Android使用OpenCV来实现bitmap独立设置每个圆角,
关于opencv集成请参考我的其他文章，这里方便起见已经封装成java方法供大家调用：
代码如下：

    public static Bitmap drawCircleRadius(int w, int h, int circleR, boolean topLeft, boolean topRight, boolean bottomLeft, boolean bottomRight, Bitmap bitmap) {
        if (bitmap == null || bitmap.isRecycled() || bitmap.getWidth() == 0)
            return null;

        Mat zeros = Mat.zeros(bitmap.getHeight(), bitmap.getWidth(), CvType.CV_8UC4);
        ByteBuffer allocate = ByteBuffer.allocate(bitmap.getByteCount());
        bitmap.copyPixelsToBuffer(allocate);
        zeros.put(0, 0, allocate.array());
        allocate.clear();
        bitmap.recycle();

        Mat ones = Mat.zeros(h, w, CvType.CV_8UC4);
        Imgproc.resize(zeros, ones, new Size(w, h));

        Mat mask = Mat.zeros(h, w, CvType.CV_8UC1);
        Imgproc.rectangle(mask, new Point(circleR, 0), new Point(w - circleR, h), Scalar.all(255), -1);
        Imgproc.rectangle(mask, new Point(0, circleR), new Point(w, h - circleR), Scalar.all(255), -1);
        if (topLeft) {
            Imgproc.circle(mask, new Point(circleR, circleR), circleR, Scalar.all(255), -1);
        } else {
            Imgproc.rectangle(mask, new Point(0, 0), new Point(circleR, circleR), Scalar.all(255), -1);
        }
        if (topRight) {
            Imgproc.circle(mask, new Point(w - circleR, circleR), circleR, Scalar.all(255), -1);
        } else {
            Imgproc.rectangle(mask, new Point(w - circleR, 0), new Point(w, circleR), Scalar.all(255), -1);
        }
        if (bottomRight) {
            Imgproc.circle(mask, new Point(w - circleR, h - circleR), circleR, Scalar.all(255), -1);
        } else {
            Imgproc.rectangle(mask, new Point(w - circleR, h - circleR), new Point(w, h), Scalar.all(255), -1);
        }

        if (bottomLeft) {
            Imgproc.circle(mask, new Point(circleR, h - circleR), circleR, Scalar.all(255), -1);
        } else {
            Imgproc.rectangle(mask, new Point(0, h - circleR), new Point(circleR, h), Scalar.all(255), -1);
        }

        Mat out = Mat.zeros(h, w, CvType.CV_8UC4);
        ones.copyTo(out, mask);

        Bitmap dst = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(out, dst);

        out.release();
        mask.release();
        ones.release();
        zeros.release();
        return dst;
    }

调用是也要首先获取宽度高度才行：例如imageview 用post方法执行；

                img.post(new Runnable() {
                    @Override
                    public void run() {
                        Bitmap bitmap = drawCircleRadius(img.getWidth(), img.getHeight(), 100, false, true, false, false, BitmapFactory.decodeResource(getResources(), R.mipmap.test_bg));
                        img.setImageBitmap(bitmap);
                    }
                });