OnGlobalLayoutListener called repeatly, and remove it

In last post, we re-layout the views when the global layout state within the view tree changes, with OnGlobalLayoutListener. But once re-layout the views, it trigger another layout state change, and repeat and repeat again.


To prevent it, we can call removeGlobalOnLayoutListener() (deprecated in API level 16) or removeOnGlobalLayoutListener() (for API Level >= 16) after layout.

MainActivity.java

package com.example.androidtouchview;

import com.example.androidtouchview.MyView.OnToggledListener;

import android.support.v7.app.ActionBarActivity;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.widget.GridLayout;
import android.widget.Toast;
import android.os.Bundle;

public class MainActivity extends ActionBarActivity 
 implements OnToggledListener{
 
 int numberOfGlobalLayoutCalled = 0;
 
 MyView[] myViews;
 
 GridLayout myGridLayout;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  myGridLayout = (GridLayout)findViewById(R.id.mygrid);
  
  int numOfCol = myGridLayout.getColumnCount();
  int numOfRow = myGridLayout.getRowCount();
  myViews = new MyView[numOfCol*numOfRow];
  for(int yPos=0; yPos<numOfRow; yPos++){
   for(int xPos=0; xPos<numOfCol; xPos++){
    MyView tView = new MyView(this, xPos, yPos);
    tView.setOnToggledListener(this);
    myViews[yPos*numOfCol + xPos] = tView;
    myGridLayout.addView(tView);
   }
  }
  
  myGridLayout.getViewTreeObserver().addOnGlobalLayoutListener(
   new OnGlobalLayoutListener(){

   @Override
   public void onGlobalLayout() {
    
    final int MARGIN = 5;
    
    int pWidth = myGridLayout.getWidth();
    int pHeight = myGridLayout.getHeight();
    int numOfCol = myGridLayout.getColumnCount();
    int numOfRow = myGridLayout.getRowCount();
    int w = pWidth/numOfCol;
    int h = pHeight/numOfRow;
    
    for(int yPos=0; yPos<numOfRow; yPos++){
     for(int xPos=0; xPos<numOfCol; xPos++){
      GridLayout.LayoutParams params = 
       (GridLayout.LayoutParams)myViews[yPos*numOfCol + xPos].getLayoutParams();
      params.width = w - 2*MARGIN;
      params.height = h - 2*MARGIN;
      params.setMargins(MARGIN, MARGIN, MARGIN, MARGIN);
      myViews[yPos*numOfCol + xPos].setLayoutParams(params);
     }
    }
    
    Toast.makeText(MainActivity.this, 
     "numberOfGlobalLayoutCalled = " + numberOfGlobalLayoutCalled, 
     Toast.LENGTH_SHORT).show();
    numberOfGlobalLayoutCalled++;
    
    //deprecated in API level 16
    myGridLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
    //for API Level >= 16
    //myGridLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
   }});
 }

 @Override
 public void OnToggled(MyView v, boolean touchOn) {

  //get the id string
  String idString = v.getIdX() + ":" + v.getIdY();

  Toast.makeText(MainActivity.this, 
   "Toogled:\n" +
   idString + "\n" +
   touchOn, 
   Toast.LENGTH_SHORT).show();
 }

}