MFC透明位圖顯示函數

研究好久才弄好，註釋的比較詳細，不明白的函數可以參考MSDN

  bool TransparentDIB(CBitmap * dib, /*要繪製的位圖*/ CDC * pDC, /*目標DC*/ CRect * rct, /*目標矩形*/ COLORREF transColor, /*透明色*/ bool bStretch /*是否拉伸位圖以適應目標矩形*/) { //驗證參數 if(dib == NULL || pDC == NULL || rct == NULL) return false; int nWidth; int nHeight; //位圖信息對象 BITMAP w_bitmap_info; //獲取位圖信息 dib->GetBitmap(&w_bitmap_info); //新建設備上下文 CDC w_memoryDC; //創建兼容內存DC w_memoryDC.CreateCompatibleDC(pDC); //根據拉伸狀態獲得圖像實際繪製尺寸 if(bStretch) { nWidth = rct->Width(); nHeight = rct->Height(); } else { nWidth = w_bitmap_info.bmWidth; nHeight = w_bitmap_info.bmHeight; } w_memoryDC.SelectObject(dib);//選入位圖對象 w_memoryDC.SetBkColor(transColor);//設置透明色 CDC w_maskDC;//創建兼容內存DC作爲掩碼DC w_maskDC.CreateCompatibleDC(pDC);//創建兼容內存DC作爲掩碼DC CBitmap w_maskBitmap;//創建新位圖作爲掩碼位圖 w_maskBitmap.CreateBitmap(w_bitmap_info.bmWidth,w_bitmap_info.bmHeight,1,1,NULL); //創建新位圖作爲掩碼位圖 w_maskDC.SelectObject(&w_maskBitmap);//選入掩碼位圖 w_maskDC.BitBlt(0,0,w_bitmap_info.bmWidth,w_bitmap_info.bmHeight,&w_memoryDC,0,0,SRCCOPY); //SRCCOPY方式將源位圖以原始大小繪製到掩碼DC pDC->StretchBlt(0,0,nWidth,nHeight,&w_memoryDC,0,0,w_bitmap_info.bmWidth,w_bitmap_info.bmHeight,SRCINVERT); //SRCINVERT方式將源位圖拉伸繪製到窗口DC pDC->StretchBlt(0,0,nWidth,nHeight,&w_maskDC,0,0,w_bitmap_info.bmWidth,w_bitmap_info.bmHeight,SRCAND); //SRCAND方式將掩碼位圖拉伸繪製到窗口DC pDC->StretchBlt(0,0,nWidth,nHeight,&w_memoryDC,0,0,w_bitmap_info.bmWidth,w_bitmap_info.bmHeight,SRCINVERT); //SRCINVERT方式將源位圖拉伸繪製到窗口DC //完成繪製 w_memoryDC.DeleteDC();//刪除內存DC w_maskDC.DeleteDC();//刪除掩碼DC return true; }