SLD Generator Maven Plugin

About

Geoserver uses .sld files as stylesheets for the layers. These stylesheets specify which features are visible and with which style. These stylesheets are large .xml files, and their syntax is cumbersome.

This plugin generates these .sld files from a simple .sld.json definition. These definitions contain the rules that the .sld file should contain.

Usage

Install Maven Plugin

Add the following plugin and (adjusted) configuration to the pom.xml file.

<plugin>
  <groupId>nl.aerius</groupId>
  <artifactId>sld-generator-maven-plugin</artifactId>
  <version>{sld-generator.version}</version>
  <configuration>
    <sourcePath>src/main/sld-rivm</sourcePath>
    <targetPath>src/main/webapp/data/workspaces/calculator/styles</targetPath>
    <targetPostfix>_generated</targetPostfix>
  </configuration>
  <executions>
    <execution>
      <goals>
        <goal>generate-sld</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Configuration

key	description
sourcePath	path to the folder where .sld.json-files are located. The folder is searched recursively for these files.
targetPath	path to the folder where .sld files should be written to. Typical the styles-folder within the Geoserver workspace.
targetPostfix	Optional postfix which will be added to the .sld file names.

Example .sld.json file

{
  "zoomLevelsFile": "zoom_levels_default.json",
  "rules": [
    {
      "condition": "deposition > 1900 && deposition <= 2200",
      "fillColor": "CC4C02",
      "strokeColor": "FFFFFF"
    },
    {
      "condition": "deposition > 2200",
      "fillColor": "8C2D04",
      "strokeColor": "FFFFFF"
    }
  ]
}

key	description
zoomLevelsFile	refers to the zoom level definition file. The zoom level definition is separate because it can be shared between styles. If no zoom level file is defined, no filtering takes place on zoom level.
rules	array containing the rules

Rules

key	description
condition	contains the boolean condition to render this style to a feature
fillColor	color to fill the feature (hexadecimal)
strokeColor	color to outline the feature (hexadecimal)
imageUrl	url to an image to draw at the center of the feature. The url is relative to the final .sld file, can be a local file in geoserver, or an external image (specify full url)
customDrawSld	custom XML used in the draw part for this rule in the .sld file (for advanced options which can not be specified using above properties, specified as array)
customConditionSld	custom XML used in the condition part for this rule in the .sld file (for advanced options which can not be specified using above properties, specified as array)

Example zoom level definition

[
  {
    "zoomLevel": 1,
    "minScale": 0,
    "maxScale": 30000
  },
  {
    "zoomLevel": 2,
    "minScale": 30000,
    "maxScale": 60000
  },
  {
    "zoomLevel": 3,
    "minScale": 60000,
    "maxScale": 150000
  },
  {
    "zoomLevel": 4,
    "minScale": 150000,
    "maxScale": 300000
  },
  {
    "zoomLevel": 5,
    "minScale": 300000,
    "maxScale": 800000
  }
]

Above zoom level definition makes sure that features with zoom level 1 are only rendered below scale 30000, features with zoom level 2 are rendered between scale 30000 and 60000 and so on. These are currently the default zoom levels and their scales in AERIUS.

License

Copyright the State of the Netherlands

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see http://www.gnu.org/licenses/.