Android Property Animation API
This tutorial describes how to use Animations in Android. The tutorial is based on Eclipse 4.2, Java 1.6 and Android 4.2.
Table of Contents
Android 3.0 introduced the Properties Animation API which allow to change object properties over a predefined time interval.
The API allows to define for arbitrary object properties a start and end value and apply a time-based change to this attribute. This API can be applied on any Java object not only on
Views.The superclass of the animation API is the
Animator class. Typically the ObjectAnimator class is used to modify the attributes of an object.You can also add an
AnimatorListener class to your Animator class. This listener is called in the different phases of the animation. You can use this listener to perform actions before or after a certain animation, e.g. add or remove a View from a ViewGroup.The
ViewPropertyAnimator class introduced in Android 3.1 provides a simpler access to typical animations which are performed on Views.The
animate() method on a View will return the ViewPropertyAnimator object. This object allows to perform simultaneous animations. It has a fluent API and allows to set the duration of the animation.The target of
ViewPropertyAnimator is to provide a very simple API for typical animations.The following code shows an example of the usage of this method.
// Using hardware layer
myView.animate().translationX(400).withLayer();
For performance optimization you can also let
ViewPropertyAnimator use a hardware layout.// Using hardware layer
myView.animate().translationX(400).withLayer();
You can also directly define a
Runnable to be executed at the start and the end of the animation.// StartAction
myView.animate().translationX(100).withStartAction(new Runnable(){
public void run(){
viewer.setTranslationX(100-myView.getWidth());
// do something
}
});
// EndAction
myView.animate().alpha(0).withStartAction(new Runnable(){
public void run(){
// Remove the view from the layout called parent
parent.removeView(myView);
}
});
The
setInterpolator() allows to define an object of type TimeInterpolator which defines the change of the value over time. The standard is linear. The Android platform defines a few default ones as for example AccelerateDecelerateInterpolator where the rate of change starts and ends slowly but accelerates through the middle.Via the
setEvaluator method you can set an object of type TypeEvaluator which allow you to create animations on arbitrary property types, by providing custom evaluators for types that are not automatically understood and used by the animation system.The
LayoutTransition class allows to set animations on a layout container and a changes on theViews of this container will be animated.package com.example.android.layoutanimation;
import android.animation.LayoutTransition;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class MainActivity extends Activity {
private ViewGroup viewGroup;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LayoutTransition l = new LayoutTransition();
l.enableTransitionType(LayoutTransition.CHANGING);
viewGroup = (ViewGroup) findViewById(R.id.container);
viewGroup.setLayoutTransition(l);
}
public void onClick(View view) {
viewGroup.addView(new Button(this));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Animations can be applied to
Views but it is also possible to apply them on the transition betweenactivities.The
ActivityOptions class allows to define default or customer animations.public void onClick(View view) {
Intent intent = new Intent(this, SecondActivity.class);
ActivityOptions options = ActivityOptions.makeScaleUpAnimation(view, 0,
0, view.getWidth(), view.getHeight());
startActivity(intent, options.toBundle());
}
The following description assumes that you have already basic knowledge in Android development.
Please check the Android development tutorial to learn the basics. Also see Android development tutorials for more information about Android development.
This tutorial demonstrates the usage of the Properties Animation API.
Create a new Android project called com.vogella.android.animation.views with the activity calledAnimationExampleActivity. The layout file should be called
main.xml. Change this file to the following code.<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:id="@+id/test"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<Button
android:id="@+id/Button01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="startAnimation"
android:text="Rotate" />
<Button
android:id="@+id/Button04"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="startAnimation"
android:text="Group" >
</Button>
<Button
android:id="@+id/Button03"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="startAnimation"
android:text="Fade" />
<Button
android:id="@+id/Button02"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="startAnimation"
android:text="Animate" />
</LinearLayout>
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:src="@drawable/icon" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/imageView1"
android:layout_alignRight="@+id/imageView1"
android:layout_marginBottom="30dp"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
Create the following menu resource.
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:id="@+id/item1"
android:showAsAction="ifRoom"
android:title="Game">
</item>
</menu>
Change your activity to the following.
package com.vogella.android.animation.views;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
public class AnimationExampleActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void startAnimation(View view) {
float dest = 0;
ImageView aniView = (ImageView) findViewById(R.id.imageView1);
switch (view.getId()) {
case R.id.Button01:
dest = 360;
if (aniView.getRotation() == 360) {
System.out.println(aniView.getAlpha());
dest = 0;
}
ObjectAnimator animation1 = ObjectAnimator.ofFloat(aniView,
"rotation", dest);
animation1.setDuration(2000);
animation1.start();
// Show how to load an animation from XML
// Animation animation1 = AnimationUtils.loadAnimation(this,
// R.anim.myanimation);
// animation1.setAnimationListener(this);
// animatedView1.startAnimation(animation1);
break;
case R.id.Button02:
// shows how to define a animation via code
// also use an Interpolator (BounceInterpolator)
Paint paint = new Paint();
TextView aniTextView = (TextView) findViewById(R.id.textView1);
float measureTextCenter = paint.measureText(aniTextView.getText()
.toString());
dest = 0 - measureTextCenter;
if (aniTextView.getX() < 0) {
dest = 0;
}
ObjectAnimator animation2 = ObjectAnimator.ofFloat(aniTextView,
"x", dest);
animation2.setDuration(2000);
animation2.start();
break;
case R.id.Button03:
// demonstrate fading and adding an AnimationListener
dest = 1;
if (aniView.getAlpha() > 0) {
dest = 0;
}
ObjectAnimator animation3 = ObjectAnimator.ofFloat(aniView,
"alpha", dest);
animation3.setDuration(2000);
animation3.start();
break;
case R.id.Button04:
ObjectAnimator fadeOut = ObjectAnimator.ofFloat(aniView, "alpha",
0f);
fadeOut.setDuration(2000);
ObjectAnimator mover = ObjectAnimator.ofFloat(aniView,
"translationX", -500f, 0f);
mover.setDuration(2000);
ObjectAnimator fadeIn = ObjectAnimator.ofFloat(aniView, "alpha",
0f, 1f);
fadeIn.setDuration(2000);
AnimatorSet animatorSet = new AnimatorSet();
animatorSet.play(mover).with(fadeIn).after(fadeOut);
animatorSet.start();
break;
default:
break;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.mymenu, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Intent intent = new Intent(this, HitActivity.class);
startActivity(intent);
return true;
}
}
Create a new activity called HitActivity.
package com.vogella.android.animation.views;
import java.util.Random;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class HitActivity extends Activity {
private ObjectAnimator animation1;
private ObjectAnimator animation2;
private Button button;
private Random randon;
private int width;
private int height;
private AnimatorSet set;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.target);
width = getWindowManager().getDefaultDisplay().getWidth();
height = getWindowManager().getDefaultDisplay().getHeight();
randon = new Random();
set = createAnimation();
set.start();
set.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
int nextX = randon.nextInt(width);
int nextY = randon.nextInt(height);
animation1 = ObjectAnimator.ofFloat(button, "x", button.getX(),
nextX);
animation1.setDuration(1400);
animation2 = ObjectAnimator.ofFloat(button, "y", button.getY(),
nextY);
animation2.setDuration(1400);
set.playTogether(animation1, animation2);
set.start();
}
});
}
public void onClick(View view) {
String string = button.getText().toString();
int hitTarget = Integer.valueOf(string) + 1;
button.setText(String.valueOf(hitTarget));
}
private AnimatorSet createAnimation() {
int nextX = randon.nextInt(width);
int nextY = randon.nextInt(height);
button = (Button) findViewById(R.id.button1);
animation1 = ObjectAnimator.ofFloat(button, "x", nextX);
animation1.setDuration(1400);
animation2 = ObjectAnimator.ofFloat(button, "y", nextY);
animation2.setDuration(1400);
AnimatorSet set = new AnimatorSet();
set.playTogether(animation1, animation2);
return set;
}
}
If you run this example and press the different Buttons, the animation should start. Via the ActionBar you can navigate to your other activity.
During a Fragment transaction you can define animations which should be used based on the Property Animation API via the
setCustomAnimations() method.You can also use several standard animations provided by Android via the
setTransition()method call. These are defined via the constants starting withFragmentTransaction.TRANSIT_FRAGMENT_*.Both methods allow you to define an entry animation and an exist animation.
Jake Wharton created a library which allow to use the Properties Animation API also in Android releases before Android 4.0.
You find more information on the project website: NineOldAndroids
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