org.piccolo2d.event.PZoomEventHandler Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2011, Piccolo2D project, http://piccolo2d.org
* Copyright (c) 1998-2008, University of Maryland
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided
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*
* 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.
*
* None of the name of the University of Maryland, the name of the Piccolo2D project, or 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
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*/
package org.piccolo2d.event;
import java.awt.event.InputEvent;
import java.awt.geom.Point2D;
import org.piccolo2d.PCamera;
/**
* ZoomEventhandler provides event handlers for basic zooming of the
* canvas view with the right (third) button. The interaction is that the
* initial mouse press defines the zoom anchor point, and then moving the mouse
* to the right zooms with a speed proportional to the amount the mouse is moved
* to the right of the anchor point. Similarly, if the mouse is moved to the
* left, the the view is zoomed out.
*
* On a Mac with its single mouse button one may wish to change the standard
* right mouse button zooming behavior. This can be easily done with the
* PInputEventFilter. For example to zoom with button one and shift you would do
* this:
*
*
*
* zoomEventHandler.getEventFilter().setAndMask(InputEvent.BUTTON1_MASK |
* InputEvent.SHIFT_MASK);
*
*
*
*
* @version 1.0
* @author Jesse Grosjean
*/
public class PZoomEventHandler extends PDragSequenceEventHandler {
/**
* A constant used to adjust how sensitive the zooming will be to mouse
* movement. The larger the number, the more each delta pixel will affect zooming.
*/
private static final double ZOOM_SENSITIVITY = 0.001;
private double minScale = 0;
private double maxScale = Double.MAX_VALUE;
private Point2D viewZoomPoint;
/**
* Creates a new zoom handler.
*/
public PZoomEventHandler() {
super();
setEventFilter(new PInputEventFilter(InputEvent.BUTTON3_MASK));
}
// ****************************************************************
// Zooming
// ****************************************************************
/**
* Returns the minimum view magnification factor that this event handler is
* bound by. The default is 0.
*
* @return the minimum camera view scale
*/
public double getMinScale() {
return minScale;
}
/**
* Sets the minimum view magnification factor that this event handler is
* bound by. The camera is left at its current scale even if
* minScale is larger than the current scale.
*
* @param minScale the minimum scale, must not be negative.
*/
public void setMinScale(final double minScale) {
this.minScale = minScale;
}
/**
* Returns the maximum view magnification factor that this event handler is
* bound by. The default is Double.MAX_VALUE.
*
* @return the maximum camera view scale
*/
public double getMaxScale() {
return maxScale;
}
/**
* Sets the maximum view magnification factor that this event handler is
* bound by. The camera is left at its current scale even if
* maxScale is smaller than the current scale. Use
* Double.MAX_VALUE to specify the largest possible scale.
*
* @param maxScale the maximum scale, must not be negative.
*/
public void setMaxScale(final double maxScale) {
this.maxScale = maxScale;
}
/**
* Records the start point of the zoom. Used when calculating the delta for
* zoom speed.
*
* @param event event responsible for starting the zoom interaction
*/
protected void dragActivityFirstStep(final PInputEvent event) {
viewZoomPoint = event.getPosition();
super.dragActivityFirstStep(event);
}
/**
* Updates the current zoom periodically, regardless of whether the mouse
* has moved recently.
*
* @param event contains information about the current state of the mouse
*/
protected void dragActivityStep(final PInputEvent event) {
final PCamera camera = event.getCamera();
final double dx = event.getCanvasPosition().getX() - getMousePressedCanvasPoint().getX();
double scaleDelta = 1.0 + ZOOM_SENSITIVITY * dx;
final double currentScale = camera.getViewScale();
final double newScale = currentScale * scaleDelta;
if (newScale < minScale) {
scaleDelta = minScale / currentScale;
}
if (maxScale > 0 && newScale > maxScale) {
scaleDelta = maxScale / currentScale;
}
camera.scaleViewAboutPoint(scaleDelta, viewZoomPoint.getX(), viewZoomPoint.getY());
}
}