android 圆角图片 处理

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在Activity中调用

  /* 将头像转为圆形 */
     Resources res = getResources();
     Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.head);
     head.setImageBitmap(ImageHelper.toRoundBitmap(bmp));

//处理类
public class ImageHelper {
    /**
     * 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;
    }

    // 下载图片转为bitmap
    public static Bitmap getHttpBitmap(String url) {
      URL u = null;
      Bitmap bmp = null;
       try {
          u = new URL(url);

      } catch (Exception e) {
          // TODO: handle exception
      }
       try {
          HttpURLConnection conn = (HttpURLConnection) u.openConnection();
          conn.setConnectTimeout(0);
          conn.setDoInput( true);
          conn.connect();
          InputStream ins = conn.getInputStream();
          bmp = BitmapFactory. decodeStream(ins);
          ins.close();
      } catch (Exception e) {
          // TODO: handle exception
      }
       return bmp;
    }
}