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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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  • DllImport and char*

    - by Malfist
    I have a method I want to import from a DLL and it has a signature of: BOOL GetDriveLetter(OUT char* DriveLetter) I've tried [DllImport("mydll.dll")] public static extern bool GetDriveLetter(byte[] DriveLetter); and [DllImport("mydll.dll")] public static extern bool GetDriveLetter(StringBuilder DriveLetter); but neither returned anything in the DriveLetter variable.

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  • DbgHelp.dll : Problem calling SymGetModuleInfo64 from C#

    - by Civa
    Hello everyone, I have quite strange behaviour calling SymGetModuleInfo64 from C# code.I always get ERROR_INVALID_PARAMETER (87) with Marshal.GetLastWin32Error().I have already read a lot of posts regarding problems with frequent updates of IMAGEHLP_MODULE64 struct and I just downloaded latest Debugging Tools For Windows (x86) , loaded dbghelp.dll from that location and I was quite sure it would work.Nevertheless I am getting the same error.Can anyone point me what is wrong here? IMAGEHLP_MODULE64 struct is defined in my code as follows : [StructLayout(LayoutKind.Sequential)] public struct IMAGEHELP_MODULE64 { //************************************************ public int SizeOfStruct; public long BaseOfImage; public int ImageSize; public int TimeDateStamp; public int CheckSum; public int NumSyms; public SymType SymType; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)] public string ModuleName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)] public string ImageName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)] public string LoadedImageName; //************************************************ //new elements v2 //************************************************* [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)] public string LoadedPdbName; public int CVSig; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 780)] public string CVData; public int PdbSig; public GUID PdbSig70; public int PdbAge; public bool PdbUnmatched; public bool DbgUnmatched; public bool LineNumbers; public bool GlobalSymbols; public bool TypeInfo; //************************************************ //new elements v3 //************************************************ public bool SourceIndexed; public bool Publics; //************************************************ //new elements v4 //************************************************ public int MachineType; public int Reserved; //************************************************ } the piece of code that actually calls SymGetModuleInfo64 is like this : public void GetSymbolInfo(IntPtr hProcess,long modBase64,out bool success) { success = false; DbgHelp.IMAGEHELP_MODULE64 moduleInfo = new DbgHelp.IMAGEHELP_MODULE64(); moduleInfo.SizeOfStruct = Marshal.SizeOf(moduleInfo); try { success = DbgHelp.SymGetModuleInfo64(hProcess, modBase64, out moduleInfo); if (success) { //Do the stuff here } } catch (Exception exc) { } } Im stuck here...always with error 87.Please someone points me to the right direction. By the way modBase64 is value previously populated by : modBase64 = DbgHelp.SymLoadModule64(_handle, IntPtr.Zero, fileName, null, baseAddress, size); where _handle is process handle of process being debugged,fileName is path of current loaded module, baseAddress is address base of currently loaded module and size is of course the size of current loaded module.I call this code when I get LOAD_DLL_DEBUG_EVENT. Edit : Sorry, I forgot to mention that SymGetModuleInfo64 signature is like this : [DllImport("dbghelp.dll", SetLastError = true)] public static extern bool SymGetModuleInfo64(IntPtr hProcess, long ModuleBase64, out IMAGEHELP_MODULE64 imgHelpModule); Best regards, Civa

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  • Retrieving virtual disk file name from disk number

    - by Josip Medved
    When I list virtual disks within diskpart: DISKPART> list vdisk VDisk ### Disk ### State Type File --------- -------- -------------------- --------- ---- VDisk 0 Disk 2 Attached not open Fixed C:\Disk.vhd Interesting part for me here is file name. I tried to find equivalent of function that would give me file name (under File column) if I know disk number. Any idea which function that might be?

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  • Best practices for organizing .NET P/Invoke code to Win32 APIs

    - by Paul Sasik
    I am refactoring a large and complicated code base in .NET that makes heavy use of P/Invoke to Win32 APIs. The structure of the project is not the greatest and I am finding DllImport statements all over the place, very often duplicated for the same function, and also declared in a variety of ways: The import directives and methods are sometimes declared as public, sometimes private, sometimes as static and sometimes as instance methods. My worry is that refactoring may have unintended consequences but this might be unavoidable. Are there documented best practices I can follow that can help me out? My instict is to organize a static/shared Win32 P/Invoke API class that lists all of these methods and associated constants in one file... (The code base is made up of over 20 projects with a lot of windows message passing and cross-thread calls. It's also a VB.NET project upgraded from VB6 if that makes a difference.)

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  • BitBlt code not working

    - by MusiGenesis
    I'm trying to use this code to draw a Bitmap directly onto a PictureBox: Bitmap bmp = (Bitmap)Bitmap.FromFile(@"C:\Users\Ken\Desktop\Load2.bmp"); Graphics grDest = Graphics.FromHwnd(pictureBox1.Handle); Graphics grSrc = Graphics.FromImage(bmp); IntPtr hdcDest = grDest.GetHdc(); IntPtr hdcSrc = grSrc.GetHdc(); BitBlt(hdcDest, 0, 0, pictureBox1.Width, pictureBox1.Height, hdcSrc, 0, 0, (uint)TernaryRasterOperations.SRCCOPY); // 0x00CC0020 grDest.ReleaseHdc(hdcDest); grSrc.ReleaseHdc(hdcSrc); but instead of rendering the Bitmap's contents it just draws a solid block of nearly-black. I'm pretty sure the problem is with the source hDC, because if I change SRCCOPY to WHITENESS in the above code, it draws a solid white block, as expected. Note: this next snippet works fine, so there's nothing wrong with the bitmap itself: Bitmap bmp = (Bitmap)Bitmap.FromFile(@"C:\Users\Ken\Desktop\Load2.bmp"); pictureBox1.Image = bmp;

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  • Marshal struct to unmanaged array

    - by Pedro
    Hi guys, I have a C# struct to represent a cartesian vector, something like this: public struct Vector { private double x; private double y; private double z; //Some properties/methods } Now I have an unmanaged C dll that I need to call with P/Invoke. Some methods expect a double[3] parameter. The unmanaged C signature is something like void Cross(double a[3], double b[3], double c[3]); Is there any way to set up a P/Invoke signature so I can pass instances of my Vector struct and marshal them transparently to unmanaged double[3]? I would also need bidirectional marshaling as the unmanaged function needs to write the output to the argument array, so I guess I would need to marshal as LpArray. Any ideas? Thanks Pedro

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  • How to show printer properties/preferences dialog?

    - by Patrick Klug
    I can't figure out how to properly show the printer preference dialog of a given printer so that the user can change the printer settings. Most of the examples that I can find online manage to show the dialog but any changes the user might make are lost which makes it useless. Example: http://www.codeproject.com/KB/system/PrinterPropertiesWindow.aspx (I tried to change the code as suggested by BartJoy but that didn't fix it) Does anyone know how to do this properly?

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  • error CS0133: Assigning the result of a function to a const in C#.net

    - by Greg
    Trying to tidy up scope and avoid possible multiple calls to RegisterWindowMessage. Currently have a class used once with the following member [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)] static extern int RegisterWindowMessage(string lpString); private int m_message = RegisterWindowMessage("MY_MSG"); As we only have one instance this seems ok, but think it would be more tidy to use. With my basic C# understanding this should call RegisterWindowMessage and assign the result to int and not allow it to change. private const int message = RegisterWindowMessage("MY_MSG"); however attempting to do so leads to a error CS0133: The expression being assigned to 'someclass.messageEvent' must be constant so now I'm confused, does this mean the function was being assigned and called each time m_message was used previously, is there something else missing?

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  • ShSetFolderPath works on win7, doesn't on XP

    - by pipboy3k
    Hey. I'm trying to use ShSetFolderPath function in C#. I work on Win7, I've managed to use ShSetKnownFolderPath and it works fine. Since this function is unavaible in WinXP, i tried to invoke ShSetFolderPath. Because i'm not familiar with invoking, I've done some searching and found something on some French forum. I don't speak French, but this declaration makes sense (as written in Remarks of function documentation in MSDN library): [DllImport( "Shell32.dll", CharSet = CharSet.Unicode, EntryPoint = "#232" ) ] private static extern int SHSetFolderPath( int csidl, IntPtr hToken, uint flags, string path ); I call it like that: private static int CSIDL_DESKTOP = 0x0000; public static void SetDesktopPath(string path) { int ret; ret = SHSetFolderPath(CSIDL_DESKTOP, IntPtr.Zero, 0, path); if (ret != 0) { Console.WriteLine(ret); Console.WriteLine(Marshal.GetExceptionForHR(ret)); } } It works in Win7, but in XP function returns -2147024809, which means "Value does not fall within the expected range". My guess is, it's something wrong with Dll importing. Any idea?

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  • Blittable Value Types

    - by Michael Covelli
    Here is a list of blittable types. It contains Int32 and Int64. But I don't see just plain "int" on the list. How does C# treat the plain "int" type? Does it just get replaced with Int32 or Int64 depending on the system? Or is there a subtle difference? Will using "int" ever cause a performance hit for marshalling?

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  • Is it valid to use unsafe struct * as an opaque type instead of IntPtr in .NET Platform Invoke?

    - by David Jeske
    .NET Platform Invoke advocates declaring pointer types as IntPtr. For example, the following [DllImport("user32.dll")] static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); However, I find when interfacing with interesting native interfaces, that have many pointer types, flattening everything into IntPtr makes the code very hard to read and removes the typical typechecking that a compiler can do. I've been using a pattern where I declare an unsafe struct to be an opaque pointer type. I can store this pointer type in a managed object, and the compiler can typecheck it form me. For example: class Foo { unsafe struct FOO {}; // opaque type unsafe FOO *my_foo; class if { [DllImport("mydll")] extern static unsafe FOO* get_foo(); [DllImport("mydll")] extern static unsafe void do_something_foo(FOO *foo); } public unsafe Foo() { this.my_foo = if.get_foo(); } public unsafe do_something_foo() { if.do_something_foo(this.my_foo); } While this example may not seem different than using IntPtr, when there are several pointer types moving between managed and native code, using these opaque pointer types for typechecking is a godsend. I have not run into any trouble using this technique in practice. However, I also have not seen an examples of anyone using this technique, and I wonder why. Is there any reason that the above code is invalid in the eyes of the .NET runtime? My main question is about how the .NET GC system treats "unsafe FOO *my_foo". Is this pointer something the GC system is going to try to trace, or is it simply going to ignore it? My hope is that because the underlying type is a struct, and it's declared unsafe, that the GC would ignore it. However, I don't know for sure. Thoughts?

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  • How to find that Mutex in C# is acquired?

    - by TN
    How can I find from mutex handle in C# that a mutex is acquired? When mutex.WaitOne(timeout) timeouts, it returns false. However, how can I find that from the mutex handle? (Maybe using p/invoke.) UPDATE: public class InterProcessLock : IDisposable { readonly Mutex mutex; public bool IsAcquired { get; private set; } public InterProcessLock(string name, TimeSpan timeout) { bool created; var security = new MutexSecurity(); security.AddAccessRule(new MutexAccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MutexRights.Synchronize | MutexRights.Modify, AccessControlType.Allow)); mutex = new Mutex(false, name, out created, security); IsAcquired = mutex.WaitOne(timeout); } #region IDisposable Members public void Dispose() { if (IsAcquired) mutex.ReleaseMutex(); } #endregion } Currently, I am using my own property IsAcquired to determine whether I should release a mutex. Not essential but clearer, would be not to use a secondary copy of the information represented by IsAcquired property, but rather to ask directly the mutex whether it is acquired by me. Since calling mutex.ReleaseMutex() throws an exception if it is not acquired by me. (By acquired state I mean that the mutex is in not-signaled state when I am owning the mutex.)

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  • Running DllImport commands from CreateRemoteThread

    - by Gbps
    I have a function named Msg that's imported from a dll named tier0.dll. I can DllImport this just fine, but the command only works when the dll is attached to another process which can complete the Msg command. Using CreateRemoteThread, it is possible that I could call Msg using C# while still letting it have access to the variables of the attached process it needs to complete the command? Thanks!

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  • Problem getting correct parameters for C# P/Invoke call to C++ dll

    - by Jim Jones
    Trying to Interop a functionality from the Outside In API from Oracle. Have the following function: SCCERR EXOpenExport {VTHDOC hDoc, VTDWORD dwOutputId, VTDWORD dwSpecType, VTLPVOID pSpec, VTDWORD dwFlags, VTSYSPARAM dwReserved, VTLPVOID pCallbackFunc, VTSYSPARAM dwCallbackData, VTLPHEXPORT phExport); From the header files I reduced the parameters to: typedef VTSYSPARAM VTHDOC, VTLPHDOC * typedef DWORD_PTR VTSYSPARAM typedef unsigned long DWORD_PTR typedef unsigned long VTDWORD typedef VTVOID* VTLPVOID #define VTVOID void typedef VTHDOC VTHEXPORT, *VTLPEXPORT These are for 32 bit windows Going through the header files, the example programs, and the documentation I found: 1. That pSpec could be a pointer to a buffer or NULL, so I set it to a IntPtr.Zero (documentation). 2. That dwFlags and dwReserved according to the documentation "Must be set by the developer to 0". 3. That pCallbackFunc can be set to NULL if I don't want to handle callbacks. 4. That the last two are based on structs that I wrote C# wrappers for using the [StructLayout(LayoutKind.Sequential)]. Then instatiated an instance and generated the parameters by first creating a IntPtr with Marshal.AllocHGlobal(Marshal.SizeOf(instance)), then getting the address value which is passed as a uint for dwCallbackData and a IntPtr for phExport. The final parameter list is as follows: 1. phDoc as a IntPtr which was loaded with an address by the DAOpenDocument function called before. 2. dwOutputId as uint set to 1535 which represents FI_JPEGFIF 3. dwSpecType as int set to 2 which represents IOTYPE_ANSIPATH 4. pSpec as an IntPtr.Zero where the output will be written 5. dwFlags as uint set to 0 as directed 6. dwReserved as uint set to 0 as directed 7. pCallbackFunc as IntPtr set to NULL as I will handle results 8. dwCallBackDate as uint the address of a buffer for a struct 9. phExport as IntPtr to another struct buffer still get an undefined error from the API. Meaning that the call returns a 961 which is not defined in any of the header files. In the past I have gotten this when my choice of parameter types are incorrect. I started out using Interop Assistant which was helpful in learning how many of the parameter types get translated. It is however limited by how well I am able to glean the correct native type from the header files. For example the hDoc parameter used in the preceding function was defined as a non-filesytem handle, so attempted to use Marshal to create a handle, then used an IntPtr, and finally it turned out to be an int (actually it was &phDoc used here). So is there a more scientific way of doing this, other than trial and error? Jim

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  • How to refresh to entire device's screen (Windows Mobile)?

    - by walidad
    Hi everybody, I'm working on a simple application that draws an alpha-blended picture on the screen's Device Context every 2 secs, I want to refresh the screen contents before the drawing operation (To erase the drawn pic), I have used many many trick but unfortunately, the screen won't refresh correctly, some regions still keep portions of the drawn pic I'm really frustrated from this issue :( These are the sources codes I have used, I'm using C# SendMessage(HWND_BROADCAST, WM_SYSCOLORCHANGE, IntPtr.Zero, IntPtr.Zero); // wasted time in the refreshing process is enough to keep this. UpdateWindow(HWND_BROADCAST);// does not work at all! InvalidateRect(IntPtr.Zero,IntPtr.Zero,true); // the same goes here. SendMessage(HWND_BROADCAST, WM_PAINT, IntPtr.Zero, IntPtr.Zero); // pfffff ! SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, new IntPtr(SPI_SETNONCLIENTMETRICS), IntPtr.Zero); // trying to refresh the explorer, no resutl I used also EnumWindows and call back , very slow and does not fit my case. I wanna refresh the whole screen Help please! Regards Waleed

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  • How to get window opened/closed/minimized messages from a native app?

    - by Josh Santangelo
    It's tough to write a good title for this one. I'm working on a WPF application which needs to know about the existence of all other open windows on the system. I'm able to do this by calling the native EnumWindows method just fine, and I can call other native methods to filter out just the windows I'm interested in. This works well. The problem I'm having is that I want to know when a window is opened or closed (and, ideally, minimized). I can do this by polling with EnumWindows, but I'm finding that to be pretty slow, even if I push it off to another thread. Is there a better way to get notifications of window opened/closed/minimized? Keep in mind that my knowledge of non-managed code is pretty limited.

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  • C#: Access 32-bit/64-bit DLL depending on platform

    - by Thorsten Dittmar
    Hi, we use a self-written 32bit C++ DLL from our C# applications. Now we've noticed that when the C# applications are run on a 64bit system, the 64bit runtime is automatically used and of course the 32bit DLL can not be accessed from the 64bit runtime. My question is: is there a way of using the 32bit DLL? If not, if I created a 64bit version of the DLL, would it be easily possible to let the application choose which one to P/Invoke to? I'm thinking of creating two helper classes in C#: One that imports the functions from the 32bit DLL and one that imports from the 64bit DLL, then creating a wrapper class with one function for each imported function that calls either the 32bit importer or the 64bit importer depending on the "bittyness" of the OS. Would that work? Or is there another easy way to do things?

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  • PostMessage does not seem to be working.

    - by Vaccano
    I am trying to use PostMessage to send a tab key. Here is my code: // This class allows us to send a tab key when the the enter key // is pressed for the mooseworks mask control. public class MaskKeyControl : MaskedEdit { // [DllImport("coredll.dll", SetLastError = true, CharSet = CharSet.Auto)] // static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); [return: MarshalAs(UnmanagedType.Bool)] // I am calling this on a Windows Mobile device so the dll is coredll.dll [DllImport("coredll.dll", SetLastError = true)] static extern bool PostMessage(IntPtr hWnd, uint Msg, Int32 wParam, Int32 lParam); public const Int32 VK_TAB = 0x09; public const Int32 WM_KEYDOWN = 0x100; protected override void OnKeyDown(KeyEventArgs e) { if (e.KeyData == Keys.Enter) { PostMessage(this.Handle, WM_KEYDOWN, VK_TAB, 0); return; } base.OnKeyDown(e); } protected override void OnKeyPress(KeyPressEventArgs e) { if (e.KeyChar == '\r') e.Handled = true; base.OnKeyPress(e); } } When I press enter the code gets called, but nothing happens. Then I press TAB and it works fine. (So there is something wrong with my sending of the Tab Message.)

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  • What kind of assemblies can be called using P/Invoke ?

    - by milan
    Hi all, I allready asked at: Is it possible to call unmanaged code using C# reflection from managed code ? if it is possible to call C/C++ library unmanaged function with Invoke and reflection from .NET and the answer is yes. What I am not clear about is can I call using P/Invoke ANY assembly written/compiled/build with other compilers on my Windows PC like Labwindows/CVI(have some kind of C compiler) or Java written dll's, exe. If this is possible is it the same as explained in above given link using "Marshal.GetDelegateForFunctionPointer" ? Thanks! Milan.

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