从 C++ CLR/CLI 项目的资源文件加载图像

Question

我的项目是 c++ CLR/CLI，我的资源文件中有一些 PNG 图像，我想在单击按钮时更改 System::Windows::Forms::Button 的 BackgroundImage，我的代码如下：

#include <Windows.h>
#include "resource.h"

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
    HBITMAP hBitMap = (HBITMAP) LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_PNG2), IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
    Bitmap^  bitMap = Bitmap::FromHbitmap((IntPtr) hBitMap);
    DeleteObject(hBitMap);
    button1->BackgroundImage = (System::Drawing::Image^) bitMap;
}

这是我的 resource.h:

//{{NO_DEPENDENCIES}}
// Microsoft Visual C++ generated include file.
// Used by Disneyy.rc
//
#define IDB_PNG1                        101
#define IDB_PNG2                        102
#define IDB_PNG3                        103

// Next default values for new objects
// 
#ifdef APSTUDIO_INVOKED
#ifndef APSTUDIO_READONLY_SYMBOLS
#define _APS_NEXT_RESOURCE_VALUE        104
#define _APS_NEXT_COMMAND_VALUE         40001
#define _APS_NEXT_CONTROL_VALUE         1001
#define _APS_NEXT_SYMED_VALUE           101
#endif
#endif

编译时出现此错误：

1>MyForm.obj : error LNK2028: unresolved token (0A000036) "extern "C" void * __stdcall LoadImageW(struct HINSTANCE__ *,wchar_t const *,unsigned int,int,int,unsigned int)" (?LoadImageW@@$$J224YGPAXPAUHINSTANCE__@@PB_WIHHI@Z) referenced in function "private: void __clrcall Disneyy::MyForm::button1_Click(class System::Object ^,class System::EventArgs ^)" (?button1_Click@MyForm@Disneyy@@$$FA$AAMXP$AAVObject@System@@P$AAVEventArgs@4@@Z)
1>MyForm.obj : error LNK2028: unresolved token (0A00003F) "extern "C" int __stdcall DeleteObject(void *)" (?DeleteObject@@$$J14YGHPAX@Z) referenced in function "private: void __clrcall Disneyy::MyForm::button1_Click(class System::Object ^,class System::EventArgs ^)" (?button1_Click@MyForm@Disneyy@@$$FA$AAMXP$AAVObject@System@@P$AAVEventArgs@4@@Z)
1>MyForm.obj : error LNK2019: unresolved external symbol "extern "C" void * __stdcall LoadImageW(struct HINSTANCE__ *,wchar_t const *,unsigned int,int,int,unsigned int)" (?LoadImageW@@$$J224YGPAXPAUHINSTANCE__@@PB_WIHHI@Z) referenced in function "private: void __clrcall Disneyy::MyForm::button1_Click(class System::Object ^,class System::EventArgs ^)" (?button1_Click@MyForm@Disneyy@@$$FA$AAMXP$AAVObject@System@@P$AAVEventArgs@4@@Z)
1>MyForm.obj : error LNK2019: unresolved external symbol "extern "C" int __stdcall DeleteObject(void *)" (?DeleteObject@@$$J14YGHPAX@Z) referenced in function "private: void __clrcall Disneyy::MyForm::button1_Click(class System::Object ^,class System::EventArgs ^)" (?button1_Click@MyForm@Disneyy@@$$FA$AAMXP$AAVObject@System@@P$AAVEventArgs@4@@Z)

编辑： 好的，我通过将 User32.lib 添加到 Additional Dependencies 并将入口点指定为 main 来修复它。但是这一行有问题：

HBITMAP hBitMap = (HBITMAP) LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_PNG2), IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);

现在我收到这个错误：

First-chance exception at 0x77130c3f in Disneyy.exe: 0xC0000005: Access violation reading location 0x00000066.
A first chance exception of type 'System.AccessViolationException' occurred in Disneyy.exe
An unhandled exception of type 'System.AccessViolationException' occurred in Disneyy.exe
Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

编辑： 我再次通过将 IMAGE_BITMAP 更改为 BI_PNG 来修复它，但现在出现了一个新错误：Bitmap^ bitMap = Bitmap::FromHbitmap((IntPtr) hBitMap);

A first chance exception of type 'System.Runtime.InteropServices.ExternalException' occurred in System.Drawing.dll
An unhandled exception of type 'System.Runtime.InteropServices.ExternalException' occurred in System.Drawing.dll
Additional information: A generic error occurred in GDI+.

Answer 1

经过数小时的研究，我终于找到了一个适用的解决方案，效果很好！

此解决方案结合了 Giuseppe Pischedda 的回答：https://www.codeproject.com/Articles/17996/Load-JPEG-images-from-DLL-with-LoadResource-in-Man

和 Bordon 的回答：https://social.msdn.microsoft.com/Forums/de-DE/c8dea6f9-0564-49d6-9782-117207031140/loadfromresource-fails-for-loading-png-files-from-resource?forum=vcmfcatl

由我改编为 PNG 图片：

public: System::Drawing::Image^  getImageFromRes(long resource_ID) {
    // Function getImageFromRes
    // A function for loading PNG images from resources in C++ CLR/CLI
    // Copyright (C) Giuseppe Pischedda 2007 for most code
    // and a little part of this code by Bordon and adapted by me for PNG images in C++ CLR/CLI.

    //Load the resource module:
    HMODULE hInst = NULL;

    // Find the resource using the resource ID from file "resource.h"
    HRSRC hResource = ::FindResource(hInst, MAKEINTRESOURCE(resource_ID), L"PNG");
    if (!hResource) return nullptr;

    // Load the resource and save the total size.
    DWORD Size = SizeofResource(hInst, hResource);
    HGLOBAL MemoryHandle = LoadResource(hInst, hResource);
    if (MemoryHandle == NULL) return nullptr;

    //Create a cli::array of byte with size = total size + 2
    cli::array<BYTE>^  MemPtr = gcnew array<BYTE>(Size + 2);

    //Cast from LPVOID to char *
    char *lkr = (char *) (LockResource(MemoryHandle));

    //Copy from unmanaged memory to managed array
    System::Runtime::InteropServices::Marshal::Copy((IntPtr) lkr, MemPtr, 0, Size);

    // Create a new MemoryStream with size = MemPtr
    System::IO::MemoryStream^  stream = gcnew System::IO::MemoryStream(MemPtr);

    //Write in the MemoryStream
    stream->Write(MemPtr, 0, Size);

    //Set the position for read the stream
    stream->Position = 0;

    //Free allocated resources
    FreeLibrary(hInst);

    //Create an Image abstract class pointer
    System::Drawing::Image^  ptrPNG;

    //Assign the stream to abstract class pointer
    ptrPNG = System::Drawing::Image::FromStream(stream);
    return ptrPNG;
}

用法：

System::Drawing::Image^  image = getImageFromRes(IDB_PNG2);
if (image != nullptr) button1->BackgroundImage = image;

从 C++ CLR/CLI 项目的资源文件加载图像

Load image from Resource Files of a c++ CLR/CLI project

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