图片形状圆角

一定要先转换成PNG格式的否则会不透明


 1     /**
     * 方形转换图片成圆形
     * 
     * @param bitmap
     *            传入Bitmap对象
     * @return
     */
    public 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;
            left = 0;
            top = 0;
            right = width;
            bottom = 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);// 设置画笔无锯齿

        canvas.drawARGB(0, 0, 0, 0); // 填充整个Canvas
        paint.setColor(color);

        // 以下有两种方法画圆,drawRounRect和drawCircle
        // canvas.drawRoundRect(rectF, roundPx, roundPx, paint);//
        // 画圆角矩形，第一个参数为图形显示区域，第二个参数和第三个参数分别是水平圆角半径和垂直圆角半径。
        canvas.drawCircle(roundPx, roundPx, roundPx, paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));// 设置两张图片相交时的模式,参考http://trylovecatch.iteye.com/blog/1189452
        canvas.drawBitmap(bitmap, src, dst, paint); // 以Mode.SRC_IN模式合并bitmap和已经draw了的Circle

        return output;
    }

// 矩形将图片的四角圆化
    public static Bitmap getRoundedCornerBitmap(Bitmap bitmap) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
                bitmap.getHeight(), Config.ARGB_8888);
        // 得到画布
        Canvas canvas = new Canvas(output);
        // 将画布的四角圆化
        final int color = Color.RED;
        final Paint paint = new Paint();
        // 得到与图像相同大小的区域 由构造的四个值决定区域的位置以及大小
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(rect);
        // 值越大角度越明显
        final float roundPx = 30;
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        // drawRoundRect的第2,3个参数一样则画的是正圆的一角，如果数值不同则是椭圆的一角
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }