帧动画Drawable Animation入门_html/css_WEB-ITnose

Drawable Animation

Drawable animation lets you load a series of Drawable resources one after another to create an animation. This is a traditional animation in the sense that it is created with a sequence of different images, played in order, like a roll of film. TheAnimationDrawableclass is the basis for Drawable animations.

  Drawable animation是一个一个的加载一些列的图片来创建动画的，他是一种传统的动画，事实上就是一个不同图片的序列AnimationDrawable是Drawable animations 的基类

While you can define the frames of an animation in your code, using theAnimationDrawableclass API, it's more simply accomplished with a single XML file that lists the frames that compose the animation. The XML file for this kind of animation belongs in the res/drawable/ directory of your Android project. In this case, the instructions are the order and duration for each frame of the animation.

 虽然可以使用AnimationDrawable类在代码中定义帧动画，但最好是使用XML文件列出组成动画的所有帧。这个xml文件放在 res/drawable/目录下，事实上，所有的指令就是每一个帧动画的顺序和持续时间

The XML file consists of an element as the root node and a series of child nodes that each define a frame: a drawable resource for the frame and the frame duration. Here's an example XML file for a Drawable animation:

   xml文件由根元素 和一系列子元素组成，其中定义了每个帧对应的图片和持续时间，如下：

<animation-list xmlns:android="http://schemas.android.com/apk/res/android" android:oneshot="true">    <item android:drawable="@drawable/rocket_thrust1" android:duration="200"></item>    <item android:drawable="@drawable/rocket_thrust2" android:duration="200"></item>    <item android:drawable="@drawable/rocket_thrust3" android:duration="200"></item></animation-list>

上面的例子是一个3帧动画， 通过将android:oneshot设置为true，那他就只会循环一次，并停留在最后一个帧上，若为false的话，就会循环运行

AnimationDrawable rocketAnimation;public void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.main);  ImageView rocketImage = (ImageView) findViewById(R.id.rocket_image);  rocketImage.setBackgroundResource(R.drawable.rocket_thrust);  rocketAnimation = (AnimationDrawable) rocketImage.getBackground();}public boolean onTouchEvent(MotionEvent event) {  if (event.getAction() == MotionEvent.ACTION_DOWN) {    rocketAnimation.start();    return true;  }  return super.onTouchEvent(event);}

注意：start()方法不能在你的Activity的onCreate()方法中调用，因为那时候AnimationDrawable尚未完全附着于窗口。如果你必须立刻调用动画，切没有交互的话，可以在onWindowFocusChanged()中调用。因为这个方法是窗口获得焦点时调用的

For more information on the XML syntax, available tags and attributes, see Animation Resources.