/*
 * Copyright 2009, Google Inc.
 * All rights reserved.
 *
 * 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 Google Inc. 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
 * OWNER 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.
 */


/**
 * The Zoom tool allows the user to Zoom around the view by clicking and
 * dragging.
 */
function ZoomTool(camera) {
  this.camera = camera;
  this.dragging = false;
  this.lastOffsetY = null;
}

ZoomTool.prototype.handleMouseDown = function(e) {
  this.lastOffsetY = e.y;
  this.dragging = true;
};

ZoomTool.prototype.handleMouseMove = function(e) {
  if (this.dragging && e.x !== undefined) {
    dY = (e.y - this.lastOffsetY);
    this.lastOffsetY = e.y;

    var zoomLevels = Math.abs(dY / 6);
    var zoomChange;
    if (dY < 0) {
      zoomChange = Math.pow(11 / 12, zoomLevels);
    } else {
      zoomChange = Math.pow((1 + 1 / 12), zoomLevels);
    }
    this.camera.eye.distanceFromTarget *= zoomChange;

    this.camera.update();
  }
};

ZoomTool.prototype.handleMouseUp = function(e) {
  this.dragging = false;
};

ZoomTool.prototype.handleKeyDown = function(e) {
  return false;
};

ZoomTool.prototype.handleKeyUp = function(e) {
  return false;
};