Mentaer: Created page with 'The following plugin code enables to derive convex hull for a point layer whereby the convexh hull algorithm (minimum enclosing polygon) utilized is taken from the [http://forge.…'

2009-10-22T19:38:45Z

Created page with 'The following plugin code enables to derive convex hull for a point layer whereby the convexh hull algorithm (minimum enclosing polygon) utilized is taken from the [http://forge.…'

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The following plugin code enables to derive convex hull for a point layer whereby the convexh hull algorithm (minimum enclosing polygon) utilized is taken from the [http://forge.osor.eu/plugins/wiki/index.php?id=13&type=g Sextante] processing libraries. (Note, Sextante actually uses the JTS algorithm, which is also used in our standard implementation)

<pre>
package org.openjump.core.ui.plugin.tools;

import java.io.IOException;

import javax.swing.JComboBox;

import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jump.feature.FeatureCollection;
import com.vividsolutions.jump.task.TaskMonitor;
import com.vividsolutions.jump.workbench.WorkbenchContext;
import com.vividsolutions.jump.workbench.model.Layer;
import com.vividsolutions.jump.workbench.model.StandardCategoryNames;
import com.vividsolutions.jump.workbench.plugin.AbstractPlugIn;
import com.vividsolutions.jump.workbench.plugin.EnableCheckFactory;
import com.vividsolutions.jump.workbench.plugin.MultiEnableCheck;
import com.vividsolutions.jump.workbench.plugin.PlugInContext;
import com.vividsolutions.jump.workbench.plugin.ThreadedPlugIn;
import com.vividsolutions.jump.workbench.ui.GUIUtil;
import com.vividsolutions.jump.workbench.ui.MultiInputDialog;
import com.vividsolutions.jump.workbench.ui.plugin.FeatureInstaller;

import es.unex.sextante.core.OutputFactory;
import es.unex.sextante.core.OutputObjectsSet;
import es.unex.sextante.core.ParametersSet;
import es.unex.sextante.core.Sextante;
import es.unex.sextante.dataObjects.IVectorLayer;
import es.unex.sextante.exceptions.GeoAlgorithmExecutionException;
import es.unex.sextante.openjump.core.OpenJUMPOutputFactory;
import es.unex.sextante.openjump.core.OpenJUMPVectorLayer;
import es.unex.sextante.outputs.Output;
import es.unex.sextante.parameters.Parameter;
import es.unex.sextante.vectorTools.minimumEnclosingPolygon.MinimumEnclosingPolygonAlgorithm;

/**
* @description: OpenJUMP plugin to demonstrate the utilization and access to Sextante algorithms
*
* @author sstein
*
**/
public class SextanteTestPlugIn extends AbstractPlugIn implements ThreadedPlugIn{

private String sSidebar ="Testplugin that uses an algorithm that generates a convex hull (i.e. minimum enclosing polygon) from Sextante";
private final String sLAYERPTS = "Layer with Point Geometries";
private Layer input = null;
private MultiInputDialog dialog;
private PlugInContext context = null;

GeometryFactory gfactory = new GeometryFactory();

public void initialize(PlugInContext context) throws Exception {

FeatureInstaller featureInstaller = new FeatureInstaller(context.getWorkbenchContext());
featureInstaller.addMainMenuItem(
this, //exe
new String[] {"OJ-Sextante"}, //menu path
"Sextante Test Plugin",
//AbstractPlugIn.createName(CalculateMinimumConvexPolygonPlugIn.class),
false, //checkbox
null, //icon
createEnableCheck(context.getWorkbenchContext())); //enable check
}

public static MultiEnableCheck createEnableCheck(WorkbenchContext workbenchContext) {
EnableCheckFactory checkFactory = new EnableCheckFactory(workbenchContext);

return new MultiEnableCheck()
.add(checkFactory.createAtLeastNLayersMustExistCheck(1));
}

public boolean execute(PlugInContext context) throws Exception{
//Unlike ValidatePlugIn, here we always call #initDialog because we want
//to update the layer comboboxes.
initDialog(context);
dialog.setVisible(true);
if (!dialog.wasOKPressed()) {
return false;
}
else{
this.getDialogValues(dialog);
}
return true;
}

public void run(TaskMonitor monitor, PlugInContext context) throws Exception{
System.gc(); //flush garbage collector
this.context = context;
monitor.allowCancellationRequests();
FeatureCollection resultC = this.calculateHull(this.input, context, monitor);
if(resultC != null){
context.addLayer(StandardCategoryNames.RESULT, this.input.getName() + "-hull", resultC);
}
System.gc();
}

private void initDialog(PlugInContext context) {

dialog = new MultiInputDialog(context.getWorkbenchFrame(), "Generate Hull", true);
dialog.setSideBarDescription(sSidebar);
try {
JComboBox addLayerComboBoxRegions = dialog.addLayerComboBox(this.sLAYERPTS, context.getCandidateLayer(0), null, context.getLayerManager());
}
catch (IndexOutOfBoundsException e) {}
GUIUtil.centreOnWindow(dialog);
}

private void getDialogValues(MultiInputDialog dialog) {
this.input = dialog.getLayer(this.sLAYERPTS);
}

private FeatureCollection calculateHull(Layer stefanspoints,
PlugInContext context, TaskMonitor monitor)
throws GeoAlgorithmExecutionException, IOException {

OutputFactory outputFactory = new OpenJUMPOutputFactory(context.getWorkbenchContext());

monitor.report("initialize sextante");
Sextante.initialize();

monitor.report("prepare computation");
OpenJUMPVectorLayer layer = new OpenJUMPVectorLayer();
layer.create(stefanspoints);
MinimumEnclosingPolygonAlgorithm alg = new MinimumEnclosingPolygonAlgorithm();

ParametersSet params = alg.getParameters();
Parameter layerParam = (Parameter)params.getParameter(MinimumEnclosingPolygonAlgorithm.POINTS);
boolean worked = layerParam.setParameterValue(layer);
if(worked){
//method values: 0 - for convex hull, 1 - for circle, 2 - envelope
params.getParameter(MinimumEnclosingPolygonAlgorithm.METHOD).setParameterValue(new Integer(2));
params.getParameter(MinimumEnclosingPolygonAlgorithm.USECLASSES).setParameterValue(false);
//-- not sure why the following param needs to be set, if I set false before
params.getParameter(MinimumEnclosingPolygonAlgorithm.FIELD).setParameterValue(new Integer(0));

OutputObjectsSet outputs = alg.getOutputObjects();
Output polygon = outputs.getOutput(MinimumEnclosingPolygonAlgorithm.RESULT);
monitor.report("computation");
alg.execute(null, outputFactory);

monitor.report("retrieving results");
IVectorLayer result = (IVectorLayer)polygon.getOutputObject();
Layer resultOJLayer = (Layer)result.getBaseDataObject();
return resultOJLayer.getFeatureCollectionWrapper().getWrappee();
}
else{
context.getWorkbenchFrame().warnUser("layer not a point layer; has ShapeType: " + layer.getShapeType());
return null;
}
}

}
</pre>

Example Plugin For Accessing Sextante Algorithms - Revision history

Mentaer: Created page with 'The following plugin code enables to derive convex hull for a point layer whereby the convexh hull algorithm (minimum enclosing polygon) utilized is taken from the [http://forge.…'