Hi Marin,
> how can I draw for example a JTS Geometry Line object in a JFrame?
> JPanel ...
>
The example below draws JTS LineStrings on a JPanel.
Hope this helps.
Michael
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;
private boolean recalculateTransform = true;
public void addLine(LineString line) {
lines.add(line);
recalculateTransform = true;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (!lines.isEmpty()) {
if (recalculateTransform) {
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);
recalculateTransform = false;
}
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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