Android 将一张图片变为圆形图片

前度时间做的一个项目中有这样的需求，把网络请求下来的图片变为圆形图片显示在客服端。开始想了很久，都没找到好的解决方案，最后还是通过Bitmap.createBitmap方法解决的。具体实现如下：

将图片转换为圆形图片，输入需要一个Bitmap的对象

/**
     * 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;
            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);
        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);
        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;
    }

将drawable中的图片转为Bitmap对象

/**
     * drawable2Bitmap
     * 
     * @param bitmap
     *            传入Drawable对象
     * @return
     */

    @SuppressWarnings("deprecation")
    public static Bitmap drawable2Bitmap(int a ,Context context) {
        Resources resources = context.getResources();
        Drawable drawable = resources.getDrawable(a);
        if (drawable instanceof BitmapDrawable) {
            return ((BitmapDrawable) drawable).getBitmap();
        } else if (drawable instanceof NinePatchDrawable) {
            Bitmap bitmap = Bitmap
                    .createBitmap(
                            drawable.getIntrinsicWidth(),
                            drawable.getIntrinsicHeight(),
                            drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                                    : Bitmap.Config.RGB_565);
            Canvas canvas = new Canvas(bitmap);
            drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
                    drawable.getIntrinsicHeight());
            drawable.draw(canvas);
            return bitmap;
        } else {
            return null;
        }
    }

图片旋转
/**
* rotateImage
*
* @param id
* 传入derawable id
* @return bitmap
*/

public Bitmap rotateImage(int id,Context context,float rotate){
    Bitmap bitmap = ((BitmapDrawable) context.getResources().getDrawable(id)).getBitmap();
    Matrix matrix = new Matrix();
    matrix.setRotate(rotate);
    bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
    return bitmap;
}