth between the functions in the loop. Each click of the trigger also increments the global variable so that subsequent calls of the loop have a unique local variable. Then, within the loop, before the next step of each loop is called, it checks to see if the variable it has still matches the global variable. If not, it knows that a new loop has already been activated so it just ends the existing loop. Thoughts on this? Valid solution? Better options? Caveats? Dangers? UPDATE: I'm using John's suggestion below via the clearTimeout option. However, I can't quite get it to work. The logic is as such: var slideNumber = 0; var timeout = null; function startLoop(slideNumber) { ...do stuff here to set up the slide based on slideNumber... slideFadeIn() } function continueCheck(){ if (timeout != null) { // cancel the scheduled task. clearTimeout(timeout); timeout = null; return false; }else{ return true; } }; function slideFadeIn() { if (continueCheck){ // a new loop hasn't been called yet so proceed... // fade in the LI $currentListItem.fadeIn(fade, function() { if(multipleFeatures){ timeout = setTimeout(slideFadeOut,display); } }); }; function slideFadeOut() { if (continueLoop){ // a new loop hasn't been called yet so proceed... slideNumber=slideNumber+1; if(slideNumber==features.length) { slideNumber = 0; }; timeout = setTimeout(function(){startLoop(slideNumber)},100); }; startLoop(slideNumber); The above kicks of the looping. I then have navigation items that, when clicked, I want the above loop to stop, then restart with a new beginning slide: $(myNav).click(function(){ clearTimeout(timeout); timeout = null; startLoop(thisItem); }) If I comment out 'startLoop...' from the click event, it, indeed, stops the initial loop. However, if I leave that last line in, it doesn't actually stop the initial loop. Why? What happens is that both loops seem to run in parallel for a period. So, when I click my navigation, clearTimeout is called, which clears it.

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How to retrieve email from GMail account using PHP?

- by Tatu Ulmanen

Hi, I'm trying to automatically retrieve some email from my GMail account for further parsing, but I can't get my head around on how to do that. I've searched the internets and it suggested that I use PHP's imap functions, like this: $server = '{imap.gmail.com:993/ssl}'; $connection = imap_open($server, '[email protected]', 'password'); But using that code, I get: Warning: imap_open() [function.imap-open]: Couldn't open stream {imap.gmail.com:993/ssl} Any idea what I am doing wrong? Any server setting that might be preventing me from making a connection to GMail (I'm using a shared service)? Is the address even right? Has anyone ever managed to do something like this? I've found tons of examples on how to send email via GMail, but very little of retrieving. Any help is much appreciated.

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Build a JavaScript wrapper for a rails-generated XML API?

- by Thor Thurn

I am working with a large website written in Ruby on Rails. Thanks to the support for REST in Rails 2, the site's business logic is all accessible via a consistent XML API. Now I want to be able to easily write one or more JavaScript frontends to the site that interact with the generated Rails XML API. Ideally, an automated wrapper for the API could be created in JavaScript, since this would minimize the effort required in writing XML processing code for the more than 500 API functions. How, then, can I automatically generate a wrapper around a given XML API in JavaScript so that it's more pleasant to work with? I've worked with solutions of this nature for Java that generate classes and methods to wrap an API, so my current thinking is that I want something of that nature for JavaScript. I'd be open to an alternative take on the problem, though.

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Why ruby object has two to_s and inspect methods that (looks like) do the same thing?

- by prosseek

The p calls inspect, and puts/print calls to_s for representing its object. If I run class Graph def initialize @nodeArray = Array.new @wireArray = Array.new end def to_s # called with print / puts "Graph : #{@nodeArray.size}" end def inspect # called with p "G" end end if __FILE__ == $0 gr = Graph.new p gr print gr puts gr end I get G Graph : 0Graph : 0 Then, why does ruby has two functions do the same thing? What makes the difference between to_s and inspect? And what's the difference between puts/print/p? If I comment out the to_s or inspect function, I get as follows. #<Graph:0x100124b88>#<Graph:0x100124b88>

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Flex - How do I get the absolute X and Y coordinate including HTML offset?

- by Mauricio

Hey everyone, I am calling a JS function through the ExternalInterface using Flex which requires the absolute X and Y coordinates to create a pop-up menu. The Flex application is displayed on the center of an HTML page, therefore there is an HTML X and Y offset to consider. I have tried using the LocalToGlobal and ContentToGlobal functions, but these are just giving me the X and Y coordinates relative to the Flex application, it is not considering the HTML X and Y offset of having the Flex app in the center of the page or varying different screen resolutions. Is the best approach to retrieve the HTML X and Y offset using JavaScript? Is there a Flex function I can use that provides the absolute X and Y coordinates based on the HTML page? Thanks!

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