图片合成

private Bitmap onCompositeImages(){           Bitmap bmp = null;                   bmp = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());           final Paint paint = new Paint();           final Canvas canvas = new Canvas(bmp);           canvas.drawBitmap(srcBitmap, 0, 0, paint);                             paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));           canvas.drawBitmap(dstBitmap, 0, 0, paint);                      return bmp;   }