Can I do animation on Android?

Animation allows developers to add visual effects and motion to apps, making the user experience more engaging and intuitive. On mobile devices like Android, animation provides important visual cues that inform users about what’s happening in the app as they interact with it (source). For example, animations can indicate when a screen loads or an item is clicked. Without animation, transitions between app states would feel abrupt.

Android provides a robust framework for animating views and graphics in apps. There are several different APIs available:

• Property animations – animate changes to view properties like scale and transparency
• View animations – predefined animations like fade ins and outs
• Drawable animations – animate vector drawables
• 2D graphics animations – animate Canvas objects
• 3D graphics animations – animate 3D scenes and objects

These allow developers to add a wide range of animated effects with relatively little code. Later sections will explore Android’s animation capabilities in more depth.

Android Animation APIs

Android provides several APIs and libraries for creating animations. The core animation frameworks are Property Animation, View Animation, and Drawable Animation.

Property Animation

The Property Animation system allows you to animate almost anything, from view properties like rotation and alpha to custom properties on any object. It provides high-level APIs for creating animations that are easier to use and more powerful than the classic View animations. Some key capabilities include:

• Animate movement, size, rotation, and transparency of views
• Animate any property on any object
• Automatically animate between layout changes
• Share animations across multiple views

View Animation

View animations are a legacy animation system that allow simple transformations like translating, scaling, rotating, and fading views. They are simpler to use than Property animations but more limited. View animations can:

• Animate movement, size, rotation, and transparency of views
• Define animations in XML for reuse
• Target animation to specific views

Drawable Animation

Drawable animations allow you to animate transitions between drawable resources. This is useful for animating more complex vector graphics. Drawable animations can:

• Animate transitions between SVG/vector drawables
• Create complex movement and transformations
• Reduce APK size by using vector drawables instead of PNGs

Property Animation

Property animation allows you to animate object properties like position, size, color etc. over a specified duration. The key classes for property animation are:

• Animator – Base animation class that provides timing engine and callbacks.
• ObjectAnimator – Animates properties on target objects.
• AnimatorSet – Allows playing animations in sequence or parallel.
• Keyframe – Specifies values for properties at certain points in the animation.
• TimeInterpolator – Defines the rate of change in an animation.

To create a property animation, first define the object and property to animate using ObjectAnimator. Then call methods like setDuration(), setInterpolator() etc. to configure the animation. Finally, call start() to start the animation.

Multiple animations can be grouped together in AnimatorSet and played sequentially or in parallel. Keyframes can be used to define non-linear animation values.

Some common time interpolators are AccelerateDecelerateInterpolator for a smooth change of pace and BounceInterpolator for a bouncing effect.

Overall, property animations provide a powerful way to animate UIs and visual elements in Android apps with full control over animation parameters and playback.

Source

View Animation

View animations allow simple animation effects like translating, rotating, scaling, and fading views. Some key points on view animations in Android:

Translate Animations: The Android developer documentation explains that translate animations will move a view across the screen. You can specify the start and end positions, or have it automatically calculate the positions.

Rotate Animations: Rotate animations will rotate a view around its pivot point. You can control the number of degrees, pivot point, and duration of the rotation animation.

Scale Animations: With scale animations, you can grow or shrink views by specifying scale factors. This allows views to zoom in or out during the animation.

Fade Animations: Fade animations will adjust the visibility and transparency of a view. You can fade views in or out by animating the alpha property.

Drawable Animation

Drawable animations in Android allow you to animate vector graphics and bitmaps. There are two main ways to create drawable animations:

• XML drawable animations – You can define frame-by-frame animations in XML using the tag. Each frame is defined in a tag with a drawable resource. You control the animation timing by setting android:duration on each item.
• Loading drawable frames – You can dynamically load drawable frames from resource files during runtime and display them sequentially to create an animation. This involves loading each drawable frame and displaying it with setImageDrawable() or setBackgroundDrawable().

Some key classes for drawable animations include AnimationDrawable, AnimatedVectorDrawable, and AnimatedStateListDrawable. These allow you to define frame animations in XML and load them dynamically in code.

Compared to view and property animations, drawable animations are relatively simple and limited in capabilities. However, they can be useful for animating icons, progress indicators, and other vector graphics in an Android app.

2D Graphics Animation

Android provides a powerful 2D graphics API for drawing and animating views and graphics through the Canvas and Drawable classes. Some key aspects of 2D graphics animation in Android include:

The Canvas class allows you to draw bitmap images, shapes, text and more onto a view’s surface. It provides methods like drawBitmap(), drawLine(), drawText() etc. You obtain a Canvas by overriding the onDraw() method of a View.

You can animate the drawing of bitmaps by loading bitmap frames into memory and drawing them sequentially inside the onDraw() method. This allows you to create frame-by-frame animations and sprite sheets.

To optimize performance, you should only redraw the minimum area needed when contents change, using invalidate() to flag a view as needing redrawing. This will call onDraw() again to redraw just the invalidated region.

By leveraging the 2D graphics APIs and redrawing strategies above, you can achieve powerful animations and graphics on Android.

3D Graphics Animation

OpenGL ES provides powerful APIs for performing hardware-accelerated 3D graphics and animation on Android. Some key concepts include:

OpenGL ES allows you to specify 3D objects and environments using vertex and fragment shaders. Vertex shaders transform 3D vertex positions into screen space while fragment shaders compute pixel colors. You can manipulate vertices directly or load 3D models to animate.

With OpenGL ES, you can apply 3D transformations like rotation, scaling, and translation to objects in your 3D scene. By changing transformation parameters over time, you can create smooth animations as objects move and spin in 3D space.

For example, you could rotate a 3D cube continuously along the Y axis to create a spinning animation. Or move a 3D character model forward and backward to make it walk. The vertex shader applies these transformations to all the vertices making up your 3D models.

Advanced techniques like keyframe animation and spline interpolation can be used to precisely control how objects move along predefined paths. You can make objects follow curved trajectories and accelerate or decelerate over time for natural, lifelike motion.

Overall, OpenGL ES opens up limitless possibilities for building interactive 3D games, simulations, and other animated experiences on Android. With practice, you can create stunning real-time 3D graphics and animations to bring your apps to life.

Animation Performance

For smooth, high performance animations on Android, it’s important to properly optimize your code. Here are some tips:

Enable hardware acceleration for your animations whenever possible. Hardware acceleration uses the GPU to render the animations instead of the CPU, allowing for faster and smoother graphics (source).

Optimize complex animations by keeping your drawable sizes small, using simple drawable shapes, and reducing the animation frame rate to only what’s needed. Anything higher than 15fps often negatively impacts battery life without improving visual quality (source).

For RecyclerViews, use the RecyclerView.ItemAnimator to animate only the views that change instead of the entire list. Setting up item animations properly can significantly improve performance.

Use profiling tools like Systrace to identity animation bottlenecks. Look for long frames times and optimize the expensive sections of your animations.

By following best practices and optimizing your animation code, you can achieve smooth 60fps animations even on low-end Android devices.

Animation Libraries

There are several popular animation libraries for Android that make it easier to create complex animations and transitions in apps.

One of the most popular is Lottie by Airbnb. Lottie allows you to use Adobe After Effects animations and export them as JSON files that can be rendered natively on Android and iOS. This makes it easy to create intricate animations designed by professional designers. Lottie is used by many top apps and offers a high level of performance.

Facebook Rebound is a Java library that implements Spring Dynamics for building animations that feel natural by introducing real world physics. Rebound allows you to achieve realistic motions and interactions easily with just a few lines of code.

The Android Transition Framework allows you to animate motion and changes during UI state changes in a standardized way. This helps create smooth animated transitions between activities, fragments, layout changes and more. The framework handles most of the work for you and allows transition customization.

Conclusion

In summary, Android provides robust animation capabilities through various APIs and libraries. The key animation options on Android include:

• Property animations for animating object properties
• View animations for predefined animations between views
• Drawable animations for animating drawables and images
• 2D graphics animations with Canvas and RenderScript
• 3D graphics animations with OpenGL ES

Performance and optimization are important considerations when implementing animations. The Android animation system and libraries like React Native Animatable provide tools to optimize animation performance.

For further learning, refer to the official Android animation documentation and Animation in Android tutorials.