The Android system provides a flexible animation system that allows you to animate almost anything, either programmatically or declaratively with XML. There are two - animation systems that you can choose from: property + animation systems that you can choose from: property animation and view animation. You can use whichever system that matches your needs, but use only one system for each object that you are animating.
@@ -91,7 +91,7 @@ page.title=AnimationMost of the property animation system's features can be found in {@link android.animation android.animation}. Because the - view animation system already defines many interpolators in {@link android.view.animation android.view.animation}, you will use those to define your animation's interpolation in the property animation system as well. @@ -163,7 +163,7 @@ page.title=Animation
The Android system provides a set of common interpolators in {@link android.view.animation android.view.animation}. If none of these suits your needs, you can implement the {@link android.animation.TimeInterpolator} interface and create - your own. See Interpolators for more information on + your own. See Using interpolators for more information on how to write a custom interpolator.
@@ -286,14 +286,13 @@ animation.start(); android.animation.AnimatorListenerAdapter} for just the {@link android.animation.Animator.AnimatorListener#onAnimationEnd onAnimationEnd()} callback: +ValueAnimator fadeAnim = ObjectAnimator.ofFloat(newBall, "alpha", 1f, 0f);
fadeAnim.setDuration(250);
fadeAnim.addListener(new AnimatorListenerAdapter() {
public void onAnimationEnd(Animator animation) {
balls.remove(((ObjectAnimator)animation).getTarget());
-}
-
-
+}
Instantiating an {@link android.animation.ObjectAnimator} is similar to a {@link android.animation.ValueAnimator}, but you also specify the object and that object's property (as a String) that you want to animate:
--ObjectAnimator anim = ObjectAnimator.ofFloat(foo, "alpha", 0f, 1f); +ObjectAnimator anim = ObjectAnimator.ofFloat(foo, "alpha", 0f, 1f); anim.setDuration(1000); -anim.start(); -+anim.start();
To have the {@link android.animation.ObjectAnimator} update properties correctly, you must do the following:
@@ -355,7 +352,7 @@ anim.start(); -If you want to animate a type that is unknown to the Android system, you can create your own evaluator by implementing the {@link @@ -369,15 +366,13 @@ anim.start(); This allows the animator that you are using to return an appropriate value for your animated property at the current point of the animation. The {@link android.animation.FloatEvaluator} class demonstrates how to do this:
-
-public class FloatEvaluator implements TypeEvaluator {
+ public class FloatEvaluator implements TypeEvaluator {
public Object evaluate(float fraction, Object startValue, Object endValue) {
float startFloat = ((Number) startValue).floatValue();
return startFloat + fraction * (((Number) endValue).floatValue() - startFloat);
}
-}
-
+}
Note: When {@link android.animation.ValueAnimator} (or {@link android.animation.ObjectAnimator}) runs, it calculates a current elapsed @@ -387,7 +382,7 @@ public class FloatEvaluator implements TypeEvaluator { parameter, so you do not have to take into account the interpolator when calculating animated values.
-An interpolator define how specific values in an animation are calculated as a function of time. For example, you can specify animations to happen @@ -414,12 +409,12 @@ public class FloatEvaluator implements TypeEvaluator {
AccelerateDecelerateInterpolator
public float getInterpolation(float input) {
return (float)(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
- }
+}
LinearInterpolator
public float getInterpolation(float input) {
return input;
- }
+}
The following table represents the approximate values that are calculated by these interpolators for an animation that lasts 1000ms:
@@ -488,7 +483,7 @@ public class FloatEvaluator implements TypeEvaluator { {@link android.view.animation.LinearInterpolator} between 200ms and 600ms and slower between 600ms and 1000ms. -A {@link android.animation.Keyframe} object consists of a time/value pair that lets you define a specific state at a specific time of an animation. Each keyframe can also @@ -505,19 +500,18 @@ public class FloatEvaluator implements TypeEvaluator { object, you can obtain an animator by passing in the {@link android.animation.PropertyValuesHolder} object and the object to animate. The following code snippet demonstrates how to do this:
-
- Keyframe kf0 = Keyframe.ofFloat(0f, 0f);
- Keyframe kf1 = Keyframe.ofFloat(.9999f, 360f);
- Keyframe kf2 = Keyframe.ofFloat(1f, 0f);
- PropertyValuesHolder pvhRotation = PropertyValuesHolder.ofKeyframe("rotation", kf0, kf1, kf2);
- ObjectAnimator rotationAnim = ObjectAnimator.ofPropertyValuesHolder(target, pvhRotation)
- rotationAnim.setDuration(5000ms);
-
-For a more complete example on how to use keyframes, see the Keyframe kf0 = Keyframe.ofFloat(0f, 0f);
+Keyframe kf1 = Keyframe.ofFloat(.9999f, 360f);
+Keyframe kf2 = Keyframe.ofFloat(1f, 0f);
+PropertyValuesHolder pvhRotation = PropertyValuesHolder.ofKeyframe("rotation", kf0, kf1, kf2);
+ObjectAnimator rotationAnim = ObjectAnimator.ofPropertyValuesHolder(target, pvhRotation)
+rotationAnim.setDuration(5000ms);
+
+For a more complete example on how to use keyframes, see the - MultiPropertyAnimation sample in APIDemos. + MultiPropertyAnimation
sample in APIDemos. -In many cases, you want to play an animation that depends on when another animation starts or finishes. The Android system lets you bundle animations together into an @@ -559,7 +553,7 @@ animatorSet.start();
As with view animation, you can declare property animations with +
As with view animation, you can declare property animations with XML instead of doing it programmatically. The following Android classes also have XML declaration support with the following XML tags:
@@ -639,14 +633,13 @@ animatorSet.start(); android:propertyName="y" android:duration="500" android:valueTo="300" - android:valueType="int" > - </set> - <objectAnimator - android:propertyName="alpha" - android:duration="500" - android:valueTo="0f"/> - </set> - + android:valueType="int"/> + </set> + <objectAnimator + android:propertyName="alpha" + android:duration="500" + android:valueTo="0f"/> +</set>In order to run this animation, you must inflate the XML resources in your code to an {@link android.animation.AnimatorSet} object, and then set the target objects for all of @@ -698,40 +691,38 @@ animatorSet.start();
The following XML from one of the ApiDemos is used to stretch, then simultaneously spin and rotate a View object.
--<set android:shareInterpolator="false"> - <scale - android:interpolator="@android:anim/accelerate_decelerate_interpolator" - android:fromXScale="1.0" - android:toXScale="1.4" - android:fromYScale="1.0" - android:toYScale="0.6" - android:pivotX="50%" - android:pivotY="50%" - android:fillAfter="false" - android:duration="700" /> - <set android:interpolator="@android:anim/decelerate_interpolator"> - <scale - android:fromXScale="1.4" - android:toXScale="0.0" - android:fromYScale="0.6" - android:toYScale="0.0" - android:pivotX="50%" - android:pivotY="50%" - android:startOffset="700" - android:duration="400" - android:fillBefore="false" /> - <rotate - android:fromDegrees="0" - android:toDegrees="-45" - android:toYScale="0.0" - android:pivotX="50%" - android:pivotY="50%" - android:startOffset="700" - android:duration="400" /> - </set> -</set> -+
<set android:shareInterpolator="false"> + <scale + android:interpolator="@android:anim/accelerate_decelerate_interpolator" + android:fromXScale="1.0" + android:toXScale="1.4" + android:fromYScale="1.0" + android:toYScale="0.6" + android:pivotX="50%" + android:pivotY="50%" + android:fillAfter="false" + android:duration="700" /> + <set android:interpolator="@android:anim/decelerate_interpolator"> + <scale + android:fromXScale="1.4" + android:toXScale="0.0" + android:fromYScale="0.6" + android:toYScale="0.0" + android:pivotX="50%" + android:pivotY="50%" + android:startOffset="700" + android:duration="400" + android:fillBefore="false" /> + <rotate + android:fromDegrees="0" + android:toDegrees="-45" + android:toYScale="0.0" + android:pivotX="50%" + android:pivotY="50%" + android:startOffset="700" + android:duration="400" /> + </set> +</set>
Screen coordinates (not used in this example) are (0,0) at the upper left hand corner, and increase as you go down and to the right.
@@ -805,8 +796,7 @@ spaceshipImage.startAnimation(hyperspaceJumpAnimation); image to a View and then called to play. Here's an example Activity, in which the animation is added to an {@link android.widget.ImageView} and then animated when the screen is touched: -
-AnimationDrawable rocketAnimation;
+ AnimationDrawable rocketAnimation;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
@@ -823,8 +813,7 @@ public boolean onTouchEvent(MotionEvent event) {
return true;
}
return super.onTouchEvent(event);
-}
-
+}
It's important to note that the start() method called on the
AnimationDrawable cannot be called during the onCreate() method of your