Style support

mapterm reads MapLibre style documents. A terminal cell has a character, a foreground color and a background color, so only the properties that map onto those are used.

Layers and properties

Layer type	Paint	Layout
background	background-color, background-opacity	visibility
fill	fill-color, fill-opacity, fill-outline-color	visibility
line	line-color, line-opacity, line-width (1 to 3 dots thick), line-dasharray (dotted)	visibility
circle	circle-color, circle-opacity	visibility, mapterm:glyph
symbol	text-color, text-opacity, icon-color, icon-opacity	visibility, text-field, text-font (bold, italic), text-transform, text-anchor, text-variable-anchor, text-offset, symbol-placement, symbol-spacing, symbol-sort-key, icon-image (as a one-cell glyph), mapterm:glyph
raster	raster-opacity (blended with the background in cell-color mode)	visibility

Every layer also uses source, source-layer, filter, minzoom and maxzoom.

Skipped

• line-blur, line-gap-width and casings: a braille line is one to three dots wide, with no room for an outline. Widths and dash patterns are evaluated at the tile’s zoom.
• Sprite images (known icon-image names become one-cell symbols instead), patterns, and glyph fonts beyond bold and italic.
• fill-extrusion (3D), hillshade, heatmap, and terrain.
• Text halos, offsets and sizes.

Sources

Source type
vector	url (TileJSON or pmtiles://) or tiles templates; promoteId; attribution
geojson	Inline data, or data as a URL; cluster, clusterRadius, clusterMaxZoom; promoteId; attribution
raster	tiles templates, a TileJSON url, or pmtiles://

raster-dem, image and video sources are skipped with a warning. mapbox:// URLs need Mapbox’s API; use the https:// URL instead.

A source’s attribution (or its TileJSON or PMTiles metadata) is shown in the viewer’s status bar while its layers are drawn.

Expressions

See Expressions for the supported operators, including feature-state. An unsupported expression is an error for that one property: it falls back to the default, or for a filter the layer is hidden, and a warning is recorded (Map::warnings, or the MAPTERM_LOG file in the viewer).

The mapterm:glyph extension

The character drawn for a point: ● by default for circles. Symbols draw it before their text; without it, a known icon-image (hospital, airport, restaurant, bus stop, …) becomes a one-cell symbol, else they show only text. Any string expression works:

{ "id": "stops", "type": "circle", "source": "transit",
  "layout": { "mapterm:glyph": ["match", ["get", "mode"], "rail", "◆", "•"] } }