package org.geotools.jts;
import java.io.File;
import java.util.List;
import java.util.Random;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.geom.MultiLineString;
import com.vividsolutions.jts.index.SpatialIndex;
import com.vividsolutions.jts.index.strtree.STRtree;
import com.vividsolutions.jts.linearref.LinearLocation;
import com.vividsolutions.jts.linearref.LocationIndexedLine;
import org.geotools.data.FeatureSource;
import org.geotools.data.FileDataStore;
import org.geotools.data.FileDataStoreFinder;
import org.geotools.feature.FeatureCollection;
import org.geotools.geometry.jts.ReferencedEnvelope;
import org.geotools.swing.data.JFileDataStoreChooser;
import org.geotools.util.NullProgressListener;
import org.opengis.feature.Feature;
import org.opengis.feature.FeatureVisitor;
import org.opengis.feature.simple.SimpleFeature;
public class SnapToLine {
public static void main(String[] args) throws Exception {
/*
* Open a shapefile. You should choose one with line features
* (LineString or MultiLineString geometry)
*
*/
File file = JFileDataStoreChooser.showOpenFile("shp", null);
if (file == null) {
return;
}
FileDataStore store = FileDataStoreFinder.getDataStore(file);
FeatureSource source = store.getFeatureSource();
// Check that we have line features
Class<?> geomBinding = source.getSchema().getGeometryDescriptor().getType().getBinding();
boolean isLine = geomBinding != null
&& (LineString.class.isAssignableFrom(geomBinding) ||
MultiLineString.class.isAssignableFrom(geomBinding));
if (!isLine) {
System.out.println("This example needs a shapefile with line features");
return;
}
// load shapefile end (docs marker)
final SpatialIndex index = new STRtree();
FeatureCollection features = source.getFeatures();
System.out.println("Slurping in features ...");
features.accepts(new FeatureVisitor() {
@Override
public void visit(Feature feature) {
SimpleFeature simpleFeature = (SimpleFeature) feature;
Geometry geom = (MultiLineString) simpleFeature.getDefaultGeometry();
// Just in case: check for null or empty geometry
if (geom != null) {
Envelope env = geom.getEnvelopeInternal();
if (!env.isNull()) {
index.insert(env, new LocationIndexedLine(geom));
}
}
}
}, new NullProgressListener());
// cache features end (docs marker)
/*
* For test data, we generate a large number of points placed randomly
* within the bounding rectangle of the features.
*/
final int NUM_POINTS = 10000;
ReferencedEnvelope bounds = features.getBounds();
Coordinate[] points = new Coordinate[NUM_POINTS];
Random rand = new Random(file.hashCode());
for (int i = 0; i < NUM_POINTS; i++) {
points[i] = new Coordinate(
bounds.getMinX() + rand.nextDouble() * bounds.getWidth(),
bounds.getMinY() + rand.nextDouble() * bounds.getHeight());
}
// generate points end (docs marker)
/*
* We defined the maximum distance that a line can be from a point
* to be a candidate for snapping (1% of the width of the feature
* bounds for this example).
*/
final double MAX_SEARCH_DISTANCE = bounds.getSpan(0) / 100.0;
// Maximum time to spend running the snapping process (milliseconds)
final long DURATION = 5000;
int pointsProcessed = 0;
int pointsSnapped = 0;
long elapsedTime = 0;
long startTime = System.currentTimeMillis();
while (pointsProcessed < NUM_POINTS &&
(elapsedTime = System.currentTimeMillis() - startTime) < DURATION) {
// Get point and create search envelope
Coordinate pt = points[pointsProcessed++];
Envelope search = new Envelope(pt);
search.expandBy(MAX_SEARCH_DISTANCE);
/*
* Query the spatial index for objects within the search envelope.
* Note that this just compares the point envelope to the line envelopes
* so it is possible that the point is actually more distant than
* MAX_SEARCH_DISTANCE from a line.
*/
List<LocationIndexedLine> lines = index.query(search);
// Initialize the minimum distance found to our maximum acceptable
// distance plus a little bit
double minDist = MAX_SEARCH_DISTANCE + 1.0e-6;
Coordinate minDistPoint = null;
for (LocationIndexedLine line : lines) {
LinearLocation here = line.project(pt);
Coordinate point = line.extractPoint(here);
double dist = point.distance(pt);
if (dist < minDist) {
minDist = dist;
minDistPoint = point;
}
}
if (minDistPoint == null) {
// No line close enough to snap the point to
System.out.println(pt + "- X");
} else {
System.out.printf("%s - snapped by moving %.4f\n",
pt.toString(), minDist);
pointsSnapped++;
}
}
System.out.printf("Processed %d points (%.2f points per second). \n"
+ "Snapped %d points.\n\n",
pointsProcessed,
1000.0 * pointsProcessed / elapsedTime,
pointsSnapped);
}
}