Dynamic layers in templates

Available since Maria GDK 3.1.+.

It is possible to dynamically build up templates using overlay-templates and corresponding tags. This is done by creating a (basemap) template containing references to (overlay) templates. (Overlay-templates use the same syntax as regular templates, but are NOT regarded as "normal" templates by Maria GDK). The purpose is to ease the process of replacing and adding maps to a basemap without continously having to update the template.xml.

First you need to add templatefilters (with tags for referencing) in overlay-templates.

<compositemaptemplate name="testOverlay" id="0CB9BB2B-3C4E-4922-889B-7442E683C2AB" type="overlay">
  <templatefilter tags="groundraster" pri="500"/> <!-- tag this overlay -->
  <layer type="OverlayLayer" name="OpenstreetMap">
    <opacity>1</opacity>
    <brightness>0</brightness>
    <gamma>1</gamma>
    <contrast>0</contrast>
    <grayscale>false</grayscale>
    <compression>Any</compression>
    <minscalevisible>100</minscalevisible>
    <maxscalevisible>128000000</maxscalevisible>
    <datasource>
      <mapsignature>wms</mapsignature>
      <maptype>WmsMap</maptype>
      <hostcategory>DontCare</hostcategory>
      <showlabels>false</showlabels>
      <usecache>false</usecache>
    </datasource>
    <visible>true</visible>
    <property key="serviceType" value="OpenstreetMap" />
    <property key="osMapStyle" value="Standard" />
  </layer>
  </compositemaptemplate>

Then add templatefilters in basemap-templates to reference maplayers or datasources in overlay-templates.

Either example 1:

<compositemaptemplate name="testTemplateRef" id="5497D2A9-25C6-429B-AA9A-0ADAB98721C0">
  <!-- reference all layers in overlays tagged with groundraster and seaoverlay-->
  <templatefilter refs="groundraster, seaoverlay"/> 
</compositemaptemplate>

or example 2 (only available since Maria GDK 3.1.1(?)):

<compositemaptemplate name="TestDatasourceRef" id="5497D2A9-25C6-429B-AA9A-0ADAB98721C0">
  <layer type="MapLayer" name="Groundrasters"> 
    <.../>
    <datasource>
      <!-- reference all overlays tagged with groundraster but include only datasource information -->
      <templatefilter refs="groundraster"/> 
    </datasource>
    <visible>true</visible> 
  </layer>
</compositemaptemplate>

When Maria GDK is loading the basemaptemplate - all available overlay-templates with a referenced tag will be included. Templatefilters located outside the layer-block(s) (example 1) will include all maplayers from the referenced overlays. Templatefilters located inside the datasource-block (example 2) will include only the datasouce-blocks (from the referenced overlays).

Overlay-templates will also provide a prioritynumber used for sorting the overlay-templates when including them in the basemap. Lower number equals higher priority. Default value is 100.

Map layers specified directly in the basemap-template will always be placed first in the completed maptemplate and thus drawn first (lowest priority layers). The ordering of map layers internally in an overlay-template will not be disturbed when included into a basemap via tag references.