学习一些常用的混合模式之BlendMode. dst

The source pixels are discarded, leaving the destination intact.

代码

 canvas.saveLayer(Rect.fromLTWH(0, 0, width, height), Paint());
    Paint dstPaint = Paint()..color = Colors.red;
    dstPaint.style = ui.PaintingStyle.fill;
    canvas.drawImageRect(image1!, Rect.fromLTWH(0, 0, image!.width.toDouble(), image!.height.toDouble()), Rect.fromLTWH(0, 0, width/2, height/2), dstPaint);


    var srcPaint = Paint()
      ..color = Colors.red
      ..blendMode = ui.BlendMode.dst; // 源颜色：蓝色; // 混合模式
    canvas.drawRect(Rect.fromLTWH(0, 0, width, height), srcPaint);

    canvas.restore();

重叠部分只保留dst的内容,清空所有的src。非重叠部分只保留dst的内容,清空所有的src。所以效果就是图片全部展示,红色矩形全部不显示。

效果图如下：