ViewAnimator with xml attribute to set initial child

attr.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="ToolableViewAnimator">
        <attr name="initialView" format="integer" />
    </declare-styleable>

</resources>

example_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    >

    <org.packagename.ToolableViewAnimator
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        custom:initialView="1"
        >

</LinearLayout>

ToolableViewAnimator.java

/*
 * Copyright (C) 2015 Vincent Breitmoser <[email protected]>
 * 
 * The MIT License (MIT)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package org.packagename.ToolableViewAnimator;


import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ViewAnimator;

import org.sufficientlysecure.keychain.R;


/** This view is essentially identical to ViewAnimator, but allows specifying the initial view
 * for preview as an xml attribute. */
public class ToolableViewAnimator extends ViewAnimator {

    private int mInitChild = -1;

    public ToolableViewAnimator(Context context) {
        super(context);
    }

    public ToolableViewAnimator(Context context, AttributeSet attrs) {
        super(context, attrs);

        if (isInEditMode()) {
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ToolableViewAnimator);
            mInitChild = a.getInt(R.styleable.ToolableViewAnimator_initialView, -1);
            a.recycle();
        }
    }

    public ToolableViewAnimator(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs);

        if (isInEditMode()) {
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ToolableViewAnimator, defStyleAttr, 0);
            mInitChild = a.getInt(R.styleable.ToolableViewAnimator_initialView, -1);
            a.recycle();
        }
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (isInEditMode() && mInitChild-- > 0) {
            return;
        }
        super.addView(child, index, params);
    }
}