C++ 具有UpdateLayeredWindow的透明度

我有分层窗口（

WS_EX_layered

），我正在尝试使用

UpdateLayeredWindow

在窗口上显示位图

位图是一种不规则形状，具有纯色背景

RGB（30,30,30）

。我想使用

ULW\u COLORKEY

选项使背景透明

当我调用

UpdateLayeredWindow

时，图像在屏幕上呈现，但背景是不透明的

    // Draw background rectangle
    COLORREF transparent_colour = RGB(30, 30, 30);
    HBRUSH hTranparentBrush = CreateSolidBrush(transparent_colour);
    HBRUSH hOldBrush = SelectObject(hSrcDC, hTransparentBrush);

    // the rectangle is the size of the splash screen / layered window
    hresult =  Rectangle(hSrcDC, 0, 0, szSplash.cx, szSplash.cy);
    //error checking has been removed

    // Paint rotated bitmap over background
    hresult = SetGraphicsMode(hSrcDC, GM_ADVANCED);

    float s = math::sin(degree * pi / 180);
    float c = math::cos(degree * pi / 180);
    XFORM x;
    x.em11 = c;
    x.em12 = s;
    x.em21 = -s;
    x.em22 = c;
    x.eDx = (1-c)*szImg.cx + s*szImg.cy;
    x.eDy = (1-c)*szImg.cy - s*szImg.cx;

    hresult = SetWorldTransform(hSrcDC, x);

    // the BitBlt below succeeds. hSrcDC contains a bitmap with a solid
    // background and the rotated image over it.
    hresult = BitBlt(hSrcDC, 100, 100, szImg.cx, szImg.cy, hImgDC, 0, 0, SRCCOPY);

    // Print to screen
    POINT ptZero = {0, 0};

    SIZE szBmp = szSplash; //size of the splash screen

    BLENDFUNCTION blend;
    blend.BlendOp = ARC_SRC_OVER;
    blend.BlendFlags = 0;
    blend.SourceConstantAlpha = 255;
    blend.AlphaFormat = AC_SRC_ALPHA;

    //this call succeeds - the bitmap is printed to the screen, but the
    //background is still visible?
    hresult = UpdateLayeredWindow(hwndSplash, 
                                  hSplashDC, 
                                  &ptZero, 
                                  &szBmp, 
                                  hSrcDC, 
                                  &ptZero, 
                                  transparent_colour, 
                                  &blend, 
                                  ULW_COLORKEY);

---

如果我将

ULW_COLORKEY

替换为

ULW_ALPHA

，则图像的背景和其他部分都会变得透明，看起来很糟糕。我只希望背景是透明的-我缺少什么吗？

你能发布你的参数（ptZero，ptZero，blend）中的值吗？

&hSrcDC

首先应该是

hSrcDC

，但是如果没有更多的代码，我们就无法知道你是否犯了其他错误。谢谢大家，我已经添加了更多的代码。