Geomajas geomajas-plugin-wmsclient plug-in guide

This plugin extends the default Geomajas injection definitions, by providing it's own GIN module definition and GIN injector interface. If you have an application wherin you want to define a GIN injector that supports the GIN modules of both the PureGWT face and the WMS client plugin, you can define it as follows:

@GinModules({ GeomajasGinModule.class, WmsClientGinModule.class })
public interface MyApplicationGinjector extends WmsClientGinjector, GeomajasGinjector {
}

Creating a new WmsLayer instance, is done through the GIN injection framework. You need to define a GIN injector (see previous paragraph), and have this injector create the instance for you:

// It is best to define your own injector, and make it a global static variable...
// (you need only one for your app)
WmsClientGinjector injector = GWT.create(WmsClientGinjector.class);

// We create a new map:
MapPresenter mapPresenter = injector.getMapPresenter()
mapPresenter.initialize("puregwt-app", "mapEmpty"); // Map with an empty configuration
mapPresenter.getEventBus().addMapInitializationHandler(new MapInitializationHandler() {

    // When the map has been initialized, we can start adding WMS layers:
    public void onMapInitialized(MapInitializationEvent event) {

        // First we define a WMS configuration object:
        WmsLayerConfiguration wmsConfig = new WmsLayerConfiguration();
        wmsConfig.setFormat("image/jpeg");
        wmsConfig.setLayers("bluemarble");
        wmsConfig.setVersion(WmsVersion.v1_1_1);
        wmsConfig.setBaseUrl("http://apps.geomajas.org/geoserver/wms");

        // Then we define a Tile Configuration object:
        Coordinate tileOrigin = new Coordinate(mapPresenter.getViewPort().getMaximumBounds().getX(),
                mapPresenter.getViewPort().getMaximumBounds().getY());
        WmsTileConfiguration tileConfig = new WmsTileConfiguration(256, 256, tileOrigin);

        // Create the WMS layer and add it to the map:
        WmsLayer wmsLayer = injector.getWmsLayerFactory().createWmsLayer("bluemarble",
                wmsConfig, tileConfig);
        mapPresenter.getLayersModel().addLayer(wmsLayer);
    }
});

For parsing a GetCapabilities file, we need the WmsService. This service must be acquired through the GIN injector:

// It is best to define your own injector, and make it a global static variable...
// (you need only one for your app)
WmsClientGinjector injector = GWT.create(WmsClientGinjector.class);

// Get the WMS Service:
WmsService wmsService = injector.getWmsService();

wmsService.getCapabilities("http://apps.geomajas.org/geoserver/wms", WmsVersion.v1_1_1,
        new Callback<WmsGetCapabilitiesInfo, String>() {

    public void onFailure(String reason) {
        Window.alert(reason);
    }

    public void onSuccess(WmsGetCapabilitiesInfo result) {
        // Get the list of layers:
        List<WmsLayerInfo> layers = result.getLayers(); // These are the WMS layer definitions...

        // Let's add the first layer to the map:
        WmsLayerInfo layerInfo = layers.get(0);

        WmsLayerConfiguration wmsConfig = new WmsLayerConfiguration();
        wmsConfig.setBaseUrl(urlBox.getValue());
        wmsConfig.setLayers(layerInfo.getName());

        Coordinate origin = new Coordinate(layerInfo.getBoundingBox().getX(), 
                layerInfo.getBoundingBox().getY());
        WmsTileConfiguration tileConfig = new WmsTileConfiguration(256, 256, origin);

        // Create a WMS layer and add it to the map:
        WmsLayer layer = injector.getWmsLayerFactory().createWmsLayer(layerInfo.getTitle(), 
                wmsConfig, tileConfig);
        mapPresenter.getLayersModel().addLayer(layer);

        // Make sure we enable animation for our newly add layer - it's just nicer:
        mapPresenter.getMapRenderer().setNrAnimatedLayers(mapPresenter.getLayersModel().
                getLayerCount());
    }
});

Often your WMS server will have a different domain than the application you're creating. In such cases the browser will not allow cross-domain requests, and as a result you will most likely use a proxy servlet that takes care of this problem. The trick is to have the WmsService make use of your proxy servlet.

For this purpose, the WmsService allows you to specify a WmsUrlTransformer object that will transform WMS request URLs to your liking. It can go as far as to specify different transformations for different types of WMS request. For example, you may want the GetCapabilities and GetFeatureInfo requests to make use of a proxy servlet, while your GetMap and GetLegendGraphic requests must remain untouched (GetMap and GetLegendGraphic are URLs point to images, where the cross-domain problem does not exist).

The following example will add a proxy servlet for the GetCapabilities and GetFeatureInfo requests, while the other WMS requests are left untouched:

wmsService.setWmsUrlTransformer(new WmsUrlTransformer() {

    public String transform(WmsRequest request, String url) {
        switch (request) {
            case GetCapabilities:
            case GetFeatureInfo:
                return "/proxy?url=" + url;
            default:
        }
        return url;
    }
});