Thanks a lot.
在2009-05-11，"Michael Bedward" <[email protected]> 写道：
>Hi Zeng,
>
>I'm posting the code here so that if anyone else spots glaring errors
>in it they can warn you :-)
>
>Note, in my app I was only working with double valued, single-band
>coverages but it would be easy to extend this class to deal with more
>types and multi-band data.
>
>Let me know if you have any problems with it.
>
>Michael
>
>
>package org.cafeanimal.geo.gridlayer;
>
>import java.awt.geom.Point2D;
>import java.awt.geom.Rectangle2D;
>import java.awt.image.DataBuffer;
>import java.io.File;
>import java.io.IOException;
>import java.util.ArrayList;
>import java.util.Arrays;
>import java.util.List;
>import javax.media.jai.TiledImage;
>import javax.media.jai.iterator.RandomIterFactory;
>import javax.media.jai.iterator.WritableRandomIter;
>import javax.media.jai.operator.FormatDescriptor;
>import org.geotools.coverage.grid.GridCoverage2D;
>import org.geotools.geometry.Envelope2D;
>import org.geotools.image.ImageWorker;
>import org.opengis.coverage.PointOutsideCoverageException;
>import org.opengis.geometry.Envelope;
>import org.opengis.referencing.operation.MathTransform2D;
>import org.opengis.referencing.operation.NoninvertibleTransformException;
>import org.opengis.referencing.operation.TransformException;
>
>/**
> *
> * @author Michael Bedward and Murray Ellis
> */
>public class WritableGridCoverage {
>
> private GridCoverage2D gridCov;
> private MathTransform2D worldToGrid = null;
> private double[] dbuf = new double[1];
> private static final int MAX_PENDING_VALUES = 10000;
>
> private static class PendingValue {
> Point2D.Double pos;
> boolean isGeographic;
> double value;
> }
>
> private List<PendingValue> pendingValues = new ArrayList<PendingValue>();
>
> /**
> * Constructor
> * @param gridCov the GridCoverage2D object to be wrapped
> */
> public WritableGridCoverage(GridCoverage2D gridCov) {
> this.gridCov = gridCov;
> }
>
> public GridCoverage2D getGridCoverage() {
> flushCache(true);
> return gridCov;
> }
>
> public String getName() {
> return gridCov.getName().toString();
> }
>
> public int getNumRows() {
> return gridCov.getRenderedImage().getHeight();
> }
>
> public int getNumCols() {
> return gridCov.getRenderedImage().getWidth();
> }
>
> public Rectangle2D.Double getBounds() {
> Envelope2D env = gridCov.getEnvelope2D();
> return new Rectangle2D.Double(env.x, env.y, env.width, env.height);
> }
>
> public double getPixelWidth() {
> return gridCov.getEnvelope2D().getWidth() / getNumCols();
> }
>
> public double getValueAtPos(Point2D pos) {
> flushCache(true);
>
> try {
> gridCov.evaluate(pos, dbuf);
> } catch (PointOutsideCoverageException ex) {
> return Double.NaN;
> }
>
> return dbuf[0];
> }
>
> public int getValueAtPosAsInt(Point2D pos, int defaultValue) {
> double val = getValueAtPos(pos);
> if (Double.isNaN(val)) {
> return defaultValue;
> } else {
> return (int) Math.round(val);
> }
> }
>
> public double[] getValuesAtPos(Point2D pos, double[] buf) {
> flushCache(true);
>
> if (buf == null) {
> buf = new double[gridCov.getNumSampleDimensions()];
> }
>
> try {
> buf = gridCov.evaluate(pos, buf);
> } catch (PointOutsideCoverageException ex) {
> Arrays.fill(buf, Double.NaN);
> }
>
> return buf;
> }
>
> public void saveAsJPEG(File path) {
> try {
> ImageWorker iw = new ImageWorker(gridCov.getRenderedImage());
> if (!iw.isBytes()) {
>
>iw.setImage(FormatDescriptor.create(gridCov.getRenderedImage(),
>DataBuffer.TYPE_BYTE, null));
> }
> iw.write(path);
> } catch (IOException ex) {
> System.out.println(ex.getMessage());
> }
> }
>
> public void setValueAtPos(Point2D pos, int value) {
> Number n = Integer.valueOf(value);
> doSetValue(pos, n);
> }
>
> public void setValueAtPos(Point2D pos, float value) {
> Number n = new Float(value);
> doSetValue(pos, n);
> }
>
> public void setValueAtPos(Point2D pos, double value) {
> Number n = new Double(value);
> doSetValue(pos, n);
> }
>
> private void doSetValue(Point2D pos, Number value) {
> PendingValue pv = new PendingValue();
> pv.pos = new Point2D.Double(pos.getX(), pos.getY());
> pv.isGeographic = true;
> pv.value = value.doubleValue();
> pendingValues.add(pv);
> flushCache(false);
> }
>
> private void flushCache(boolean force) {
> if (pendingValues.size() >= MAX_PENDING_VALUES || (force &&
>pendingValues.size() > 0)) {
> if (worldToGrid == null) {
> try {
> worldToGrid =
>gridCov.getGridGeometry().getGridToCRS2D().inverse();
> } catch (NoninvertibleTransformException ex) {
> throw new RuntimeException("Could not create
>geographic to grid coords transform");
> }
> }
>
> TiledImage tImg = new TiledImage(gridCov.getRenderedImage(), true);
> WritableRandomIter writeIter =
>RandomIterFactory.createWritable(tImg, null);
>
> Point2D.Double gridPos = new Point2D.Double();
> for (PendingValue pv : pendingValues) {
> if (pv.isGeographic) {
> try {
> worldToGrid.transform(pv.pos, gridPos);
> } catch (TransformException ex) {
> throw new RuntimeException("Could not
>transform location [" +
> pv.pos + "] to grid coords");
> }
> } else {
> gridPos.setLocation(pv.pos);
> }
>
> writeIter.setSample((int) gridPos.x, (int) gridPos.y,
>0, pv.value);
> }
>
> pendingValues.clear();
>
> String name = getName();
> Envelope env = gridCov.getEnvelope();
> }
> }
>}
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