保存DC到bmp图片的两种方法

程序员文章站 2024-03-21 23:31:52

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这里主要记录一下平时经常用到的控件贴图方法，在必要的时候将DC保存成bmp文件方便检查程序中贴图有时背景不正确的情况。

方法1:

纯Win32 GDI的方法，保存HBITMAP用的是CImage类

void SaveDC2BMP(HWND hwnd, TCHAR *path)
{
    HBITMAP hBitmap;
    HDC hdc, hTempDC;
    RECT rect;
    int w, h;
    
    
    hdc = ::GetDC(hwnd);
    ::GetClientRect(hwnd, &rect);

    w = rect.right - rect.left;
    h = rect.bottom - rect.top;

    hTempDC = ::CreateCompatibleDC(hdc);
    hBitmap = ::CreateCompatibleBitmap(hdc, w, h);
    ::SelectObject(hTempDC, hBitmap);

    ::BitBlt(hTempDC, 0, 0, w, h, hdc, 0, 0, SRCCOPY);

    CImage image;
    image.Attach(hBitmap);
    image.Save(path);
    
    ::DeleteDC(hTempDC);
    ::DeleteObject(hBitmap);
    ::ReleaseDC(hwnd, hdc);
}

方法2：

MFC的方法，其中保存BMP文件用了网上找的一个例子，可以实现和CImage一样效果

void SaveCDC2BMP(CWnd *pWnd, TCHAR *path)
{
    CDC tempDC;
    CBitmap bitmp;
    CDC *pDC = pWnd->GetDC(); 

    CRect rect;

    pWnd->GetClientRect(&rect);
    
    tempDC.CreateCompatibleDC(pDC);
    bitmp.CreateCompatibleBitmap(pDC, rect.Width(), rect.Height());
    tempDC.SelectObject(&bitmp);

    tempDC.BitBlt(0, 0, rect.Width(), rect.Height(), pDC, 0, 0, SRCCOPY);
 
    //CImage image;
    //image.Attach(bitmp.operator HBITMAP());
    //image.Save(path);

    SaveBmp(bitmp.operator HBITMAP(), path);
         
    bitmp.DeleteObject();
    tempDC.DeleteDC();
    pDC->DeleteDC();
}

BOOL SaveBmp(HBITMAP hBitmap, TCHAR* fileName)
{
    HDC   hDC;
    //当前分辨率下每象素所占字节数     
    int   iBits;
    //位图中每象素所占字节数     
    WORD  wBitCount;
    //定义调色板大小，位图中像素字节大小，位图文件大小，写入文件字节数  
    DWORD dwPaletteSize = 0, dwBmBitsSize = 0, dwDIBSize = 0, dwWritten = 0;
    //位图属性结构       
    BITMAP   Bitmap;
    //位图文件头结构     
    BITMAPFILEHEADER   bmfHdr;
    //位图信息头结构       
    BITMAPINFOHEADER   bi;
    //指向位图信息头结构         
    LPBITMAPINFOHEADER lpbi;
    //定义文件，分配内存句柄，调色板句柄       
    HANDLE  fh, hDib, hPal, hOldPal = NULL;

    //计算位图文件每个像素所占字节数       
    hDC = CreateDC(_T("DISPLAY"), NULL, NULL, NULL);
    iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
    DeleteDC(hDC);
    if (iBits <= 1)wBitCount = 1;
    else if (iBits <= 4) wBitCount = 4;
    else if (iBits <= 8) wBitCount = 8;
    else wBitCount = 24;

    GetObject(hBitmap, sizeof(Bitmap), (LPSTR)&Bitmap);
    bi.biSize = sizeof(BITMAPINFOHEADER);
    bi.biWidth = Bitmap.bmWidth;
    bi.biHeight = Bitmap.bmHeight;
    bi.biPlanes = 1;
    bi.biBitCount = wBitCount;
    bi.biCompression = BI_RGB;
    bi.biSizeImage = 0;
    bi.biXPelsPerMeter = 0;
    bi.biYPelsPerMeter = 0;
    bi.biClrImportant = 0;
    bi.biClrUsed = 0;

    dwBmBitsSize = ((Bitmap.bmWidth * wBitCount + 31) / 32) * 4 * Bitmap.bmHeight;

    //   为位图内容分配内存       
    hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER));
    lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
    *lpbi = bi;

    //   处理调色板         
    hPal = GetStockObject(DEFAULT_PALETTE);
    if (hPal)
    {
        hDC = ::GetDC(NULL);
        //hDC   =   m_pDc->GetSafeHdc();     
        hOldPal = ::SelectPalette(hDC, (HPALETTE)hPal, FALSE);
        RealizePalette(hDC);
    }
    //   获取该调色板下新的像素值       
    GetDIBits(hDC, hBitmap, 0, (UINT)Bitmap.bmHeight, (LPSTR)lpbi + sizeof(BITMAPINFOHEADER)
        + dwPaletteSize, (BITMAPINFO *)lpbi, DIB_RGB_COLORS);

    //   恢复调色板         
    if (hOldPal)
    {
        ::SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
        RealizePalette(hDC);
        ::ReleaseDC(NULL, hDC);
    }

    //   创建位图文件         
    fh = CreateFile(fileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
        FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);

    if (fh == INVALID_HANDLE_VALUE)
    {
        GlobalUnlock(hDib);
        GlobalFree(hDib);
        return FALSE;
    }

    //   设置位图文件头       
    bmfHdr.bfType = 0x4D42;   //   ;BM;  
    dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize;
    bmfHdr.bfSize = dwDIBSize;
    bmfHdr.bfReserved1 = 0;
    bmfHdr.bfReserved2 = 0;
    bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER) + dwPaletteSize;
    //   写入位图文件头  
    WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
    //   写入位图文件其余内容  
    WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);

    //   清除  
    GlobalUnlock(hDib);
    GlobalFree(hDib);
    CloseHandle(fh);

    return TRUE;
}

下面是一个测的demo效果，分别获取主窗口背景、static控件背景、和桌面背景

保存DC到bmp图片的两种方法