ZoomHelpers.java

/*
Copyright 2011-2016 Google Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package com.google.security.zynamics.zylib.yfileswrap.gui.zygraph.helpers;

import y.view.Graph2DView;

import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

public class ZoomHelpers {
  public static final double MAX_ZOOM = 3.;

  /**
   * Makes sure that the current zoom level does not exceed the maximum zoom level.
   */
  private static void decreaseToMaxZoom(final Graph2DView view) {
    if (view.getZoom() > MAX_ZOOM) {
      view.setZoom(MAX_ZOOM);
    }
  }

  /**
   * Makes sure that the current zoom level does not exceed the minimum zoom level.
   */
  private static void increaseToMinZoom(final Graph2DView view) {
    final double minZoom = getMinimumZoom(view);

    if (view.getZoom() < minZoom) {
      view.setZoom(minZoom);
    }
  }

  /**
   * Calculates the smallest valid zoom level.
   * 
   * @return The smallest valid zoom level.
   */
  public static double getMinimumZoom(final Graph2DView view) {
    double zoomlevel = view.getZoom();

    if (zoomlevel < 0) {
      zoomlevel = 1;
    }

    final Point2D viewPoint = view.getViewPoint2D();
    final Rectangle2D box = view.getGraph2D().getBoundingBox();
    view.zoomToArea(box.getX(), box.getY(), box.getWidth(), box.getHeight()); // why? => to gain the
                                                                              // minimum zoom level
                                                                              // in the next line
    final double minZoom = view.getZoom();
    view.setZoom(zoomlevel); // why? => to reset the original zoom level after the minimum zoom
                             // level was calulated
    view.setViewPoint2D(viewPoint.getX(), viewPoint.getY()); // why? => to reset the original view
                                                             // point
    return minZoom - (minZoom / 2);
  }

  /**
   * Keeps the zoom level within valid bounds.
   */
  public static void keepZoomValid(final Graph2DView view) {
    decreaseToMaxZoom(view);
    increaseToMinZoom(view);
  }

}