Legend graphics¶

By default, QWC2 will obtain the legend graphics of a layer from QGIS Server.

Customizing the GetLegendGraphics request¶

You can customize the GetLegendGraphics request by specifying additional query parameters in via extraLegendParameters in the theme configuration block. The list of supported query parameters is documented in the QGIS Server documentation.

Providing custom legend images¶

You can provide custom legend images by enabling the qwc-legend-service.

Mount the legend folder into the qwc-legend-service container, i.e.:

  qwc-legend-service:
    image: sourcepole/qwc-feature-info-service:vYYYY.MM.DD
    volumes:
      ...
      - ./volumes/legends:/legends

Note: If mounting to another location than /legends, set the legend_images_path in the legend service configuration in tenantConfig.json:

{
  "name": "legend",
  "config": {
    "legend_images_path": "/<path>/"
  }
}

Then, legend images will be searched for in this order (the first one found is used):

• A <legend_images_path>/<service_name>/<layername><suffix>.png file, where
  • service_name is the name of the WMS service
  • layername is the WMS layer name
  • suffix: empty, or one of _thumbnail, _tooltip. The suffix is passed by QWC2 to the legend service depending on the requested image type.
• A <legend_images_path>/<legend_image> file with legend_image as specified for the desired layer in the legend service configuration, for example:

{
  "name": "legend",
  "config": ...,
  "resources": {
    "wms_services": [
      {
        "name": "<service name>",
        "root_layer": {
          "name": "<root_layer_name>",
          "layers": [
            {
              "name": "<layer_name>",
              "legend_image": "edit_points.png"
            }
          ]
        }
      }
    ]
  }
}

• A <legend_images_path>/default<suffix>.png file for a default legend image, with suffix as documented above.