Using SLD <Mark> to construct multi-character font symbols

Question

I've been trying to figure out different approaches to constructing circles with text inside of them in SLD/GeoServer. Single character font-based "external" symbols work fine, with the "text" part being e.g.:

<PointSymbolizer>
  <Graphic>
    <Mark>
      <WellKnownName>ttf://Arial#0x70</WellKnownName>
      <Fill>
        <CssParameter name="fill">#000000</CssParameter>
      </Fill>
    </Mark>
    <Size>7</Size>
  </Graphic>
</PointSymbolizer>

My question is, is it possible to combine several characters into one WellKnownName tag in the hex format? Haven't found anything at least in the SLD documentations / references. Or does one always have to generate several PointSymbolizer entities with single characters accompanied by some offset technique to generate multi-character text symbols? Looking for the cleanest, least-markup approach here.

For instance if I'd want a text "AA" inside a circle, the HEX code would be 4141, but so far it seems one can only single letters, e.g. ttf://Arial#0x41. At least ttf://Arial#0x4141 doesn't seem to work.

Of course one can create texts inside circles with TextSymbolizer but that runs into all kinds of label removal/placement issues.

Answer 1

Sadly TTFMarkFactory where the magic happens only handles a single TTF code at a time.

AFAIK the only way to do this is to implement a custom MarkFactory or an ExternalGraphicsFactory. There is a page of documentation here that should get you started.

Alternatively you could look at using SVG to define the marks you need.