Android--逐帧动画、补间动画学习
I、逐帧动画
逐帧动画用以指定一系列用作View的背景的Drawable对象，感觉类似于幻灯片。
public class AnimationDrawable extends DrawableContainer implements Runnable, Animatable
public class DrawableContainer extends Drawable implements Drawable.Callback
一、应用实例：
1、在res/drawabe文件下建立<animation-list>
<?xml version="1.0"encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<item android:drawable="@drawable/icon0" android:duration="500"/>
<item android:drawable="@drawable/icon1" android:duration="500"/>
<item android:drawable="@drawable/icon2" android:duration="500"/>
<item android:drawable="@drawable/icon3" android:duration="500"/>
</animation-list>
android:oneshot为false时表示循环播放，默认为false
2、代码中使用逐帧动画
myImageView=(ImageView)findViewById(R.id.myImageView);
myImageView.setBackgroundResource(R.drawable.myanimation);
AnimationDrawable animationDrawable =(AnimationDrawable) myImageView.getBackground();
animationDrawable.start();
//animationDrawable.stop();
二、扩展知识：AnimationDrawable类
1、提供函数：
public void start() public void stop() public boolean isRunning() public int getNumberOfFrames() public Drawable getFrame(int index) public int getDuration(int i) public boolean isOneShot() public void setOneShot(boolean oneShot) /**Add a frame to the animation */ public void addFrame(Drawable frame, int duration)
2、已定义了一个帧动画，如何做到播放其中的某几个连续帧；（比如本文中有4个帧，播放2-3帧）
分析：AnimationDrawable类提供了getFrame和getDuration方法，但是未提供相应的setter函数来控制播放的帧位置。AnimationDrawable类中有一个私有变量mCurFrame表示当前的播放帧。定义如下：
/** The current frame, may be -1 when not animating. */
private int mCurFrame = -1;
因为其为private变量，且未提供相应setter函数，故采用反射技术进行读写。
public class MyImageView extends ImageView{
private AnimationDrawable animationDrawable;
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setBackgroundResource(R.drawable.myanimation);
animationDrawable = (AnimationDrawable) getBackground();
setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
animationDrawable.start();
}
});
}
@Override
public void onDraw(Canvas canvas)
{
try
{
Field field = AnimationDrawable.class.getDeclaredField("mCurFrame");
field.setAccessible(true);
int curFrame = field.getInt(animationDrawable);
if(curFrame == 2)
field.setInt(animationDrawable, 0);
} catch(Exception e)
{
Log.e("AnimationDrawable", e.toString());
}
super.onDraw(canvas);
}
}
II、补间动画：
不同于逐帧动画，即设定好动画起始终止状态，中间由系统来补充
一、四种基本动画
1、缩放scale---ScaleAnimation
方法一：在res/anim文件下创建xml文件：
<!-- 缩放 -->
<scale
android:fromXScale="0.0" android:toXScale="1.0"
android:fromYScale="0.0" android:toYScale="1.0"
android:pivotX="50%"
android:pivotY="50%"
android:duration="1000"
android:repeatCount="-1"
android:repeatMode="reverse"
/>
<!-- fromXScale：沿X,Y轴的缩放比例 from-to-->
<!-- pivotX：缩放的中心点位置，（占View大小的百分比） -->
<!-- duration：持续时间 -->
<!-- repeatCount:重复次数，默认为0，代表旋转一次；则设为n，旋转n+1次；设为-1或infinite，则为无限循环 -->
<!-- repeatMode：重复模式，默认为restart-->
代码中使用：
Animation animation =AnimationUtils.loadAnimation(MainActivity.this,R.anim.anim_set);
myImageView.startAnimation(animation);
方法二：
ScaleAnimation animation = new ScaleAnimation(0, 1, 0, 1);
animation.setDuration(1000);
animation.setRepeatCount(-1);
animation.setRepeatMode(Animation.RESTART);
myImageView.startAnimation(animation);
下面用法大同小异：
2、透明度alpha --- AlphaAnimation
<!-- 透明度 -->
<alpha
android:fromAlpha="0.0" android:toAlpha="1.0"
android:duration="1000"
android:repeatCount="-1"
android:repeatMode="reverse"
/>
3、旋转rotate --- RotateAnimation
<!-- 旋转 -->
<rotate
android:fromDegrees="0" android:toDegrees="360"
android:pivotX="50%"
android:pivotY="50%"
android:duration="1000"
android:repeatCount="2"
android:repeatMode="restart"
/>
4、移动translate --- TranslateAnimation
<!-- 移动 -->
<translate
android:fromXDelta="0" android:toXDelta="1000"
android:fromYDelta="0" android:toYDelta="1000"
android:duration="1000"
/>
二、几种Anim的组合set
<?xmlversion="1.0"encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:interpolator="@android:anim/accelerate_interpolator"
android:repeatMode="reverse"
android:repeatCount="2"
>
<!-- 移动 -->
<translate
android:fromXDelta="0" android:toXDelta="1000"
android:fromYDelta="0" android:toYDelta="1000"
android:duration="1000"
/>
<!-- 缩放 -->
<scale
android:fromXScale="0.0" android:toXScale="1.0"
android:fromYScale="0.0" android:toYScale="1.0"
android:pivotX="50%"
android:pivotY="50%"
android:duration="1000"
/>
<!-- 透明度 -->
<alpha
android:fromAlpha="0.0" android:toAlpha="1.0"
android:duration="1000"
/>
<rotate
android:fromDegrees="0" android:toDegrees="360"
android:pivotX="50%"
android:pivotY="50%"
android:duration="1000"
/>
</set>
android:interpolator是指每个动画开始和结束值间转换中所使用的插值器，默认为AccelerateDecelerateInterpolator
也可通过setInterpolator设置；
AccelerateDecelerateInterpolator: 开始和结束时变化较慢，中间时候加速
An interpolator where the rate of change starts and ends slowly but accelerates through the middle
AccelerateInterpolator : 开始较慢，然后逐渐加速
An interpolator where the rate of change starts out slowly and and then accelerates.
AnticipateInterpolator ： 开始时向后，然后再向前急冲
An interpolator where the change starts backward then flings forward.
AnticipateOvershootInterpolator：开始时向后，然后再向前急冲一定值之后，最后回到最终值
An interpolator where the change starts backward then flings forward and overshoots the target value and finally goes back to the final value.
BounceInterpolator ： 动画结束时弹起
An interpolator where the change bounces at the end.
DecelerateInterpolator ; 开始时速度较快，然后减速
An interpolator where the rate of change starts out quickly and and then decelerates.
LinearInterpolator ; 变化速度为常量
An interpolator where the rate of change is constant
OvershootInterpolator ; 开始向前急冲，超过最终值，然后返回
An interpolator where the change flings forward and overshoots the last value then comes back.
三、添加动画监听器 AnimationListener
animation.setAnimationListener(new AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
Log.i("AnimationListener", "动画开始");
}
@Override
public void onAnimationRepeat(Animation animation) {
Log.i("AnimationListener", "动画重复");
}
@Override
public void onAnimationEnd(Animation animation) {
Log.i("AnimationListener", "动画结束");
}
});
四、为ViewGroup添加动画
布局动画LayoutAnimation:
1、在res/anim下创建xml文件：layout_anim.xml
<?xmlversion="1.0"encoding="utf-8"?>
<layoutAnimation
xmlns:android="http://schemas.android.com/apk/res/android"
android:delay="1.0"
android:animationOrder="random"
android:animation="@anim/anim_set"
/>
<!-- delay 子类动画时间间隔（延迟） -->
<!-- animationOrder 子类的显示方式: normal(0 默认) reverse(1 倒序) random(2 随机) -->
<!-- animation : 对应动画 -->
2、使用：在activity的layout界面布局中写入：
android:layoutAnimation="@anim/layout_anim"
3、在Java代码中使用：
<为ListView（ViewGroup的子类）添加动画>
String[] mMenuItemStr = { "Bear", "Bird", "Cat", "Tigers", "Panda" ,"Bear", "Bird", "Cat", "Tigers", "Panda"};
listView.setAdapter(new ArrayAdapter<String>(this, R.layout.item_left_menu,mMenuItemStr));
Animation animation = AnimationUtils.loadAnimation(this, R.anim.anim_set);
LayoutAnimationController controller = new LayoutAnimationController(animation);
controller.setOrder(LayoutAnimationController.ORDER_NORMAL);
controller.setDelay(1);
listView.setLayoutAnimation(controller);
4、实现效果是为ViewGroup中每一个子View添加了动画，并按照Random等方式进行加载
5、ViewGroup第一次进行布局时加载布局动画。可以通过listView.scheduleLayoutAnimation();强制其再次执行
6、添加动画监听：
listView.setLayoutAnimationListener(new AnimationListener() {
@Override
publicvoid onAnimationStart(Animation animation) {
}
@Override
publicvoid onAnimationRepeat(Animation animation) {
}
@Override
publicvoid onAnimationEnd(Animation animation) {
}
});
五、拓展：
1、现有两个补间动画(anim1.xml,anim2.xml)，如何做到两个补间动画在一个播放完后就立刻播放另一个动画。
使用动画监听，重写onAnimationEnd方法即可
private Animation animation1, animation2;
privateclass myAnimationListener implements AnimationListener
{
@Override
publicvoid onAnimationStart(Animation animation) {
}
@Override
publicvoid onAnimationEnd(Animation animation) {
if(animation.hashCode() == animation1.hashCode())
myImageView.startAnimation(animation2);
else
myImageView.startAnimation(animation1);
}
@Override
publicvoid onAnimationRepeat(Animation animation) {
}
}
在Activity中使用得：
animation1 = AnimationUtils.loadAnimation(MainActivity.this, R.anim.anim1);
animation2 = AnimationUtils.loadAnimation(MainActivity.this, R.anim.anim2);
myAnimationListener myAnimationListener = new myAnimationListener();
animation1.setAnimationListener(myAnimationListener);
animation2.setAnimationListener(myAnimationListener);
myImageView.startAnimation(animation1);
2、自定义动画渲染器interpolator
private class myInterpolator implements Interpolator
{
@Override
public float getInterpolation(floatinput) {
/**input: 取值范围 0.0-1.0,表示动画的加载进度
* 返回值：<1.0表示还未达到目标点；越接近1.0表示离目标点越近；大于1.0表示动画对象已经超过了目标点**/
if(input <= 0.5)
return input * input;
else
return (1 - input) * (1 - input);
}
}
在代码中使用：
Animation animation = AnimationUtils.loadAnimation(MainActivity.this, R.anim.anim1);
animation.setInterpolator(new myInterpolator());
myImageView.startAnimation(animation);
对比看一下AccelerateInterpolator的源码：
/**
* An interpolator where the rate of change starts out slowly and
* and then accelerates.
*
*/
@HasNativeInterpolator
public class AccelerateInterpolator implements Interpolator, NativeInterpolatorFactory {
private final floatmFactor;
private final doublemDoubleFactor;
public AccelerateInterpolator() {
mFactor = 1.0f;
mDoubleFactor = 2.0;
}
/**
* Constructor
*
* @param factor Degree to which the animation should be eased. Seting
* factor to 1.0f produces a y=x^2 parabola. Increasing factor above
* 1.0f exaggerates the ease-in effect (i.e., it starts even
* slower and ends evens faster)
*/
public AccelerateInterpolator(floatfactor) {
mFactor = factor;
mDoubleFactor = 2 * mFactor;
}
public AccelerateInterpolator(Context context, AttributeSet attrs) {
this(context.getResources(), context.getTheme(), attrs);
}
/** @hide */
public AccelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
TypedArray a;
if (theme != null) {
a = theme.obtainStyledAttributes(attrs, R.styleable.AccelerateInterpolator, 0, 0);
} else {
a = res.obtainAttributes(attrs, R.styleable.AccelerateInterpolator);
}
mFactor = a.getFloat(R.styleable.AccelerateInterpolator_factor, 1.0f);
mDoubleFactor = 2 * mFactor;
a.recycle();
}
public float getInterpolation(float input) {
if (mFactor == 1.0f) {
return input * input;
} else {
return (float)Math.pow(input, mDoubleFactor);
}
}
/** @hide */
@Override
public long createNativeInterpolator() {
return NativeInterpolatorFactoryHelper.createAccelerateInterpolator(mFactor);
}
}