Android之画一个圆角图形

最近在看OpenCamera的源码，表示受益很深，项目地址：https://github.com/almalence/OpenCamera

画一个圆角的图，使用PorterDuff.Mode的属性，话不多说，直接上代码

/**
     *  方形圆角图片
     *
     * @param bitmap       图片
     * @param size         要显示的大小，如果需要截图从中心截图
     * @param borderRadius 圆角弧度 到一定值就为圆了
     * @param color        图片边缘颜色
     * @param borderWidth  图片边缘宽度
     * @return
     */
    private Bitmap getRoundedCornerBitmap(Bitmap bitmap, int size, int borderRadius, @ColorInt int color, int borderWidth) {
        final int side = Math.min(bitmap.getWidth(), bitmap.getHeight());

        final Bitmap bitmapCropped = Bitmap.createBitmap(bitmap, (bitmap.getWidth() - side) / 2,
                (bitmap.getHeight() - side) / 2, side, side);

        final Bitmap output = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);

        Canvas canvas = new Canvas(output);

        final Paint paint = new Paint();
        final Rect rectSrc = new Rect(0, 0, bitmapCropped.getWidth(), bitmapCropped.getHeight());
        final Rect rect = new Rect(borderWidth, borderWidth, output.getWidth() - borderWidth, output.getHeight() - borderWidth);
        final RectF rectF = new RectF(rect);
        final RectF rectFBorder = new RectF(0, 0, output.getWidth(), output.getHeight());
        final float roundPx = borderRadius;

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));//取两层绘制交集,显示上层
        // 第一个Rect 代表要绘制的bitmap 区域，第二个 Rect 代表的是要将bitmap 绘制在屏幕的什么地方
        canvas.drawBitmap(bitmapCropped, rectSrc, rect, paint);

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));//取下层非交集部分与上层交集部分
        canvas.drawRoundRect(rectFBorder, roundPx, roundPx, paint);

        return output;
    }