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">Animating View State Changes</a></li>
  <li><a href="#drawabletint">Drawable Tinting</a></li>
  <li><a href="#colorextract">Extracting Colors from an Image</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>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>In most cases, this functionality should be applied in your view XML by specifying the
background as <code>?android:attr/selectableItemBackground</code> for a bounded ripple or
<code>?android:attr/selectableItemBackgroundBorderless</code> for a ripple that extends beyond
the view bounds. You can also create a <code>RippleDrawable</code> and set
it as the background of your view. Alternatively, you can define a <code>RippleDrawable</code>
as an XML resource using the <code>ripple</code> element. The
Android L Developer Preview animates the selection color with a ripple effect.</p>

<p>You can assign a color to <code>RippleDrawable</code> objects. To change the default touch
feedback color, use the theme's <code>android:colorControlHighlight</code> attribute.</p>


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

<p>The <code>ViewAnimationUtils.createCircularReveal</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 =
    ViewAnimationUtils.createCircularReveal(myView, 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 =
    ViewAnimationUtils.createCircularReveal(myView, 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>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 the 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>

<p>The Android L Developer Preview supports these enter and exit transitions:</p>

<ul>
<li><em>explode</em> - Moves views in or out from the center of the scene.</li>
<li><em>slide</em> - Moves views in or out from one of the edges of the scene.</li>
<li><em>fade</em> - Mades views in or out of the scene.</li>
</ul>

<p>Any transition that extends the <code>android.transition.Visibility</code> class is supported
as an enter or exit transition. For more information, see the API reference for the
<code>android.transition.Transition</code> class.</p>

<p>The Android L Developer Preview also supports these shared elements transitions:</p>

<ul>
<li><em>changeBounds</em> - Animates the changes in layout bounds of target views.</li>
<li><em>changeClipBounds</em> - Animates the changes in clip bounds of target views.</li>
<li><em>changeTransform</em> - Animates the changes in scale and rotation of target views.</li>
<li><em>moveImage</em> - Animates changes in size and scale type for an image view.</li>
</ul>

<p>When you enable activity transitions in your app, the default cross-fading transition is
activated between the entering and exiting activities.</p>

<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. You can also specify
enter, exit, and shared element transitions in your style definition:</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>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;/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 (if you did not enable transitions in your theme)
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>

<p>The <code>setExitTransition</code> and <code>setSharedElementExitTransition</code> methods
define the exit transition for the calling activity. The <code>setEnterTransition</code> and
<code>setSharedElementEnterTransition</code> methods define the enter transition for the called
activity.</p>

<p>To get the full effect of a transition, you must enable window content transitions on both the
calling and called activities. Otherwise, the calling activity will start the exit transition,
but then you'll see a window transition (like scale or fade).</p>

<p>To start an enter transition as soon as possible, use the
<code>Window.setAllowEnterTransitionOverlap</code> method on the called activity. This lets you
have more dramatic enter transitions. The same applies for the calling activity and exit
transitions with the <code>Window.setAllowExitTransitionOverlap</code> method.</p>

<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.</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.image_small);

// 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>

<p>To reverse the scene transition animation when you finish the second activity, call the
<code>Activity.finishAfterTransition</code> method instead of <code>Activity.finish</code>.</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,
        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>Animator.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">Animating 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 translationZ 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="translationZ"
        android:duration="100"
        android:valueTo="2"
        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="translationZ"
        android:duration="100"
        android:valueTo="2"
        android:valueType="floatType"/>
    &lt;/set>
  &lt;/item>
&lt;/selector>
</pre>

<p class="note"><strong>Note:</strong> There is a known issue in the L Developer Preview release
that requires valueFrom values to be provided in StateListAnimator animations to get the correct
behavior.</p>

<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 or nine-patches as alpha masks and
to tint them using a color resource or a theme attribute that resolves to a color resource (for
example, <code>?android:attr/colorPrimary</code>). You can create these assets only once and color them
automatically to match your theme.</p>

<p>To apply a tint to a bitmap, use the <code>setTint</code> method or the <code>android:tint</code>
attribute for <code>BitmapDrawable</code> and <code>NinePatchDrawable</code>.</p>

<p>The <code>setTint</code> method also lets you set the Porter-Duff mode used to blend the
tint color for <code>NinePatchDrawable</code> and <code>BitmapDrawable</code> objects in your code.
To set the tint mode in your layouts, use the <code>android:tintMode</code> attribute.</p>


<h2 id="colorextract">Extracting Prominent Colors from an Image</h2>

<p>The Android L Developer Preview Support Library includes the <code>Palette</code> class,
which lets you extract prominent colors from an image. This class extracts the following
prominent colors:</p>

<ul>
<li>Vibrant</li>
<li>Vibrant dark</li>
<li>Vibrant light</li>
<li>Muted</li>
<li>Muted dark</li>
<li>Muted light</li>
</ul>

<p>To extract these colors, pass a <code>Bitmap</code> object to the
<code>Palette.generate</code> static method in the background thread where you load your images.
If you can't use that thread, call the <code>Palette.generateAsync</code> method instead and
provide a listener.</p>

<p>To retrieve the prominent colors from the image, use the getter methods in the
<code>Palette</code> class, such as <code>Palette.getVibrantColor</code>.</p>

<p>For more information, see the API reference for the
<code>android.support.v7.graphics.Palette</code> class.</p>