Question

我想使用单个CDC来绘制位于CDC中的3位图，然后将其传递给UpdateLayeredWindow。我的问题是我无法正确获取UpdateLayeredWindow函数的SIZE* psize参数！有人可以帮忙吗？我该怎么办？

BLENDFUNCTION bBlendFnc = {
    AC_SRC_OVER,
    0,
    255,
    AC_SRC_ALPHA
};

CBitmap btCdcBuff;
CBitmap* cache;
BITMAP hbCdcBuff;

btCdcBuff.CreateCompatibleBitmap(pCdcMain, szWndSize.cx, szWndSize.cy); btCdcBuff.GetBitmap(&hbCdcBuff);

cache = pCdcMain->SelectObject(&btCdcBuff); // pCdcMain is a compatible CDC with the screen (pCdcScreen)

Blend(&btIcon); // This function just creates a compatible CDC from a CPaintDC, selects the passed in CBitmap via SelectObject and AlphaBlends it to the pCdcMain.
pCdcMain->SelectObject(cache);

UpdateLayeredWindow(pCdcScreen, NULL, new CSize(hbCdcBuff.bmWidth, hbCdcBuff.bmHeight), pCdcMain, new CPoint(0, 0), 0, &bBlendFnc, ULW_ALPHA) // This fails and returns false

Answer 1

将CreateCompatibleBitmap与UpdateLayeredWindow一起使用时，请确保传入屏幕的CDC（即pCdcScreen而不是pCdcMain），以便创建的位图格式正确。请参阅此主题：http://social.msdn.microsoft.com/Forums/en/windowsuidevelopment/thread/1fbcf5e4-b9eb-4537-bf0b-d330aa333fea

在MFC中的一个设备上下文中绘制多个位图 - winapi

1 个答案: