Demonstrating morphing a search icon into a search field. To do this we use an AnimatedVectorDrawable (https://developer.android.com/reference/android/graphics/drawable/AnimatedVectorDrawable.html) made up of two paths. The first is the search icon (as a single line) the second is the horizontal bar. We then animate the 'trimPathStart' property …

1 search_bar.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2015 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="150dp"
        android:height="24dp"
        android:viewportWidth="150"
        android:viewportHeight="24">
    <path
        android:name="search"
        android:pathData="@string/path_search"
        android:strokeWidth="2"
        android:strokeColor="#ffffff"
        android:strokeAlpha="0.8"
        android:strokeLineCap="round" />
    <path
        android:name="bar"
        android:pathData="M0,23 L149,23"
        android:strokeWidth="2"
        android:strokeColor="#ffffff"
        android:strokeAlpha="0.8"
        android:strokeLineCap="square" />
</vector>

2 anim_search_to_bar.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2015 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<animated-vector
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/search_bar">

    <target
        android:name="search"
        android:animation="@animator/anim_search_empty" />

    <target
        android:name="bar"
        android:animation="@animator/anim_bar_fill" />

</animated-vector>

3 anim_search_empty.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2015 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<objectAnimator
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:propertyName="trimPathStart"
        android:valueFrom="0"
        android:valueTo="1"
        android:valueType="floatType"
        android:duration="@integer/duration_search"
        android:interpolator="@android:interpolator/fast_out_slow_in" />

4 anim_bar_fill.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2015 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<objectAnimator
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:propertyName="trimPathStart"
        android:valueFrom="1"
        android:valueTo="0"
        android:valueType="floatType"
        android:duration="@integer/duration_bar"
        android:interpolator="@android:interpolator/linear_out_slow_in" />

5 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2015 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="?android:colorPrimary"
    tools:context=".MainActivity"
    android:onClick="animate">

    <ImageView
        android:id="@+id/search"
        android:layout_gravity="center"
        android:layout_width="150dp"
        android:layout_height="24dp"
        android:src="@drawable/search_bar"
        android:onClick="animate" />

    <EditText
        android:id="@+id/text"
        android:layout_width="150dp"
        android:layout_height="22dp"
        android:layout_gravity="center"
        android:background="@null"
        android:textSize="12sp"
        android:paddingStart="4dp"
        android:textColor="?android:colorAccent"
        android:alpha="0" />

</FrameLayout>

6 MainActivity.java

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.example.searchbar;

import android.app.Activity;
import android.graphics.drawable.AnimatedVectorDrawable;
import android.os.Bundle;
import android.view.View;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

    private ImageView iv;
    private TextView text;
    private AnimatedVectorDrawable searchToBar;
    private AnimatedVectorDrawable barToSearch;
    private float offset;
    private Interpolator interp;
    private int duration;
    private boolean expanded = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv = (ImageView) findViewById(R.id.search);
        text = (TextView) findViewById(R.id.text);
        searchToBar = (AnimatedVectorDrawable) getResources().getDrawable(R.drawable.anim_search_to_bar);
        barToSearch = (AnimatedVectorDrawable) getResources().getDrawable(R.drawable.anim_bar_to_search);
        interp = AnimationUtils.loadInterpolator(this, android.R.interpolator.linear_out_slow_in);
        duration = getResources().getInteger(R.integer.duration_bar);
        // iv is sized to hold the search+bar so when only showing the search icon, translate the
        // whole view left by half the difference to keep it centered
        offset = -71f * (int) getResources().getDisplayMetrics().scaledDensity;
        iv.setTranslationX(offset);
    }

    public void animate(View view) {

        if (!expanded) {
            iv.setImageDrawable(searchToBar);
            searchToBar.start();
            iv.animate().translationX(0f).setDuration(duration).setInterpolator(interp);
            text.animate().alpha(1f).setStartDelay(duration - 100).setDuration(100).setInterpolator(interp);
        } else {
            iv.setImageDrawable(barToSearch);
            barToSearch.start();
            iv.animate().translationX(offset).setDuration(duration).setInterpolator(interp);
            text.setAlpha(0f);
        }
        expanded = !expanded;
    }
}