2013-01-18 11:33:00
最近遇到UpdateLayeredWindow在远程协助下会失败，但是GetLastError返回0。 后来看了http://blog.csdn.net/debehe/article/details/4767472，解决了，记一笔。 原代码：
1void Update()
2{
3 CDC dc = GetDC(m_hWnd);
4 CDC dcMemory;
5 dcMemory.CreateCompatibleDC(dc);
6
7 CRect rect;
8 GetClientRect(m_hWnd, &rect);
9
10 CBitmap bmp = CreateCompatibleBitmap(dc, rect.Width(), rect.Height());
11 dcMemory.SelectBitmap(bmp);
12
13 {
14 Graphics g(dcMemory);
15 g.SetInterpolationMode(InterpolationModeNearestNeighbor);
16 g.SetPixelOffsetMode(PixelOffsetModeHalf);
17
18 // Rendering...
19 }
20
21 POINT pt = { 0, 0};
22 BLENDFUNCTION stBlend = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
23 SIZE szWindow = { rect.Width(), rect.Height() };
24 UpdateLayeredWindow(m_hWnd, dc, NULL, &szWindow, dcMemory, &pt, 0, &stBlend, ULW_ALPHA);
25}
新代码：
1void Update()
2{
3 CDC dc = GetDC(m_hWnd);
4 CDC dcMemory;
5 dcMemory.CreateCompatibleDC(dc);
6
7 CRect rect;
8 GetClientRect(m_hWnd, &rect);
9
10 //
11 // 注意：一定要自己创建一个 32 位位图，不要 CreateCompatibleBitmap，否则远程协助下可能无法正常显示
12 //
13
14 BITMAPINFOHEADER bmih = { sizeof(BITMAPINFOHEADER) };
15 bmih.biWidth = rect.Width();
16 bmih.biHeight = rect.Height();
17 bmih.biPlanes = 1;
18 bmih.biBitCount = 32; // !注意：要 32 位
19 bmih.biCompression = BI_RGB;
20
21 BYTE *pBits = NULL;
22 HBITMAP hBitmap = CreateDIBSection(NULL, (BITMAPINFO *)&bmih, 0, (LPVOID *)&pBits, NULL, 0);
23
24 if (hBitmap == NULL)
25 {
26 return;
27 }
28
29 CBitmap bmp(hBitmap);
30 dcMemory.SelectBitmap(bmp);
31
32 {
33 Graphics g(dcMemory);
34 g.SetInterpolationMode(InterpolationModeNearestNeighbor);
35 g.SetPixelOffsetMode(PixelOffsetModeHalf);
36
37 // Rendering...
38 }
39
40 POINT pt = { 0, 0};
41 BLENDFUNCTION stBlend = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
42 SIZE szWindow = { rect.Width(), rect.Height() };
43 UpdateLayeredWindow(m_hWnd, dc, NULL, &szWindow, dcMemory, &pt, 0, &stBlend, ULW_ALPHA);
44}
首发：http://www.cppblog.com/Streamlet/archive/2013/01/18/197382.html