上端兩個圓角，下端兩個直角

package com.example.clipviewdemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;

public class RoundCornerLayout extends FrameLayout {
    private int mRadius = 50;
    private Paint mPaint = new Paint();
    private Path mPath = new Path();

    public RoundCornerLayout(Context context) {
        this(context, null);
    }

    public RoundCornerLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public RoundCornerLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        fixClipPathUnsupportedOperationException(this);
        mPaint = new Paint();
        mPaint.setColor(Color.WHITE);
        mPaint.setAntiAlias(true);
        mPaint.setStyle(Paint.Style.FILL);
        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
        setWillNotDraw(false);
    }

    @Override
    public void draw(Canvas canvas) {
        RectF leftRect1 = new RectF(0, 0, mRadius, mRadius);

        // 上端兩個圓角，下端是兩個直角圖形
        mPath.arcTo(leftRect1,180,90);
        RectF leftRect2 = new RectF(getWidth() - mRadius, 0, getWidth(), mRadius);
        mPath.arcTo(leftRect2,270,90);

        mPath.lineTo(getWidth(), getHeight());
        mPath.lineTo(0, getHeight());
        mPath.lineTo(0, mRadius);


        mPath.close();
        canvas.save();
        //裁剪canvas，限定繪製區域
        canvas.clipPath(mPath);
        super.draw(canvas);
        canvas.restore();
    }

    public static void fixClipPathUnsupportedOperationException(View view) {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR2
                && Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        }
    }
}