/**
     * 转换图片成圆形
     * 
     * @param bitmap
     *            传入Bitmap对象
     * @return
     */
    public static Bitmap toRoundBitmap(Bitmap bitmap) {
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        float roundPx;
        float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
        if (width <= height) {
            roundPx = width / 2;
            top = 0;
            bottom = width;
            left = 0;
            right = width;
            height = width;
            dst_left = 0;
            dst_top = 0;
            dst_right = width;
            dst_bottom = width;
        } else {
            roundPx = height / 2;
            float clip = (width - height) / 2;
            left = clip;
            right = width - clip;
            top = 0;
            bottom = height;
            width = height;
            dst_left = 0;
            dst_top = 0;
            dst_right = height;
            dst_bottom = height;
        }

        Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect src = new Rect((int) left, (int) top, (int) right,
                (int) bottom);
        final Rect dst = new Rect((int) dst_left, (int) dst_top,
                (int) dst_right, (int) dst_bottom);
        final RectF rectF = new RectF(dst);

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, src, dst, paint);
        return output;
    }

    /**

     * to圆角Bitmap
     * @param bitmap
     * @return
     */
    public static Bitmap getRoundedCornerBitmap(Bitmap bitmap,float roundPx) {
        try {
            Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
                    bitmap.getHeight(), Config.ARGB_8888);
            Canvas canvas = new Canvas(output);
            final int color = 0xff424242;// 颜色值（0xff---alpha）
            final Paint paint = new Paint();
            final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
            final RectF rectF = new RectF(rect);// Rect是使用int类型作为数值，RectF是使用float类型作为数值
            // --------抗锯齿-------//
            paint.setAntiAlias(true);
            canvas.drawARGB(0, 0, 0, 0);
            paint.setColor(color);
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
            paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
            final Rect src = new Rect(0, 0, bitmap.getWidth(),
                    bitmap.getHeight());
            canvas.drawBitmap(bitmap, null, rect, paint);
            return output;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }