Property Animations | Graphics And Animation | Android Development Tutorial

Introduction

Property Animations in Android allow you to animate various properties of UI elements over time. This includes changing size, position, rotation, and other properties to create rich visual effects. Unlike View Animations, Property Animations can change any property of any object, not just Views.

Setting Up

To get started with Property Animations, ensure your Android project is set up correctly. Add the following dependencies in your build.gradle file if they are not already present:

implementation 'com.android.support:appcompat-v7:28.0.0'

Basic Property Animation

The basic way to create a property animation is by using the ObjectAnimator class. Here is an example of animating the alpha property of a TextView:

TextView textView = findViewById(R.id.textView);
ObjectAnimator animation = ObjectAnimator.ofFloat(textView, "alpha", 0f, 1f);
animation.setDuration(2000);
animation.start();

This code snippet animates the alpha property of the textView from 0 (completely transparent) to 1 (fully opaque) over 2 seconds.

Animating Multiple Properties

You can animate multiple properties at the same time using AnimatorSet. Here’s an example:

TextView textView = findViewById(R.id.textView);
ObjectAnimator alphaAnimation = ObjectAnimator.ofFloat(textView, "alpha", 0f, 1f);
ObjectAnimator scaleXAnimation = ObjectAnimator.ofFloat(textView, "scaleX", 0.5f, 1f);
ObjectAnimator scaleYAnimation = ObjectAnimator.ofFloat(textView, "scaleY", 0.5f, 1f);

AnimatorSet animatorSet = new AnimatorSet();
animatorSet.playTogether(alphaAnimation, scaleXAnimation, scaleYAnimation);
animatorSet.setDuration(2000);
animatorSet.start();

This code snippet animates the alpha, scaleX, and scaleY properties of the textView simultaneously.

Using XML for Property Animations

Property animations can also be defined in XML. Create an XML file in the res/animator directory:

<set xmlns:android="http://schemas.android.com/apk/res/android">
    <objectAnimator
        android:propertyName="alpha"
        android:valueFrom="0"
        android:valueTo="1"
        android:duration="2000" />
    <objectAnimator
        android:propertyName="scaleX"
        android:valueFrom="0.5"
        android:valueTo="1"
        android:duration="2000" />
    <objectAnimator
        android:propertyName="scaleY"
        android:valueFrom="0.5"
        android:valueTo="1"
        android:duration="2000" />
</set>

You can then load and start this animation in your Java or Kotlin code:

AnimatorSet animatorSet = (AnimatorSet) AnimatorInflater.loadAnimator(this, R.animator.property_animation);
animatorSet.setTarget(textView);
animatorSet.start();

Advanced Techniques

For more complex animations, you can use ValueAnimator to compute values for any property, not just View properties. Here’s an example of changing the background color of a TextView:

ValueAnimator colorAnimation = ValueAnimator.ofObject(new ArgbEvaluator(), Color.RED, Color.BLUE);
colorAnimation.setDuration(3000); // 3 seconds
colorAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animator) {
        textView.setBackgroundColor((int) animator.getAnimatedValue());
    }
});
colorAnimation.start();

This snippet animates the background color of the textView from red to blue over 3 seconds using ValueAnimator and ArgbEvaluator.

Conclusion

Property Animations in Android provide a powerful way to create smooth and visually appealing UI transitions. By mastering the use of ObjectAnimator, AnimatorSet, and ValueAnimator, you can create complex animations that enhance the user experience of your app.

Property Animations in Android Development