设置图片透明度alpha注意

imgTextGray = new ImageView(this);
     imgTextGray.setBackgroundResource(R.drawable.slidetext_gray);
     

 

private void alphaSlideText(int alphaValue){
  if(imgTextGray != null){
   Log.e(TAG, "alphaSlideText = "+alphaValue);
   imgTextGray.getBackground().setAlpha(alphaValue);//注意不能写成imgTextGray.setAlpha(alphaValue);否则ALPHA会不起作用.
   imgTextGray.invalidate();
   
  }
 }