c++ - How to get Pixel data \ Pixel buffer from a window and extract RGB?

Question

I'm drawing text (textOut) and Rectangles on my window... and I would like to get the RGB buffer from it... How can I do it?

Answer 1

有2个选项：

首先，您可以使用 GetPixel()。我用了很多。它工作正常：

COLORREF GetPixel(
  HDC hdc, 
  int nXPos, 
  int nYPos
); 

在我们的时代，使用此功能的处理器甚至可以在某些情况下使用矩形。

其次，您可以将屏幕内容复制到位图中。之后，您可以将其放在剪贴板中，使用您的代码进行处理等。核心功能是：

BOOL BitBlt(
  _In_  HDC hdcDest,
  _In_  int nXDest,
  _In_  int nYDest,
  _In_  int nWidth,
  _In_  int nHeight,
  _In_  HDC hdcSrc,
  _In_  int nXSrc,
  _In_  int nYSrc,
  _In_  DWORD dwRop
);

如果需要，我可以发布更详细的代码段。

// Pick up the DC.
HDC hDC = ::GetDC(m_control);

// Pick up the second DC.
HDC hDCMem = ::CreateCompatibleDC(hDC);

// Create the in memory bitmap.
HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, bmp_size_x, bmp_size_y);

// Put bitmat into the memory DC. This will make it functional.
HBITMAP hBmpOld = (HBITMAP)::SelectObject(hDCMem, hBitmap);

// Clear the background.
HBRUSH hBkgr = ::CreateSolidBrush(props.bkgr_brush);
RECT bitmap_rect = { 0, 0, bmp_size_x, bmp_size_y };
::FillRect(hDCMem, &bitmap_rect, hBkgr);
::DeleteObject(hBkgr);

// Do the job.
::BitBlt(hDCMem, margins_rect.left, margins_rect.top,
    size_to_copy_x, size_to_copy_y, hDC,
    screen_from_x, screen_from_y, SRCCOPY);