カスタム中空長方形

public class TestView extends View {


    public TestView(Context context) {
        super(context);
    }

    public TestView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public TestView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public TestView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //父容器宽高
        int width = getWidth();
        int height = getHeight();
        //获取相机边框图片
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.img_scanner);
        //图片宽高
        int bitmapWidth = bitmap.getWidth();
        int bitmapHeight = bitmap.getHeight();
        //确定矩形左边和上边的距离
        int strokeWidth = (width-bitmapWidth)/2;
        int strokeHeight = (height-bitmapHeight)/2;

        RectF rectF = new RectF();
        Paint shellPaint = new Paint();
        shellPaint.setAntiAlias(true);
        /*图片周围的颜色*/
        int myColor = this.getResources().getColor(R.color.colorBlack3);
        shellPaint.setColor(myColor);
        /*设置画笔宽度，中间漏空情况下，画笔宽度=左边宽度或右边宽度或上边宽度或下边宽度
        加粗是围绕中间矩形的边向两边平分扩散*/
        shellPaint.setStrokeWidth(strokeWidth*2);
        //设置画笔的样式（这里设置的是空心矩形）
        shellPaint.setStyle(Paint.Style.STROKE);

        //根据左上右下的四个点确定空心矩形的位置
        rectF.left = strokeWidth;
        rectF.top = strokeHeight;
        rectF.right = width - strokeWidth;
        rectF.bottom = height - strokeHeight;

        canvas.drawRect(rectF, shellPaint);



        canvas.drawBitmap(bitmap, strokeWidth, strokeHeight, shellPaint);

        RectF rectF1 = new RectF();
        rectF1.left = 0;
        rectF1.right =getWidth();
        rectF1.top = 0;
        //因为画笔宽度设置成二倍，所以这里需要减去一倍，也就是strokeWidth
        rectF1.bottom = strokeHeight-strokeWidth;
        Paint paint = new Paint();
        paint.setColor(myColor);
        canvas.drawRoundRect(rectF1,0,0,paint);
        RectF rectF2 = new RectF();
        rectF2.left = 0;
        rectF2.right =getWidth();
        rectF2.top = height-(strokeHeight-strokeWidth);
        rectF2.bottom = height;
        canvas.drawRoundRect(rectF2,0,0,paint);

    }
}