animation - Android properties that can be animated with ObjectAnimator - Stack Overflow

 

android property animation example

The object property that you are animating must have a setter function (in camel case) in the form of set(). Because the ObjectAnimator automatically updates the property during animation, it must be able to access the property with this setter method. For example, if the property name is foo, you need to have a setFoo() method. Making a move: Using Property Animation in your apps. You can use Android’s Property Animation system to animate just about anything, not only visual objects. Property animations modify the properties of an object over time. Our tutorial app shows you how . Jan 28,  · ValueAnimator provides a timing engine for running animation which calculates the animated values and set them on the target objects. By ValueAnimator you can animate a .


Property Animation Overview | Android Developers


The property animation system is a robust framework that allows you to animate almost anything. You can define an animation to change any object property over time, regardless of whether it draws to the screen or not.

A property animation changes a property's a field in an object value over a specified length of time. To animate something, you specify the object property that you want to animate, such as an object's position on the screen, how long you want to animate it for, and what values you want to animate between. To see a full example of property animation, see the ChangeColor class in the android-CustomTransition sample on GitHub.

First, let's go over how an animation works with a simple example. Figure 1 depicts a hypothetical object that is animated with its x property, which represents its horizontal location on a screen. The duration of the animation is set to 40 ms and the distance to travel is 40 pixels.

Every 10 ms, which is the default frame refresh rate, the object moves horizontally by 10 pixels. At the end of 40ms, the animation stops, and the object ends at horizontal position android property animation example This is an example of an animation with linear interpolation, meaning the object moves at a constant speed.

You can also specify animations to have a non-linear interpolation. Figure 2 illustrates a hypothetical object that accelerates at android property animation example beginning of the animation, and decelerates at the end android property animation example the animation.

The object still moves 40 pixels in 40 ms, but non-linearly. In the beginning, android property animation example, this animation accelerates up to the halfway point then decelerates from the halfway point until the end of the animation. As Figure 2 shows, the distance traveled at the beginning and end of the animation is less than in the middle.

Let's take a detailed look at how the important components of the property animation system would calculate animations like the ones illustrated above. Figure 3 depicts how the main classes work with one another. The ValueAnimator object keeps track of your animation's timing, such as how long the animation has been running, and the current value of the property that it is animating.

The ValueAnimator encapsulates a TimeInterpolatorwhich defines animation interpolation, and a TypeEvaluatorwhich defines how to calculate values for the property being animated. To start an animation, create a ValueAnimator and give it the starting and ending values for the property that you want to animate, along with the duration of the animation.

When you call start the animation begins. During the whole animation, the ValueAnimator calculates an elapsed fraction between 0 and 1, based on the duration of the animation and how much time has elapsed, android property animation example. When the ValueAnimator is done calculating an elapsed fraction, it calls the TimeInterpolator that is currently set, to calculate an interpolated fraction. An interpolated fraction maps android property animation example elapsed fraction to a new fraction that takes into account the time interpolation that is set.

For example, in Figure 2, because the animation slowly accelerates, the interpolated fraction, about. In Figure 1, the interpolated fraction is always the same as the elapsed fraction. When the interpolated fraction is calculated, ValueAnimator calls the appropriate TypeEvaluator android property animation example, to calculate the value of the property that android property animation example are animating, based on the interpolated fraction, the starting value, and the ending value of the animation.

For example, in Figure 2, the interpolated fraction was. The view animation system provides the capability to android property animation example animate View objects, so if you wanted to animate non- View objects, you have to implement your own code to do so.

The view animation system is also constrained in the fact that it only exposes a few aspects of a View object to animate, such as the scaling android property animation example rotation of a View but not the background color, android property animation example, for instance.

Another disadvantage of the view animation system is that it only modified where the View was drawn, and not the actual View itself. For instance, android property animation example, if you animated a button to move across the screen, the button draws correctly, android property animation example the actual location where you can click the button does not change, android property animation example, so you have to android property animation example your own logic to handle this.

With the property animation system, these constraints are completely removed, and you can animate any property of any object Views and non-Views and the object itself is actually modified.

The property animation system android property animation example also more robust in the way it carries out animation. At a high level, you assign animators to the properties that you want to animate, such as color, position, or size and can define aspects of the animation such as interpolation and synchronization of multiple animators.

The view animation system, however, takes less time to setup and requires less code to write. If view animation accomplishes everything that you need to do, android property animation example, or if your existing code already works the way you want, there is no need to use the property animation system. It also might make sense to use both animation systems for different situations if the use case arises.

You can find most of the property animation system's APIs in android. Because the view animation system already defines many interpolators in android. The following tables describe the main components of the property animation system. The Animator class provides the basic structure for creating animations.

You normally do not use this class directly as it only provides minimal functionality that must be extended to fully support animating values. The following subclasses extend Animator :. Evaluators tell the property animation system how to calculate values for a given property. They take the timing data that is provided by an Animator class, android property animation example, the animation's start and end value, android property animation example, and calculate the animated values of the property based on this data.

The property animation system provides the following evaluators:. A time interpolator defines how specific values in an animation are calculated as a function of time. For example, you can specify animations to happen linearly across the whole animation, meaning the animation moves evenly the entire time, or you can specify animations to use non-linear time, android property animation example, for example, accelerating at the beginning and decelerating at the end of the animation.

Table 3 describes the interpolators that are contained in android. If none of the provided interpolators suits your needs, implement the TimeInterpolator interface and create your own. See Using interpolators for more information on how to write a custom interpolator. The ValueAnimator class lets you animate values of some type for the duration of an animation by specifying a set of intfloator color values to animate through. For example:. In this code, the ValueAnimator starts calculating the values of the animation, between 0 andfor a duration of ms, when the start method runs.

In this code, the ValueAnimator starts calculating the values of the animation, between startPropertyValue and endPropertyValue using the logic supplied by MyTypeEvaluator for a duration of ms, when the start method runs. You can use the values of the animation by adding an AnimatorUpdateListener to the ValueAnimator object, as shown in the following code:, android property animation example. In the onAnimationUpdate method you can access the updated animation value and use it in a property of one of your views, android property animation example.

For more information on listeners, see the section about Animation listeners. The ObjectAnimator is a subclass of the ValueAnimator discussed in the previous section and combines the timing engine and value computation of ValueAnimator with the ability to animate a named property of a target object. This makes animating any object much easier, as you no longer need to implement the ValueAnimator, android property animation example.

AnimatorUpdateListenerbecause the animated property updates automatically. Instantiating an ObjectAnimator is similar to a ValueAnimatorbut you also specify the object and the name of that object's property as a String along with the values to animate between:. To have the ObjectAnimator update properties correctly, you must do the following:, android property animation example.

In many cases, you want to play an animation that depends on when another animation starts or finishes, android property animation example. The Android system lets you bundle animations together into an AnimatorSetandroid property animation example, so that you can specify whether to start animations simultaneously, sequentially, or after a specified delay. You can also nest AnimatorSet objects within each other. The following code snippet plays the following Animator objects in the following manner:.

You android property animation example listen for important events during an animation's duration with the listeners described below. Listen to this event to use the calculated values generated by ValueAnimator during an animation.

To use the value, query the ValueAnimator object passed into the event to get the current animated value with the getAnimatedValue method. Implementing this listener is required if you use ValueAnimator. Depending on what property or object you are animating, you might need to call invalidate on a View to force that area of the screen to redraw itself with the new animated values.

For example, animating the color property of a Drawable object only cause updates to the screen when that object redraws itself. All of the property setters on View, such as setAlpha and setTranslationX invalidate the View properly, so you do not need to invalidate the View when calling these methods with new values.

You can extend the AnimatorListenerAdapter class instead of implementing the Animator. AnimatorListener interface, if you do not want to implement all of the methods of the Animator, android property animation example. AnimatorListener interface. The AnimatorListenerAdapter class provides empty implementations of the methods that you can choose to override. For example, the following code snippet creates an AnimatorListenerAdapter for just the onAnimationEnd callback:.

The property animation system provides the capability to animate changes to ViewGroup objects as well as provide an easy way to animate View objects themselves. You can animate layout changes within a ViewGroup with the LayoutTransition class. The remaining Views in the ViewGroup can also animate into their new positions when you add or remove Views, android property animation example.

You can define the following animations in a LayoutTransition object by calling setAnimator and passing in an Animator object with one of the following LayoutTransition constants:. You can define your own custom animations for these four types of events to customize the look of your layout transitions or just tell the animation system to use the default animations. The LayoutAnimations sample in API Demos shows you how to define animations for layout transitions and then set the animations on the View objects that you want to animate.

The only thing that you need to do is to set the android:animateLayoutchanges attribute to true for the ViewGroup. Setting this attribute to true automatically animates Views that are added or removed from the ViewGroup as well as the remaining Views in the ViewGroup. The StateListAnimator class lets you define animators that run when the state of a view changes.

This object behaves as a wrapper for an Animator object, calling that animation whenever the specified view state such as "pressed" or "focused" changes. For example, the following file creates a state list animator that changes the x and y scale of the view when it's pressed:. To attach the state list animator to a view, add the android:stateListAnimator attribute as follows:.

Or to instead assign a state list animator to a view in your code, use the AnimatorInflater. Or instead of animating properties of the view, you can play a drawable animation between state changes, using AnimatedStateListDrawable.

Some of the system widgets in Android 5. If you want to animate a type that is unknown to the Android system, you can create your own evaluator by implementing the TypeEvaluator interface. The types that are known by the Android system are intfloator a color, which are supported by the IntEvaluatorFloatEvaluatorand ArgbEvaluator type evaluators.

There is only one method to implement in the TypeEvaluator interface, the evaluate method.

 

Using animations in Android application - Tutorial

 

android property animation example

 

The object property that you are animating must have a setter function (in camel case) in the form of set(). Because the ObjectAnimator automatically updates the property during animation, it must be able to access the property with this setter method. For example, if the property name is foo, you need to have a setFoo() method. Android allows changing object properties over a certain time interval via the properties animation API. The superclass of the animation API is the Animator class. The ObjectAnimator class can be used to modify attributes of an object. Via the setInterpolator() method you register an. To see a full example of property animation, see the ChangeColor class in the android-CustomTransition sample on GitHub. How property animation works. First, let's go over how an animation works with a simple example. Figure 1 depicts a hypothetical object that is animated with its x property, which represents its horizontal location on a.