在MFC中的一個設備上下文中繪製多個位圖 - winapi

Question

我想使用一個CDC，其中繪製3位圖，位於CDC，然後將它傳遞到UpdateLayeredWindow。我的問題是，我無法獲得UpdateLayeredWindow函數的SIZE* psize參數！誰可以幫忙？我該怎麼辦？

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

當使用CreateCompatibleBitmap用UpdateLayeredWindow，請確保您在CDC通過對屏幕（即pCdcScreen不pCdcMain），從而使創建位圖格式正確的。看到這個帖子：http://social.msdn.microsoft.com/Forums/en/windowsuidevelopment/thread/1fbcf5e4-b9eb-4537-bf0b-d330aa333fea