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  • Delphi - WndProc() in thread never called

    - by Robert Oschler
    I had code that worked fine when running in the context of the main VCL thread. This code allocated it's own WndProc() in order to handle SendMessage() calls. I am now trying to move it to a background thread because I am concerned that the SendMessage() traffic is affecting the main VCL thread adversely. So I created a worker thread with the sole purpose of allocating the WndProc() in its thread Execute() method to ensure that the WndProc() existed in the thread's execution context. The WndProc() handles the SendMessage() calls as they come in. The problem is that the worker thread's WndProc() method is never triggered. Note, doExecute() is part of a template method that is called by my TThreadExtended class which is a descendant of Delphi's TThread. TThreadExtended implements the thread Execute() method and calls doExecute() in a loop. I triple-checked and doExecute() is being called repeatedly. Also note that I call PeekMessage() right after I create the WndProc() in order to make sure that Windows creates a message queue for the thread. However something I am doing is wrong since the WndProc() method is never triggered. Here's the code below: // ========= BEGIN: CLASS - TWorkerThread ======================== constructor TWorkerThread.Create; begin FWndProcHandle := 0; inherited Create(false); end; // --------------------------------------------------------------- // This call is the thread's Execute() method. procedure TWorkerThread.doExecute; var Msg: TMsg; begin // Create the WndProc() in our thread's context. if FWndProcHandle = 0 then begin FWndProcHandle := AllocateHWND(WndProc); // Call PeekMessage() to make sure we have a window queue. PeekMessage(Msg, FWndProcHandle, 0, 0, PM_NOREMOVE); end; if Self.Terminated then begin // Get rid of the WndProc(). myDeallocateHWnd(FWndProcHandle); end; // Sleep a bit to avoid hogging the CPU. Sleep(5); end; // --------------------------------------------------------------- procedure TWorkerThread.WndProc(Var Msg: TMessage); begin // THIS CODE IS NEVER CALLED. try if Msg.Msg = WM_COPYDATA then begin // Is LParam assigned? if (Msg.LParam > 0) then begin // Yes. Treat it as a copy data structure. with PCopyDataStruct(Msg.LParam)^ do begin ... // Here is where I do my work. end; end; // if Assigned(Msg.LParam) then end; // if Msg.Msg = WM_COPYDATA then finally Msg.Result := 1; end; // try() end; // --------------------------------------------------------------- procedure TWorkerThread.myDeallocateHWnd(Wnd: HWND); var Instance: Pointer; begin Instance := Pointer(GetWindowLong(Wnd, GWL_WNDPROC)); if Instance <> @DefWindowProc then begin // Restore the default windows procedure before freeing memory. SetWindowLong(Wnd, GWL_WNDPROC, Longint(@DefWindowProc)); FreeObjectInstance(Instance); end; DestroyWindow(Wnd); end; // --------------------------------------------------------------- // ========= END : CLASS - TWorkerThread ======================== Thanks, Robert

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  • Why doesn't SetNotifyWindowMessage() call my WndProc()?

    - by manuel
    I'm using WinForms, and I'm trying to get SetNotifyWindowMessage() to call the WndProc, but it does not do so. The function call: HRESULT initSAPI(HWND hWnd) { ... if(FAILED( g_cpRecoCtxt->SetNotifyWindowMessage( hWnd, WM_RECOEVENT, 0, 0 ))) MessageBoxW(hWnd, L"Error sending window message", L"SAPI Initialization Error", 0); ... } The WndProc: LRESULT WndProc (HWND hWnd, UINT message, WPARAM wparam, LPARAM lparam) { case WM_RECOEVENT: ProcessRecoEvent(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } Note: initSAPI() is called on a mouse click event.

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  • Concept of WNDCLASSEX, good programming habits and WndProc for system classes

    - by luiscubal
    I understand that the Windows API uses "classes", relying to the WNDCLASS/WNDCLASSEX structures. I have successfully gone through windows API Hello World applications and understand that this class is used by our own windows, but also by Windows core controls, such as "EDIT", "BUTTON", etc. I also understand that it is somehow related to WndProc(it allows me to define a function for it) Although I can find documentation about this class, I can't find anything explaining the concept. So far, the only thing I found about it was this: A Window Class has NOTHING to do with C++ classes. Which really doesn't help(it tells me what it isn't but doesn't tellme what it is). In fact, this only confuses me more, since I'd be tempted to associate WNDCLASSEX to C++ classes and think that "WNDCLASSEX" represents a control type . So, my first question is What is it? In second place, I understand that one can define a WndProc in a class. However, a window can also get messages from the child controls(or windows, or whatever they are called in the Windows API). How can this be? Finally, when is it a good programming practise to define a new class? Per application(for the main frame), per frame, one per control I define(if I create my own progress bar class, for example)? I know Java/Swing, C#/Windows.Form, C/GTK+ and C++/wxWidgets, so I'll probably understand comparisons with these toolkits.

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  • Problems with Window Functions Wndproc and about

    - by BrianHuangverinem
    I really having problems with this problem ,it would be nice if someone help me on this. Every time I try to build my source file the same errors occur every time for the two window functions CALLBACK Wndproc and CALLBACK About. error: "local function definitions are illegal" Can you tell me what mistake I made? LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent; PAINTSTRUCT ps; HDC hdc; wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); switch (message) { case WM_COMMAND: // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_PAINT: hdc = BeginPaint(hWnd, &ps); CaptureImage(hWnd); EndPaint(hWnd, &ps); break; case WM_DESTROY: PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0; } // Message handler for about box. INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE; }

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  • Strange WndProc bug in .Net. VB.Net more specifically.

    - by Jules
    ETA: I use visual studio 2008 express edition. If I override WndProc and mess up somehow, I'll usually backtrack by commenting out code until it works again. The strange thing with WndProc though is you can strip it down to: Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message) MyBase.WndProc((m)) End Sub and it still throws the error. I have to remove the code and retype it in to reset the error. Anyone else experienced this?

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  • How to use WndProc from a C++ dll?

    - by Priyank Bolia
    I want to handle some SAPI messages from a DLL, which is some sort of plugin. How to handle messages/events inside a VC++ dll. The SAPI event handling is shown in the example at: http://msdn.microsoft.com/en-us/library/ms720165%28VS.85%29.aspx

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  • NativeWindow WndProc not receiving messages

    - by BadNinja
    Could someone shed some light on why my WndProc method as implemented below isn't receiving any messages? If I put this class below in a WinForms application and pass in that application's handle, WndProc receives messages as I would expect. However, using the IntPtr returned from GetForegroundWindow() as I have below doesn't yield the same results. (FWIW, I have my code set up to execute GetForegroundWindow() when my application is hidden, so I'm certain that the IntPtr is referring to an outside application.) public class MyNativeWindow : NativeWindow { [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)] private static extern IntPtr GetForegroundWindow(); public MyNativeWindow() { this.AssignHandle(GetForegroundWindow()); } // Never called... I set a breakpoint [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] protected override void WndProc(ref Message m) { base.WndProc(ref m); } }

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  • SendMessage vs. WndProc

    - by Poma
    I'm trying to extend TextBox control to add watermarking functionality. The example I've found on CodeProject is using imported SendMessage function. [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)] static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam); void SetWatermark() { SendMessage(this.Handle, 0x1501, 0, "Sample"); } I'm wondering why not use protected WndProc instead void SetWatermark() { var m =new Message() { HWnd = this.Handle, Msg = 0x1501, WParam = (IntPtr)0, LParam = Marshal.StringToHGlobalUni("Sample") }; WndProc(ref m); } Both seem to work fine. Almost all examples I've seen on internet use SendMessagefunction. Why is that? Isn't WndProc function designed to replace SendMessage? P.S. I don't know right to convert string to IntPtr and found that Marshal.StringToHGlobalUni works ok. Is it right function to do this?

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  • C# override WndProc in Control level to detect

    - by Nullstr1ng
    I have overridden WndProc in UserControl level to detect MouseDown, MouseUp, and MouseMove to any Control added in that UserControl. protected override void WndProc(ref Message m) { Point mouseLoc = new Point(); switch (m.Msg) { case WM_LBUTTONDOWN: System.Diagnostics.Debug.WriteLine("mouse down"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X, mouseLoc.Y, 0)); break; case WM_LBUTTONUP: System.Diagnostics.Debug.WriteLine("mouse up"); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; case WM_MOUSEMOVE: int lParam = m.LParam.ToInt32(); //mouseLoc.X = lParam & 0xFFFF; //mouseLoc.Y = (int)(lParam & 0xFFFF0000 >> 16); mouseLoc.X = (Int16)m.LParam; mouseLoc.Y = (Int16)((int)m.LParam >> 16); System.Diagnostics.Debug.WriteLine("mouse move: " + mouseLoc.X + ", " + mouseLoc.Y); //this.OnMouseDown(new MouseEventArgs(MouseButtons.Left, 1, mouseLoc.X,mouseLoc.Y, 0)); break; } base.WndProc(ref m); } MouseMove, Down, and Up are working when the mouse pointer is in UserControl but when the mouse pointer is on other control (inside my UserControl) it doesn't work. Am I doing something wrong? Currently developing a flick and scroll control.

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  • Scrolling textboxes programmatically using WndProc messages.

    - by Hannes Nel
    Hi, I'm trying to scroll a textbox using the form's WndProc method. The code I've come up with so far, after scouring the internet, looks like this: private void ScrollTextBox() { scrollMessage = Message.Create(TabContents.Handle, 0x00B6, new IntPtr(0x0003), new IntPtr(0x0000)); this.WndProc(ref scrollMessage); } where TabContents is a TextBox. For some reason, nothing happens when i call this method. I'd like to know why. I realise that i can accomplish the same with the MoveToCaret method, but I'm curious why this is not working.

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  • WndProc to detect device unplug and plug

    - by Kev Fixx
    How can I know a devices is plug or unplug in WPF? I am using the code below to detect device changes: private void OnSourceInitialized(object sender, EventArgs e) { IntPtr windowHandle = (new WindowInteropHelper(this)).Handle; HwndSource src = HwndSource.FromHwnd(windowHandle); src.AddHook(new HwndSourceHook(WndProc)); } private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled) { // Handle WM_DEVICECHANGE... if (msg == 0x219) { InitHead(); } return IntPtr.Zero; } Thank you. EDITED: I did the below, still not working: if (msg == 0x0219) { switch (wParam.ToInt32()) { case 0x8000: { InitHead(); } break; } }

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  • How do I send/receive windows messages between VB6 and c#?

    - by cabgef
    I know I can receive messages with the code below in c#, how do I send to vb6, and receive in vb6, and send from vb6? [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] protected override void WndProc(ref Message m) { int _iWParam = (int)m.WParam; int _iLParam = (int)m.LParam; switch ((ECGCardioCard.APIMessage)m.WParam) { // handling code goes here } base.WndProc(ref m); }

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  • Sample source code for processing messages of a window created by an external program?

    - by David
    I know I have to use SetWindowLongPtr with GWLP_WNDPROC and create my own WndProc that handles the message I want (such as WM_GETMINMAXINFO and modify the MINMAXINFO structure). However, because I want to do this for a window created by another program (like notepad.exe), I can't do this from my C#/WinForms program, I have to create a native C/C++ DLL that I have to inject in the the process that created the window. Can you provide a link or the sample code to do this (the native C++ DLL and the way to call it from C# and inject it into the external process)? Thank you

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  • Win32 WndProc Name: why can't I change its name ?

    - by asksuperuser
    I have compiled a simple win32 app successfully with bc++ (2 lines excerpt only): LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM); wincl.lpfnWndProc = WindowProcedure; Why can't I rename WindowProcedure and compile this: LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM); wincl.lpfnWndProc = WndProc; as error message gives: Turbo Incremental Link 5.00 Copyright (c) 1997, 2000 Borland Error: Unresolved external 'stdcall WndProc(HWND *, unsigned int, unsigned int, long)' referenced from C:\PROGRAMMING\SALLY\WIN32TUTORIAL\MAIN.OBJ

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  • AccessViolationException from a combo: Attempted to read or write protected memory

    - by Sparky
    Users are occassionally getting the above error when using our application (VB.Net, Winforms, using v2 of the framework). I'm not able to reproduce it. The callstack is as follows: : System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ComboBox.WndProc(Message& m) at ControlEx.AutoCompleteCombo.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) The code for ControlEx.AutoCompleteCombo.WndProc is as follows: Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message) Try If Not m_fReadOnly Then MyBase.WndProc(m) Else Select Case m.Msg Case WM_LBUTTONDOWN, WM_LBUTTONDBLCLK ' do nothing Case Else MyBase.WndProc(m) End Select End If Catch ex As OutOfMemoryException Throw New OutOfMemoryException("Exception during WndProc for combo " & Me.Name, ex) End Try End Sub The error handling was added so we can determine which combo causes the problem when we get an OutOfMemoryException. Any clues as to what causes this would be muchly appreciated! :-)

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  • WM_NOTIFY and superclass chaining issue in Win32

    - by DasMonkeyman
    For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

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  • What causes my borderless C++/CLI app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • What causes my borderless C++ app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • How to handle Win+Shift+LEft/Right on Win7 with custom WM_GETMINMAXINFO logic?

    - by Steven Robbins
    I have a custom windows implementation in a WPF app that hooks WM_GETMINMAXINFO as follows: private void MaximiseWithTaskbar(System.IntPtr hwnd, System.IntPtr lParam) { MINMAXINFO mmi = (MINMAXINFO)Marshal.PtrToStructure(lParam, typeof(MINMAXINFO)); System.IntPtr monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST); if (monitor != System.IntPtr.Zero) { MONITORINFO monitorInfo = new MONITORINFO(); GetMonitorInfo(monitor, monitorInfo); RECT rcWorkArea = monitorInfo.rcWork; RECT rcMonitorArea = monitorInfo.rcMonitor; mmi.ptMaxPosition.x = Math.Abs(rcWorkArea.left - rcMonitorArea.left); mmi.ptMaxPosition.y = Math.Abs(rcWorkArea.top - rcMonitorArea.top); mmi.ptMaxSize.x = Math.Abs(rcWorkArea.right - rcWorkArea.left); mmi.ptMaxSize.y = Math.Abs(rcWorkArea.bottom - rcWorkArea.top); mmi.ptMinTrackSize.x = Convert.ToInt16(this.MinWidth * (desktopDpiX / 96)); mmi.ptMinTrackSize.y = Convert.ToInt16(this.MinHeight * (desktopDpiY / 96)); } Marshal.StructureToPtr(mmi, lParam, true); } It all works a treat and it allows me to have a borderless window maximized without having it sit on to of the task bar, which is great, but it really doesn't like being moved between monitors with the new Win7 keyboard shortcuts. Whenever the app is moved with Win+Shift+Left/Right the WM_GETMINMAXINFO message is received, as I'd expect, but MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST) returns the monitor the application has just been moved FROM, rather than the monitor it is moving TO, so if the monitors are of differing resolutions the window end up the wrong size. I'm not sure if there's something else I can call, other then MonitorFromWindow, or whether there's a "moving monitors" message I can hook prior to WM_GETMINMAXINFO. I'm assuming there is a way to do it because "normal" windows work just fine.

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  • WndProc(ref Message m), Prevent minimize Games, Send key strokes.

    - by Stanomatic
    Overview: I am going to create a touch application that interfaces with games and other apps. This concept is similar to the app found on touch-buddy.com but I will be using C# and WPF instead of how the application is written in Perl. I have a few challenges I would like to evaluate. The touch-buddy app uses two approaches while interacting with games; 1. Client mode (Same machine runs both game and touch-buddy). 2. Server / Client mode where a separate box sends commands to the game machine. The reason I believe for this method was to circumvent the issue with games minimizing. In Client only mode I am faced with the issue where I touch a screen OTHER than the main screen where the game is viewed and then the game minimizes. Not all games have this behavior but I would like to conquer the games that do minimize and prevent it. Is it possible to keep a game front and center Focused and prevent minimizing utilizing C# WndProc(ref Message m)? I have been experimenting with WndProc(ref Message m) where I created a win form and when I press minimize on my own Win form and it will close an instance of notepad. This proves to me that I can capture a message, prevent that message from bubbling up and then send a message to another application. I then tried to click on notepad with my touch screen and keep my win form application in focus and not minimize. At this point I am unsuccessful. I need more time understanding message codes. Is this the right approach? Can it be done? Should I look at other libraries such as Windows Automation? Key input is my other concern. What is the best way to send key strokes to other apps/games. Should I tap into DirectX, use some kind of send key, Automation Framework? Can any of these handle the multiple key strokes that some simulation games require? I appreciate any links and or insight you may have. If you have gone down this path for any reason I would love to hear your comments. Stan

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  • paint.NET crasing when using the menus

    - by bobber205
    Whenever I go to the menus in paint.NET it crashes with an error log saying the below. I tried the newest version as well as verison 2.7 Any ideas on what's going on? :P Exception details: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e) at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met) at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met) at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ToolStrip.WndProc(Message& m) at System.Windows.Forms.MenuStrip.WndProc(Message& m) at PaintDotNet.SystemLayer.MenuStripEx.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

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  • Illegal cross thread operation exception, unable to handle it

    - by yeah1000
    Hello, i am using visual C# express 2008. I SOMETIMES get the illegal cross thread operation in my invoke method when i try to run my project. It use the same invoke method in many places but its only at the beginning of another thread that i get the error. I check the InvokeRequired property, invoke the same method and in the 'else' condition and create a temporary variable and assign it the text of my control. But on that line, in the 'else' statement, inside the Invoking method i sometimes get the exception. What could be the cause? How to get rid of it? It does not occur often, but it is still a bug... Code: // Delegate: private delegate void ChangeTextDelegate(string text); // Method: public static void ChangeText(string text) { if (richtextbox1.InvokeRequired) { richtextbox1.Invoke(new ChangeTextDelegate(ChangeText), new object[] { text }); } else { int startIndex; startIndex = richtextbox1.TextLength; // <- Exception points here. // ... } } Stack trace: System.InvalidOperationException was unhandled Message="Cross-thread operation not valid: Control 'SomeClass' accessed from a thread other than the thread it was created on." Source="System.Windows.Forms" StackTrace: at System.Windows.Forms.Control.get_Handle() at System.Windows.Forms.Control.get_InternalHandle() at System.Windows.Forms.Control.WmWindowPosChanged(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.TextBoxBase.WndProc(Message& m) at System.Windows.Forms.RichTextBox.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WmCreate(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.TextBoxBase.WndProc(Message& m) at System.Windows.Forms.RichTextBox.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at System.Windows.Forms.Control.CreateHandle() at System.Windows.Forms.TextBoxBase.CreateHandle() at System.Windows.Forms.Control.get_Handle() at System.Windows.Forms.RichTextBox.get_TextLength() at SomeNamespace.SomeClass.Changetext(String text, Color color) in C:\...\SomeClass.cs:line 827 at SomeNamespace.SomeClass.SomeThreadFun() in C:\...\SomeClass.cs:line 112 at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: TY

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