Android Open Source - flingbox Scene Gesture Detector

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License

The source code is released under:
GNU General Public License
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Java Source Code

/*
 *  Flingbox - An OpenSource physics sandbox for Google's Android
 *  Copyright (C) 2009  Jon Ander Pealba & Endika Gutirrez
 */* www. ja  va2s .c  o  m*/
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package edu.eside.flingbox.input;

import android.content.Context;
import android.util.Log;
import android.view.MotionEvent;
import android.view.GestureDetector;

/**
 * Custom gesture detection class
 * 
 * Listener should implement {@link OnInputListener}.
 */
public class SceneGestureDetector extends GestureDetector {
  
  public interface OnInputListener extends OnGestureListener {
    /**
     * Called when user stops scrolling
     * @param ev
     * @return
     */
    public boolean onUp(MotionEvent ev);

        public boolean onPinch(MotionEvent ev1, MotionEvent ev2, float scale,
                float dX, float dY);
  }
  
  /** Handler of processed gesture events */
  private final OnInputListener mListener;
  
  private MotionEvent mLastMotionEvent;

  /**
   * @param context
   * @param listener
   */
  public SceneGestureDetector(Context context, OnInputListener listener) {
    super(context, listener);
    mListener = listener;
  }

  /**
   * Should be called on touch event
   */
  public boolean onTouchEvent(MotionEvent ev) {
    boolean handled = false;
    
    // Check for an Up event
    if (ev.getAction() == MotionEvent.ACTION_UP)
      handled |= mListener.onUp(ev);
    
    // Check for multitouch event
    if (ev.getPointerCount() > 1) {
        handled |= this.onMultitouchEvent(ev);
        // Cancel last event
        super.onTouchEvent(MotionEvent.obtain(0, 0, MotionEvent.ACTION_CANCEL, 0f, 0f, 0));
    }
    
    mLastMotionEvent = ev;
        return handled ? true : super.onTouchEvent(ev);
  }
  
  public boolean onMultitouchEvent(MotionEvent ev) {
      if (ev.getPointerCount() < 2)
          return false;
      
      switch (ev.getAction()) {
      case MotionEvent.ACTION_MOVE:
          if (mLastMotionEvent == null || mLastMotionEvent.getPointerCount() < 2)
              break;
          final float lastX0 = ev.getHistoricalX(0, 1), lastX1 = ev.getHistoricalX(1, 1),
                  lastY0 = ev.getHistoricalY(0, 1), lastY1 = ev.getHistoricalY(1, 1);
          final float x0 = ev.getX(0), x1 = ev.getX(1), 
                  y0 = ev.getY(0), y1 = ev.getY(1);
          
          if (lastX0 == 0 || lastX1 == 0 || lastY0 == 0 || lastY1 == 0
                  || x0 == 0 || x1 == 0 || y0 == 0 || y1 == 0)
              return false;
          
          
          final float dx = -((x0 - lastX0) + (x1 - lastX1)) / 2;
          final float dy = -((y0 - lastY0) + (y1 - lastY1)) / 2;

          final float scale = (float) Math.sqrt(
                  ((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0))
                    / ((lastX1 - lastX0) * (lastX1 - lastX0) + (lastY1 - lastY0) * (lastY1 - lastY0))
                    );
          
          if ((scale < 1.25 && scale > 0.8) 
                  && (dx > -40 && dx < 40 && dy > -40 && dy < 40))
              mListener.onPinch(mLastMotionEvent, ev, scale, dx, dy);
          
          return true;
      }
      return false;
  }
  
}
Java Source Code List
