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));