要创建一个反向弧形圆角Drawable/Canvas，可以使用以下代码：

public class ReverseCurveCornerDrawable extends Drawable {
    private Paint mPaint;
    private int mWidth;
    private int mHeight;
    private int mRadius;
    private Path mPath;

    public ReverseCurveCornerDrawable(int color, int radius) {
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(color);
        mRadius = radius;
        mPath = new Path();
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawPath(mPath, mPaint);
    }

    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter colorFilter) {
        mPaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);
        mWidth = bounds.width();
        mHeight = bounds.height();
        mPath.reset();
        mPath.moveTo(0, 0);
        mPath.lineTo(mWidth - mRadius, 0);
        mPath.quadTo(mWidth, 0, mWidth, mRadius);
        mPath.lineTo(mWidth, mHeight);
        mPath.lineTo(0, mHeight);
        mPath.close();
    }
}

这个类继承了Drawable类，可以使用它来进行视图绘制。它使用了一个Path来绘制圆角边缘。在onBoundsChange方法中，它计算出每个角落的位置，并使用quadTo方法创建曲线路径。mRadius是要创建的圆角的半径，mWidth和mHeight是Drawable的宽度和高度。 使用以下步骤创建Drawable对象：

ReverseCurveCornerDrawable drawable = new ReverseCurveCornerDrawable(Color.RED, 50);
imageView.setBackground(drawable); //or set to any view.

设置颜色和半径即可。 这样做可以为