ZoomingPanControl.java

package prefuse.controls;

import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.MouseEvent;

import javax.swing.SwingUtilities;

import prefuse.Display;
import prefuse.activity.Activity;
import prefuse.activity.SlowInSlowOutPacer;


/**
 * <p>Allows users to pan over a display such that the display zooms in and
 * out proportionally to how fast the pan is performed.</p>
 * 
 * <p>The algorithm used is that of Takeo Igarishi and Ken Hinckley in their
 * research paper
 * <a href="http://citeseer.ist.psu.edu/igarashi00speeddependent.html">
 * Speed-dependent Automatic Zooming for Browsing Large Documents</a>,
 * UIST 2000.</p>
 *
 * @author <a href="http://jheer.org">jeffrey heer</a>
 */
public class ZoomingPanControl extends ControlAdapter {

    private boolean repaint = true, started = false;
    
    private Point mouseDown, mouseCur, mouseUp;
    private int dx, dy;
    private double d = 0;
    
    private double v0 = 75.0, d0 = 50, d1 = 400, s0 = .1;
    
    private UpdateActivity update = new UpdateActivity();
    private FinishActivity finish = new FinishActivity();
    
    /**
     * Create a new ZoomingPanControl.
     */
    public ZoomingPanControl() {
        this(true);
    }
    
    /**
     * Create a new ZoomingPanControl.
     * @param repaint true if repaint requests should be issued while
     * panning and zooming. false if repaint requests will come from
     * elsewhere (e.g., a continuously running action).
     */
    public ZoomingPanControl(boolean repaint) {
        this.repaint = repaint;
    }
    
    /**
     * @see java.awt.event.MouseListener#mousePressed(java.awt.event.MouseEvent)
     */
    public void mousePressed(MouseEvent e) {
        if ( SwingUtilities.isLeftMouseButton(e) ) {
            Display display = (Display)e.getComponent();
            display.setCursor(
                    Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
            mouseDown = e.getPoint();
        }        
    }
    
    /**
     * @see java.awt.event.MouseMotionListener#mouseDragged(java.awt.event.MouseEvent)
     */
    public void mouseDragged(MouseEvent e) {
        if ( SwingUtilities.isLeftMouseButton(e) ) {
            mouseCur = e.getPoint();
            dx = mouseCur.x - mouseDown.x;
            dy = mouseCur.y - mouseDown.y;
            d  = Math.sqrt(dx*dx + dy*dy);
            
            if ( !started ) {
                Display display = (Display)e.getComponent();
                update.setDisplay(display);
                update.run();
            }
        }
    }
    
    /**
     * @see java.awt.event.MouseListener#mouseReleased(java.awt.event.MouseEvent)
     */
    public void mouseReleased(MouseEvent e) {
        if ( SwingUtilities.isLeftMouseButton(e) ) {
            update.cancel();
            started = false;
            
            Display display = (Display)e.getComponent();
            mouseUp = e.getPoint();
            
            finish.setDisplay(display);
            finish.run();
            
            display.setCursor(Cursor.getDefaultCursor());
        }
    }
    
    private class UpdateActivity extends Activity {
        private Display display;
        private long lastTime = 0;
        public UpdateActivity() {
            super(-1,15,0);
        }
        public void setDisplay(Display display) {
            this.display = display;
        }
        protected void run(long elapsedTime) {
            double sx = display.getTransform().getScaleX();
            double s, v;
            
            if ( d <= d0 ) {
                s = 1.0;
                v = v0*(d/d0);
            } else {
                s = ( d >= d1 ? s0 : Math.pow(s0, (d-d0)/(d1-d0)) );
                v = v0;
            }
            
            s = s/sx;
            
            double dd = (v*(elapsedTime-lastTime))/1000;
            lastTime = elapsedTime;
            double deltaX = -dd*dx/d;
            double deltaY = -dd*dy/d;
            
            display.pan(deltaX,deltaY);
            if (s != 1.0)
                display.zoom(mouseCur, s);
            
            if ( repaint )
                display.repaint();
        }
    } // end of class UpdateActivity
    
    private class FinishActivity extends Activity {
        private Display display;
        private double scale;
        public FinishActivity() {
            super(1500,15,0);
            setPacingFunction(new SlowInSlowOutPacer());
        }
        public void setDisplay(Display display) {
            this.display = display;
            this.scale = display.getTransform().getScaleX();
            double z = (scale<1.0 ? 1/scale : scale);
            setDuration((long)(500+500*Math.log(1+z)));
        }
        protected void run(long elapsedTime) {
            double f = getPace(elapsedTime);
            double s = display.getTransform().getScaleX();
            double z = (f + (1-f)*scale)/s;
            display.zoom(mouseUp,z);
            if ( repaint )
                display.repaint();
        }
    } // end of class FinishActivity
    
} // end of class ZoomingPanControl