Android 自定义帧动画

Android L ； Android Studio

帧动画

和gif图片类似，顺序播放准本好的图片文件；图片资源在xml文件中配置好
将图片按照预定的顺序一张张切换，即成动画

Android 帧动画例子

可以把动画放进子线程中启动，也可以在主线程直接启动动画
主线程更容易控制动画的启停；
子线程需要关注线程的状态，不好控制动画

主线程的UI不能放进子线程去设置；即子线程不能直接修改主UI；
屏幕旋转后，activity重启；动画也就停止了；
在 AndroidManifest.xml 设置 configChanges 即可

<activity
    android:name=".MainActivity"
    android:configChanges="orientation|keyboardHidden|screenSize"
    android:label="@string/app_name"
    android:theme="@style/AppTheme.NoActionBar" >
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

动画资源

图片资源来自Android L Launcher3 res
图片全部放在 res/drawable 里面

配置文件 transition_stack.xml
oneshot="false" 动画会一直循环播放下去

<animation-list
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/transition_stack" android:oneshot="false">
    <item android:drawable="@drawable/stack_00000" android:duration="30" />
    <item android:drawable="@drawable/stack_00001" android:duration="30" />
......
</animation-list>

Java代码

• 1.取得ImageView
• 2.为ImageView设置背景资源文件

• 3.把ImageView的背景赋给动画AnimationDrawable

  public class MainActivity extends AppCompatActivity {
  private ImageView mTransitionIcon;
  private ImageView mStackIcon;
  private AnimationDrawable frameAnimation;
  private AnimationDrawable stackAnimation;
  private Thread stackThread;
  private Button stopButton;
  public boolean action = false;
  
  private TextView tvState;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
      setSupportActionBar(toolbar);
      tvState = (TextView) findViewById(R.id.tv_state);
  
      stopButton = (Button) findViewById(R.id.btn_stop);
      Button btn1 = (Button) findViewById(R.id.btn1);
      Button btn2 = (Button) findViewById(R.id.btn2);
  
      /*************************************************
       * AnimationDrawable extends DrawableContainer
       *************************************************/
       // 1.取得ImageView
      mTransitionIcon = (ImageView) findViewById(R.id.settings_transition_image);
      // 2.为ImageView设置背景资源文件
      mTransitionIcon.setBackgroundResource(R.drawable.transition_none);
      // 3.把ImageView的背景赋给动画AnimationDrawable
      frameAnimation = (AnimationDrawable) mTransitionIcon.getBackground();
  
      mStackIcon = (ImageView) findViewById(R.id.transition_stack);
      mStackIcon.setBackgroundResource(R.drawable.transition_stack);
      stackAnimation = (AnimationDrawable) mStackIcon.getBackground();
      stackThread = new Thread() {
          @Override
          public void run() {
              stackAnimation.start();// 子线程中开始动画
          }
      };
  
      btn1.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              action = !action;// 主线程中控制动画启动与停止
              if (action) {
                  frameAnimation.start(); // 启动（重启）动画
              } else {
                  frameAnimation.stop(); // 停止动画
              }
          }
      });
  
      btn2.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              if (stackThread.getState() == (Thread.State.NEW))
                  stackThread.start();// 放到子线程中开启动画
          }// 先查询子线程状态再启动，避免Thread报错导致app退出
      });
  
      stopButton.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              String s = "";// 用于显示状态
              s = action ? "action! " + stackThread.getState().toString() :
                      "stop!" + stackThread.getState().toString();
              tvState.setText(s);
          }
      });
  }
  }

  Thread 类

  状态一览：

  /**
   * A representation of a thread's state. A given thread may only be in one
   * state at a time.
   */
  public enum State {
      /**
       * The thread has been created, but has never been started.
       */
      NEW,
      /**
       * The thread may be run.
       */
      RUNNABLE,
      /**
       * The thread is blocked and waiting for a lock.
       */
      BLOCKED,
      /**
       * The thread is waiting.
       */
      WAITING,
      /**
       * The thread is waiting for a specified amount of time.
       */
      TIMED_WAITING,
      /**
       * The thread has been terminated.
       */
      TERMINATED
  }

  一个Button用于启动子线程，可以先判断子线程的状态，再决定是否启动