android_frameworks_base/docs/html/preview/material/animations.jd

page.title=Animations

@jd:body

<div id="qv-wrapper">
<div id="qv">
<h2>In this document</h2>
<ol>
  <li><a href="#touch">Touch Feedback</a></li>
  <li><a href="#reveal">Reveal Effect</a></li>
  <li><a href="#transitions">Activity Transitions</a></li>
  <li><a href="#curvedmotion">Curved Motion</a></li>
  <li><a href="#viewstate">View State Changes</a></li>
  <li><a href="#drawabletint">Drawable Tinting</a></li>
</ol>
</div>
</div>

<p>Animations in material design give users feedback on their actions and provide visual
continuity as users interact with your app. The material theme provides some default animations
for buttons and activity transitions, and the Android L Developer Preview provides additional
APIs that let you customize these animations and create new ones:</p>

<ul>
<li>Touch feedback</li>
<li>Reveal effect</li>
<li>Activity transitions</li>
<li>Curved motion</li>
<li>View state changes</li>
</ul>


<h2 id="touch">Touch Feedback</h2>

<p>In the Android L Developer Preview the default touch feedback animations for buttons use the new
<code>RippleDrawable</code> class, which transitions between different states with a ripple
effect.</p>

<p>To use this functionality in your custom views, create a <code>RippleDrawable</code> and set
it as the background of your view. You can define a <code>RippleDrawable</code> as an XML resource
using the <code>ripple</code> element.</p>


<h2 id="reveal">Reveal Effect</h2>

<p>The <code>View.createRevealAnimator</code> method enables you to animate a clipping circle
to reveal or hide a view.</p>

<p>To reveal a previously invisible view using this effect:</p>

<pre>
// previously invisible view
View myView = findViewById(R.id.my_view);

// get the center for the clipping circle
int cx = (myView.getLeft() + myView.getRight()) / 2;
int cy = (myView.getTop() + myView.getBottom()) / 2;

// get the final radius for the clipping circle
int finalRadius = myView.getWidth();

// create and start the animator for this view
// (the start radius is zero)
ValueAnimator anim = myView.createRevealAnimator(cx, cy, 0, finalRadius);
anim.start();
</pre>

<p>To hide a previously visible view using this effect:</p>

<pre>
// previously visible view
final View myView = findViewById(R.id.my_view);

// get the center for the clipping circle
int cx = (myView.getLeft() + myView.getRight()) / 2;
int cy = (myView.getTop() + myView.getBottom()) / 2;

// get the initial radius for the clipping circle
int initialRadius = myView.getWidth();

// create the animation (the final radius is zero)
ValueAnimator anim = myView.createRevealAnimator(cx, cy, initialRadius, 0);

// make the view invisible when the animation is done
anim.addListener(new AnimatorListenerAdapter() {
    &#64;Override
    public void onAnimationEnd(Animator animation) {
        super.onAnimationEnd(animation);
        myView.setVisibility(View.INVISIBLE);
    }
});

// start the animation
anim.start();
</pre>


<h2 id="transitions">Activity Transitions</h2>

<p>The Android L Developer Preview enables your app to customize the default animations for
activity transitions. You can specify custom animations for enter and exit transitions and for
transitions of shared elements between activities.</p>

<ul>
  <li>An <strong>enter</strong> transition determines how views in an activity enter the scene.
  For example, in the <em>explode</em> enter transition the views enter the scene from outside
  and fly in towards the center of the screen.</li>

  <li>An <strong>exit</strong> transition determines how views in an activity exit the scene. For
  example, in the <em>explode</em> exit transition the views exit the scene away from the
  center.</li>

  <li>A <strong>shared elements</strong> transition determines how views that are shared between
  two activities transition between these activities. For example, if two activities have the same
  image in different positions and sizes, the <em>moveImage</em> shared element transition
  translates and scales the image smoothly between these activities.</li>
</ul>

<img src="/preview/material/images/SceneTransition.png" alt=""
     id="figure1" style="width:600px;margin-top:20px"/>
<p class="img-caption">
  <strong>Figure 1</strong> - A scene transition with one shared element.
</p>

<h3>Specify custom transitions</h3>

<p>First, enable window content transitions with the <code>android:windowContentTransitions</code>
attribute when you define a style that inherits from the material theme:</p>

<pre>
&lt;style name="BaseAppTheme" parent="android:Theme.Material">
  &lt;!-- enable window content transitions -->
  &lt;item name="android:windowContentTransitions">true&lt;/item>

  &lt;!-- specify enter and exit transitions -->
  &lt;item name="android:windowEnterTransition">@transition/explode&lt;/item>
  &lt;item name="android:windowExitTransition">@transition/explode&lt;/item>

  &lt;!-- specify shared element transitions -->
  &lt;item name="android:windowSharedElementEnterTransition">
    &#64;transition/move_image&lt;/item>
  &lt;item name="android:windowSharedElementExitTransition">
    &#64;transition/move_image&lt;/item>
&lt;/style>
</pre>

<p>You can also specify enter, exit, and shared element transitions in your style definition.
The <code>move_image</code> transition in this example is defined as follows:</p>

<pre>
&lt;!-- res/transition/move_image.xml -->
&lt;!-- (see also Shared Transitions below) -->
&lt;transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
  &lt;moveImage>
    &lt;targets>
      &lt;!-- shared view in the first activity -->
      &lt;target android:targetId="@id/image_small" />
      &lt;!-- shared view in the second activity -->
      &lt;target android:targetId="@id/image_big" />
    &lt;/targets>
  &lt;/moveImage>
&lt;/transitionSet>
</pre>

<p>The <code>moveImage</code> element corresponds to the <code>android.transition.MoveImage</code>
class. For more information, see the API reference for <code>android.transition.Transition</code>.
</p>

<p>To enable window content transitions in your code instead, call the
<code>Window.requestFeature</code> method:</p>

<pre>
// inside your activity
getWindow().requestFeature(Window.FEATURE_CONTENT_TRANSITIONS);

// set an exit transition
getWindow().setExitTransition(new Explode());
</pre>

<p>To specify transitions in your code, call these methods with a <code>Transition</code>
object:</p>

<ul>
  <li><code>Window.setEnterTransition</code></li>
  <li><code>Window.setExitTransition</code></li>
  <li><code>Window.setSharedElementEnterTransition</code></li>
  <li><code>Window.setSharedElementExitTransition</code></li>
</ul>

<h3>Start an activity using transitions</h3>

<p>If you enable transitions and set an exit transition for an activity, the transition is activated
when you launch another activity with the <code>startActivity</code> method. If you have set an
enter transition for the second activity, the transition is also activated when the activity
starts.</p>

<h3>Shared elements transitions</h3>

<p>To make a screne transition animation between two activities that have a shared element:</p>

<ol>
<li>Enable window content transitions in your style.</li>
<li>Specify a shared elements transition in your style.</li>
<li>Define your transition as an XML resource specifying the IDs of the target views.</li>
<li>Assign a common name to the shared elements in both layouts with the
    <code>android:viewName</code> attribute.</li>
<li>Use the <code>ActivityOptions.makeSceneTransitionAnimation</code> method.</li>
</ol>

<pre>
// get the element that receives the click event
final View imgContainerView = findViewById(R.id.img_container);

// get the common element for the transition in this activity
final View androidRobotView = findViewById(R.id.android_robot_img);

// define a click listener
imgContainerView.setOnClickListener(new View.OnClickListener() {
    &#64;Override
    public void onClick(View view) {
        Intent intent = new Intent(this, Activity2.class);
        // create the transition animation - the images in the layouts
        // of both activities are defined with android:viewName="robot"
        ActivityOptions options = ActivityOptions
            .makeSceneTransitionAnimation(this, androidRobotView, "robot");
        // start the new activity
        startActivity(intent, options.toBundle());
    }
});
</pre>

<p>For shared dynamic views that you generate in your code, use the <code>View.setViewName</code>
method to specify a common element name in both activities.</p>

<h3>Multiple shared elements</h3>

<p>To make a scene transition animation between two activities that have more than one shared
element, define the shared elements in both layouts with the <code>android:viewName</code>
attribute (or use the <code>View.setViewName</code> in both activities), and create an
<code>ActivityOptions</code> object as follows:</p>

<pre>
ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(this,
    new Pair[] {
        Pair.create(view1, "agreedName1"),
        Pair.create(view2, "agreedName2"),
        ...
    }
);
</pre>


<h2 id="curvedmotion">Curved Motion</h2>

<p>Animations in material design rely on curves for time interpolation and spatial movement
patterns. The Android L Developer Preview provides new APIs that enable you to define custom
timing curves and curved motion patterns for animations.</p>

<p>The <code>PathInterpolator</code> class is a new interpolator based on a Bézier curve or a
<code>Path</code> object. This interpolator specifies a motion curve in a 1x1 square, with anchor
points at (0,0) and (1,1) and control points as specified using the constructor arguments. You can
also define a <code>PathInterpolator</code> as an XML resource:</p>

<pre>
&lt;pathInterpolator xmlns:android="http://schemas.android.com/apk/res/android"
    android:controlX1="0.4"
    android:controlY1="0"
    android:controlX2="1"
    android:controlY2="1"/>
</pre>

<p>The Android L Developer Preview provides XML resources for the three basic curves in the
material design specification:</p>

<ul>
  <li><code>&#64;interpolator/fast_out_linear_in.xml</code></li>
  <li><code>&#64;interpolator/fast_out_slow_in.xml</code></li>
  <li><code>&#64;interpolator/linear_out_slow_in.xml</code></li>
</ul>

<p>You can pass a <code>PathInterpolator</code> object to the
<code>Animation.setInterpolation</code> method.</p>

<p>The <code>ObjectAnimator</code> class has new constructors that enable you to animate
coordinates along a path using two or more properties at once. For example, the following animator
uses a <code>Path</code> object to animate the X and Y properties of a view:</p>

<pre>
ObjectAnimator mAnimator;
mAnimator = ObjectAnimator.ofFloat(view, View.X, View.Y, path);
...
mAnimator.start();
</pre>


<h2 id="viewstate">View State Changes</h2>

<p>The new <code>StateListAnimator</code> class lets you define animators that run when the state
of a view changes. The following example shows how to define an <code>StateListAnimator</code> as
an XML resource:</p>

<pre>
&lt;!-- animate the elevation property of a view when pressed -->
&lt;selector xmlns:android="http://schemas.android.com/apk/res/android">
  &lt;item android:state_pressed="true">
    &lt;set>
      &lt;objectAnimator android:propertyName="elevation"
        android:duration="100"
        android:valueTo="60"
        android:valueType="floatType"/>
        &lt;!-- you could have other objectAnimator elements
             here for "x" and "y", or other properties -->
    &lt;/set>
  &lt;/item>
  &lt;item android:state_enabled="true"
    android:state_pressed="false"
    android:state_focused="true">
    &lt;set>
      &lt;objectAnimator android:propertyName="elevation"
        android:duration="100"
        android:valueTo="10"
        android:valueType="floatType"/>
    &lt;/set>
  &lt;/item>
&lt;/selector>
</pre>

<p>The new <code>AnimatedStateListDrawable</code> class lets you create drawables that show
animations between state changes of the associated view. Some of the system widgets in the
Android L Developer Preview use these animations by default. The following example shows how
to define an <code>AnimatedStateListDrawable</code> as an XML resource:</p>

<pre>
&lt;!-- res/drawable/myanimstatedrawable.xml -->
&lt;animated-selector
    xmlns:android="http://schemas.android.com/apk/res/android">

    &lt;!-- provide a different drawable for each state-->
    &lt;item android:id="@+id/pressed" android:drawable="@drawable/drawableP"
        android:state-pressed="true"/>
    &lt;item android:id="@+id/focused" android:drawable="@drawable/drawableF"
        android:state-focused="true"/>
    &lt;item android:id="@id/default"
        android:drawable="@drawable/drawableD"/>

    &lt;!-- specify a transition -->
    &lt;transition android:fromId="@+id/default" android:toId="@+id/pressed">
        &lt;animation-list>
            &lt;item android:duration="15" android:drawable="@drawable/dt1"/>
            &lt;item android:duration="15" android:drawable="@drawable/dt2"/>
            ...
        &lt;/animation-list>
    &lt;/transition>
    ...
&lt;/animated-selector>
</pre>


<h2 id="drawabletint">Drawable Tinting</h2>

<p>The Android L Developer Preview enables you to define bitmaps as an alpha mask and to tint
them using a color resource or a theme attribute that resolves to a color resource. You can
create these assets only once and color them automatically to match your theme.</p>

<p>To apply a tint to a bitmap in your code, use the <code>setTint</code> method in these
classes:</p>

<ul>
<li><code>PaintDrawable</code></li>
<li><code>NinePatchDrawable</code></li>
<li><code>RippleDrawable</code></li>
</ul>

<p>In your layouts, use the <code>android:tint</code> attribute instead.</p>

<p>The <code>setTint</code> method also lets you set the tint blending mode for
<code>NinePatchDrawable</code> and <code>RippleDrawable</code> objects in your code. To set the
tint mode in your layouts, use the <code>android:tintMode</code> attribute.</p>