在C - windows中截图

inn6fuwd  于 2021-05-29  发布在  Windows
关注(0)|答案(2)|浏览(160)

我想在我的windows机器上用C截图，然后保存为jpg或bmp或其他格式。无论如何，我试着自己做，它没问题，工作很好，但它慢得令人无法忍受，不像prt scr键-我想知道是否有一种方法可以访问prt scr剪贴板，并以某种方式粘贴在jpg/png文件或如果有更快的方法来获得所有的屏幕像素。这是我的代码：

  1. int main()
  2. {
  3.     bitmap_t pic;
  4.     int i, j;
  5.     pic.width = GetSystemMetrics(SM_CXSCREEN);
  6.     pic.height = GetSystemMetrics(SM_CYSCREEN);
  8.     pic.pixels = (pixel_t**)malloc(sizeof(pixel_t*)*pic.width);
  9.     for(i = 0 ; i < pic.height ; i++)
  10.     {
  11.         pic.pixels[i] = (pixel_t*)malloc(sizeof(pixel_t)*pic.height);
  12.     }
  14.     HDC hdc = GetDC(NULL);
  15.     COLORREF c;
  16.     printf("Size of your monitor is %d by %d.\n", pic.width, pic.height);
  17.     for(i = 0 ; i < pic.width ; i++)
  18.     {
  19.         for(j = 0 ; j < pic.height ; j++)
  20.         {
  21.             c = GetPixel(hdc, i, j);
  22.             pic.pixels[i][j].red = (uint8_t)GetRValue(c);
  23.             pic.pixels[i][j].green = (uint8_t)GetGValue(c);
  24.             pic.pixels[i][j].blue = (uint8_t)GetBValue(c);
  25.         }
  26.     }
  28.     ReleaseDC(NULL, hdc);
  29.     save_png_to_file(&pic, "D:\\pic.png");
  31.     for(i = 0 ; i < pic.height ; i++)
  32.     {
  33.         free(pic.pixels[i]);
  34.     }
  35.     free(pic.pixels);
  37.     return 0;
  38. }

字符串
函数save_png_to_file工作正常，循环时间太长（我的屏幕是1366 x768，超过百万个循环条目）-为什么当键prt scr轻松完成时，它会这么慢？

windows

2条答案

按热度按时间
64jmpszr

64jmpszr1#

嗯. GetPixel()本身真的很慢，然后将它结合在一个循环中，并进行多次重复.

  1. BOOL SaveToFile(HBITMAP hBitmap3, LPCTSTR lpszFileName)
  2. {   
  3.   HDC hDC;
  4.   int iBits;
  5.   WORD wBitCount;
  6.   DWORD dwPaletteSize=0, dwBmBitsSize=0, dwDIBSize=0, dwWritten=0;
  7.   BITMAP Bitmap0;
  8.   BITMAPFILEHEADER bmfHdr;
  9.   BITMAPINFOHEADER bi;
  10.   LPBITMAPINFOHEADER lpbi;
  11.   HANDLE fh, hDib, hPal,hOldPal2=NULL;
  12.   hDC = CreateDC("DISPLAY", NULL, NULL, NULL);
  13.   iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
  14.   DeleteDC(hDC);
  15.   if (iBits <= 1)
  16.     wBitCount = 1;
  17.   else if (iBits <= 4)
  18.     wBitCount = 4;
  19.   else if (iBits <= 8)
  20.     wBitCount = 8;
  21.   else
  22.     wBitCount = 24; 
  23.   GetObject(hBitmap3, sizeof(Bitmap0), (LPSTR)&Bitmap0);
  24.   bi.biSize = sizeof(BITMAPINFOHEADER);
  25.   bi.biWidth = Bitmap0.bmWidth;
  26.   bi.biHeight =-Bitmap0.bmHeight;
  27.   bi.biPlanes = 1;
  28.   bi.biBitCount = wBitCount;
  29.   bi.biCompression = BI_RGB;
  30.   bi.biSizeImage = 0;
  31.   bi.biXPelsPerMeter = 0;
  32.   bi.biYPelsPerMeter = 0;
  33.   bi.biClrImportant = 0;
  34.   bi.biClrUsed = 256;
  35.   dwBmBitsSize = ((Bitmap0.bmWidth * wBitCount +31) & ~31) /8
  36.                                                 * Bitmap0.bmHeight; 
  37.   hDib = GlobalAlloc(GHND,dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER));
  38.   lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
  39.   *lpbi = bi;
  41.   hPal = GetStockObject(DEFAULT_PALETTE);
  42.   if (hPal)
  43.   { 
  44.     hDC = GetDC(NULL);
  45.     hOldPal2 = SelectPalette(hDC, (HPALETTE)hPal, FALSE);
  46.     RealizePalette(hDC);
  47.   }
  49.   GetDIBits(hDC, hBitmap3, 0, (UINT) Bitmap0.bmHeight, (LPSTR)lpbi + sizeof(BITMAPINFOHEADER) 
  50.     +dwPaletteSize, (BITMAPINFO *)lpbi, DIB_RGB_COLORS);
  52.   if (hOldPal2)
  53.   {
  54.     SelectPalette(hDC, (HPALETTE)hOldPal2, TRUE);
  55.     RealizePalette(hDC);
  56.     ReleaseDC(NULL, hDC);
  57.   }
  59.   fh = CreateFile(lpszFileName, GENERIC_WRITE,0, NULL, CREATE_ALWAYS, 
  60.     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL); 
  62.   if (fh == INVALID_HANDLE_VALUE)
  63.     return FALSE; 
  65.   bmfHdr.bfType = 0x4D42; // "BM"
  66.   dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize;
  67.   bmfHdr.bfSize = dwDIBSize;
  68.   bmfHdr.bfReserved1 = 0;
  69.   bmfHdr.bfReserved2 = 0;
  70.   bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER) + dwPaletteSize;
  72.   WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
  74.   WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);
  75.   GlobalUnlock(hDib);
  76.   GlobalFree(hDib);
  77.   CloseHandle(fh);
  79.   return TRUE;
  80. } 
  82. int screenCapture(int x, int y, int w, int h, LPCSTR fname)
  83. {
  84.     HDC hdcSource = GetDC(NULL);
  85.     HDC hdcMemory = CreateCompatibleDC(hdcSource);
  87.     int capX = GetDeviceCaps(hdcSource, HORZRES);
  88.     int capY = GetDeviceCaps(hdcSource, VERTRES);
  90.     HBITMAP hBitmap = CreateCompatibleBitmap(hdcSource, w, h);
  91.     HBITMAP hBitmapOld = (HBITMAP)SelectObject(hdcMemory, hBitmap);
  93.     BitBlt(hdcMemory, 0, 0, w, h, hdcSource, x, y, SRCCOPY);
  94.     hBitmap = (HBITMAP)SelectObject(hdcMemory, hBitmapOld);
  96.     DeleteDC(hdcSource);
  97.     DeleteDC(hdcMemory);
  99.     HPALETTE hpal = NULL;
  100.     if(SaveToFile(hBitmap, fname)) return 1;
  101.     return 0;
  102. }
  104. int main()
  105. {
  106.     screenCapture(0, 0, GetSystemMetric, 768, "D:\\MyFirstScreeshot.bmp");
  108.     return 0;
  109. }

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x3naxklr

x3naxklr2#

这是在这里解释：
http://msdn.microsoft.com/en-us/library/dd183402(v=vs.85).aspx
请参阅示例中的CaptureAnImage()函数。整个代码有点复杂，因为它是一个完整的win32应用程序，但它显示了如何捕获特定窗口并保存到filename.bmp。

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