《Pro Android Graphics》读书笔记之第四节
Android Procedural Animation: : XML, Concepts and Optimization
Procedural Animation Concepts: Tweens and Interpolators
Procedural Animation Data Values: Ranges and Pivot Point
范围和中心点
Procedural Animation Transforms: Rotate, Scale, Translate
scale：One of them involves size
rotation：involves orientation (which direction that something is facing)
translation：involves movement
Procedural Animation Compositing: Alpha Blending
Procedural Animation Timing: Using Duration and Offsets
Procedural Animation Loops: RepeatCount and RepeatMode
repeatCount interger（loop forever use infinite(-1)）
RepeatMode：restart (1)
reverse (2)
The <set> Tag: Using XML to Group Procedural Animation
android.view.animation
rule of thumb is to apply your transformational parameters locally
Procedural Animation vs. Frame Animation: The Trade-Off
Frame Animation
memory intensive（须要很多其它内存）：Displaying the image from memory onto the View is fairly straightforward and does not require any complex calculations, so all processing involves moving each frame’s image asset from memory over to display screen.
Procedural animation
tends to be more processing intensive（须要很多其它计算）
Creating a Procedural Animation Definition Using XML
Animation pagAni = AnimationUtils.loadAnimation(this, R.anim.pag_anim); （view）pag.startAnimation(pagAni);
