batik-swing/src/main/java/org/apache/batik/swing/gvt/AbstractZoomInteractor.java

/*

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You 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 org.apache.batik.swing.gvt;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.Line2D;

/**
 * This class represents a zoom interactor.
 * To use it, just redefine the {@link
 * InteractorAdapter#startInteraction(java.awt.event.InputEvent)} method.
 *
 * @author <a href="mailto:stephane@hillion.org">Stephane Hillion</a>
 * @version $Id$
 */
public class AbstractZoomInteractor extends InteractorAdapter {

    /**
     * Whether the interactor has finished.
     */
    protected boolean finished = true;

    /**
     * The mouse x start position.
     */
    protected int xStart;

    /**
     * The mouse y start position.
     */
    protected int yStart;

    /**
     * The mouse x current position.
     */
    protected int xCurrent;

    /**
     * The mouse y current position.
     */
    protected int yCurrent;

    /**
     * The zoom marker top line.
     */
    protected Line2D markerTop;

    /**
     * The zoom marker left line.
     */
    protected Line2D markerLeft;

    /**
     * The zoom marker bottom line.
     */
    protected Line2D markerBottom;

    /**
     * The zoom marker right line.
     */
    protected Line2D markerRight;

    /**
     * The overlay.
     */
    protected Overlay overlay = new ZoomOverlay();

    /**
     * Used to draw marker
     */
    protected BasicStroke markerStroke = new BasicStroke(1,
                                                         BasicStroke.CAP_SQUARE,
                                                         BasicStroke.JOIN_MITER,
                                                         10,
                                                         new float[] { 4, 4 }, 0);

    /**
     * Tells whether the interactor has finished.
     */
    public boolean endInteraction() {
        return finished;
    }

    // MouseListener ///////////////////////////////////////////////////////
        
    /**
     * Invoked when a mouse button has been pressed on a component.
     */
    public void mousePressed(MouseEvent e) {
        if (!finished) {
            mouseExited(e);
            return;
        }
        
        finished = false;
        markerTop = null;
        markerLeft = null;
        markerBottom = null;
        markerRight = null;

        xStart = e.getX();
        yStart = e.getY();
        JGVTComponent c = (JGVTComponent)e.getSource();
        c.getOverlays().add(overlay);
    }

    /**
     * Invoked when a mouse button has been released on a component.
     */
    public void mouseReleased(MouseEvent e) {
        finished = true;
        JGVTComponent c = (JGVTComponent)e.getSource();
        c.getOverlays().remove(overlay);
        overlay.paint(c.getGraphics());

        xCurrent = e.getX();
        yCurrent = e.getY();

        if ((xCurrent - xStart) != 0 &&
            (yCurrent - yStart) != 0) {

            int dx = xCurrent - xStart;
            int dy = yCurrent - yStart;
            
            if (dx < 0) {
                dx = -dx;
                xStart = xCurrent;
            }
            if (dy < 0) {
                dy = -dy;
                yStart = yCurrent;
            }

            Dimension size = c.getSize();

            // Zoom factor
            float scaleX = size.width / (float)dx;
            float scaleY = size.height / (float)dy;
            float scale = (scaleX < scaleY) ? scaleX : scaleY;
        
            // Zoom translate
            AffineTransform at = new AffineTransform();
            at.scale(scale, scale);
            at.translate(-xStart, -yStart);

            at.concatenate(c.getRenderingTransform());
            c.setRenderingTransform(at);
        }
    }

    /**
     * Invoked when the mouse exits a component.
     */
    public void mouseExited(MouseEvent e) {
        finished = true;
        JGVTComponent c = (JGVTComponent)e.getSource();
        c.getOverlays().remove(overlay);
        overlay.paint(c.getGraphics());
    }

    // MouseMotionListener /////////////////////////////////////////////////

    /**
     * Invoked when a mouse button is pressed on a component and then 
     * dragged.  Mouse drag events will continue to be delivered to
     * the component where the first originated until the mouse button is
     * released (regardless of whether the mouse position is within the
     * bounds of the component).
     */
    public void mouseDragged(MouseEvent e) {
        JGVTComponent c = (JGVTComponent)e.getSource();

        overlay.paint(c.getGraphics());

        xCurrent = e.getX();
        yCurrent = e.getY();

        // Constrain rectangle to window's Aspect Ratio.
        float xMin, yMin, width, height;
        if (xStart < xCurrent) {
            xMin = xStart;
            width = xCurrent - xStart;
        } else {
            xMin = xCurrent;
            width = xStart - xCurrent;
        }
        if (yStart < yCurrent) {
            yMin = yStart;
            height = yCurrent - yStart;
        } else {
            yMin = yCurrent;
            height = yStart - yCurrent;
        }
        Dimension d = c.getSize();
        float compAR = d.width/(float)d.height;
        if (compAR > width/height) {
            width = compAR*height;
        } else {
            height = width/compAR;
        }

        markerTop    = new Line2D.Float(xMin, yMin, xMin+width,  yMin);
        markerLeft   = new Line2D.Float(xMin, yMin, xMin, yMin+height);
        markerBottom = new Line2D.Float(xMin, yMin+height,  
                                        xMin+width,  yMin+height);
        markerRight  = new Line2D.Float(xMin+width,  yMin,  
                                        xMin+width,  yMin+height);

        overlay.paint(c.getGraphics());
    }

    /**
     * To paint the interactor.
     */
    protected class ZoomOverlay implements Overlay {
        
        /**
         * Paints this overlay.
         */
        public void paint(Graphics g) {
            if (markerTop != null) {
                Graphics2D g2d = (Graphics2D)g;

                g2d.setXORMode(Color.white);
                g2d.setColor(Color.black);
                g2d.setStroke(markerStroke);

                g2d.draw(markerTop);
                g2d.draw(markerLeft);
                g2d.draw(markerBottom);
                g2d.draw(markerRight);
            }
        }
    }
}