Transcript Introduction to XML

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
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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
<?xml version="1.0" encoding="utf-8" ?>
<rotate xmlns:android="http://schemas.android.com/apk/res/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
<?xml version="1.0" encoding="utf-8" ?>
<translate
xmlns:android="http://schemas.android.com/apk/res/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="http://schemas.android.com/apk/res/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="http://schemas.android.com/apk/res/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
• AnimationUtils class
– a way to manage animations
– loadAnimation ties an animation xml file to an
instance of an Animation
Animation class
• 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)
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:toYDelta="80"
android:duration="10000"
/>
<alpha
android:fromAlpha="0.75"
android:toAlpha="0.25"
android:duration= "2000"
android:startOffset= "4000"
/>
</set>
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);