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Articles indexed in March 2010

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  • Problem with waveOutWrite and waveOutGetPosition deadlock

    - by MusiGenesis
    I'm working on an app that plays audio continuously using the waveOut... API from winmm.dll. The app uses "leapfrog" buffers, which are basically a bunch of arrays of samples that you dump into the audio queue. Windows plays them seamlessly in sequence, and as each buffer completes Windows calls a callback function. Inside this function, I load the next set of samples into the buffer, process them however, and then dump the buffer back into the audio queue. In this way, the audio plays indefinitely. For animation purposes, I'm trying to incorporate waveOutGetPosition into the application (since the "buffer done" callbacks are irregular enough to cause jerky animation). waveOutGetPosition returns the current position of playback, so it's hyper-precise. The problem is that in my application, making calls to waveOutGetPosition eventually causes the application to lock up - the sound stops and the call never returns. I've boiled things down to a simple app that demonstrates the problem. You can run the app here: http://www.musigenesis.com/SO/waveOut%20demo.exe If you just hear a tiny bit of piano over and over, it's working. It's just meant to demonstrate the problem. The source code for this project is here: http://www.musigenesis.com/SO/WaveOutDemo.zip The first button runs the app in leapfrog mode without making the calls to waveOutGetPosition. If you click this, the app will play forever without breaking (the X button will close it and shut it off). The second button starts the leapfrogger and also starts a forms timer that calls the waveOutGetPosition and displays the current position. Click this and the app will run for a short while and then lock up. On my laptop, it usually locks up in 15-30 seconds; at most it's taken a minute. I have no idea how to fix this, so any help or suggestions would be most welcome. I've found very few posts on this issue, but it seems that there is a potential deadlock, either from multiple calls to waveOutGetPosition or from calls to that and waveOutWrite that occur at the same time. It's possible that I'm calling this too frequently for the system to handle.

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  • WCF Async callback setup for polled device

    - by Mark Pim
    I have a WCF service setup to control a USB fingerprint reader from our .Net applications. This works fine and I can ask it to enroll users and so on. The reader allows identification (it tells you that a particular user has presented their finger, as opposed to asking it to verify that a particular user's finger is present), but the device must be constantly polled while in identification mode for its status - when a user is detected the status changes. What I want is for an interested application to notify the service that it wants to know when a user is identified, and provide a callback that gets triggered when this happens. The WCF service will return immediately and spawn a thread in the background to continuously poll the device. This polling could go on for hours at a time if no one tries to log in. What's the best way to acheive this? My service contract is currently defined as follows: [ServiceContract (CallbackContract=typeof(IBiometricCallback))] public interface IBiometricWcfService { ... [OperationContract (IsOneWay = true)] void BeginIdentification(); ... } public interface IBiometricCallback { ... [OperationContract(IsOneWay = true)] void IdentificationFinished(int aUserId, string aMessage, bool aSuccess); ... } In my BeginIdentification() method can I easily spawn a worker thread to poll the device, or is it easier to make the WCF service asynchronous?

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  • C++ cin questions

    - by Kim
    This seems to be weird: int main(int argc, char* argv[]) { cout << "function main() .." << '\n'; char ch = 0; double number_value=1.1; cin >> ch; cin.putback(ch); cin >> number_value; cout << "1 .. " << " " << cin.good() << " " << number_value << '\n'; cin >> number_value; cout << "2 .. " << " " << cin.good() << " " << number_value << '\n'; return 0; } If I input the following: 7a 1 I get the following: function main() .. 7a 1 1 .. 1 7 2 .. 0 0 I understand the: 1 .. 1 7 but why the variable number_value is 0. cin.good() shows failure so nothing would have read and the value in number_value from the previous assignment would remain. I expect the value of 7.

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  • What are the suggested alternatives for Class<T>.isAssignableFrom(Class<?> cls)?

    - by Wing C. Chen
    Currently I am doing the profiling to a piece of code. During the profiling, I discovered that this very method call, Class<T>.isAssignableFrom(Class<?> cls) takes up to quite amount of the entire time. Because this is a method from reflection, it takes a lot of time compared to normal keywords or method calls. I am wondering if there are some good alternatives for this method calls?

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  • Is it better to alloc/dealloc new UIBarButtonItems when toggling Edit/Done? Why?

    - by cambria
    Apple's documentation implies that for a UITableView editable with an "Edit/Done" button, you should create and destroy the button each time it's toggled. Here's a snippet of code "BonjourWeb" sample code project that does this: if (editing) { // Add the "done" button to the navigation bar UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(doneAction:)]; self.navigationItem.leftBarButtonItem = doneButton; [doneButton release]; [self addAddButton:YES]; } else { if ([self.customs count]) { // Add the "edit" button to the navigation bar UIBarButtonItem *editButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemEdit target:self action:@selector(editAction:)]; self.navigationItem.leftBarButtonItem = editButton; [editButton release]; } Is this really better than just editing the title of the button? Is there some performance optimisation that I'm not seeing? Or is this just bad example source?

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  • What is the equivalent of OnRender in Silverlight?

    - by John Weldon
    I'm working on porting an app from WPF to Silverlight. The app uses custom types derived from FrameworkElement (in WPF) to describe shapes, and text to be rendered on a Canvas. The WPF app root node overrides OnRender() to iterate through a collection of 'child' nodes, calling Render on each child node to build the Visual Tree. Silverlight doesn't expose OnRender, but there are hints that the same effect can be achieved using ControlTemplate. Is this the way to go, and are there any good examples of using this method available? I've done some googling (binging?) and found nothing really conclusive.

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  • How to turn off project mirroring from SourcForge to launchpad?

    - by C.W.Holeman II
    I have project Emle in Launchpad. I set it to import from emle.svn.sourceforge.net. My intention was to do a single import of the files from SourceForge. EmleBranches2.0 shows that what I actually did was set it to mirror the SourceForge project. Import details Import Status: Reviewed This branch is an import of the Subversion branch from https://emle.svn.sourceforge.net/svnroot/emle/trunk. The next import is scheduled to run in 35 minutes. Last successful import was 5 hours ago. Import started 5 hours ago on russkaya and finished 5 hours ago taking 30 seconds — see the log Import started 12 hours ago on neumayer and finished 12 hours ago taking 30 seconds — see the log Import started 20 hours ago on russkaya and finished 20 hours ago taking 30 seconds — see the log How can I turn off the mirroring?

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  • appexchange, facebook, google app store platform architecture

    - by ktasy
    how does appexchange or facebook build their app store architecture? I work for a company that is Saas based and we would like to start building an app store ourselves. We would like to have third party developers develop apps on top of our Saas application similar to appexchange and facebook's applications. If people could led me in the right direction on architecting an app store on the web that would be great.

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  • Does it ever make sense to make a fundamental (non-pointer) parameter const?

    - by Scott Smith
    I recently had an exchange with another C++ developer about the following use of const: void Foo(const int bar); He felt that using const in this way was good practice. I argued that it does nothing for the caller of the function (since a copy of the argument was going to be passed, there is no additional guarantee of safety with regard to overwrite). In addition, doing this prevents the implementer of Foo from modifying their private copy of the argument. So, it both mandates and advertises an implementation detail. Not the end of the world, but certainly not something to be recommended as good practice. I'm curious as to what others think on this issue. Edit: OK, I didn't realize that const-ness of the arguments didn't factor into the signature of the function. So, it is possible to mark the arguments as const in the implementation (.cpp), and not in the header (.h) - and the compiler is fine with that. That being the case, I guess the policy should be the same for making local variables const. One could make the argument that having different looking signatures in the header and source file would confuse others (as it would have confused me). While I try to follow the Principle of Least Astonishment with whatever I write, I guess it's reasonable to expect developers to recognize this as legal and useful.

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  • setOpaque(true/false); Java

    - by Trizicus
    In Java2D when you use setOpaque I am a little confused on what the true and false does. For example I know that in Swing Opaque means that when painting Swing wont paint what is behind the component. Or is this backwards? Which one is it? Thanks

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  • How to vertically align images in <td>

    - by Ricky
    I got a <td> where two images () reside shown as follows. One is much higher than the other. How do I let the shorter one align to the top of <td />? <td style="padding-left: 0px; cursor: pointer; vertical-align: top;"> <img width="85px" src=".../xyz.png"/> <img src=".../icon_live.gif" /> // shorter one </td>

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  • Delphi 2009 - Strip non alpha numeric from string

    - by Brad
    I've got the following code, and need to strip all non alpha numeric characters. It's not working in delphi 2009 ` unit Unit2; //Used information from // http://stackoverflow.com/questions/574603/what-is-the-fastest-way-of-stripping-non-alphanumeric-characters-from-a-string-in interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; Type TExplodeArray = Array Of String; TForm2 = class(TForm) Memo1: TMemo; ListBox1: TListBox; Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } Function Explode ( Const cSeparator, vString : String ) : TExplodeArray; Function Implode ( Const cSeparator : String; Const cArray : TExplodeArray ) : String; Function StripHTML ( S : String ) : String; function allwords(data:string):integer; end; var Form2: TForm2; allword, allphrase: TExplodeArray; implementation {$R *.dfm} Function TForm2.StripHTML ( S : String ) : String; Var TagBegin, TagEnd, TagLength : Integer; Begin TagBegin := Pos ( '<', S ); // search position of first < While ( TagBegin > 0 ) Do Begin // while there is a < in S TagEnd := Pos ( '>', S ); // find the matching > TagLength := TagEnd - TagBegin + 1; Delete ( S, TagBegin, TagLength ); // delete the tag TagBegin := Pos ( '<', S ); // search for next < End; Result := S; // give the result End; Function TForm2.Implode ( Const cSeparator : String; Const cArray : TExplodeArray ) : String; Var i : Integer; Begin Result := ''; For i := 0 To Length ( cArray ) - 1 Do Begin Result := Result + cSeparator + cArray [i]; End; System.Delete ( Result, 1, Length ( cSeparator ) ); End; Function TForm2.Explode ( Const cSeparator, vString : String ) : TExplodeArray; Var i : Integer; S : String; Begin S := vString; SetLength ( Result, 0 ); i := 0; While Pos ( cSeparator, S ) 0 Do Begin SetLength ( Result, Length ( Result ) + 1 ); Result[i] := Copy ( S, 1, Pos ( cSeparator, S ) - 1 ); Inc ( i ); S := Copy ( S, Pos ( cSeparator, S ) + Length ( cSeparator ), Length ( S ) ); End; SetLength ( Result, Length ( Result ) + 1 ); Result[i] := Copy ( S, 1, Length ( S ) ); End; //Copied from JclStrings function StrKeepChars(const S: AnsiString; const Chars: TSysCharSet): AnsiString; var Source, Dest: PChar; begin SetLength(Result, Length(S)); UniqueString(Result); Source := PChar(S); Dest := PChar(Result); while (Source < nil) and (Source^ < #0) do begin if Source^ in Chars then begin Dest^ := Source^; Inc(Dest); end; Inc(Source); end; SetLength(Result, (Longint(Dest) - Longint(PChar(Result))) div SizeOf(AnsiChar)); end; function ReplaceNewlines(const AValue: string): string; var SrcPtr, DestPtr: PChar; begin SrcPtr := PChar(AValue); SetLength(Result, Length(AValue)); DestPtr := PChar(Result); while SrcPtr < {greater than less than} #0 do begin if (SrcPtr[0] = #13) and (SrcPtr[1] = #10) then begin DestPtr[0] := '\'; DestPtr[1] := 't'; Inc(SrcPtr); Inc(DestPtr); end else DestPtr[0] := SrcPtr[0]; Inc(SrcPtr); Inc(DestPtr); end; SetLength(Result, DestPtr - PChar(Result)); end; function StripNonAlphaNumeric(const AValue: string): string; var SrcPtr, DestPtr: PChar; begin SrcPtr := PChar(AValue); SetLength(Result, Length(AValue)); DestPtr := PChar(Result); while SrcPtr < #0 do begin if SrcPtr[0] in ['a'..'z', 'A'..'Z', '0'..'9'] then begin DestPtr[0] := SrcPtr[0]; Inc(DestPtr); end; Inc(SrcPtr); end; SetLength(Result, DestPtr - PChar(Result)); end; function TForm2.allwords(data:string):integer; var i:integer; begin listbox1.Items.add(data); data:= StripHTML ( data ); listbox1.Items.add(data); ////////////////////////////////////////////////////////////// data := StrKeepChars(data, ['A'..'Z', 'a'..'z', '0'..'9']); // Strips out everything data comes back blank in Delphi 2009 ////////////////////////////////////////////////////////////// listbox1.Items.add(data); data := stringreplace(data,' ',' ', [rfReplaceAll, rfIgnoreCase] ); //Replace two spaces with one. listbox1.Items.add(data); allword:= explode(' ',data); { // Converting the following PHP code to Delphi $text = ereg_replace("[^[:alnum:]]", " ", $text); while(strpos($text,' ')!==false) $text = ereg_replace(" ", " ", $text); $text=$string=strtolower($text); $text=explode(" ",$text); return count($text); } for I := 0 to Length(allword) - 1 do listbox1.Items.Add(allword[i]); end; procedure TForm2.Button1Click(Sender: TObject); begin //[^[:alnum:]] allwords(memo1.Text); end; end. ` How else would I go about doing this? Thanks

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  • How to make movable type to use relative path

    - by haohaolee
    Commonly movable type will publish HTML files which contains absolute path, but if I want to host the site under different domain(e.g., both HTTP and HTTPS), it is very inconvenient. So is there a way to change all the paths to resource of my site to absolute ones? Thanks

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  • can we have one attribute with multiple values in an eav design?

    - by Shekhar
    i am doing a database design using EAV. I am facing an issue when i try to model an entity with attribute having multiple values? For example Entity id | name | description 1 | configuration1 | configuration1 Attribute id | entityId | name | type 1 | 1 |att1 | string 2 | 1 |att2 | int 3 |1 | att3 | List (How will i model this?) Value id | attributeId | value 1 | 1 | a 2 | 2 | 1 3 | 3 | b 4 | 3 | c 5 | 3 |d Is this the correct way to handle list of values? Please provide any helpful link to model this? Thanks Shekhar

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  • Clickonce installation fails after addition of WCF service project

    - by Ant
    So I have a winform solution, deployed via clickonce. Eveything worked fine until i added a WCF project. (see error in parsing the manifest file at end of post) Now I notice that MSBuild compiles the service into a _PublishedWebsites dir. I don't know what the need for this is, but I am suspecting this is the cause of the problem. This wcf project references some other projects within the solution. I am actually hosting the wcf service within the application so I don't really need MSBuild to do all this for me. Any ideas? ===================================================================================== PLATFORM VERSION INFO Windows : 5.1.2600.131072 (Win32NT) Common Language Runtime : 2.0.50727.3603 System.Deployment.dll : 2.0.50727.3053 (netfxsp.050727-3000) mscorwks.dll : 2.0.50727.3603 (GDR.050727-3600) dfdll.dll : 2.0.50727.3053 (netfxsp.050727-3000) dfshim.dll : 2.0.50727.3053 (netfxsp.050727-3000) SOURCES Deployment url : file:///C:/applications/abc/dev/abc.Application.application IDENTITIES Deployment Identity : Flow Management System.app, Version=1.4.0.0, Culture=neutral, PublicKeyToken=8453086392175e0f, processorArchitecture=msil APPLICATION SUMMARY * Installable application. * Trust url parameter is set. ERROR SUMMARY Below is a summary of the errors, details of these errors are listed later in the log. * Activation of C:\applications\abc\dev\abc.Application.application resulted in exception. Following failure messages were detected: + Exception reading manifest from file:///C:/applications/abc/dev/1.4.0.0/abc.Application.exe.manifest: the manifest may not be valid or the file could not be opened. + Parsing and DOM creation of the manifest resulted in error. Following parsing errors were noticed: -HRESULT: 0x80070c81 Start line: 0 Start column: 0 Host file: + Exception from HRESULT: 0x80070C81 COMPONENT STORE TRANSACTION FAILURE SUMMARY No transaction error was detected. WARNINGS There were no warnings during this operation. OPERATION PROGRESS STATUS * [12/03/2010 6:33:53 PM] : Activation of C:\applications\abc\dev\abc.Application.application has started. * [12/03/2010 6:33:53 PM] : Processing of deployment manifest has successfully completed. * [12/03/2010 6:33:53 PM] : Installation of the application has started. ERROR DETAILS Following errors were detected during this operation. * [12/03/2010 6:33:53 PM] System.Deployment.Application.InvalidDeploymentException (ManifestParse) - Exception reading manifest from file:///C:/applications/abc/dev/1.4.0.0/abc.Application.exe.manifest: the manifest may not be valid or the file could not be opened. - Source: System.Deployment - Stack trace: at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri) at System.Deployment.Application.DownloadManager.DownloadManifest(Uri& sourceUri, String targetPath, IDownloadNotification notification, DownloadOptions options, ManifestType manifestType, ServerInformation& serverInformation) at System.Deployment.Application.DownloadManager.DownloadApplicationManifest(AssemblyManifest deploymentManifest, String targetDir, Uri deploymentUri, IDownloadNotification notification, DownloadOptions options, Uri& appSourceUri, String& appManifestPath) at System.Deployment.Application.ApplicationActivator.DownloadApplication(SubscriptionState subState, ActivationDescription actDesc, Int64 transactionId, TempDirectory& downloadTemp) at System.Deployment.Application.ApplicationActivator.InstallApplication(SubscriptionState& subState, ActivationDescription actDesc) at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivation(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl) at System.Deployment.Application.ApplicationActivator.ActivateDeploymentWorker(Object state) --- Inner Exception --- System.Deployment.Application.InvalidDeploymentException (ManifestParse) - Parsing and DOM creation of the manifest resulted in error. Following parsing errors were noticed: -HRESULT: 0x80070c81 Start line: 0 Start column: 0 Host file: - Source: System.Deployment - Stack trace: at System.Deployment.Application.Manifest.AssemblyManifest.LoadCMSFromStream(Stream stream) at System.Deployment.Application.Manifest.AssemblyManifest..ctor(FileStream fileStream) at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri) --- Inner Exception --- System.Runtime.InteropServices.COMException - Exception from HRESULT: 0x80070C81 - Source: System.Deployment - Stack trace: at System.Deployment.Internal.Isolation.IsolationInterop.CreateCMSFromXml(Byte[] buffer, UInt32 bufferSize, IManifestParseErrorCallback Callback, Guid& riid) at System.Deployment.Application.Manifest.AssemblyManifest.LoadCMSFromStream(Stream stream) COMPONENT STORE TRANSACTION DETAILS No transaction information is available.

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  • How to get arc4Sin() output into label/NSString

    - by Moshe
    I'm trying to take the output of arc4sin and put it into a label. (EDIT: You can ignore this and just post sample code, if this is too irrelevant.) I've tried: // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; NSString *number = [[NSString alloc] stringWithFormat: @"%@", arc4random() % 9]; label.text = number; } I've created an IBOutlet for "label" and connected it. What's wrong here?

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  • Issues with SharePoint 2010 Development

    - by Rahul Soni
    I am planning to use my laptop for SharePoint 2010 development and I have only 4 GB RAM which is not even upgradable. Just because of RAM constraint, my VS 2010 keeps crawling if I try to run it along with SharePoint 2010 on the same machine. Hence, I've reformatted my machine and looking for alternate solutions until I get a new laptop. Currently, I have installed VS 2010 ONLY on my laptop and wanted to create an empty SharePoint project. Once done with my project, I want to deploy it on a different machine (which is a 4GB RAM machine as well, but contains only SharePoint 2010). I thought this will work and give me a bit of breather if everything is configured well. Unfortunately, when I tried creating a new SharePoint Empty Project in VS 2010, it says... A SharePoint server is not installed on this computer. A SharePoint server must be installed to work with SharePoint projects. Is there a way out?

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