BLENDFUNCTION bf;
bf.BlendOp = AC_SRC_OVER;
bf.BlendFlags = 0;
bf.AlphaFormat = 0;
bf.SourceConstantAlpha = 100;//透明度,0为全透明,255为不透明
AlphaBlend(hdc,rc.left,,rc.right-rc.left,rc.bottom-,hdc_button,0,0,rc.right-rc.left,rc.bottom-,bf);