Basic Animation

Animation 4 options – Animated.gif – Frame by Frame animation – Tweened animation This is our focus – OpenGL ES Graphics API for more robust animation – Popular for mobile game programming – Supports 3D

Tweened animation Components of tweened animation – Drawable image file (.png,.jpg,.gif) xml file ShapeDrawable instance – Anim resource anim folder within the res folder must be created contains xml describing the animation – Java code AnimationUtils class Animation class AnimationListener class AnimationSet class

Anim resource anim folder within res folder

Tweened animation Types of tweened animation – rotate (spin) – translate (move) – alpha (fade) – scale (shrink/stretch)

Tweened animation Rotate options – Setting rotation parameters fromDegrees toDegrees – Setting the pivot point pivotX pivotY – Duration duration – time in milliseconds

Tweened animation Sample rotate.xml file <rotate xmlns:android=" android:fromDegrees="0" android:toDegrees="720" android:pivotX="25%" android:pivotY="75%" />

Tweened animation Translate options – Setting movement parameters toXDelta – positive is number of pixels to the right toYDelta – positive is number of pixels down – Duration duration – time in milliseconds

Tweened animation Sample translate.xml file <translate xmlns:android=" android:toYDelta="80" android:duration="1000" />

Tweened animation Alpha options – Setting alpha (transparency) parameters fromAlpha and toAlpha – Number between 0.0 and 1.0 – 1.0 is non-transparent, 0.0 is fully-transparent – Duration duration – time in milliseconds

Tweened animation Sample alpha.xml file <alpha xmlns:android=" android:fromAlpha= "0.75" android:toAlpha="0.25" android:duration="2000" />

Tweened animation Scale options – Setting scaling (shrink/stretch) parameters fromXScale and toXScale (or YScale) – numbers are relative to each other – Setting the pivot point pivotX pivotY – Duration duration – time in milliseconds

Tweened animation Sample scale.xml file <scale xmlns:android=" android:fromXScale="1.0" android:toXScale="0.33" android:fromYScale="1.0" android:toYScale="0.33" android:pivotX="50%" android:pivotY="50%" android:duration="5000" />

Java code Relevant animation classes

AnimationUtils class – a way to manage animations – loadAnimation ties an animation xml file to an instance of an Animation

Animation class – An animation that can be applied to views – relevant methods setRepeatCount – default is 0 setFillAfter – If argument is true, Animation persists after it ends » i.e. If object is moved, it stays where it was moved to – default is false setAnimationListener – a way to execute code as soon as an animation starts, repeats, or ends – must assign a user defined class that extends AnimationListener

Sample code Single animation – without Listener ImageView iv = (ImageView)findViewById(R.id.myIV); Animation an = AnimationUtils.loadAnimation(this, R.anim.myXMLFile); an.setRepeatCount(3); iv.startAnimation(an);

AnimationListener class Allows an Animation to ‘Listen’ for: – animation start – animation repeat – animation end Is often written as an Inner class

AnimationListener sample code class MyAnimationListener implements AnimationListener { public void onAnimationEnd(Animation animation) { //Code to execute when animation ends } public void onAnimationRepeat(Animation animation) { //Code to execute when animation repeats } public void onAnimationStart(Animation animation) { //Code to execute when animation starts }

Sample code Single animation – with Listener ImageView iv = (ImageView)findViewById(R.id.myIV); Animation an = AnimationUtils.loadAnimation(this, R.anim.myXMLFile); an.setRepeatCount(3); an.setAnimationListener(new MyAnimationListener()); iv.startAnimation(an);

AnimationSet Collection of a group of animations that will be played simultaneously Any properties set at the AnimationSet level override properties at individual Animation level – duration Constructor accepts boolean – true for our purposes – indicates to share an Interpolator (allows acceleration and deceleration of animation) Sets can listen in the same way individual animations can Known issue – Sets do not respond to setRepeatCount()

AnimationSet – implemented via java ImageView iv = (ImageView)findViewById(R.id.myImageView); AnimationSet animations = new AnimationSet(true); Animation an1 = AnimationUtils.loadAnimation(this, R.anim.xmlFile1); animations.addAnimation(an1); Animation an2 = AnimationUtils.loadAnimation(this, R.anim.xmlFile2); animations.addAnimation(an2); animations.setDuration(4000); iv.startAnimation(animations);

AnimationSet – implemented via xml Advantage of doing a set in xml is that each animation can be given a different duration (duration cannot be put at the set level in xml) <translate android:toYDelta="80" android:duration="10000" /> <alpha android:fromAlpha="0.75" android:toAlpha="0.25" android:duration= "2000" android:startOffset= "4000" />

AnimationSet – implemented via xml Java code treats as normal animation ImageView iv = (ImageView)findViewById(R.id.myIV); Animation an = AnimationUtils.loadAnimation(this, R.anim.myAnimXMLFile); iv.startAnimation(an);