Android中实现iOS中的毛玻璃效果

 
private 
 void applyBlur() { 
  image.getViewTreeObserver().addOnPreDrawListener(new  
ViewTreeObserver.OnPreDrawListener() { 
    @Override 
    public boolean onPreDraw() { 
      image.getViewTreeObserver().removeOnPreDrawListener(this); 
      image.buildDrawingCache(); 
      Bitmap bmp = image.getDrawingCache(); 
      blur(bmp, text, true); 
      return true; 
    } 
  }); 
} 
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1) 
private void blur(Bitmap bkg, View view) { 
  long startMs = System.currentTimeMillis(); 
  float radius = 20; 
  Bitmap overlay = Bitmap.createBitmap((int)(view.getMeasuredWidth()), 
 (int)(view.getMeasuredHeight()), Bitmap.Config.ARGB_8888); 
  Canvas canvas = new Canvas(overlay); 
  canvas.translate(-view.getLeft(), -view.getTop()); 
  canvas.drawBitmap(bkg, 0, 0, null); 
  RenderScript rs = RenderScript.create(SecondActivity.this); 
  Allocation overlayAlloc = Allocation.createFromBitmap(rs, overlay); 
  ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(rs,  
overlayAlloc.getElement()); 
  blur.setInput(overlayAlloc); 
  blur.setRadius(radius); 
  blur.forEach(overlayAlloc); 
  overlayAlloc.copyTo(overlay); 
  view.setBackground(new BitmapDrawable(getResources(), overlay)); 
  rs.destroy(); 
  statusText.setText("cost " + (System.currentTimeMillis() - startMs) + 
 "ms"); 
} 

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