Package com.luciad.wms.server

Interface ILcdWMSGetLegendGraphicRequestEncoder

All Known Implementing Classes:
TLcdDefaultWMSGetLegendGraphicEncoder
public interface ILcdWMSGetLegendGraphicRequestEncoder
This interface specifies methods to encode the result of a GetLegendGraphic request.
The type of encoding is defined by the actual implementations.
Each ILcdWMSLegendGraphicRequestEncoder has a content type that identifies the type of data encoded by the implementation. This is the MIME - TYPE of the encoded result. Allowed values are the same as for the FORMAT parameter of the WMS GetMap request. This list contains a number of basic image formats like png and jpeg, but also non image formats like pdf and kml. The user can select any format from this list as long as the data written to the output stream complies with the expected MIME - TYPE, most clients however offer only support for image formats.
To plug in your own implementation you need to override ALcdOGCWMSCommandDispatcherFactory.createWMSGetLegendGraphicEncoders(ServletConfig) and add your encoder to the array that is returned.

  • Method Details

    • getContentType

      String getContentType()
      Returns the content MIME type of the encoder.
      Returns:
      the MIME-type as String.

    • encode

      boolean encode(TLcdWMSGetLegendGraphicRequestContext aWMSGetLegendGraphicRequestContext, TLcdWMSRequestContext aWMSRequestContext, OutputStream aOutputStream) throws IOException
      Encodes the legend graphic for a given layer and sends it to the given OutputStream.
      Parameters:
      aWMSGetLegendGraphicRequestContext - a container for all relevant information that might be useful when generating legends
      aWMSRequestContext - a container for the original request and other related request parameters.
      aOutputStream - the OutputStream to write the output to. The type of data is given by getContentType().
      Returns:
      True if the encoder can handle this case, false if it does not.
      Throws:
      IOException - for any I/O Exceptions.
      Since:
      2022.0

    • getLegendURL

      default TLcdWMSLegendURLParameters getLegendURL(ALcdWMSLayer aLayer, ALcdWMSLayerStyle aLayerStyle, TLcdWMSLegendURLParameters aDefaultLegendURL)
      Determines the online resource, width and height to advertise in the LegendURL for the given layer and style.

      aDefaultLegendURL holds the parameters that would otherwise be advertised: an online resource pointing to a GetLegendGraphic request on this encoder, and the default configured legend dimensions. Implementations can:

      • return aDefaultLegendURL unchanged, to keep that default behavior;
      • return a different TLcdWMSLegendURLParameters, to override the width, the height, the online resource, or all three — for example to advertise a static, externally-hosted legend image instead of a dynamically-generated one;
      • return null, to indicate this encoder has no opinion on this layer and style. If another encoder shares this encoder's content type, that encoder is consulted next; if none of them return a non-null result, no LegendURL is advertised for this content type, for this layer and style.
      Returning aDefaultLegendURL unchanged is not the same as returning null: the former confirms the default is correct for this layer and style and stops any further encoders sharing this content type from being consulted, while the latter defers that decision to them.

      By default, returns aDefaultLegendURL unchanged, which preserves the behavior prior to the introduction of this method.

      Parameters:
      aLayer - the layer for which a LegendURL is being advertised.
      aLayerStyle - the style for which a LegendURL is being advertised.
      aDefaultLegendURL - the parameters that would otherwise be advertised.
      Returns:
      the parameters to advertise, a modified copy of aDefaultLegendURL, or null.
      Since:
      2026.0.15