Hi. I am alban I 'm a french beginner in Geotools.
For my current project I shall build a png image only containing point for
each cities of 5000hab in a defined square.
So only black points and all the image should be transparent.
I got my features in a collection, I got my Enveloppe on the earth.
Then I build a MapContent then I add the layer of all features, styling the
layer with black points.
then I save the MapContent using ImageWriter and GTRender.
My code is very very similar to the geotools tutorial.
But in result I only get a white png file with no point.
*******************************************************
/**
* Features to map content.
*
* @param envelope the feature envelope
* @param featuresSource the features source
* @param imageWidth the image width
* @param imageHeight the image height
* @return the map content
* @throws CartographyException the cartography exception
*/
public static MapContent featuresToMapContent(final Envelope2D envelope,
final FeatureCollection<SimpleFeatureType,
SimpleFeature> featuresSource, final int imageWidth, final
int
imageHeight) throws CartographyException {
// Create a map viewport
final MapViewport viewport = new MapViewport() ;
viewport.setBounds(new ReferencedEnvelope(envelope));
viewport.setCoordinateReferenceSystem(envelope.getCoordinateReferenceSystem());
viewport.setScreenArea(new Rectangle(imageWidth, imageHeight));
// create Mapcontent
final MapContent map = new MapContent();
map.setTitle("Map");
map.setViewport(viewport);
// Create a basic Style to render the features
final Style style = ShapeUtils.createPointStyle(Color.BLACK, 5);
style.featureTypeStyles();
// Add the features and the associated Style object to
// the MapContent as a new Layer
final Layer layer = new FeatureLayer(featuresSource, style,
"featuresLayer");
layer.setVisible(true);
layer.setSelected(true);
//add layer and dispose Map
map.addLayer(layer);
map.dispose();
return map;
}
/**
* Save image.
*
* @param map the map
* @param outPutFile the output png file
* @param imageWidth the image width
* @param imageHeight the image height
* @throws CartographyException the cartography exception
*/
public static void saveImage(final MapContent map, final File
outPutFile, final int imageWidth, final int imageHeight) throws
CartographyException {
try {
// get the renderer
final GTRenderer renderer = new StreamingRenderer();
renderer.setMapContent(map);
// define bounds : mapbounds and screenToDisplay
final ReferencedEnvelope mapBounds =
map.getViewport().getBounds();
final Rectangle imageBounds = new
Rectangle(0,0,imageWidth,imageHeight);
// create the image
final BufferedImage image = new
BufferedImage(imageBounds.width,
imageBounds.height, BufferedImage.TYPE_INT_RGB);
final Graphics2D gr = image.createGraphics();
gr.setPaint(Color.WHITE);
gr.fill(imageBounds);
gr.dispose();
// paint the image
final AffineTransform world2screen =
RendererUtilities.worldToScreenTransform(mapBounds, imageBounds);
renderer.paint(gr, imageBounds, mapBounds, world2screen);
ImageIO.write(image, "png", outPutFile);
} catch (IOException e) {
throw new CartographyException(e);
}
}
************************************************
I read almost all internet on this subject and I don't find my mistake. If
you would have a look it will be greate for me. Thanks a lot !
Alban
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