Android Open Source - AndroIUT Simple Zoom Listener

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License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Copyright (c) 2010, Sony Ericsson Mobile Communication AB. All rights reserved.
 *//from  w w w .j  a  v a2 s. co  m
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 *    * Redistributions of source code must retain the above copyright notice, this 
 *      list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *    * Neither the name of the Sony Ericsson Mobile Communication AB nor the names
 *      of its contributors may be used to endorse or promote products derived from
 *      this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.iutdijon.androiut2.util.zoom;


import android.view.MotionEvent;
import android.view.View;

/**
 * Simple on touch listener for zoom view
 */
public class SimpleZoomListener implements View.OnTouchListener {

    /**
     * Which type of control is used
     */
    public enum ControlType {
        PAN, ZOOM
    }

    /** State being controlled by touch events */
    private ZoomState mState;

    /** Current control type being used */
    private ControlType mControlType = ControlType.ZOOM;

    /** X-coordinate of previously handled touch event */
    private float mX;

    /** Y-coordinate of previously handled touch event */
    private float mY;

    /**
     * Sets the zoom state that should be controlled
     * 
     * @param state Zoom state
     */
    public void setZoomState(ZoomState state) {
        mState = state;
    }

    /**
     * Sets the control type to use
     * 
     * @param controlType Control type
     */
    public void setControlType(ControlType controlType) {
        mControlType = controlType;
    }

    // implements View.OnTouchListener
    @Override
  public boolean onTouch(View v, MotionEvent event) {
        final int action = event.getAction();
        final float x = event.getX();
        final float y = event.getY();

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mX = x;
                mY = y;
                break;

            case MotionEvent.ACTION_MOVE: {
                final float dx = (x - mX) / v.getWidth();
                final float dy = (y - mY) / v.getHeight();

                if (mControlType == ControlType.ZOOM) {
                    mState.setZoom(mState.getZoom() * (float)Math.pow(20, -dy));
                    mState.notifyObservers();
                } else {
                    mState.setPanX(mState.getPanX() - dx);
                    mState.setPanY(mState.getPanY() - dy);
                    mState.notifyObservers();
                }

                mX = x;
                mY = y;
                break;
            }

        }

        return true;
    }

}

Java Source Code List

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