/*
* Open Source Physics software is free software as described near the bottom of this code file.
*
* For additional information and documentation on Open Source Physics please see:
* <http://www.opensourcephysics.org/>
*/
package org.opensourcephysics.display;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.geom.GeneralPath;
import org.opensourcephysics.controls.XML;
import org.opensourcephysics.controls.XMLControl;
import org.opensourcephysics.controls.XMLLoader;
/**
* TrailBezier defines a trail of points connected by a Bezier spline. This object is often used to
* show the path of a moving object.
*
* @author Wolfgang Christian
* @version 1.0
*/
public class TrailBezier extends AbstractTrail {
GeneralPath path = new GeneralPath();
GeneralPath pathStart = new GeneralPath();
GeneralPath pathEnd = new GeneralPath();
float x0, y0, x1, y1, x2, y2;
float[] endPts = new float[4];
float dxEstimate = 0, dyEstimate = 0;
float slack = (float) 0.15;
float dx2, dy2;
/**
* Adds a point to the trail.
* @param x double
* @param y double
*/
public synchronized void addPoint(double x, double y) {
if(closed) {
throw new IllegalStateException("Cannot add points to a closed trail."); //$NON-NLS-1$
}
xmin = Math.min(xmin, x);
xmax = Math.max(xmax, x);
ymin = Math.min(ymin, y);
ymax = Math.max(ymax, y);
if(numpts==0) {
pathStart.moveTo((float) x, (float) y);
endPts[0] = x0 = (float) x;
endPts[1] = y0 = (float) y;
} else if(numpts==1) {
endPts[2] = x1 = (float) x;
endPts[3] = y1 = (float) y;
path.moveTo(x1, y1);
} else if(numpts==2) {
x2 = (float) x;
y2 = (float) y;
dx2 = x2-endPts[0];
dy2 = y2-endPts[1];
float dx1 = -2*x2-4*endPts[0]+6*endPts[2];
float dy1 = -2*y2-4*endPts[1]+6*endPts[3];
pathStart.curveTo(endPts[0]+slack*dx1, endPts[1]+slack*dy1, endPts[2]-slack*dx2, endPts[3]-slack*dy2, endPts[2], endPts[3]);
endPts[0] = endPts[2];
endPts[1] = endPts[3];
endPts[2] = x2;
endPts[3] = y2;
} else {
float dx1 = dx2, dy1 = dy2;
float fx = (float) x;
float fy = (float) y;
dx2 = fx-endPts[0];
dy2 = fy-endPts[1];
path.curveTo(endPts[0]+slack*dx1, endPts[1]+slack*dy1, endPts[2]-slack*dx2, endPts[3]-slack*dy2, endPts[2], endPts[3]);
dxEstimate = 2*endPts[0]+4*fx-6*endPts[2];
dyEstimate = 2*endPts[1]+4*fy-6*endPts[3];
endPts[0] = endPts[2];
endPts[1] = endPts[3];
endPts[2] = fx;
endPts[3] = fy;
}
numpts++;
}
/**
* Sets the slack which determines the position of the control points.
* @param slack double
*/
public void setSlack(double slack) {
this.slack = (float) slack;
}
/**
* Closes the trail by connecting the first point to the last point.
*/
public void closeTrail() {
addPoint(x0, y0);
addPoint(x1, y1);
addPoint(x2, y2);
closed = true;
pathStart.reset();
pathEnd.reset();
path.closePath();
}
/**
* Clears all points from the trail.
*/
public synchronized void clear() {
numpts = 0;
xmin = Double.MAX_VALUE;
xmax = -Double.MAX_VALUE;
ymin = Double.MAX_VALUE;
ymax = -Double.MAX_VALUE;
path.reset();
pathStart.reset();
pathEnd.reset();
closed = false;
}
/**
* Draw the trail on the panel.
* @param g
*/
public void draw(DrawingPanel panel, Graphics g) {
if(numpts==0) {
return;
}
Graphics2D g2 = (Graphics2D) g;
g2.setColor(color);
// transform paths from world to pixel coordinates
Shape s = path.createTransformedShape(panel.getPixelTransform());
if(drawingStroke!=null) {
Stroke stroke = g2.getStroke();
g2.setStroke(drawingStroke);
g2.draw(s);
g2.setStroke(stroke);
} else {
g2.draw(s);
}
if(closed) {
return;
}
s = pathStart.createTransformedShape(panel.getPixelTransform());
g2.draw(s);
if(numpts>2) {
drawPathEnd(panel, g2);
}
}
/**
* Draws the points that have not yet been added to the spline.
* @param panel DrawingPanel
* @param g2 Graphics2D
*/
protected void drawPathEnd(DrawingPanel panel, Graphics2D g2) {
pathEnd.reset();
path.moveTo(endPts[0], endPts[1]); // start the path at the last point
path.curveTo(endPts[0]+slack*dx2, endPts[1]+slack*dy2, endPts[2]-slack*dxEstimate, endPts[3]-slack*dyEstimate, endPts[2], endPts[3]);
Shape s = pathEnd.createTransformedShape(panel.getPixelTransform());
g2.draw(s);
}
/**
* Returns the XML.ObjectLoader for this class.
*
* @return the object loader
*/
public static XML.ObjectLoader getLoader() {
return new Loader();
}
/**
* Determines if this trail scales the drawing panel.
*
* @return boolean
*/
public boolean isMeasured() {
return enableMeasure&&(this.numpts>0);
}
/**
* Gets the minimum x value in the trail.
* @return double
*/
public double getXMin() {
return xmin;
}
/**
* Gets the maximum x value in the trail.
* @return double
*/
public double getXMax() {
return xmax;
}
/**
* Gets the minimum y value in the trail.
* @return double
*/
public double getYMin() {
return ymin;
}
/**
* Gets the maximum y value in the trail.
* @return double
*/
public double getYMax() {
return ymax;
}
/**
* A class to save and load Dataset data in an XMLControl.
*/
private static class Loader extends XMLLoader {
public void saveObject(XMLControl control, Object obj) {
TrailBezier trail = (TrailBezier) obj;
control.setValue("closed", trail.closed); //$NON-NLS-1$
control.setValue("color", trail.color); //$NON-NLS-1$
control.setValue("number of pts", trail.numpts); //$NON-NLS-1$
//control.setValue("general path", trail.generalPath);
}
public Object createObject(XMLControl control) {
return new TrailBezier();
}
public Object loadObject(XMLControl control, Object obj) {
TrailBezier trail = (TrailBezier) obj;
trail.closed = control.getBoolean("closed"); //$NON-NLS-1$
trail.color = (Color) control.getObject("color"); //$NON-NLS-1$
trail.numpts = control.getInt("number of pts"); //$NON-NLS-1$
//trail.generalPath = (GeneralPath) control.getObject("general path");
return obj;
}
}
}
/*
* Open Source Physics software is free software; you can redistribute
* it and/or modify it under the terms of the GNU General Public License (GPL) as
* published by the Free Software Foundation; either version 2 of the License,
* or(at your option) any later version.
*
* Code that uses any portion of the code in the org.opensourcephysics package
* or any subpackage (subdirectory) of this package must must also be be released
* under the GNU GPL license.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307 USA
* or view the license online at http://www.gnu.org/copyleft/gpl.html
*
* Copyright (c) 2007 The Open Source Physics project
* http://www.opensourcephysics.org
*/