Re: [Geotools-gt2-users] Problems with the unsupported SWT module

[Jonas S. <jon...@go...>]

Hello,

i managed to get an e4 application with geotools 20.5 and also the swt
module on 20.5 to run. But i still get exceptions when adding shapefiles or
wms-layers to the map.
The next step will be an attempt to upgrade the swt module version by
version. Before that i would like to be able to display a shapefile layer
and a wms layer on the same mappane, without problems, as a proof of
concept.

When adding a shapefile layer, i get the exception enclosed in
exception1.txt.

When adding a wms layer i get the exception enclosed in exception2.txt.

Part code:
@PostConstruct
public void postConstruct(Composite parent, IEclipseContext context) {
    handleImages();
    MapContent content = new MapContent();
    SashForm sashForm = new SashForm(parent, SWT.HORIZONTAL | SWT.NULL);
    Composite mainComposite = sashForm;
    MapLayerComposite mapLayerTable = new MapLayerComposite(mainComposite,
SWT.BORDER);
    mapPane = new SwtMapPane(mainComposite, SWT.BORDER | SWT.NO_BACKGROUND);
    mapPane.setMapContent(content);
    mapLayerTable.setMapPane(mapPane);
    sashForm.setWeights(new int[] { 1, 3 });

mapPane.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
    StreamingRenderer renderer = new StreamingRenderer();
    mapPane.setRenderer(renderer);
    context.set(SwtMapPane.class, mapPane);
}

Import shapefile code:
@Execute
public void execute(SwtMapPane mapPane) {
    Display display = Display.getCurrent();
    Shell shell = new Shell(display);
    File file = JFileDataStoreChooser.showOpenFile(new String[] { "*.shp"
}, shell);
    try {
        if (file != null && file.exists()) {
           MapContent mapContent = mapPane.getMapContent();
           FileDataStore store = FileDataStoreFinder.getDataStore(file);
           SimpleFeatureSource featureSource = store.getFeatureSource();
           Style style = Utils.createStyle(file, featureSource);
           Layer layer = new FeatureLayer(featureSource, style);
           //Add viewport line here
           mapContent.addLayer(layer);
           mapPane.redraw();
        }
    ...
}

Import WMS code:
@Execute
public void execute(SwtMapPane mapPane) {
    WebMapServer wms = null;
    try {
        wms = new WebMapServer(new URL("
http://ows.mundialis.de/services/service?"));
    } catch ...
    }
    WMSCapabilities capabilities = wms.getCapabilities();
    MapContent mapContent = mapPane.getMapContent();
    WMSLayer layer = new WMSLayer(wms, capabilities.getLayerList().get(1));
    //Add viewport line here
    mapContent.addLayer(displayLayer);
    mapPane.redraw();
}

I noticed that the SwtMapPane::getDisplayArea method (which is called here:
 at org.geotools.swt.SwtMapPane.setCrs(SwtMapPane.java:428)) returns a
ReferencedEnvelope where the crs is null, because the viewport of the
mapcontent is still null.
So i thought i need to initialize it somewhere somehow, but this is not
shown in any tutorial i think. So maybe i'm just missing a simple line in
the part code?

I found out that adding the line
mapContent.getViewport().setBounds(layer.getBounds()); in the shapefile/wms
code as indicated by the comments is a quick fix for the exception, but not
a solution because it just works for one layer.

When only using shapefiles, as soon as a second one is added (from the same
example dataset so a assume same crs) the bounds of the first one are
overwritten by the second one and if they happen to be samller, the borders
of the first shapefile are not displayed correctly anymore.
And if i try to combine both, there are obviously major problems, because
of, i assume, different crs and so on.
When trying to display a wms layer on top of a shapefile layer, the wms
layer is stretched and as soon as i try to change anything, like visibility
i get an exception (enclosed in exception3.txt) and the layers won't render
again.
Same when trying to display a shapefile layer on top of a wmslayer, i also
get an exception (enclosed in exception4.txt). But those are expected, as
my "fix" only takes one layer into account.

So the final question is: What am i missing to avoid those "sourceCRS can't
be null" exceptions and what do i have to do to correctly overlay multiple
different layers like shapefile and WMS?
And should i follow the developers guide when trying to update the swt
module and talk to the dev mailing list and get the contributers license
and so on?

Best regards
Jones