StyledWMSCoverageReader

/**
 * A grid coverage readers backing onto a WMS server by issuing GetMap
 * with a named style for layer
 */
public class StyledWMSCoverageReader extends WMSCoverageReader {

    /** The logger for the map module. */
    static public final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geotools.map");

    protected String styleName;
    /**
     * Builds a new WMS coverage reader
     *
     * @param wms
     * @param layer
     */
    public StyledWMSCoverageReader(WebMapServer wms, Layer layer, String stylename) {
        super(wms, layer);
        this.styleName = stylename;
    }

    /**
     * Sets up a max request with the provided parameters, making sure it is compatible with
     * the layers own native SRS list
     * @param bbox
     * @param width
     * @param height
     * @return
     * @throws IOException
     */
    @Override
    protected ReferencedEnvelope initMapRequest(ReferencedEnvelope bbox, int width, int height, Color backgroundColor)
            throws IOException {
        ReferencedEnvelope gridEnvelope = bbox;
        String requestSrs = srsName;
        try {
            // first see if we can cascade the request in its native SRS
            // we first look for an official epsg code
            String code = null;
            Integer epsgCode = CRS.lookupEpsgCode(bbox.getCoordinateReferenceSystem(), false);
            if(epsgCode != null) {
                code = "EPSG:" + epsgCode;
            } else {
                // otherwise let's make a fuller scan, but this method is more fragile...
                code = CRS.lookupIdentifier(bbox.getCoordinateReferenceSystem(), false);
            }

            if (code != null && validSRS.contains(code)) {
                requestSrs = code;
            } else {
                // first reproject to the map CRS
                gridEnvelope = bbox.transform(getCrs(), true);

                // then adjust the form factor
                if (gridEnvelope.getWidth() < gridEnvelope.getHeight()) {
                    height = (int) Math.round(width * gridEnvelope.getHeight()
                            / gridEnvelope.getWidth());
                } else {
                    width = (int) Math.round(height * gridEnvelope.getWidth()
                            / gridEnvelope.getHeight());
                }
            }
        } catch (Exception e) {
            throw (IOException) new IOException("Could not reproject the request envelope")
                    .initCause(e);
        }

        GetMapRequest mapRequest = wms.createGetMapRequest();
        // for some silly reason GetMapRequest will list the layers in the opposite order...
        List<Layer> reversed = new ArrayList<Layer>(layers);
        Collections.reverse(reversed);
        for (Layer layer : reversed) {
            mapRequest.addLayer(layer, styleName);
        }
        mapRequest.setDimensions(width, height);
        mapRequest.setFormat(format);
        if(backgroundColor == null) {
            mapRequest.setTransparent(true);
        } else {
            String rgba = Integer.toHexString(backgroundColor.getRGB());
            String rgb = rgba.substring(2, rgba.length());
            mapRequest.setBGColour("0x" + rgb.toUpperCase());
            mapRequest.setTransparent(backgroundColor.getAlpha() < 255);
        }

        try {
            this.requestCRS = CRS.decode(requestSrs);
        } catch(Exception e) {
            throw new IOException("Could not decode request SRS " + requestSrs);
        }

        ReferencedEnvelope requestEnvelope = gridEnvelope;
        mapRequest.setBBox(requestEnvelope);
        mapRequest.setSRS(requestSrs);

        this.mapRequest = mapRequest;
        this.requestedEnvelope = gridEnvelope;
        this.width = width;
        this.height = height;

        return gridEnvelope;
    }

}