Style Specification Support

BasemapLayer implements a subset of the MapLibre Style Specification. This page lists the parts of the specification and what the module currently does with each. Properties that are not listed are not supported. Follow-up changes update the table as gaps close.

Status	Meaning
Supported	Implemented as the specification describes, apart from the notes.
Partial	Implemented with a documented approximation, or for some of the values.
Not supported	Ignored, so a style that uses it renders without it, unless a note says otherwise.

Layer types

See Layers. Layers of an unsupported type are skipped.

Layer type	Status	Notes
background	Partial	background-color and background-opacity. background-pattern is not drawn and, as in the specification, disables background-color, so a patterned background draws nothing.
fill	Partial	See Paint properties.
line	Partial	See Paint properties and Layout properties.
symbol	Partial	Text and icons at anchor points: one per point, line and polygon. See Symbols.
fill-extrusion	Partial	Patterns, translation and the style's light are not supported. See Paint properties.
raster	Partial	Inline tiles, or a TileJSON url. The style's own source properties take precedence over the TileJSON's, and only the TileJSON's tiles, minzoom, maxzoom, attribution, bounds, scheme, tileSize and encoding are used. scheme: "tms" and bounds are not applied. If the TileJSON cannot be fetched, is invalid or lists no tiles, a warning is logged and the source falls back to its own tiles; without them, its layers are skipped.
circle	Partial	Points and multipoints of vector sources; circles are not drawn at line and polygon vertices. On a globe, a circle near a tile edge can draw twice, once from each overlapping tile. See Paint properties and Layout properties.
heatmap	Not supported
hillshade	Not supported
color-relief	Not supported

Sources

See Sources.

Source type	Status	Notes
vector	Partial	Inline tiles, or a TileJSON url. The style's own source properties take precedence over the TileJSON's, and only the TileJSON's tiles, minzoom, maxzoom, attribution, bounds, scheme, tileSize and encoding are used. scheme: "tms" and bounds are not applied. If the TileJSON cannot be fetched, is invalid or lists no tiles, a warning is logged and the source falls back to its own tiles; without them, its layers are skipped.
raster	Partial	Inline tiles, or a TileJSON url. The style's own source properties take precedence over the TileJSON's, and only the TileJSON's tiles, minzoom, maxzoom, attribution, bounds, scheme, tileSize and encoding are used. scheme: "tms" and bounds are not applied. If the TileJSON cannot be fetched, is invalid or lists no tiles, a warning is logged and the source falls back to its own tiles; without them, its layers are skipped.
raster-dem	Not supported	Its url is not fetched, and its layers are skipped.
geojson	Not supported	Layers that use a GeoJSON source are skipped.
image	Not supported	Its url is not fetched, and its layers are skipped.
video	Not supported	Its url is not fetched, and its layers are skipped.

Expressions and filters

See Expressions.

Feature	Status	Notes
Constant and data-driven values	Supported	Evaluated with @maplibre/maplibre-gl-style-spec, per feature where the property allows it.
Zoom-dependent values	Partial	Evaluated at the zoom rounded down to a 0.25 step, not interpolated continuously.
feature-state	Not supported	Feature state is always empty.
filter	Supported	Evaluated per feature. ["zoom"] in a filter uses the integer zoom, as the specification says.
Legacy ref layers	Supported	Resolved when the style loads.

Layer visibility and zoom range

Feature	Status	Notes
minzoom / maxzoom	Supported	Compared with the exact zoom.
Overzoom past source maxzoom	Supported	The deepest tiles are scaled up; layers keep drawing.
layout.visibility	Supported	A layer with visibility: "none" is not drawn. To change it, pass a new style object, as for other style edits.

Paint properties

See Layers for the properties of each type.

Property	Status	Notes
fill-color, fill-opacity	Supported	Per feature. On a globe, fills are drawn opaque. A fill-pattern disables fill-color, as in the specification.
fill-outline-color	Partial	A 1 CSS pixel outline; MapLibre's is one device pixel. Not drawn when fill-antialias is false.
fill-pattern	Partial	Per feature, with fill-opacity (also on a globe). Switches at integer zooms without cross-fading. WebGPU draws none.
fill-translate, fill-translate-anchor	Partial	Moves the fill and its outline; on a globe, not its pattern. WebGL only; WebGPU draws fills untranslated.
line-color, line-opacity, line-width	Supported	Per feature.
line-dasharray	Partial	One dash and one gap per period; longer patterns merge their dashes. Switches at integer zooms instead of cross-fading.
line-offset, line-gap-width	Partial	Per feature. Sharp corners break open on the outside, and a gap's two lines end apart instead of capped together.
line-blur	Partial	Per feature, except with both line-dasharray and line-offset or line-gap-width, where a per-feature blur draws sharp. With a per-feature line-offset, where line-blur is more than half of line-gap-width the two lines of the gap overlap and draw their fades twice, darker than MapLibre. WebGL only; on WebGPU lines draw without blur, and the two lines of a gap line-blur pixels wider.
line-gradient, line-pattern, line-translate	Not supported
fill-extrusion-color, -height, -base	Supported	Per feature, heights in meters. The alpha of the color is ignored, as in MapLibre.
fill-extrusion-opacity	Partial	Applied to each surface, so walls behind a building can show through.
fill-extrusion-pattern, -translate, -vertical-gradient	Not supported	Extrusions use deck.gl's default lighting, not the style's light.
raster-opacity	Supported	While tiles load, a translucent layer can briefly show its lower-zoom placeholder tiles through the new ones.
raster-brightness-min, -max	Supported	MapLibre's formulas. WebGL only.
raster-saturation, -contrast, -hue-rotate	Supported	MapLibre's formulas. WebGL only.
raster-resampling, resampling	Supported	nearest magnifies with the nearest texel and minifies linearly, as in MapLibre.
raster-fade-duration	Not supported	Tiles appear without fading in.
circle-radius, circle-color, circle-opacity	Supported	Per feature.
circle-stroke-width, -color, -opacity	Supported	Per feature. The stroke is drawn outside circle-radius, as in MapLibre.
circle-blur	Partial	Per feature. WebGL only; WebGPU draws without blur. The edge between fill and stroke stays sharp.
circle-translate	Partial	circle-translate-anchor is not read: with viewport alignment the offset does not turn with the bearing.
circle-pitch-alignment	Partial	On a globe, circles always face the viewer.
circle-pitch-scale	Partial	Circles shrink with distance under pitch, as with map, the default; viewport is ignored.

Layout properties

Property	Status	Notes
line-cap, line-join	Partial	Per feature. deck.gl has no square cap or bevel join: square caps are drawn as butt, so a zero-length dash draws nothing where MapLibre draws a square, and bevel joins are cut flat half the line width from the vertex.
line-miter-limit	Partial	Per feature. A miter beyond the limit is cut flat at the limit rather than bevelled.
symbol-*, text-*, icon-*	See Symbols
circle-sort-key	Partial	Orders the circles within a tile. Tiles draw one after another, so circles in different tiles are not ordered by key.
Other properties	Not supported	For example line-sort-key, fill-sort-key, line-round-limit, text-radial-offset, text-writing-mode, symbol-avoid-edges, symbol-z-order, the *-translate and *-pitch-alignment properties, text-rotation-alignment for point placement and icon-halo-*.

Symbols

Feature	Status	Notes
symbol-placement: point	Partial	Points are labelled at the point, and each polygon at its pole of inaccessibility, as in MapLibre. Line features are labelled at the middle vertex of their first part. A polygon in two tiles' buffers is labelled by the tile that holds its pole. Polygon label search is bounded per tile; on a tile with unusually heavy polygon geometry, the remaining polygons are not labelled.
symbol-placement: line / line-center	Partial	Symbols are placed along line features as in MapLibre: line repeats them every symbol-spacing pixels, line-center places one at the middle of the line by length. With line, features with the same text whose ends meet are joined first, and a label within half a symbol-spacing of an earlier one with the same text on the tile is dropped. A placement is skipped where the symbol does not fit on the line or, for text, where the line bends more than text-max-angle under it. The symbol's length is the longer of its icon and its text, measured in the label font at the text-size of zoom 18 (estimated from the character count while the font loads). Text and icons with *-rotation-alignment: map (or auto) are turned to the line's direction and drawn flat on the map; text is kept upright (text-keep-upright), and icons add icon-rotate. With viewport they stay upright billboards. The text itself is straight: it does not curve with the line. Placement uses the tile's zoom, so symbols do not move while zooming within a tile. Placement work is bounded per tile; on a tile with unusually heavy line geometry, the remaining symbols are not placed. text-offset is not turned with the label; on a steep line, an offset larger than half the label's length can leave the label's collision box off its anchor, so the label stays hidden. Polygon features are not labelled.
text-field	Supported	Expressions and legacy {token} strings.
text-color, text-opacity	Supported	Per feature.
text-size	Supported	Per feature. A size of 0 hides the label.
text-offset, text-anchor	Supported	Per feature.
text-font	Partial	Mapped to a CSS font family list, weight and style; no glyphs are loaded. One font per style layer and zoom step. See Label fonts.
text-halo-color, text-halo-width	Partial	Per feature. Drawn around the glyphs, at most a quarter of the text size wide, as in MapLibre. Widths are rounded to 0.25 px. Each distinct halo in a tile is drawn by its own text sublayer, for at most 8 halos per tile and style layer: the most common ones. Labels with any other halo get the most common halo; labels without a halo never get one. The halo's outline width depends on the text size, so each data-driven text-size value also needs its own halo; past the cap, a label drawn with another size's halo is off by the ratio of the two text sizes. Where labels with different halos overlap, they stack by sublayer rather than in label order. Translucent text (a text-color alpha or text-opacity below 1, or a label fading in or out) is drawn twice inside the glyph, so a halo makes it more opaque: an alpha of 0.5 draws as 0.75. MapLibre draws the halo under the glyph instead. All labels, with or without a halo, use a signed distance field font atlas with an 18 px buffer around each 64 px glyph: the atlas holds about half as many glyphs as a plain one within the GPU's texture size limit (about 1,600 distinct ideographs per font at 16,384 px), and each glyph's collision footprint includes the buffer, about 0.28 em beyond the glyph.
text-halo-blur	Partial	Per feature, rounded to 0.25 px. As in MapLibre, the halo edge fades over 1.19 * blur px on each side. Each distinct blur in a tile needs its own halo, within the same cap of 8. The fade ends where the glyph distance field ends, about 0.28 of the text size past the glyph. WebGL only; WebGPU draws a sharp halo.
text-max-width	Supported	Per feature, for symbol-placement: point. Lines are balanced and broken at spaces, hyphens and between ideographs, as in MapLibre; a word longer than the width is not broken. Widths are measured with the browser font rather than MapLibre glyph metrics, so breaks can differ slightly. Labels over 256 characters, or past a per-tile work budget, are not wrapped.
text-line-height	Supported	One value per style layer and zoom step, as in the style spec.
text-transform	Supported	Per feature.
text-justify	Supported	Per feature. auto follows text-anchor. The default, center, centers the lines of a left- or right-anchored label within it, as in MapLibre. Labels along lines are centered.
text-letter-spacing	Supported	Per feature. Added after each character but the last of a line, so the label and its collision box widen; counted in text-max-width line breaking and in the length of labels along lines, as in MapLibre. Text in a cursive script, such as Arabic, is not spaced, as in MapLibre.
text-rotate, text-variable-anchor	Not supported
symbol-sort-key	Supported	Orders labels within a style layer. Later symbol layers in the style take priority over earlier ones. Without a sort key, labels are ranked by a built-in heuristic on OpenMapTiles fields (capital, class, water names), which MapLibre does not do.
Label collision	Partial	Labels are hidden where they collide, using deck.gl's CollisionFilterExtension, which tests an area around each label's anchor rather than its full box. Of two colliding labels with equal priority in one tile, the first one wins, as in MapLibre.
text-allow-overlap, text-ignore-placement, text-optional, text-overlap	Partial	A symbol's text and icon share one collision test at its anchor, so a part is shown without its optional partner only when that part allows overlap. text-overlap: cooperative is treated as never. A part that ignores placement, and each symbol of an icon-only layer, still mark a box of 4 pixels on each side of the anchor, whatever the text-offset, which can hide a lower-priority symbol anchored there; MapLibre blocks nothing in that case.
text-padding	Partial	At the stepped zoom. Widens each label's collision box by that many pixels on each side, so the label also hides the lower-priority symbols anchored within the padding. The collision test samples each symbol at its anchor, so only the padding of the symbol that hides counts; MapLibre keeps the two padded boxes apart. Between symbols of equal priority, the padding hides a label only where the label's own glyphs do not cover its anchor.
icon-image	Supported	Expressions and legacy {token} names, from the style's sprites.
icon-size, icon-opacity, icon-anchor, icon-offset	Supported	Per feature.
icon-color	Supported	For SDF images.
Icon collision	Partial	Icons collide with labels and with each other, and an icon and its text are placed or hidden as one unit, in the same anchor-based test as labels. The whole icon box collides. As in MapLibre, a symbol whose text is empty, or whose icon is empty or missing from the sprites, follows the placement rules of its one part.
icon-allow-overlap, icon-ignore-placement, icon-optional, icon-overlap	Partial	As for the text-* properties above.
icon-rotate	Supported	Per feature, clockwise; along lines, added to the line's direction. As in MapLibre, the icon turns about its anchor point, with its icon-anchor and icon-offset. The icon collides with its turned box, where MapLibre uses the axis-aligned box around it.
icon-rotation-alignment	Partial	map, or auto along lines: the icon is drawn flat on the map and turns with it, and along lines it is turned to the line's direction. viewport, or auto at points: the icon is a billboard, turned only by icon-rotate. icon-pitch-alignment is not read: an icon lies flat exactly when it turns with the map. On a globe, icons are always billboards, turned on screen.
icon-padding	Partial	Per feature, one to four values. Widens each icon's collision box, so the icon also hides the lower-priority symbols anchored within the padding; only the padding of the symbol that hides counts, as for text-padding. The boxes are scaled with one factor per sprite and style layer in a tile, set for the tile's median icon; other icons are padded in proportion to their size. Both axes grow by the larger of the horizontal and vertical padding, split evenly between the two sides.
icon-text-fit	Not supported

Style resources

Feature	Status	Notes
sprite	Supported	A single URL or the array form. @2x is requested first when the device pixel ratio is above 1, as in MapLibre. URLs may carry query strings.
glyphs	Not supported	Labels use browser fonts (see text-font).
light	Not supported
sky, terrain	Not supported
projection	Not supported	Use deck.gl's MapView or GlobeView, with the mode prop.

Rendering

Feature	Status	Notes
Draw order	Partial	Style layers draw in style order across sources and tiles, as in MapLibre: each layer draws in every tile before the next, so a tile's fills do not cover a neighbouring tile's labels. A vector source split by another source's layers draws as one tile layer per run, and the runs share one cache of decoded tiles per source. A flat layer after a fill-extrusion layer is hidden behind the buildings.
Globe view	Partial	mode: 'globe' draws on deck.gl's GlobeView, with an optional atmosphere (see the globe prop). Labels and icons whose anchor is beyond the globe's horizon are hidden, on WebGL only; they disappear at once, where MapLibre GL JS fades them out.