WM_PRINTCLIENT为BMP出来全黑 [英] WM_PRINTCLIENT to BMP coming out all black

问题描述

我是新来使用MFC和位图工作。我有一个 HWND ，我想打印到使用 WM_PRINTCLIENT 的位图。这是我迄今：

I am new to working with MFC and bitmaps. I have a HWND, which I want to print onto a bitmap using WM_PRINTCLIENT. This is what I have thus far:

编辑：

CRect rcWindow;
GetClientRect(hWnd, &rcWindow);         

HDC hDC = GetDC(hWnd);          
HDC hBitmapDC = CreateCompatibleDC(hDC);
HBITMAP hBitmap = CreateCompatibleBitmap(hDC, rcWindow.Width(), rcWindow.Height());             

SelectObject(hBitmapDC, hBitmap);

SendMessage(hWnd, WM_PRINTCLIENT, (WPARAM)hBitmapDC, PRF_CHILDREN | PRF_CLIENT | PRF_NONCLIENT);                                

CImage image;
image.Attach(hBitmap);
image.Save(_T("C:\\Test.bmp"), Gdiplus::ImageFormatBMP);

然而，这导致了位图，它是全黑的。任何人都可以看到我在做什么错了？

This however results in a bitmap that is all black. Can anyone see what I am doing wrong?

推荐答案

请尝试以下操作：

    HDC hBitmapDC = ::CreateCompatibleDC(hDC);
    HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, rcWindow.Width(), rcWindow.Height());
    ::SelectObject(hBitmapDC, hBitmap);

    // Blt the existing background into the bitmap DC
    ::BitBlt(hBitmapDC, 
             0, 0, rcWindow.Width(), rcWindow.Height(), 
             hDC, rcWindow.left, rcWindow.top, SRCCOPY);

不要忘了删除使用:: DeleteObject的使用DeleteDC，位图DC的位图对象，当您与他们完成...

Don't forget to delete the bitmap object using ::DeleteObject, and the bitmap DC using DeleteDC, when you've finished with them...

希望这有助于

这篇关于WM_PRINTCLIENT为BMP出来全黑的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！