Android生成圆角图片

封装方法：

/**
   * @author chenzheng
   * @since 2014-5-14
   * @Description: 生成圆角图片
   * @throws
   * @param bitmap
   * @param pixels
   * @return
   * Bitmap
   */
  public static Bitmap genRoundCorner(Bitmap bitmap, int pixels) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
        bitmap.getHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(output);
    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);
    final float roundPx = pixels;
    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, rect, rect, paint);
    return output;
  }

当我们需要圆角的时候，调用这个方法，第一个参数是传入需要转化成圆角的图片，第二个参数是圆角的度数，数值越大，圆角越大 

调用方法：

Drawable drawable = getResources().getDrawable(R.drawable.bg);     
      BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;      
      Bitmap bitmap = bitmapDrawable.getBitmap();              
    BitmapDrawable bbb = new BitmapDrawable(toRoundCorner(bitmap, 30));      
    layout.setBackgroundDrawable(bbb);       
    //ImageView imageView = (ImageView) findViewById(R.id.imgShow);        
    //imageView.setImageBitmap(MyActivity.toRoundCorner(bitmap, 20));