Android Open Source - lucene Rotate Controller

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License

The source code is released under:

GNU General Public License

Java Source Code

/**
 * Copyright (C) 2011-2012 Takahiro Yoshimura
 *// w w  w. j  a  v a  2s  . 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
 * 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/>.
 *
 * 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.
 */

package com.gmail.altakey.lucene.motion;

import android.widget.ImageView;
import android.graphics.PointF;
import android.graphics.Matrix;
import android.view.MotionEvent;

public final class RotateController
{
  private static final int UNLOCKED = -1;
  private static final float UNDETERMINED = 999.0f;

  private final ImageView view;

  private PointF[] points = new PointF[2];
  private int pivot_id = UNLOCKED;
  private int pointer_id = UNLOCKED;
  private float angle = UNDETERMINED;

  public RotateController(final ImageView view)
  {
    this.view = view;
    this.points[0] = new PointF();
    this.points[1] = new PointF();
  }

  public void begin(final MotionEvent e)
  {
    this.down(e);
  }

  public void update(final MotionEvent e)
  {
    if (this.pivot_id != UNLOCKED && this.pointer_id != UNLOCKED)
    {
      int pivot_index = e.findPointerIndex(this.pivot_id);
      int pointer_index = e.findPointerIndex(this.pointer_id);

      this.points[0].x = e.getX(pivot_index);
      this.points[0].y = e.getY(pivot_index);
      this.points[1].x = e.getX(pointer_index);
      this.points[1].y = e.getY(pointer_index);

      float angle = this.findAngle();
      PointF pivot = this.findPivot();
      
      if (this.angle != UNDETERMINED)
        this.apply(pivot, angle - this.angle);
      
      this.angle = angle;
    }
  }

  public void down(final MotionEvent e)
  {
    int index = e.getActionIndex();
    int id = e.getPointerId(index);
    if (this.pivot_id == UNLOCKED)
    {
      this.pivot_id = id;
      this.points[0].x = e.getX(index);
      this.points[0].y = e.getY(index);
    }
    else if (this.pointer_id == UNLOCKED)
    {
      this.pointer_id = id;
      this.points[1].x = e.getX(index);
      this.points[1].y = e.getY(index);
    }
  }

  public void up(final MotionEvent e)
  {
    int id = e.getPointerId(e.getActionIndex());
    if (this.pivot_id == id)
    {
      this.pivot_id = UNLOCKED;
      this.angle = UNDETERMINED;
    }

    if (this.pointer_id == id)
    {
      this.pointer_id = UNLOCKED;
      this.angle = UNDETERMINED;
    }      
  }

  public void end()
  {
    this.angle = UNDETERMINED;
    this.pivot_id = UNLOCKED;
    this.pointer_id = UNLOCKED;
  }

  private void apply(final PointF pivot, float dtheta)
  {
    Matrix m = new Matrix(this.view.getImageMatrix());
    if (dtheta > 270)
      dtheta -= 360;
    if (dtheta < -270)
      dtheta += 360;

    m.postRotate(dtheta, pivot.x, pivot.y);
    this.view.setImageMatrix(m);
  }

  private float findAngle()
  {
    final double RAD_TO_DEG = 180/Math.PI;
    PointF vector = new PointF(this.points[1].x - this.points[0].x, this.points[1].y - this.points[0].y);      
    return (float)(Math.atan2(vector.y, vector.x) * RAD_TO_DEG);
  }

  private PointF findPivot()
  {
    return new PointF(
      (this.points[1].x + this.points[0].x) / 2,
      (this.points[1].y + this.points[0].y) / 2
    );
  }
}

Java Source Code List

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