Android 中设置 Bitmap 任意角度

public class BitmapUtils
{
    public static Bitmap fillet(Bitmap bitmap, int roundPx,
                                boolean topLeft, boolean topRight, boolean bottomLeft, boolean bottomRight)
    {
        try
        {
            // 其原理就是：先建立一个与图片大小相同的透明的Bitmap画板
            // 然后在画板上画出一个想要的形状的区域。
            final int width = bitmap.getWidth();
            final int height = bitmap.getHeight();

            Bitmap paintingBoard = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
            Canvas canvas = new Canvas(paintingBoard);
            canvas.drawARGB(Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT, Color.TRANSPARENT);

            final Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(Color.BLACK);

            //画出4个圆角
            final RectF rectF = new RectF(0, 0, width, height);
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

            //把不需要的圆角去掉
            if (topLeft)
            {
                clipTopLeft(canvas, paint, roundPx, width, height);
            }
            if (topRight)
            {
                clipTopRight(canvas, paint, roundPx, width, height);
            }
            if (bottomLeft)
            {
                clipBottomLeft(canvas, paint, roundPx, width, height);
            }
            if (bottomRight)
            {
                clipBottomRight(canvas, paint, roundPx, width, height);
            }
            paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

            final Rect src = new Rect(0, 0, width, height);
            final Rect dst = src;
            canvas.drawBitmap(bitmap, src, dst, paint);
            return paintingBoard;
        } catch (Exception exp)
        {
            return bitmap;
        }
    }

    private static void clipTopLeft(final Canvas canvas, final Paint paint, int offset, int width, int height) {
        final Rect block = new Rect(0, 0, offset, offset);
        canvas.drawRect(block, paint);
    }

    private static void clipTopRight(final Canvas canvas, final Paint paint, int offset, int width, int height) {
        final Rect block = new Rect(width - offset, 0, width, offset);
        canvas.drawRect(block, paint);
    }

    private static void clipBottomLeft(final Canvas canvas, final Paint paint, int offset, int width, int height) {
        final Rect block = new Rect(0, height - offset, offset, height);
        canvas.drawRect(block, paint);
    }

    private static void clipBottomRight(final Canvas canvas, final Paint paint, int offset, int width, int height) {
        final Rect block = new Rect(width - offset, height - offset, width, height);
        canvas.drawRect(block, paint);
    }
}