Android Open Source - Android-Charts Zoom Gesture Detector

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License

The source code is released under:

Apache License??Version 2.0, January 2004??http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and condi...

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Java Source Code

/*
 * ZoomGestureDetector.java// ww  w.  j a v  a  2s . c  o  m
 * Android-Charts
 *
 * Created by limc on 2014.
 *
 * Copyright 2011 limc.cn All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package cn.limc.androidcharts.event;
import android.view.MotionEvent;


/** 
 * <p>en</p>
 * <p>jp</p>
 * <p>cn</p>
 *
 * @author limc 
 * @version v1.0 2014/06/20 17:33:01 
 *  
 */
public class ZoomGestureDetector<T extends IZoomable> extends TouchGestureDetector<ITouchable>{
  
  public static final int TOUCH_MODE_NONE = 0;
  public static final int TOUCH_MODE_SINGLE = 1;
  public static final int TOUCH_MODE_MULTI = 2;
  
  public static final int MIN_DISTANCE = 5;
  
  protected int touchMode = TOUCH_MODE_NONE;

  protected float olddistance;
  protected float newdistance;
  
  protected OnZoomGestureListener onZoomGestureListener;
  
  public ZoomGestureDetector(IZoomable zoomable){
    super(zoomable);
    if (zoomable != null) {
      onZoomGestureListener = zoomable.getOnZoomGestureListener();
    }
  }
  
  protected float calcDistance(MotionEvent event) {
    if(event.getPointerCount() <= 1) {
      return 0f;
    }else{
      float x = event.getX(0) - event.getX(1);
      float y = event.getY(0) - event.getY(1);
      return (float) Math.sqrt(x * x + y * y);
    }
  }
  
  @Override
  public boolean onTouchEvent(MotionEvent event) {

    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
      if (event.getPointerCount() == 1) {
        touchMode = TOUCH_MODE_SINGLE;
      }
      break;
    case MotionEvent.ACTION_UP:
      touchMode = TOUCH_MODE_NONE;
      break;
    case MotionEvent.ACTION_POINTER_UP:
      touchMode = TOUCH_MODE_NONE;
      break;
    case MotionEvent.ACTION_POINTER_DOWN:
      olddistance = calcDistance(event);
      if (olddistance > MIN_DISTANCE) {
        touchMode = TOUCH_MODE_MULTI;
      }
      return true;
      //break;
    case MotionEvent.ACTION_MOVE:
      if (touchMode == TOUCH_MODE_MULTI) {
        newdistance = calcDistance(event);
        if (newdistance > MIN_DISTANCE
            && Math.abs(newdistance - olddistance) > MIN_DISTANCE) {
          if (onZoomGestureListener != null) {
            if (newdistance > olddistance) {
              onZoomGestureListener.onZoomIn((IZoomable)instance,event);
            } else {
              onZoomGestureListener.onZoomOut((IZoomable)instance,event);
            }
          }
          olddistance = newdistance;
        }
        
        return true;
      }
      break;
    }
    return super.onTouchEvent(event);
  }

  /**
   * @return the onZoomGestureListener
   */
  public OnZoomGestureListener getOnZoomGestureListener() {
    return onZoomGestureListener;
  }

  /**
   * @param onZoomGestureListener the onZoomGestureListener to set
   */
  public void setOnZoomGestureListener(OnZoomGestureListener onZoomGestureListener) {
    this.onZoomGestureListener = onZoomGestureListener;
  }
}

Java Source Code List