Graphics & Animationin Android

Android rendering options

• The Canvas API• Renderscript• OpenGL wrappers• NDK OpenGL

http://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

The Canvas API

• Standard rendering for a typical SDK application that uses View objects (standard and custom)

• consists of calls to each View's onDraw() method. This method takes a single parameter, Canvas, which is the object used by the view to draw its content.

http://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

Renderscript

• Introduced in Android 3.0• API targeted high-performance 3D rendering

and compute operations• a 3D rendering API on top of hardware

acceleration, language C99• executing native code on the device still cross-

platform• use of extensions that are placed into the

application packagehttp://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

Renderscript

• Live Wallpapers, the video wall view in the YouTube application, and the Books application (including that beautiful page-turn effect).

• http://www.youtube.com/watch?v=uQ5NumRfHN4

http://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

Open GL Wrappers

• OpenGL APIs at the SDK level• not a recommended practice as a general

approach for complex scenes that require high-performance graphics

• difficult to achieve high performance levels equivalent to native access to OpenGL due to the overhead of calling down from the SDK

• Music application that shipped with Android 3.0 used this approach

http://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

NDK OpenGL

• no access to the View objects, or the events, or the rest of the infrastructure that is provided in the SDK APIs

• graphics environment sufficient for some specific purposes: game developers

• compiles applications to specific CPU architectures

http://graphics-geek.blogspot.com/2011/06/android-rendering-options.html

Animations

• Animations prior to Android 3.0– android.view.animation– move, scale, rotate, and fade Views– combine multiple animations together in

an AnimationSet– specify animations in a LayoutAnimationController

to get automatically staggered animation – use Interpolator implementations like

AccelerateInterpolator and Bounce to get natural, nonlinear timing behaviorhttp://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

Animations

• Animations prior to Android 3.0– you can animate Views... and that's it– How to animate the position of a Drawable in a

custom drawing? Or translucency?– you can move, rotate, scale, and fade a View... and

that's it.– animating the background color of a View?– hard-coded set of things they were able to do, and

you could not make them do anything else.

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

Animations

• Animations in Android 3.0– not specific to Views– animates values over time– assigning those values to any target objects and

properties

• http://www.youtube.com/watch?feature=player_embedded&v=-9nxx066eHE#!

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

Animations

• Animator– superclass for classes which provide basic support

for animations which can be started, ended, and have AnimatorListeners added to them

java.lang.Object   ↳ android.animation.Animator     ↳ android.animation.AnimatorSet

java.lang.Object  ↳

android.animation.Animator

  ↳

android.animation.ValueAnimator

      ↳

android.animation.ObjectAnimator

Animations

• AnimatorSet– choreograph multiple animators together into a

single animation– animations can be set up to play together, in

sequence, or after a specified delay– “It is possible to set up a AnimatorSet with circular

dependencies between its animations… results of this configuration are undefined… circular dependencies should be avoided”

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

Animations

• ValueAnimator– runs the internal timing loop that causes all of a

process's animations to calculate and set values– two pieces to animating properties: calculating

the animated values and setting those values on the object and property in question. ValueAnimator takes care of the first part; calculating the values

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

Animations

• ObjectAnimator– takes care of the second part : setting animating

values on the object and property– main class in the new animation system

ObjectAnimator.ofFloat(myObject, "alpha", 0f).start();

public void setAlpha(float value);public float getAlpha();

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

• View properties– added new properties to the View class in

Honeycomb• translationX and translationY• rotation, rotationX, and rotationY• scaleX and scaleY• pivotX and pivotY• x and y• alpha

Animations

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

• AnimatorSet– choreograph multiple animations

ObjectAnimator fadeOut = ObjectAnimator.ofFloat(v1, "alpha", 0f);

ObjectAnimator mover = ObjectAnimator.ofFloat(v2, "translationX", -500f, 0f);

ObjectAnimator fadeIn = ObjectAnimator.ofFloat(v2, "alpha", 0f, 1f);

AnimatorSet animSet = new AnimatorSet().play(mover).with(fadeIn).after(fadeOut);

Animations

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html

• TypeEvaluator– The system knows how to

animate float and int values, but otherwise it needs some help knowing how to interpolate between the values you give it

– add this interface to the ValueEvaluator

Interface TypeEvaluator {public abstract T evaluate (float fraction, T startValue, T endValue)

}

Animations

http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html