Hi,
Today I've been working on a simple forced collection example for world(coord)
to screen(pixel) and screen(pixel) to world(coord)
I have 3 questions:
#1 Am I on the right track with the below methods getScreentoWorld and
getWorldtoScreen
#2 The major question I have is regarding the Rectangle width and height. Did
I use a proper approach for that???
#3 One thing I noticed is that the JMapPane has a:
public AffineTransform getWorldToScreenTransform()
public AffineTransform getScreenToWorldTransform()
Are these usable in my getScreentoWorld and getWorldtoScreen methods?
It seems like since they are already present in JMapPane that use of them would
be realistic.
I tried getting a direct call from the JMapPane to work with no luck.
The following is my OUTPUT:
================================================
Actual x: 20.222 y: 30.333
Pixel x: 44.31946815200793 Pixel y: 600.0000000000001
Coord x: 20.222 Coord y: 30.332999999999995
================================================
Actual x: 12.0 y: 52.0
Pixel x: 0.0 Pixel y: 0.0
Coord x: 11.999999999999998 Coord y: 52.0
================================================
Actual x: 123.31 y: 48.4
Pixel x: 600.0000000000001 Pixel y: 99.69077398809259
Coord x: 123.31000000000002 Coord y: 48.4
It seems like my pixel values are way off. Possibly explain....
The following is my EXAMPLE:
package org.geotools.demo;
import org.geotools.feature.FeatureCollection;
import org.geotools.feature.FeatureCollections;
import org.geotools.feature.FeatureIterator;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.data.DataUtilities;
import org.geotools.data.FeatureSource;
import org.geotools.map.DefaultMapContext;
import org.geotools.map.MapContext;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.geotools.renderer.lite.RendererUtilities;
import org.geotools.swing.JMapFrame;
import org.geotools.swing.JMapPane;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.geometry.DirectPosition2D;
import org.geotools.geometry.jts.JTSFactoryFinder;
import org.geotools.geometry.jts.ReferencedEnvelope;
import org.geotools.styling.StyleFactory;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.filter.FilterFactory;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.Point;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.io.IOException;
public class WorldScreen {
static StyleFactory styleFactory =
CommonFactoryFinder.getStyleFactory(null);
static FilterFactory filterFactory =
CommonFactoryFinder.getFilterFactory(null);
static CoordinateReferenceSystem crs = DefaultGeographicCRS.WGS84;
static final int MAX_NAME_LENGTH = 20;
static MapContext map;
static JMapFrame mapFrame;
public static void main(String[] args) throws Exception {
final SimpleFeatureType TYPE = DataUtilities.createType("Location",
"location:Point,name:String"); // see createFeatureType();
FeatureCollection<SimpleFeatureType, SimpleFeature> collection =
FeatureCollections.newCollection();
//DATA
double lon[] = {123.31, 12, 20.222};
double lat[] = {48.4, 52, 30.333};
String name[] = { "Point1", "Point2", "Point3" };
//Define Collection
GeometryFactory factory = JTSFactoryFinder.getGeometryFactory(null);
for(int i=0;i<=2;i++){
Point point = factory.createPoint( new Coordinate(lon[i],lat[i]));
SimpleFeature feature = SimpleFeatureBuilder.build( TYPE, new
Object[]{point, name[i]}, null );
collection.add( feature );
}
//Define FeatureSource
FeatureSource<SimpleFeatureType, SimpleFeature> featureSource =
DataUtilities.source(collection);
map = new DefaultMapContext();
map.setTitle("The Point");
map.addLayer(featureSource, null);
mapFrame = new JMapFrame(map);
mapFrame.setSize(600, 600);
//Iterate Collection
FeatureIterator<SimpleFeature> iterator = collection.features();
try {
while (iterator.hasNext()) {
SimpleFeature feature = iterator.next();
Geometry geometry = (Geometry) feature.getDefaultGeometry();
Coordinate[] coords = geometry.getCoordinates();
for( int i = 0; i < coords.length; i++ ) {
System.out.println("================================================");
System.out.println("Actual\t x: "+coords[i].x + " \ty: " +
coords[i].y);
//Get Pixel Value of Coordinates
Point2D pixelValue=getWorldtoScreen(coords[i].x, coords[i].y);
System.out.println("Pixel\t x: "+pixelValue.getX()+" \tPixel
y: \t"+pixelValue.getY());
//Get Coordinates from Pixel
Point2D coordValue=getScreentoWorld(pixelValue.getX(),
pixelValue.getY());
System.out.println("Coord\t x: "+coordValue.getX()+" \tCoord
y: \t"+coordValue.getY());
}
}
}
finally {
if( iterator != null ){
// YOU MUST CLOSE THE ITERATOR!
iterator.close();
}
}
mapFrame.enableStatusBar(true);
mapFrame.setVisible(true);
}
public static Point2D getWorldtoScreen(double x, double y){
Rectangle imageBounds=null;
ReferencedEnvelope mapBounds=null;
try{
mapBounds=map.getLayerBounds();
imageBounds = mapFrame.getBounds();
int width = (int)imageBounds.getWidth();
int height = (int)imageBounds.getHeight();
}catch(Exception e){
}
AffineTransform world2screen =
RendererUtilities.worldToScreenTransform(mapBounds, imageBounds);
Point2D pointScreenAbsolute = new Point2D.Double(x, y);
Point2D pointScreen = world2screen.transform(pointScreenAbsolute, null);
return pointScreen;
}
public static Point2D getScreentoWorld(double x, double y) throws Exception {
Rectangle imageBounds=null;
ReferencedEnvelope mapBounds=null;
try{
mapBounds=map.getLayerBounds();
imageBounds = mapFrame.getBounds();
int width = (int)imageBounds.getWidth();
int height = (int)imageBounds.getHeight();
}catch(Exception e){
}
AffineTransform world2screen =
RendererUtilities.worldToScreenTransform(mapBounds, imageBounds);
AffineTransform screen2world = world2screen.createInverse();
Point2D pointScreenAbsolute = new Point2D.Double(x, y);
Point2D pointScreen = screen2world.transform(pointScreenAbsolute, null);
return pointScreen;
}
}
Thanks,
Oliver
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