在地图上使图片透明

效果图太差了。

hdc=GetDC(hWnd);
   mdc=CreateCompatibleDC(hdc);
   bg=(HBITMAP)LoadImage(NULL,"sky.bmp",IMAGE_BITMAP,1050,550,
    LR_LOADFROMFILE);
   dra=(HBITMAP)LoadImage(NULL,"dra.bmp",IMAGE_BITMAP,140,117,
    LR_LOADFROMFILE);
   SelectObject(mdc,bg);
   BitBlt(hdc,0,0,1050,550,mdc,0,0,SRCCOPY);
   SelectObject(mdc,dra);
   BitBlt(hdc,100,100,140,117,mdc,140,117,SRCAND);
   BitBlt(hdc,100,100,140,117,mdc,0,0,SRCPAINT);

ReleaseDC(hWnd,mdc);
  DeleteObject(bg);
  DeleteObject(dra);