AlphaBlend使用求助
//创建缓冲
CDC BufferDC;
CBitmap ImageBuffer;
BufferDC.CreateCompatibleDC(&dc);
ImageBuffer.CreateCompatibleBitmap(&dc,rcClient.Width(),rcClient.Height());
BufferDC.SelectObject(&ImageBuffer);
//绘画背景
CImageHandle BackImageHandle(&m_ImageBack1);
//m_ImageBack1.BitBlt(BufferDC,0,0);

BLENDFUNCTION bf;
memset(&bf,0,sizeof(bf));
bf.BlendOp = AC_SRC_OVER;
bf.SourceConstantAlpha = 120;
// blend old image on top of new, in temporary DC
BufferDC.AlphaBlend(0,0,rcClient.Width(),rcClient.Height(),
&dc,
0,0,rcClient.Width(),rcClient.Height(),
bf);

// copy scratch bits to screen
m_ImageBack1.BitBlt(BufferDC, 0, 0);


这里的AlphaBlend为什么不生效？


[解决办法]
没用过， AlphaBlend 是什么？