Android Open Source - SwitchButton Animation Controller

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License

The source code is released under:
MIT License
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Java Source Code

package com.kyleduo.switchbutton.switchbutton;
//from w  w w  . j a  v a 2  s .c  o  m
import android.os.Handler;
import android.os.Message;

/**
 * controller of view animation
 * 
 * @author kyleduo
 * @since 2014-09-25
 *
 */
class AnimationController {

  private static int ANI_WHAT = 0x100;
  private static int DEFAULT_VELOCITY = 7;
  private static int DEFAULT_FRAME_DURATION = 1000 / 60;

  private AnimationHandler mHandler;
  private OnAnimateListener mOnAnimateListener;

  private boolean isAnimating = false;

  private int mFrame, mFrom, mTo;
  private int mVelocity = DEFAULT_VELOCITY;

  private AnimationController() {
    mHandler = new AnimationHandler();
  }

  /**
   * get default AnimationController
   * @return
   */
  static AnimationController getDefault() {
    AnimationController ac = new AnimationController();
    return ac;
  }

  /**
   * initial an AnimationController with a listener
   * @param onAnimateListener NOT NULL
   * @return
   */
  AnimationController init(OnAnimateListener onAnimateListener) {
    if (onAnimateListener == null) {
      throw new IllegalArgumentException("onAnimateListener can not be null");
    }
    this.mOnAnimateListener = onAnimateListener;
    return this;
  }

  private static class AnimationHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
      if (msg.what == ANI_WHAT) {
        if (msg.obj != null) {
          ((Runnable) msg.obj).run();
        }
      }
    }
  }

  void startAnimation(int from, int to) {
    this.isAnimating = true;
    this.mFrom = from;
    this.mTo = to;
    this.mFrame = mVelocity;
    if (mTo > mFrom) {
      this.mFrame = Math.abs(this.mVelocity);
    } else if (mTo < mFrom) {
      this.mFrame = -Math.abs(this.mVelocity);
    } else {
      this.isAnimating = false;
      this.mOnAnimateListener.onAnimateComplete();
      return;
    }
    this.mOnAnimateListener.onAnimationStart();
    new RequireNextFrame().run();
  }

  void stopAnimation() {
    isAnimating = false;
  }

  /**
   * configure the velocity of animation
   * @param velocity a positive number
   */
  public void setVelocity(int velocity) {
    if (velocity <= 0) {
      mVelocity = DEFAULT_VELOCITY;
      return;
    }
    mVelocity = velocity;
  }

  /**
   * calculate next frame in child thread
   * 
   * @author kyleduo
   *
   */
  class RequireNextFrame implements Runnable {
    @Override
    public void run() {
      if (!isAnimating) {
        return;
      }
      calcNextFrame();
      mOnAnimateListener.onFrameUpdate(mFrame);
      if (mOnAnimateListener.continueAnimating()) {
        requireNextFrame();
      } else {
        stopAnimation();
        mOnAnimateListener.onAnimateComplete();
        return;
      }
    }

    private void calcNextFrame() {
//      mFrame = mVelocity;
    }

    private void requireNextFrame() {
      Message msg = mHandler.obtainMessage();
      msg.what = ANI_WHAT;
      msg.obj = this;
      mHandler.sendMessageDelayed(msg, DEFAULT_FRAME_DURATION);
    }
  }

  /**
   * interface for view animation
   * 
   * @author kyle
   *
   */
  interface OnAnimateListener {
    /**
     * invoked when the animation start
     */
    public void onAnimationStart();

    /**
     * ask view whether continue Animating
     * 
     * @return boolean true for continueAnimating
     */
    public boolean continueAnimating();

    /**
     * a new frame is ready.
     * 
     * @param frame next step of the animation, for linear animation, it is equal to velocity
     */
    public void onFrameUpdate(int frame);

    /**
     * invoked when the animation complete
     */
    public void onAnimateComplete();
  }
}
Java Source Code List
