绘制蓝色半透明矩形的代码

//以下是一个绘制蓝色半透明矩形的代码
CDC memdc;
CBitmap bmp,*pOldBitmap;
memdc.CreateCompatibleDC(pDC);
bmp.CreateCompatibleBitmap(pDC,300,200);
pOldBitmap = memdc.SelectObject(&bmp);
memdc.FillSolidRect(0,0,300,200,RGB(0,0,255)); //蓝色
BLENDFUNCTION bf;
bf.BlendOp = AC_SRC_OVER;
bf.BlendFlags = 0;
bf.SourceConstantAlpha = 0x7f; //半透明
bf.AlphaFormat = 0;
pDC-> AlphaBlend(0,0,300,200,&memdc,0,0,300,200,bf);
memdc.SelectObject(pOldBitmap);