Android Open Source - lucene Zoom Controller

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The source code is released under:

GNU General Public License

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Java Source Code

 * Copyright (C) 2011-2012 Takahiro Yoshimura
 */*from  ww w.j  ava 2  s .co  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
 * 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 <>.
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * AdMob library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects for
 * all of the code used other than AdMob.  If you modify file(s) with
 * this exception, you may extend this exception to your version of
 * the file(s), but you are not obligated to do so.  If you do not
 * wish to do so, delete this exception statement from your version.
 * If you delete this exception statement from all source files in the
 * program, then also delete it here.


import android.widget.ImageView;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;

public final class ZoomController
  private final ImageView view;

  public ZoomController(final ImageView view)
    this.view = view;

  public void begin(final ScaleGestureDetector sgd)

  public void update(final ScaleGestureDetector sgd)
    float prev = sgd.getPreviousSpan();
    float now = sgd.getCurrentSpan();

    float ratio = (now - prev) / prev;
    this.apply(new PointF(sgd.getFocusX(), sgd.getFocusY()), ratio);

  public void end()

  private void apply(final PointF focalPoint, final float ratioDelta)
    Matrix m = new Matrix(this.view.getImageMatrix());
    m.postScale(1.0f + ratioDelta, 1.0f + ratioDelta, focalPoint.x, focalPoint.y);

Java Source Code List