Mmm... just ran that demo myself and realized I'd tried to be too
clever with the recalculateTransform field. Here's the demo again
with that bit removed so that it rescales the lines properly when the
frame is resized...
package org.geotools.demo;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.io.WKTReader;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class LineDrawingPanel extends JPanel {
private static final int MARGIN = 5;
private List<LineString> lines = new ArrayList<LineString>();
private AffineTransform geomToScreen;
public void addLine(LineString line) {
lines.add(line);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (!lines.isEmpty()) {
setTransform();
for (LineString line : lines) {
Point[] screenCoords = getScreenCoords(line);
for (int i = 1; i < screenCoords.length; i++) {
g.drawLine(screenCoords[i-1].x, screenCoords[i-1].y,
screenCoords[i].x, screenCoords[i].y);
}
}
}
}
private void setTransform() {
Envelope env = getGeometryBounds();
Rectangle visRect = getVisibleRect();
Rectangle drawingRect = new Rectangle(
visRect.x + MARGIN, visRect.y + MARGIN, visRect.width
- 2*MARGIN, visRect.height - 2*MARGIN);
double scale = Math.min(drawingRect.getWidth() /
env.getWidth(), drawingRect.getHeight() / env.getHeight());
double xoff = MARGIN - scale * env.getMinX();
double yoff = MARGIN + env.getMaxY() * scale;
geomToScreen = new AffineTransform(scale, 0, 0, -scale, xoff, yoff);
}
private Envelope getGeometryBounds() {
Envelope env = new Envelope();
for (LineString line : lines) {
Envelope lineEnv = line.getEnvelopeInternal();
env.expandToInclude(lineEnv);
}
return env;
}
private Point[] getScreenCoords(LineString line) {
Coordinate[] coords = line.getCoordinates();
Point[] screenCoords = new Point[coords.length];
Point2D p = new Point2D.Double();
for (int i = 0; i < coords.length; i++) {
p.setLocation(coords[i].x, coords[i].y);
geomToScreen.transform(p, p);
screenCoords[i] = new Point((int)p.getX(), (int)p.getY());
System.out.println(screenCoords[i]);
}
return screenCoords;
}
public static void main(String[] args) throws Exception {
LineDrawingPanel panel = new LineDrawingPanel();
JFrame frame = new JFrame("Draw lines");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(panel);
frame.setSize(500, 500);
WKTReader reader = new WKTReader();
LineString line = (LineString) reader.read(
"LINESTRING(20 20, 20 25, 25 25, " +
"25 15, 15 15, 15 30, 30 30, 30 10, " +
"10 10, 10 35, 35 35, 35 5)");
panel.addLine(line);
line = (LineString) reader.read("LINESTRING(-10 40, 5 50, 20
40, 35 50, 50 40)");
panel.addLine(line);
frame.setVisible(true);
}
}
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