Question

I have a custom ViewGroup (blue background) that when touched sometime during the app’s life cycle, I want to add an arbitrary xml defined view layout (whitebox to be in foreground) to that custom view.

Is there any way to do this outside of the activity’s onCreate?

whitebox.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:background="#FFFFFF"
    android:orientation="vertical" >
</LinearLayout>

TestDynamicLayoutActivity.java

package net.lapasa.testdynamiclayout;

import android.app.Activity;
import android.os.Bundle;

public class TestDynamicLayoutActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

        setContentView(new MyCustomViewGroup(this));
    }
}

MyCustomViewGroup.java

package net.lapasa.testdynamiclayout;

import java.lang.annotation.Target;

import android.content.Context;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;

public class MyCustomViewGroup extends ViewGroup
{

    private Context context;

    public MyCustomViewGroup(Context context)
{
    super(context);
    this.context = context;
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
    this.setBackgroundColor(Color.BLUE);

}

@Override
public boolean onTouchEvent (MotionEvent event)
{
    if (event.getAction() == MotionEvent.ACTION_DOWN)
    {
        View whiteBoxView= LayoutInflater.from(context).inflate(R.layout.whitebox, this);
        ViewGroup targetParent = (ViewGroup) whiteBoxView.getParent();
        targetParent.removeView(whiteBoxView);
        this.addView(whiteBoxView);
    }
    return true;
}
}

The block of code in the ACTION_DOWN doesn’t do anything except present a black screen =( What is going on?

Answer 1

Did I get that right – you just want to have some blue view containing a white view that shows up when the blue view is clicked?

Then it would be better not to implement your own ViewGroup but using one of the existing ones like FrameLayout. Set the layout’s background to blue. Add a child View with it’s background set to white and it’s visibility set to View.INVISIBLE or View.GONE.

Add a click handler to the ViewGroup that sets the visibility of your white View to View.VISIBLE.

You could do it like this:

main.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

             android:background="#00f"
             android:onClick="onBlueClick"

             android:layout_width="fill_parent"
             android:layout_height="fill_parent">
  <View android:id="@+id/whiteBox"
        android:background="#fff"
        android:visibility="gone"

        android:layout_gravity="center"
        android:layout_width="20dp"
        android:layout_height="20dp"/>
</FrameLayout>

MyActivity.java:

package com.example;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;

public class MyActivity extends Activity {

  private View whiteBox;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    whiteBox = findViewById(R.id.whiteBox);
  }

  @SuppressWarnings({"UnusedDeclaration"}) // wired by layout xml
  public void onBlueClick(final View view) {
    if (whiteBox != null) {
      whiteBox.setVisibility(whiteBox.getVisibility() == View.VISIBLE ? View.GONE : View.VISIBLE);
    }
  }
}