使用PorterDuff.Mode.SRC_ATOP将Drawable放在Imageview上

Question

我有一个ImageView：

ImageView imageView = findViewById(R.id.imageView);

我想实现这样的目标（ Atop 图）

drawable1是原始的ImageView图像，drawable2是我要放置的图像：

Drawable drawable1 =  AppCompatResources.getDrawable(context, drawable1);
Drawable drawable2 = AppCompatResources.getDrawable(context, drawable2);

LD layerDrawable = new LD(new Drawable[]{
       drawable1,
       drawable2,
});
imageView.setImageDrawable(layerDrawable);

LD课程：

public class LD extends LayerDrawable
{
    private Paint p = new Paint();

    public LD(Drawable[] layers) {
        super(layers);
        p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
    }

    @Override
    public void draw(Canvas canvas) {
        super.draw(canvas);
        int count = canvas.saveLayer(null, null, Canvas.ALL_SAVE_FLAG);

        for (int i = 0, numberOfLayers = getNumberOfLayers(); i < numberOfLayers; ++i) {
            this.getDrawable(i).draw(canvas);
            canvas.saveLayer(null, p, Canvas.ALL_SAVE_FLAG);
        }
        canvas.restoreToCount(count);

    }
}

然而这并不起作用，因为我放置的图像（drawable2）放在整个imageView上，而不仅仅放在drawable1图像的非透明内容上。

如何实现Atop数字（仅将drawable2放在＆lt; fillable1＆gt;的drawable1上）？

编辑：

p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
canvas.drawBitmap(bitmap1, 0, 0, null);
canvas.drawBitmap(bitmap2, 0, 0, p);