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• Can I destroy a class instance even if there are still references?

  - by DR

  For debugging reasons I want to destroy a class instance which still as references. Is that possible? It doesn't have to be elegant or stable, because this'll never end up in production code. To clarify: Public Sub Main Dim o as MyClass Set o = New MyClass //o is created, one reference DestroyObject o //Class_Terminate is called and the object destroyed //Further code, not using o End Sub //Possible runtime error here (don't care) Is that possible? One way would be to call IUnknown::Release to manually decrease the reference count, but how do I now how often I must call it?

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• Generic calls to OnResetDevice() and OnLostDevice()

  - by bobobobo

  This is kind of a COM question to do with DirectX. So, both ID3DXSprite and ID3DXFont and a bunch of the other ID3DX* objects require you to call OnLostDevice() when the d3d device is lost AND OnResetDevice() when the device is reset. What I want to do is maintain an array of all ID3DX* objects and simply call OnResetDevice() and OnLostDevice() on each whenever the device is lost or reset. However I can't seem to find a BASE CLASS for the ID3DX* classes... they all seem to COM-ually inherit from IUnknown. Is there a way to do this or do I have to maintain separate arrays of ID3DXFont* pointers, ID3DXSprite* pointers, etc?

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• "Exception has been thrown by the target of an invocation" Running Tests - VS2008 SP1

  - by omatrot

  I'm using Visual Studio 2008 Team Suite and I'm unable to run tests and display the Test/Windows/Test Result Window. The result is a dialog box with the following content : "Exception has been thrown by the target of an invocation". Team Explorer has been installed after Visual Studio 2008 SP1. So I have re-apllied the service pack. Searching the web I found that this error is pretty common but unfortunately, the proposed solutions does not work for me. The problem was never analysed so I decided to give it a try : I reproduced the problem on a computer, attached the process with windbg and start with the basic investigations. Following are the first results : 0:000>!dumpstack OS Thread Id: 0xdb0 (0) Current frame: USER32!NtUserWaitMessage+0x15 ChildEBP RetAddr Caller,Callee 003fec94 75a32674 USER32!DialogBox2+0x222, calling USER32!NtUserWaitMessage 003fecd0 75a3288a USER32!InternalDialogBox+0xe5, calling USER32!DialogBox2 003fecfc 75a6f8d0 USER32!SoftModalMessageBox+0x757, calling USER32!InternalDialogBox 003fed3c 6eb61996 mscorwks!Thread::ReverseLeaveRuntime+0x95, calling mscorwks!_EH_epilog3 003fedb0 75a6fbac USER32!MessageBoxWorker+0x269, calling USER32!SoftModalMessageBox 003fede0 6ea559c3 mscorwks!SetupThreadNoThrow+0x19a, calling mscorwks!_EH_epilog3_catch_GS 003fee24 6eb61d8a mscorwks!HasIllegalReentrancy+0xac, calling mscorwks!_EH_epilog3 003fee30 6ea89796 mscorwks!SimpleComCallWrapper::Release+0x2e, calling mscorwks!CompareExchangeMP 003fee38 6ea0da05 mscorwks!CLRException::HandlerState::CleanupTry+0x16, calling mscorwks!GetCurrentSEHRecord 003fee44 6ea0c9c0 mscorwks!Thread::EnablePreemptiveGC+0xf, calling mscorwks!Thread::CatchAtSafePoint 003fee4c 6ea8a241 mscorwks!Unknown_Release_Internal+0x24d, calling mscorwks!GCHolder<1,0,0>::Pop 003fee50 6ea0c86c mscorwks!_EH_epilog3_catch_GS+0xa, calling mscorwks!__security_check_cookie 003fee54 6ea8a24c mscorwks!Unknown_Release_Internal+0x258, calling mscorwks!_EH_epilog3_catch_GS 003fee7c 75a16941 USER32!UserCallWinProcCheckWow+0x13d, calling ntdll!RtlDeactivateActivationContextUnsafeFast 003feed8 7082119e msenv!ATL::CComCritSecLock<ATL::CComCriticalSection>::Lock+0xd, calling ntdll!RtlEnterCriticalSection 003fef08 75a6fe5b USER32!MessageBoxIndirectW+0x2e, calling USER32!MessageBoxWorker 003fef7c 70a1e367 msenv!MessageBoxPVoidW+0xda 003fefd4 70a1db60 msenv!VBDialogCover2+0x11b 003ff01c 70a1e4c0 msenv!VBMessageBox2W+0xf0, calling msenv!VBDialogCover2 003ff044 7087246b msenv!main_GetAppNameW+0xa, calling msenv!GetAppNameInternal 003ff04c 70a1e4f2 msenv!VBMessageBox3W+0x1c, calling msenv!VBMessageBox2W 003ff064 70a1d6d7 msenv!_IdMsgShow+0x362, calling msenv!VBMessageBox3W 003ff0cc 70951841 msenv!TaskDialogCallback+0x7e0, calling msenv!_IdMsgShow 003ff118 6eb20da4 mscorwks!Unknown_QueryInterface+0x230, calling mscorwks!_EH_epilog3_catch_GS 003ff14c 6eb20c43 mscorwks!Unknown_QueryInterface_Internal+0x3d8, calling mscorwks!_EH_epilog3_catch_GS 003ff168 02006ec4 02006ec4, calling 0247a1e8 003ff16c 6ea0c86c mscorwks!_EH_epilog3_catch_GS+0xa, calling mscorwks!__security_check_cookie 003ff198 6eb20562 mscorwks!COMToCLRWorker+0xb34, calling mscorwks!_EH_epilog3_catch_GS 003ff19c 0247a235 0247a235, calling mscorwks!COMToCLRWorker 003ff1c4 7083249f msenv!CVSCommandTarget::ExecCmd+0x937 003ff1e4 7086d5c8 msenv!VsReportErrorInfo+0x11, calling msenv!TaskDialogCallback+0xd8 003ff1f8 7093e65b msenv!CVSCommandTarget::ExecCmd+0x945, calling msenv!VsReportErrorInfo 003ff25c 7081f53a msenv!ATL::CComPtr<IVsLanguageInfo>::~CComPtr<IVsLanguageInfo>+0x24, calling msenv!_EH_epilog3 003ff260 70b18d72 msenv!LogCommand+0x4c, calling msenv!ATL::CComPtr<IVsCodePageSelection>::~CComPtr<IVsCodePageSelection> 003ff264 70b18d77 msenv!LogCommand+0x51, calling msenv!_EH_epilog3 003ff280 70a4fd0e msenv!CMsoButtonUser::FClick+0x1d1, calling msenv!CVSCommandTarget::ExecCmd 003ff2f4 70823a87 msenv!CTLSITE::QueryInterface+0x16 003ff31c 70cb7d4d msenv!TBCB::FNotifyFocus+0x204 003ff35c 70ce5fda msenv!TB::NotifyControl+0x101 003ff3bc 709910f6 msenv!TB::FRequestFocus+0x4ed, calling msenv!TB::NotifyControl 003ff414 708254ba msenv!CMsoButtonUser::FEnabled+0x3d, calling msenv!GetQueryStatusFlags 003ff428 7086222a msenv!TBC::FAutoEnabled+0x24 003ff43c 7098e1eb msenv!TB::LProcessInputMsg+0xdb4 003ff458 6bec1c49 (MethodDesc 0x6bcd7f54 +0x89 System.Windows.Forms.Form.DefWndProc(System.Windows.Forms.Message ByRef)), calling 6be3b738 003ff50c 70823ab0 msenv!FPtbFromSite+0x16 003ff520 70991c43 msenv!TB::PtbParent+0x25, calling msenv!FPtbFromSite 003ff52c 708dda49 msenv!TBWndProc+0x2da 003ff588 0203d770 0203d770, calling 0247a1e8 003ff598 70822a70 msenv!CPaneFrame::Release+0x118, calling msenv!_EH_epilog3 003ff5b0 75a16238 USER32!InternalCallWinProc+0x23 003ff5dc 75a168ea USER32!UserCallWinProcCheckWow+0x109, calling USER32!InternalCallWinProc 003ff620 75a16899 USER32!UserCallWinProcCheckWow+0x6a, calling ntdll!RtlActivateActivationContextUnsafeFast 003ff654 75a17d31 USER32!DispatchMessageWorker+0x3bc, calling USER32!UserCallWinProcCheckWow 003ff688 70847f2b msenv!CMsoComponent::FPreTranslateMessage+0x72, calling msenv!MainFTranslateMessage 003ff6b4 75a17dfa USER32!DispatchMessageW+0xf, calling USER32!DispatchMessageWorker 003ff6c4 70831553 msenv!EnvironmentMsgLoop+0x1ea, calling USER32!DispatchMessageW 003ff6f8 708eb9bd msenv!CMsoCMHandler::FPushMessageLoop+0x86, calling msenv!EnvironmentMsgLoop 003ff724 708eb94d msenv!SCM::FPushMessageLoop+0xb7 003ff74c 708eb8e9 msenv!SCM_MsoCompMgr::FPushMessageLoop+0x28, calling msenv!SCM::FPushMessageLoop 003ff768 708eb8b8 msenv!CMsoComponent::PushMsgLoop+0x28 003ff788 708ebe4e msenv!VStudioMainLogged+0x482, calling msenv!CMsoComponent::PushMsgLoop 003ff7ac 70882afe msenv!CVsActivityLogSingleton::Instance+0xdf, calling msenv!_EH_epilog3 003ff7d8 70882afe msenv!CVsActivityLogSingleton::Instance+0xdf, calling msenv!_EH_epilog3 003ff7dc 707e4e31 msenv!VActivityLogStartupEntries+0x42 003ff7f4 7081f63b msenv!ATL::CComPtr<IClassFactory>::~CComPtr<IClassFactory>+0x24, calling msenv!_EH_epilog3 003ff7f8 708b250f msenv!ATL::CComQIPtr<IUnknown,&IID_IUnknown>::~CComQIPtr<IUnknown,&IID_IUnknown>+0x1d, calling msenv!_EH_epilog3 003ff820 708e7561 msenv!VStudioMain+0xc1, calling msenv!VStudioMainLogged 003ff84c 2f32aabc devenv!util_CallVsMain+0xff 003ff878 2f3278f2 devenv!CDevEnvAppId::Run+0x11fd, calling devenv!util_CallVsMain 003ff97c 77533b23 ntdll!RtlpAllocateHeap+0xe73, calling ntdll!_SEH_epilog4 003ff9f0 77536cd7 ntdll!RtlpLowFragHeapAllocFromContext+0x882, calling ntdll!RtlpSubSegmentInitialize 003ffa10 7753609f ntdll!RtlNtStatusToDosError+0x3b, calling ntdll!RtlNtStatusToDosErrorNoTeb 003ffa14 775360a4 ntdll!RtlNtStatusToDosError+0x40, calling ntdll!_SEH_epilog4 003ffa40 775360a4 ntdll!RtlNtStatusToDosError+0x40, calling ntdll!_SEH_epilog4 003ffa44 75bd2736 kernel32!LocalBaseRegOpenKey+0x159, calling ntdll!RtlNtStatusToDosError 003ffa48 75bd2762 kernel32!LocalBaseRegOpenKey+0x22a, calling kernel32!_SEH_epilog4 003ffac4 75bd2762 kernel32!LocalBaseRegOpenKey+0x22a, calling kernel32!_SEH_epilog4 003ffac8 75bd28c9 kernel32!RegOpenKeyExInternalW+0x130, calling kernel32!LocalBaseRegOpenKey 003ffad8 75bd28de kernel32!RegOpenKeyExInternalW+0x211 003ffae0 75bd28e5 kernel32!RegOpenKeyExInternalW+0x21d, calling kernel32!_SEH_epilog4 003ffb04 6f282e2b MSVCR90!_unlock+0x15, calling ntdll!RtlLeaveCriticalSection 003ffb14 75bd2642 kernel32!BaseRegCloseKeyInternal+0x41, calling ntdll!NtClose 003ffb28 75bd25d0 kernel32!RegCloseKey+0xd4, calling kernel32!_SEH_epilog4 003ffb5c 75bd25d0 kernel32!RegCloseKey+0xd4, calling kernel32!_SEH_epilog4 003ffb60 2f321ea4 devenv!DwInitSyncObjects+0x340 003ffb90 2f327bf4 devenv!WinMain+0x74, calling devenv!CDevEnvAppId::Run 003ffbac 2f327c68 devenv!License::GetPID+0x258, calling devenv!WinMain 003ffc3c 75bd3677 kernel32!BaseThreadInitThunk+0xe 003ffc48 77539d72 ntdll!__RtlUserThreadStart+0x70 003ffc88 77539d45 ntdll!_RtlUserThreadStart+0x1b, calling ntdll!__RtlUserThreadStart 0:000> !pe -nested Exception object: 050aae9c Exception type: System.Reflection.TargetInvocationException Message: Exception has been thrown by the target of an invocation. InnerException: System.NullReferenceException, use !PrintException 050aac64 to see more StackTrace (generated): SP IP Function 003FEC2C 6D2700F7 mscorlib_ni!System.RuntimeType.CreateInstanceSlow(Boolean, Boolean)+0x57 003FEC5C 6D270067 mscorlib_ni!System.RuntimeType.CreateInstanceImpl(Boolean, Boolean, Boolean)+0xe7 003FEC94 6D270264 mscorlib_ni!System.Activator.CreateInstance(System.Type, Boolean)+0x44 003FECA4 6AD02DAF Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.Package.CreateToolWindow(System.Type, Int32, Microsoft.VisualStudio.Shell.ProvideToolWindowAttribute)+0x67 003FED30 6AD0311B Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.Package.CreateToolWindow(System.Type, Int32)+0xb7 003FED58 6AD02D12 Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.Package.FindToolWindow(System.Type, Int32, Boolean, Microsoft.VisualStudio.Shell.ProvideToolWindowAttribute)+0x7a 003FED88 6AD02D39 Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.Package.FindToolWindow(System.Type, Int32, Boolean)+0x11 003FED94 02585E30 Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.InitToolWindowVariable[[System.__Canon, mscorlib]](System.__Canon ByRef, System.String, Boolean)+0x58 003FEDD0 02585DBE Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.InitToolWindowVariable[[System.__Canon, mscorlib]](System.__Canon ByRef, System.String)+0x36 003FEDE4 02585D32 Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.ShowToolWindow[[System.__Canon, mscorlib]](System.__Canon ByRef, System.String, Boolean)+0x3a 003FEE00 02585AB4 Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.OpenTestResultsToolWindow()+0x2c 003FEE10 02585A6E Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.OnMenuViewTestResults(System.Object, System.EventArgs)+0x6 003FEE18 6CD4F993 System_ni!System.ComponentModel.Design.MenuCommand.Invoke()+0x43 003FEE40 6CD4F9D4 System_ni!System.ComponentModel.Design.MenuCommand.Invoke(System.Object)+0x8 003FEE48 6AD000FA Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.OleMenuCommandService.Microsoft.VisualStudio.OLE.Interop.IOleCommandTarget.Exec(System.Guid ByRef, UInt32, UInt32, IntPtr, IntPtr)+0x11a 003FEEA0 6AD03FB8 Microsoft_VisualStudio_Shell_9_0_ni!Microsoft.VisualStudio.Shell.Package.Microsoft.VisualStudio.OLE.Interop.IOleCommandTarget.Exec(System.Guid ByRef, UInt32, UInt32, IntPtr, IntPtr)+0x44 StackTraceString: <none> HResult: 80131604 0:000> !PrintException 050aac64 Exception object: 050aac64 Exception type: System.NullReferenceException Message: Object reference not set to an instance of an object. InnerException: <none> StackTrace (generated): SP IP Function 003FE660 078E60BE Microsoft_VisualStudio_TeamSystem_Integration!Microsoft.VisualStudio.TeamSystem.Integration.TcmResultsPublishManager..ctor(Microsoft.VisualStudio.TeamSystem.Integration.ResultsPublishManager)+0xc6 003FE674 078E5C91 Microsoft_VisualStudio_TeamSystem_Integration!Microsoft.VisualStudio.TeamSystem.Integration.ResultsPublishManager..ctor(Microsoft.VisualStudio.TeamSystem.Integration.TeamFoundationHostHelper)+0x59 003FE684 078E2FA0 Microsoft_VisualStudio_TeamSystem_Integration!Microsoft.VisualStudio.TeamSystem.Integration.VsetServerHelper..ctor(System.IServiceProvider)+0x50 003FE6A4 078E2E90 Microsoft_VisualStudio_TeamSystem_Common!Microsoft.VisualStudio.TeamSystem.Integration.Client.VsetHelper.InitializeThrow(System.IServiceProvider)+0x20 003FE6B8 078E2E2A Microsoft_VisualStudio_TeamSystem_Common!Microsoft.VisualStudio.TeamSystem.Integration.Client.VsetHelper.InitializeHelper(System.IServiceProvider)+0x22 003FE6E0 078E2DEC Microsoft_VisualStudio_TeamSystem_Common!Microsoft.VisualStudio.TeamSystem.Integration.Client.VsetHelper.CreateVsetHelper(System.IServiceProvider)+0x1c 003FE6F0 078E2DAC Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.QualityToolsPackage.get_VsetHelper()+0x14 003FE6F8 02586BBE Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.ResultsToolWindow..ctor()+0x9f6 003FE798 02585F8A Microsoft_VisualStudio_QualityTools_TestCaseManagement!Microsoft.VisualStudio.TestTools.TestCaseManagement.ResultToolWindowHost..ctor()+0x1a StackTraceString: <none> HResult: 80004003 In order to be able to continue the analysis, we need to get the parameters to see what is going on. I also tried to run devenv.exe with the /log switch. No error in the log after reproducing the problem. Finally, If Team Explorer is removed from the system, the problem goes away. Any help appreciated. TIA. Olivier.

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• Using WPF and SlimDx (DirectX 10/11)

  - by slurmomatic

  I am using SlimDX with WinForms for a while now, but want to make the switch to WPF now. However, I can't figure out how to get DX10/11 working with WPF. The February release of SlimDX provides a WPF example, which only works with DX 9 though. I found the following solution: http://jmorrill.hjtcentral.com/Home/tabid/428/EntryId/437/Direct3D-10-11-Direct2D-in-WPF.aspx but can't get it to work with SlimDX. My main problem is the shared resource handle as I don't know how to retrieve the shared handle from a SlimDX texture. I can't find any information to this topic. In C++ the code looks like this: HRESULT D3DImageEx::GetSharedHandle(IUnknown *pUnknown, HANDLE * pHandle) { HRESULT hr = S_OK; *pHandle = NULL; IDXGIResource* pSurface; if (FAILED(hr = pUnknown->QueryInterface(__uuidof(IDXGIResource), (void**)&pSurface))) return hr; hr = pSurface->GetSharedHandle(pHandle); pSurface->Release(); return hr; } Basically, what I want to do (because I think that this is the solution), is to share a texture between a Direct3d9DeviceEx (for rendering the WPF D3DImage) and a Direct3d10Device (a texture render target for my scene). Any pointers in the right direction are greatly appreciated.

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• COM Object Method Invoke Exception - Silverlight 4

  - by Adam Driscoll

  I'm trying to use the new AutomationFactory provided with Silverlight 4 to call a .NET COM class. .NET COM-Exposed Class: public class ObjectContainer { public bool GetObject([Out, MarshalAs((UnmanagedType.IUnknown)] out object obj) { obj = new SomeOtherObj(); return true; } } Silverlight Assembly: dynamic objectContainer; try { objectContainer = AutomationFactory.GetObject(ProgId); } catch { objectContainer = AutomationFactory.CreateObject(ProgId); } object obj; if (!objectContainer.GetObject(out obj)) { throw new Exception(); } When I call objectContainer.GetObject(out obj) an exception is thrown stating: Value does not fall within the expected range. at MS.Internal.ComAutomation.ComAutomationNative.CheckInvokeHResult(UInt32 hr, String memberName, String exceptionSource, String exceptionDescription, String exceptionHelpFile, UInt32 exceptionHelpContext) at MS.Internal.ComAutomation.ComAutomationNative.Invoke(Boolean tryInvoke, String memberName, ComAutomationInvokeType invokeType, ComAutomationInteropValue[] rgParams, IntPtr nativePeer, ComAutomationInteropValue& returnValue) at MS.Internal.ComAutomation.ComAutomationObject.InvokeImpl(Boolean tryInvoke, String name, ComAutomationInvokeType invokeType, Object& returnValue, Object[] args) at MS.Internal.ComAutomation.ComAutomationObject.Invoke(String name, ComAutomationInvokeType invokeType, Object[] args) at System.Runtime.InteropServices.Automation.AutomationMetaObjectProvider.TryInvokeMember(InvokeMemberBinder binder, Object[] args, Object& result) at System.Runtime.InteropServices.Automation.AutomationMetaObjectProviderBase.<.cctorb__4(Object obj, InvokeMemberBinder binder, Object[] args) at CallSite.Target(Closure , CallSite , Object , String , Object& ) at CallSite.Target(Closure , CallSite , Object , String , Object& ) at ApplicationModule.ObjectContainer.GetObject() Wha's the deal?

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• Comparing objects with IDispatch to get main frame only (BHO)

  - by shaimagz

  I don't know if anyone familiar with BHO (Browser Helper Object), but an expert in c++ can help me too. In my BHO I want to run the OnDocumentComplete() function only on the main frame - the first container and not all the Iframes inside the current page. (an alternative is to put some code only when this is the main frame). I can't find how to track when is it the main frame that being populated. After searching in google I found out that each frame has "IDispatch* pDisp", and I have to compare it with a pointer to the first one. This is the main function: STDMETHODIMP Browsarity::SetSite(IUnknown* pUnkSite) { if (pUnkSite != NULL) { // Cache the pointer to IWebBrowser2. HRESULT hr = pUnkSite->QueryInterface(IID_IWebBrowser2, (void **)&m_spWebBrowser); if (SUCCEEDED(hr)) { // Register to sink events from DWebBrowserEvents2. hr = DispEventAdvise(m_spWebBrowser); if (SUCCEEDED(hr)) { m_fAdvised = TRUE; } } } else { // Unregister event sink. if (m_fAdvised) { DispEventUnadvise(m_spWebBrowser); m_fAdvised = FALSE; } // Release cached pointers and other resources here. m_spWebBrowser.Release(); } // Call base class implementation. return IObjectWithSiteImpl<Browsarity>::SetSite(pUnkSite); } This is where I want to be aware whether its the main window(frame) or not: void STDMETHODCALLTYPE Browsarity::OnDocumentComplete(IDispatch *pDisp, VARIANT *pvarURL) { // as you can see, this function get the IDispatch *pDisp which is unique to every frame. //some code } I asked this question on Microsoft forum and I got an answer without explaining how to actually implement that: http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/7c433bfa-30d7-42db-980a-70e62640184c

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• Hooking thread exit

  - by mackenir

  Is there a way for me to hook the exit of managed threads (i.e. run some code on a thread, just before it exits?) I've developed a mechanism for hooking thread exit that works for some threads. Step 1: develop a 'hook' STA COM class that takes a callback function and calls it in its destructor. Step 2: create a ThreadStatic instance of this object on the thread I want to hook, and pass the object a managed delegate converted to an unmanaged function pointer. The delegate then gets called on thread exit (since the CLR calls IUnknown::Release on all STA COM RCWs as part of thread exit). This mechanism works on, for example, worker threads that I create in code using the Thread class. However, it doesn't seem to work for the application's main thread (be it a console or windows app). The 'hook' COM object seems to be deleted too late in the shutdown process and the attempt to call the delegate fails. (The reason I want to implement this facility is so I can run some native COM code on the exiting thread that works with STA COM objects that were created on the thread, before it's 'too late' (i.e. before the thread has exited, and it's no longer possible to work with STA COM objects on that thread.))

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• When virtual inheritance IS a good design?

  - by 7vies

  EDIT3: Please be sure to clearly understand what I am asking before answering (there are EDIT2 and lots of comments around). There are (or were) many answers which clearly show misunderstanding of the question (I know that's also my fault, sorry for that) Hi, I've looked over the questions on virtual inheritance (class B: public virtual A {...}) in C++, but did not find an answer to my question. I know that there are some issues with virtual inheritance, but what I'd like to know is in which cases virtual inheritance would be considered a good design. I saw people mentioning interfaces like IUnknown or ISerializable, and also that iostream design is based on virtual inheritance. Would those be good examples of a good use of virtual inheritance, is that just because there is no better alternative, or because virtual inheritance is the proper design in this case? Thanks. EDIT: To clarify, I'm asking about real-life examples, please don't give abstract ones. I know what virtual inheritance is and which inheritance pattern requires it, what I want to know is when it is the good way to do things and not just a consequence of complex inheritance. EDIT2: In other words, I want to know when the diamond hierarchy (which is the reason for virtual inheritance) is a good design

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• Delphi: Fast(er) widestring concatenation

  - by Ian Boyd

  i have a function who's job is to convert an ADO Recordset into html: class function RecordsetToHtml(const rs: _Recordset): WideString; And the guts of the function involves a lot of wide string concatenation: while not rs.EOF do begin Result := Result+CRLF+ '<TR>'; for i := 0 to rs.Fields.Count-1 do Result := Result+'<TD>'+VarAsString(rs.Fields[i].Value)+'</TD>'; Result := Result+'</TR>'; rs.MoveNext; end; With a few thousand results, the function takes, what any user would feel, is too long to run. The Delphi Sampling Profiler shows that 99.3% of the time is spent in widestring concatenation (@WStrCatN and @WstrCat). Can anyone think of a way to improve widestring concatenation? i don't think Delphi 5 has any kind of string builder. And Format doesn't support Unicode. And to make sure nobody tries to weasel out: pretend you are implementing the interface: IRecordsetToHtml = interface(IUnknown) function RecordsetToHtml(const rs: _Recordset): WideString; end; Update One I thought of using an IXMLDOMDocument, to build up the HTML as xml. But then i realized that the final HTML would be xhtml and not html - a subtle, but important, difference. Update Two Microsoft knowledge base article: How To Improve String Concatenation Performance

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• Receiving an object in a unmanaged callback function

  - by Daniel Baulig

  Eg. I have following delegate method I want to use as a callback function with unmanaged code: public delegate void Callback(IntPtr myObject); Callback callback; I register it in the following way: [DllImport("a.dll")] public static void registerCallback(IntPtr callbackFunction, IntPtr anObject); // ... this.myObject = new MyClass(); this.objectPin = GCHandle.Alloc(this.myObject, GCHandleType.Pinned); registerCallback(Marshal.GetFunctionPointerForDelegate(callback), objectPin.AddrOfPinnedObject()); Now whenever the callback function is called it will have a Pointer/Handle of an object of the MyClass class. I could use Marshal.PtrToStructure to convert this to an object of MyClass. However, what I would like to have is that the delegate definition already contains the class MyClass. eg.: public delegate void Callback(MyClass myObject); I tried this, but it will not work. I also tried the following, which did not work: public delegate void Callback([MarshalAs(UnmanagedType.IUnknown)]MyClass myObject); I suppose I would need something like "UnmarshalAs" at this point, but sadly this is not available. Any suggestions how I could get lost of that IntPtr in my callback function and get a it packed up as a regular, managed MyClass object?

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• Looks like COM object is created, but JScript fails to get a reference

  - by damix911

  I'm using the following code to create a COM component that I have developed and registered. var mycom = new ActiveXObject("Mirabilis.ComponentServices.1"); mycom.SetFirstNumber(5); mycom.SetSecondNumber(3); The first line runs fine, while if I alter the ProgID (that is, the string passed to ActiveXObject) I get the message Automation server can't create object. This suggests that at least the basics of the registration mechanism are working properly. I integrated some logging calls into the DLL. When I run the script I get the proof into the log file that both this call to QueryInterface: STDAPI DllGetClassObject( const CLSID &clsid, const IID &iid, void **ppv) { ... CAddFactory *pAddFact = new CAddFactory; ... HRESULT hr = pAddFact->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Class QueryInterface returned S_OK"); else writeToLogFile("Class QueryInterface failed"); return hr; ... } and this one: HRESULT __stdcall CAddFactory::CreateInstance( IUnknown *pUnknownOuter, const IID &iid, void **ppv) { ... CAddObj *pObject = new CAddObj; ... HRESULT hr = pObject->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Object QueryInterface returned S_OK"); else writeToLogFile("Object QueryInterface failed"); return hr; ... } return S_OK. However, when JScript gets to line 3 of the script, I get the following error message: 'mycom' is null or not an object Why is this happening? It looks like JScript should be able to obtain a reference. Some attempts I made I tried to return S_FALSE from DllCanUnloadNow to be sure that the DLL will not be unloaded, just in case, but with no luck.

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• Visual Studio - Edit source code located in a database

  - by mfeingold

  I am building something similar to Server Explorer for Apache CouchDB. One of the things necessary is to be able to edit CouchDB view definitions which in CouchDB are JavaScript functions. How can I trick Visual Studio into using my object to retrieve and save the content of the JavaScript function but still use the rest of it - I am happy with editor itself and have no intention of writing my own Editor/Language Service, etc. The latter would be much bigger effort than what this project warrants Edit After more digging I am still stuck. Here is what I know: IVsUIShellOpenDocument interface provides a method OpenStandardEditor which can be used to open the standard Visual Studio editor. As one of the parameters this method takes a Pointer to the IUnknown interface of the document data object. This object is supposed to implement several interfaces described in many places all over the MSDN. Visual Studio SDK also provides a 'sample' implementation of the document data object VsTextBufferClass. I can create an instance of this class and when I pass the pointer to the instance to the OpenStandardEditor I can see my editor and it seems to work ok. When I try to implement my own class implementing the same interfaces (IVsTextBuffer, VsTextBuffer, IVsTextLines) OpenStandardEditor method returns success, but VS bombs out on call editor.Show() with an access violation. My suspicion is that VsTextBufferClass also implements some other interface(s) but not in C# way but rather in the good old COM way. I just do not know which one(s). Any thoughts?

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• How to enforce users to create objects of class derived from mine with "new" only?

  - by sharptooth

  To implement reference counting we use an IUnknown-like interface and a smart pointer template class. The interface has implementation for all the reference-count methods, including Release(): void IUnknownLike::Release() { if( --refCount == 0 ) { delete this; } } The smart pointer template class has a copy constructor and an assignment operator both accepting raw pointers. So users can do the following: class Class : public IUnknownLike { }; void someFunction( CSmartPointer<Class> object ); //whatever function Class object; someFunction( &object ); and the program runs into undefined behavior - the object is created with reference count zero, the smart pointer is constructed and bumps it to one, then the function returns, smart pointer is destroyed, calls Release() which leads to delete of a stack-allocated variable. Users can as well do the following: struct COuter { //whatever else; Class inner;// IUnknownLike descendant }; COuter object; somefunction( &object.Inner ); and again an object not created with new is deleted. Undefined behavior at its best. Is there any way to change the IUnknownLike interface so that the user is forced to use new for creating all objects derived from IUnknownLike - both directly derived and indirectly derived (with classes in between the most derived and the base)?

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• What *is* an IPM.DistList?

  - by Jeremy

  I'm trying to get the recipient addresses within an IPM.DistList that is stored in a public folder (of type contacts) in Exchange 2003. The typeName of the object (once I get hold of it) is a Message (with a parent object being a Messages collection) and the messageType is "IPM.DistList". I can find all sorts of things about IPM.DistListItems, which you would think an IPM.DistList would contain, but there apparently isn't any documentation on the DistList (that I can find) and DistListItems documentation lists no parent possibilities in MSDN. I'll state it another way in case I've left you confused: We have an Exchange 2003 info store with Public Folders. Within those Public Folders is a [sub]folder (that holds items of type "Contact") that has a bunch of distribution lists (IPM.DistList's) that have contact entries, members of the list essentially. I need to get the addresses of the members of the lists in the Public Folder sub-folder using any VB language, because the company I work for hired me as a VB guy and expects me to write VB solutions, even though I could do it in C++... alas, I digress. VB is the language I'm supposed to figure this out in. (.net, script, vba, vb6, it doesn't matter which one. Yes, I know vb.net is not really related to those that came before, but they don't know that.) Anyone ran into anything like this? Am I just not finding the IPM.DistList documentation but it does actually exist somewhere? This isn't a Message.MAPIOBJECT (iUnknown) problem is it? Thanks.... Jeremy

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• MSVC 2003 doesn't see any definitions from a nested include file

  - by ezpresso

  I have a piece of code with COM class declaration as follows: #include "PathTypes.h" MIDL_INTERFACE("552C7555-0555-4444-BA86-56CF39AAFFFF") IPathCalc : public IUnknown { virtual HRESULT STDMETHODCALLTYPE GetLocation( /* [retval][out] */ GeoLocation* pLoc) = 0; virtual HRESULT STDMETHODCALLTYPE SetLocation( /* [in] */ GeoLocation* pLoc) = 0; ... }; Below is the contents of PathTypes.h file: #if !defined(PATHCALC_TYPES_INCLUDED) #define PATHCALC_TYPES_INCLUDED #include "libastro/AstronomyStructs.h" #endif And the libastro/AstronomyStructs.h from an external cross-platform library: #ifndef _ASTRONOMY_STRUCTS_INCLUDED #define _ASTRONOMY_STRUCTS_INCLUDED typedef struct { double lattitude; double longitude; } GeoLocation; ... #endif /* _ASTRONOMY_STRUCTS_INCLUDED */ When I'm trying to build this code with g++ everything goes well. That's not the case with MSVC 2003 which returns error C2061: syntax error : identifier 'GeoLocation'. Seems like MSVC doesn't "see" the definitions from the libastro/AstronomyStructs.h file. When I replace #include "PathTypes.h" with #include "libastro/AstronomyStructs.h" the code compiles without errors. How to make MSVC 2003 to actually "see" the definitions from the nested include files?

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• How do I use WMI with Delphi without drastically increasing the application's file size?

  - by Mick

  I am using Delphi 2010, and when I created a console application that prints "Hello World", it takes 111 kb. If I want to query WMI with Delphi, I add WBEMScripting_TLB, ActiveX, and Variants units to my project. If I perform a simple WMI query, my executable size jumps to 810 kb. I Is there anyway to query WMI without such a large addition to the size of the file? Forgive my ignorance, but why do I not have this issue with C++? Here is my code: program WMITest; {$APPTYPE CONSOLE} uses SysUtils, WBEMScripting_TLB, ActiveX, Variants; function GetWMIstring(wmiHost, root, wmiClass, wmiProperty: string): string; var Services: ISWbemServices; SObject: ISWbemObject; ObjSet: ISWbemObjectSet; SProp: ISWbemProperty; Enum: IEnumVariant; Value: Cardinal; TempObj: OLEVariant; loc: TSWbemLocator; SN: string; i: integer; begin Result := ''; i := 0; try loc := TSWbemLocator.Create(nil); Services := Loc.ConnectServer(wmiHost, root {'root\cimv2'}, '', '', '', '', 0, nil); ObjSet := Services.ExecQuery('SELECT * FROM ' + wmiClass, 'WQL', wbemFlagReturnImmediately and wbemFlagForwardOnly, nil); Enum := (ObjSet._NewEnum) as IEnumVariant; if not VarIsNull(Enum) then try while Enum.Next(1, TempObj, Value) = S_OK do begin try SObject := IUnknown(TempObj) as ISWBemObject; except SObject := nil; end; TempObj := Unassigned; if SObject <> nil then begin SProp := SObject.Properties_.Item(wmiProperty, 0); SN := SProp.Get_Value; if not VarIsNull(SN) then begin if varisarray(SN) then begin for i := vararraylowbound(SN, 1) to vararrayhighbound(SN, 1) do result := vartostr(SN[i]); end else Result := SN; Break; end; end; end; SProp := nil; except Result := ''; end else Result := ''; Enum := nil; Services := nil; ObjSet := nil; except on E: Exception do Result := e.message; end; end; begin try WriteLn('hello world'); WriteLn(GetWMIstring('.', 'root\CIMV2', 'Win32_OperatingSystem', 'Caption')); WriteLn('done'); except on E: Exception do Writeln(E.ClassName, ': ', E.Message); end; end.

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• How to declare and implement a COM interface on C# that inherits from another COM interface?

  - by Carlos Loth

  I'm trying to understand what is the correct why to implement COM interfaces from C# code. It is straightforward when the interface doesn't inherit from other base interface. Like this one: [ComImport, Guid("2047E320-F2A9-11CE-AE65-08002B2E1262"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] public interface IShellFolderViewCB { long MessageSFVCB(uint uMsg, int wParam, int lParam); } However things start to become weired when I need to implement an interface that inherits from other COM interfaces. For example, if I implement the IPersistFolder2 interface which inherits from IPersistFolder which inherits from IPersist as I usually on C# code: [ComImport, Guid("0000010c-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] public interface IPersist { void GetClassID([Out] out Guid classID); } [ComImport, Guid("000214EA-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] public interface IPersistFolder : IPersist { void Initialize([In] IntPtr pidl); } [ComImport, Guid("1AC3D9F0-175C-11d1-95BE-00609797EA4F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] public interface IPersistFolder2 : IPersistFolder { void GetCurFolder([Out] out IntPtr ppidl); } The operating system is not able to call the methods on my object implementation. When I'm debugging I can see the constructor of my IPersistFolder2 implementation is called many times, however the interface methods I've implemented aren't called. I'm implementing the IPersistFolder2 as follows: [Guid("A4603CDB-EC86-4E40-80FE-25D5F5FA467D")] public class PersistFolder: IPersistFolder2 { void IPersistFolder2.GetClassID(ref Guid classID) { ... } void IPersistFolder2.Initialize(IntPtr pidl) { ... } void IPersistFolder2.GetCurFolder(out IntPtr ppidl) { ... } } What seems strange is when I declare the COM interface imports as follow, it works: [ComImport, Guid("0000010c-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] internal interface IPersist { void GetClassID([Out] out Guid classID); } [ComImport, Guid("000214EA-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] internal interface IPersistFolder : IPersist { new void GetClassID([Out] out Guid classID); void Initialize([In] IntPtr pidl); } [ComImport, Guid("1AC3D9F0-175C-11d1-95BE-00609797EA4F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] internal interface IPersistFolder2 : IPersistFolder { new void GetClassID([Out] out Guid classID); new void Initialize([In] IntPtr pidl); void GetCurFolder([Out] out IntPtr ppidl); } I don't know why it works when I declare the COM interfaces that way (hidding the base interface methods using new). Maybe it is related to the way IUnknown works. Does anyone know what is the correct way of implementing COM interfaces in C# that inherits from other COM interfaces and why?

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• Lifetime issue of IDisposable unmanaged resources in a complex object graph?

  - by stakx

  This question is about dealing with unmanaged resources (COM interop) and making sure there won't be any resource leaks. I'd appreciate feedback on whether I seem to do things the right way. Background: Let's say I've got two classes: A class LimitedComResource which is a wrapper around a COM object (received via some API). There can only be a limited number of those COM objects, therefore my class implements the IDisposable interface which will be responsible for releasing a COM object when it's no longer needed. Objects of another type ManagedObject are temporarily created to perform some work on a LimitedComResource. They are not IDisposable. To summarize the above in a diagram, my classes might look like this: +---------------+ +--------------------+ | ManagedObject | <>------> | LimitedComResource | +---------------+ +--------------------+ | o IDisposable (I'll provide example code for these two classes in just a moment.) Question: Since my temporary ManagedObject objects are not disposable, I obviously have no control over how long they'll be around. However, in the meantime I might have Disposed the LimitedComObject that a ManagedObject is referring to. How can I make sure that a ManagedObject won't access a LimitedComResource that's no longer there? +---------------+ +--------------------+ | managedObject | <>------> | (dead object) | +---------------+ +--------------------+ I've currently implemented this with a mix of weak references and a flag in LimitedResource which signals whether an object has already been disposed. Is there any better way? Example code (what I've currently got): LimitedComResource: class LimitedComResource : IDisposable { private readonly IUnknown comObject; // <-- set in constructor ... void Dispose(bool notFromFinalizer) { if (!this.isDisposed) { Marshal.FinalReleaseComObject(comObject); } this.isDisposed = true; } internal bool isDisposed = false; } ManagedObject: class ManagedObject { private readonly WeakReference limitedComResource; // <-- set in constructor ... public void DoSomeWork() { if (!limitedComResource.IsAlive()) { throw new ObjectDisposedException(); // ^^^^^^^^^^^^^^^^^^^^^^^ // is there a more suitable exception class? } var ur = (LimitedComResource)limitedComResource.Target; if (ur.isDisposed) { throw new ObjectDisposedException(); } ... // <-- do something sensible here! } }

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• CLR Version issues with CorBindRuntimeEx

  - by Rick Strahl

  I’m working on an older FoxPro application that’s using .NET Interop and this app loads its own copy of the .NET runtime through some of our own tools (wwDotNetBridge). This all works fine and it’s fairly straightforward to load and host the runtime and then make calls against it. I’m writing this up for myself mostly because I’ve been bitten by these issues repeatedly and spend 15 minutes each However, things get tricky when calling specific versions of the .NET runtime since .NET 4.0 has shipped. Basically we need to be able to support both .NET 2.0 and 4.0 and we’re currently doing it with the same assembly – a .NET 2.0 assembly that is the AppDomain entry point. This works as .NET 4.0 can easily host .NET 2.0 assemblies and the functionality in the 2.0 assembly provides all the features we need to call .NET 4.0 assemblies via Reflection. In wwDotnetBridge we provide a load flag that allows specification of the runtime version to use. Something like this: do wwDotNetBridge LOCAL loBridge as wwDotNetBridge loBridge = CreateObject("wwDotNetBridge","v4.0.30319") and this works just fine in most cases.  If I specify V4 internally that gets fixed up to a whole version number like “v4.0.30319” which is then actually used to host the .NET runtime. Specifically the ClrVersion setting is handled in this Win32 DLL code that handles loading the runtime for me: /// Starts up the CLR and creates a Default AppDomain DWORD WINAPI ClrLoad(char *ErrorMessage, DWORD *dwErrorSize) { if (spDefAppDomain) return 1; //Retrieve a pointer to the ICorRuntimeHost interface HRESULT hr = CorBindToRuntimeEx( ClrVersion, //Retrieve latest version by default L"wks", //Request a WorkStation build of the CLR STARTUP_LOADER_OPTIMIZATION_MULTI_DOMAIN | STARTUP_CONCURRENT_GC, CLSID_CorRuntimeHost, IID_ICorRuntimeHost, (void**)&spRuntimeHost ); if (FAILED(hr)) { *dwErrorSize = SetError(hr,ErrorMessage); return hr; } //Start the CLR hr = spRuntimeHost->Start(); if (FAILED(hr)) return hr; CComPtr<IUnknown> pUnk; WCHAR domainId[50]; swprintf(domainId,L"%s_%i",L"wwDotNetBridge",GetTickCount()); hr = spRuntimeHost->CreateDomain(domainId,NULL,&pUnk); hr = pUnk->QueryInterface(&spDefAppDomain.p); if (FAILED(hr)) return hr; return 1; } CorBindToRuntimeEx allows for a specific .NET version string to be supplied which is what I’m doing via an API call from the FoxPro code. The behavior of CorBindToRuntimeEx is a bit finicky however. The documentation states that NULL should load the latest version of the .NET runtime available on the machine – but it actually doesn’t. As far as I can see – regardless of runtime overrides even in the .config file – NULL will always load .NET 2.0 even if 4.0 is installed. <supportedRuntime> .config File Settings Things get even more unpredictable once you start adding runtime overrides into the application’s .config file. In my scenario working inside of Visual FoxPro this would be VFP9.exe.config in the FoxPro installation folder (not the current folder). If I have a specific runtime override in the .config file like this: <?xml version="1.0"?> <configuration> <startup> <supportedRuntime version="v2.0.50727" /> </startup> </configuration> Not surprisingly with this I can load a .NET 2.0  runtime, but I will not be able to load Version 4.0 of the .NET runtime even if I explicitly specify it in my call to ClrLoad. Worse I don’t get an error – it will just go ahead and hand me a V2 version of the runtime and assume that’s what I wanted. Yuck! However, if I set the supported runtime to V4 in the .config file: <?xml version="1.0"?> <configuration> <startup> <supportedRuntime version="v4.0.30319" /> </startup> </configuration> Then I can load both V4 and V2 of the runtime. Specifying NULL however will STILL only give me V2 of the runtime. Again this seems pretty inconsistent. If you’re hosting runtimes make sure you check which version of the runtime is actually loading first to ensure you get the one you’re looking for. If the wrong version loads – say 2.0 and you want 4.0 - and you then proceed to load 4.0 assemblies they will all fail to load due to version mismatches. This is how all of this started – I had a bunch of assemblies that weren’t loading and it took a while to figure out that the host was running the wrong version of the CLR and therefore caused the assemblies loading to fail. Arrggh! <supportedRuntime> and Debugger Version <supportedRuntime> also affects the use of the .NET debugger when attached to the target application. Whichever runtime is specified in the key is the version of the debugger that fires up. This can have some interesting side effects. If you load a .NET 2.0 assembly but <supportedRuntime> points at V4.0 (or vice versa) the debugger will never fire because it can only debug in the appropriate runtime version. This has bitten me on several occasions where code runs just fine but the debugger will just breeze by breakpoints without notice. The default version for the debugger is the latest version installed on the system if <supportedRuntime> is not set. Summary Besides all the hassels, I’m thankful I can build a .NET 2.0 assembly and have it host .NET 4.0 and call .NET 4.0 code. This way we’re able to ship a single assembly that provides functionality that supports both .NET 2 and 4 without having to have separate DLLs for both which would be a deployment and update nightmare. The MSDN documentation does point at newer hosting API’s specifically for .NET 4.0 which are way more complicated and even less documented but that doesn’t help here because the runtime needs to be able to host both .NET 4.0 and 2.0. Not pleased about that – the new APIs look way more complex and of course they’re not available with older versions of the runtime installed which in our case makes them useless to me in this scenario where I have to support .NET 2.0 hosting (to provide greater ‘built-in’ platform support). Once you know the behavior above, it’s manageable. However, it’s quite easy to get tripped up here because there are multiple combinations that can really screw up behaviors.© Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  FoxPro  

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• DirectShow: Video-Preview and Image (with working code)

  - by xsl

  Questions / Issues If someone can recommend me a good free hosting site I can provide the whole project file. As mentioned in the text below the TakePicture() method is not working properly on the HTC HD 2 device. It would be nice if someone could look at the code below and tell me if it is right or wrong what I'm doing. Introduction I recently asked a question about displaying a video preview, taking camera image and rotating a video stream with DirectShow. The tricky thing about the topic is, that it's very hard to find good examples and the documentation and the framework itself is very hard to understand for someone who is new to windows programming and C++ in general. Nevertheless I managed to create a class that implements most of this features and probably works with most mobile devices. Probably because the DirectShow implementation depends a lot on the device itself. I could only test it with the HTC HD and HTC HD2, which are known as quite incompatible. HTC HD Working: Video preview, writing photo to file Not working: Set video resolution (CRASH), set photo resolution (LOW quality) HTC HD 2 Working: Set video resolution, set photo resolution Problematic: Video Preview rotated Not working: Writing photo to file To make it easier for others by providing a working example, I decided to share everything I have got so far below. I removed all of the error handling for the sake of simplicity. As far as documentation goes, I can recommend you to read the MSDN documentation, after that the code below is pretty straight forward. void Camera::Init() { CreateComObjects(); _captureGraphBuilder->SetFiltergraph(_filterGraph); InitializeVideoFilter(); InitializeStillImageFilter(); } Dipslay a video preview (working with any tested handheld): void Camera::DisplayVideoPreview(HWND windowHandle) { IVideoWindow *_vidWin; _filterGraph->QueryInterface(IID_IMediaControl,(void **) &_mediaControl); _filterGraph->QueryInterface(IID_IVideoWindow, (void **) &_vidWin); _videoCaptureFilter->QueryInterface(IID_IAMVideoControl, (void**) &_videoControl); _captureGraphBuilder->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, _videoCaptureFilter, NULL, NULL); CRect rect; long width, height; GetClientRect(windowHandle, &rect); _vidWin->put_Owner((OAHWND)windowHandle); _vidWin->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS); _vidWin->get_Width(&width); _vidWin->get_Height(&height); height = rect.Height(); _vidWin->put_Height(height); _vidWin->put_Width(rect.Width()); _vidWin->SetWindowPosition(0,0, rect.Width(), height); _mediaControl->Run(); } HTC HD2: If set SetPhotoResolution() is called FindPin will return E_FAIL. If not, it will create a file full of null bytes. HTC HD: Works void Camera::TakePicture(WCHAR *fileName) { CComPtr<IFileSinkFilter> fileSink; CComPtr<IPin> stillPin; CComPtr<IUnknown> unknownCaptureFilter; CComPtr<IAMVideoControl> videoControl; _imageSinkFilter.QueryInterface(&fileSink); fileSink->SetFileName(fileName, NULL); _videoCaptureFilter.QueryInterface(&unknownCaptureFilter); _captureGraphBuilder->FindPin(unknownCaptureFilter, PINDIR_OUTPUT, &PIN_CATEGORY_STILL, &MEDIATYPE_Video, FALSE, 0, &stillPin); _videoCaptureFilter.QueryInterface(&videoControl); videoControl->SetMode(stillPin, VideoControlFlag_Trigger); } Set resolution: Works great on HTC HD2. HTC HD won't allow SetVideoResolution() and only offers one low resolution photo resolution: void Camera::SetVideoResolution(int width, int height) { SetResolution(true, width, height); } void Camera::SetPhotoResolution(int width, int height) { SetResolution(false, width, height); } void Camera::SetResolution(bool video, int width, int height) { IAMStreamConfig *config; config = NULL; if (video) { _captureGraphBuilder->FindInterface(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, _videoCaptureFilter, IID_IAMStreamConfig, (void**) &config); } else { _captureGraphBuilder->FindInterface(&PIN_CATEGORY_STILL, &MEDIATYPE_Video, _videoCaptureFilter, IID_IAMStreamConfig, (void**) &config); } int resolutions, size; VIDEO_STREAM_CONFIG_CAPS caps; config->GetNumberOfCapabilities(&resolutions, &size); for (int i = 0; i < resolutions; i++) { AM_MEDIA_TYPE *mediaType; if (config->GetStreamCaps(i, &mediaType, reinterpret_cast<BYTE*>(&caps)) == S_OK ) { int maxWidth = caps.MaxOutputSize.cx; int maxHeigth = caps.MaxOutputSize.cy; if(maxWidth == width && maxHeigth == height) { VIDEOINFOHEADER *info = reinterpret_cast<VIDEOINFOHEADER*>(mediaType->pbFormat); info->bmiHeader.biWidth = maxWidth; info->bmiHeader.biHeight = maxHeigth; info->bmiHeader.biSizeImage = DIBSIZE(info->bmiHeader); config->SetFormat(mediaType); DeleteMediaType(mediaType); break; } DeleteMediaType(mediaType); } } } Other methods used to build the filter graph and create the COM objects: void Camera::CreateComObjects() { CoInitialize(NULL); CoCreateInstance(CLSID_CaptureGraphBuilder, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void **) &_captureGraphBuilder); CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **) &_filterGraph); CoCreateInstance(CLSID_VideoCapture, NULL, CLSCTX_INPROC, IID_IBaseFilter, (void**) &_videoCaptureFilter); CoCreateInstance(CLSID_IMGSinkFilter, NULL, CLSCTX_INPROC, IID_IBaseFilter, (void**) &_imageSinkFilter); } void Camera::InitializeVideoFilter() { _videoCaptureFilter->QueryInterface(&_propertyBag); wchar_t deviceName[MAX_PATH] = L"\0"; GetDeviceName(deviceName); CComVariant comName = deviceName; CPropertyBag propertyBag; propertyBag.Write(L"VCapName", &comName); _propertyBag->Load(&propertyBag, NULL); _filterGraph->AddFilter(_videoCaptureFilter, L"Video Capture Filter Source"); } void Camera::InitializeStillImageFilter() { _filterGraph->AddFilter(_imageSinkFilter, L"Still image filter"); _captureGraphBuilder->RenderStream(&PIN_CATEGORY_STILL, &MEDIATYPE_Video, _videoCaptureFilter, NULL, _imageSinkFilter); } void Camera::GetDeviceName(WCHAR *deviceName) { HRESULT hr = S_OK; HANDLE handle = NULL; DEVMGR_DEVICE_INFORMATION di; GUID guidCamera = { 0xCB998A05, 0x122C, 0x4166, 0x84, 0x6A, 0x93, 0x3E, 0x4D, 0x7E, 0x3C, 0x86 }; di.dwSize = sizeof(di); handle = FindFirstDevice(DeviceSearchByGuid, &guidCamera, &di); StringCchCopy(deviceName, MAX_PATH, di.szLegacyName); } Full header file: #ifndef __CAMERA_H__ #define __CAMERA_H__ class Camera { public: void Init(); void DisplayVideoPreview(HWND windowHandle); void TakePicture(WCHAR *fileName); void SetVideoResolution(int width, int height); void SetPhotoResolution(int width, int height); private: CComPtr<ICaptureGraphBuilder2> _captureGraphBuilder; CComPtr<IGraphBuilder> _filterGraph; CComPtr<IBaseFilter> _videoCaptureFilter; CComPtr<IPersistPropertyBag> _propertyBag; CComPtr<IMediaControl> _mediaControl; CComPtr<IAMVideoControl> _videoControl; CComPtr<IBaseFilter> _imageSinkFilter; void GetDeviceName(WCHAR *deviceName); void InitializeVideoFilter(); void InitializeStillImageFilter(); void CreateComObjects(); void SetResolution(bool video, int width, int height); }; #endif

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• GDI+ crashes when loading PNG from IStream

  - by konforce

  I wrote something to load PNG files from a custom C++ IStream via GDI+. It worked great until I ran it on Vista machines. Crashes every time. When compiled on VS 2008, I found that inserting code into the IStream::AddRef method, such as a cout, made the problem go away. When compiling with VS 2010, it still crashes regardless of that. I stripped the program down to its basics. I copied a FileStream straight from Microsoft's documentation. It can load PNGs when using Bitmap::FromFile. It can load JPEGs, GIFs, and BMPs via FromFile or FromStream. So in short: on Vista, PNG files loaded via Bitmap::FromStream crash. #pragma comment(lib, "gdiplus.lib") #include <iostream> #include <objidl.h> #include <gdiplus.h> class FileStream : public IStream { public: FileStream(HANDLE hFile) { _refcount = 1; _hFile = hFile; } ~FileStream() { if (_hFile != INVALID_HANDLE_VALUE) { ::CloseHandle(_hFile); } } public: HRESULT static OpenFile(LPCWSTR pName, IStream ** ppStream, bool fWrite) { HANDLE hFile = ::CreateFileW(pName, fWrite ? GENERIC_WRITE : GENERIC_READ, FILE_SHARE_READ, NULL, fWrite ? CREATE_ALWAYS : OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); if (hFile == INVALID_HANDLE_VALUE) return HRESULT_FROM_WIN32(GetLastError()); *ppStream = new FileStream(hFile); if(*ppStream == NULL) CloseHandle(hFile); return S_OK; } virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void ** ppvObject) { if (iid == __uuidof(IUnknown) || iid == __uuidof(IStream) || iid == __uuidof(ISequentialStream)) { *ppvObject = static_cast<IStream*>(this); AddRef(); return S_OK; } else return E_NOINTERFACE; } virtual ULONG STDMETHODCALLTYPE AddRef(void) { return (ULONG)InterlockedIncrement(&_refcount); } virtual ULONG STDMETHODCALLTYPE Release(void) { ULONG res = (ULONG) InterlockedDecrement(&_refcount); if (res == 0) delete this; return res; } // ISequentialStream Interface public: virtual HRESULT STDMETHODCALLTYPE Read(void* pv, ULONG cb, ULONG* pcbRead) { ULONG local_pcbRead; BOOL rc = ReadFile(_hFile, pv, cb, &local_pcbRead, NULL); if (pcbRead) *pcbRead = local_pcbRead; return (rc) ? S_OK : HRESULT_FROM_WIN32(GetLastError()); } virtual HRESULT STDMETHODCALLTYPE Write(void const* pv, ULONG cb, ULONG* pcbWritten) { BOOL rc = WriteFile(_hFile, pv, cb, pcbWritten, NULL); return rc ? S_OK : HRESULT_FROM_WIN32(GetLastError()); } // IStream Interface public: virtual HRESULT STDMETHODCALLTYPE SetSize(ULARGE_INTEGER) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE CopyTo(IStream*, ULARGE_INTEGER, ULARGE_INTEGER*, ULARGE_INTEGER*) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE Commit(DWORD) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE Revert(void) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE LockRegion(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE UnlockRegion(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE Clone(IStream **) { return E_NOTIMPL; } virtual HRESULT STDMETHODCALLTYPE Seek(LARGE_INTEGER liDistanceToMove, DWORD dwOrigin, ULARGE_INTEGER* lpNewFilePointer) { DWORD dwMoveMethod; switch(dwOrigin) { case STREAM_SEEK_SET: dwMoveMethod = FILE_BEGIN; break; case STREAM_SEEK_CUR: dwMoveMethod = FILE_CURRENT; break; case STREAM_SEEK_END: dwMoveMethod = FILE_END; break; default: return STG_E_INVALIDFUNCTION; break; } if (SetFilePointerEx(_hFile, liDistanceToMove, (PLARGE_INTEGER) lpNewFilePointer, dwMoveMethod) == 0) return HRESULT_FROM_WIN32(GetLastError()); return S_OK; } virtual HRESULT STDMETHODCALLTYPE Stat(STATSTG* pStatstg, DWORD grfStatFlag) { if (GetFileSizeEx(_hFile, (PLARGE_INTEGER) &pStatstg->cbSize) == 0) return HRESULT_FROM_WIN32(GetLastError()); return S_OK; } private: volatile HANDLE _hFile; volatile LONG _refcount; }; #define USE_STREAM int main() { Gdiplus::GdiplusStartupInput gdiplusStartupInput; ULONG_PTR gdiplusToken; Gdiplus::GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL); Gdiplus::Bitmap *bmp; #ifndef USE_STREAM bmp = Gdiplus::Bitmap::FromFile(L"test.png", false); if (!bmp) { std::cerr << " Unable to open image file." << std::endl; return 1; } #else IStream *s; if (FileStream::OpenFile(L"test.png", &s, false) != S_OK) { std::cerr << "Unable to open image file." << std::endl; return 1; } bmp = Gdiplus::Bitmap::FromStream(s, false); #endif std::cout << "Image is " << bmp->GetWidth() << " by " << bmp->GetHeight() << std::endl; Gdiplus::GdiplusShutdown(gdiplusToken); #ifdef USE_STREAM s->Release(); #endif return 0; } Tracing and debugging, shows that it does make some calls to the IStream class. It crashes inside of lastResult = DllExports::GdipCreateBitmapFromStream(stream, &bitmap); from GdiPlusBitmap.h, which is a static inline wrapper over the flat API. Other than the reference counting, the only IStream methods it calls is stat (for file size), read, and seek. Call stack looks like: ntdll.dll!_DbgBreakPoint@0() + 0x1 bytes ntdll.dll!_RtlpBreakPointHeap@4() + 0x28 bytes ntdll.dll!_RtlpValidateHeapEntry@12() + 0x70a3c bytes ntdll.dll!_RtlDebugFreeHeap@12() + 0x9a bytes ntdll.dll!@RtlpFreeHeap@16() + 0x13cdd bytes ntdll.dll!_RtlFreeHeap@12() + 0x2e49 bytes kernel32.dll!_HeapFree@12() + 0x14 bytes ole32.dll!CRetailMalloc_Free() + 0x1c bytes ole32.dll!_CoTaskMemFree@4() + 0x13 bytes GdiPlus.dll!GpPngDecoder::GetImageInfo() + 0x68 bytes GdiPlus.dll!GpDecodedImage::InternalGetImageInfo() + 0x3c bytes GdiPlus.dll!GpDecodedImage::GetImageInfo() + 0x18 bytes GdiPlus.dll!CopyOnWriteBitmap::CopyOnWriteBitmap() + 0x49 bytes GdiPlus.dll!CopyOnWriteBitmap::Create() + 0x1d bytes GdiPlus.dll!GpBitmap::GpBitmap() + 0x2c bytes I was unable to find anybody else with the same problem, so I assume there's something wrong with my implementation...

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