C＃：绘制一个位图到另一个，与透明 [英] C#: Draw one Bitmap onto Another, with Transparency

问题描述

我有两个位图，命名为largeBmp和smallBmp。我想提请smallBmp到largeBmp，那么结果绘制到屏幕上。 SmallBmp的白色像素应该是透明的。下面是我使用的代码：

I have two Bitmaps, named largeBmp and smallBmp. I want to draw smallBmp onto largeBmp, then draw the result onto the screen. SmallBmp's white pixels should be transparent. Here is the code I'm using:

public Bitmap Superimpose(Bitmap largeBmp, Bitmap smallBmp) {
    Graphics g = Graphics.FromImage(largeBmp);
    g.CompositingMode = CompositingMode.SourceCopy;
    smallBmp.MakeTransparent();
    int margin = 5;
    int x = largeBmp.Width - smallBmp.Width - margin;
    int y = largeBmp.Height - smallBmp.Height - margin;
    g.DrawImage(smallBmp, new Point(x, y));
    return largeBmp;
}

的问题是，其结果卷起透明无论smallBmp是透明的！我只是想通过对largeBmp，没有什么是它背后看到的。

The problem is that the result winds up transparent wherever smallBmp was transparent! I just want to see through to largeBmp, not to what's behind it.

推荐答案

CompositingMode.SourceCopy 是这里的问题。你想 CompositingMode.SourceOver 来获取alpha混合。

CompositingMode.SourceCopy is the problem here. You want CompositingMode.SourceOver to get alpha blending.

这篇关于C＃：绘制一个位图到另一个，与透明的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！