MapTiler QGIS plugin - supported expressions

MapTiler plugin can convert any style.json containing GL JS style definition. However, the plugin does not support all of the style definition expressions. This article covers which expressions are supported and which are not.

Filter expression

Filter expression defines which features will be affected by a specific style layer definition.

Combining filters

all, any, none

Existential filters

has, !has

match, get

Set membership filters

in, !in

Comparison filters

!, ==, !=, >=, >, <=, <

Zoom function

zoom function changes a property of a style layer based on zoom level. Value must be literal values (i.e. not functions or expressions), and appropriate for the property. For example, stop output values for a fill-color function property must be colors.

{
  "base":1,
  "stops": [
    [zoom1, value1],
    [zoom2, value2],
    [zoom3, value3]
  ]
}

Interpolation

[
  "interpolate",
  [method]          // options: ["linear"], ["exponential", base]
  ["zoom"],
  zoom1, value1,
  zoom2, value2,
  zoom3, value3
]

[
"step",
input,          // e.g. ["get", "attribute"] or ["zoom"]
step_input_0, step_output_0,
stop_input_1, stop_output_1,
stop_input_n, stop_output_n,
...
]

"line-color": ["interpolate",
                ["linear"],
                ["zoom"],
                10, "rgba(138, 195, 229, 1)",
                16, [
                  "match",
                  ["get", "class"],
                  ["river","canal"],
                  "rgba(160, 205, 236, 1)",
                  "rgba(140, 185, 226, 1)"
                ]
              ]

Paint-properties

Fill

fill-color

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

fill-outline-color

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

fill-opacity

Can be defined as a static value, using zoom function or interpolation.

If opacity is already set in color as alpha channel, this property is skipped.

fill-translate

Can be defined as a static array or using zoom function.

fill-pattern

Can be defined as a string or using zoom function

Line

line-color

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

line-width

Can be defined as a static value, using zoom function or interpolation.

line-offset

Can be defined as a static value, using zoom function or interpolation.

line-opacity

Can be defined as a static value, using zoom function or interpolation.

line-dasharray

Can be defined as a static array or using zoom function.

line-cap

Can be round, square or flat (default).

line-join

Can be bevel, round or miter (default).

Labels

text-field

Can be defined as a static string, expression, list of expression or using zoom function.

text-size

Can be defined as a static value, using zoom function or interpolation.

text-max-width

Can be defined as a static value, using zoom function or interpolation.

text-letter-spacing

Can be defined as a static value, using zoom function or interpolation.

text-font

Can be defined as a static value (string), list of string or zoom function.

If font not found on your system, the plugin will try to use fallback fonts: Open Sans Regular, Arial Unicode MS

text-color

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

text-halo-color

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

text-halo-width

Can be defined as a static value (string, hsl, hsla, RGB, rgba), using zoom function or interpolation.

text-halo-blur

Must be defined as a static value.

text-transform

Must be uppercase or lowercase.

text-offset

Can be defined as a static array or using zoom function.

text-justify

Must be one of the following: left, right, follow, center (default).

text-anchor

Must be one of the following: center(default), left, right, top, bottom, top-left, top-right, bottom-left, bottom-right.

icon-image

Can be defined as a static string or using zoom function.

Background

background-color

Can be defined as a static value(string, hsl, hsla, RGB, rgba) or zoom function.

background-opacity

Can be defined as a static value or zoom function.

Useful links:

https://docs.mapbox.com/mapbox-gl-js/style-spec/expressions/

https://docs.mapbox.com/mapbox-gl-js/style-spec/layers/

https://www.maptiler.com/qgis-plugin/

https://www.youtube.com/watch?v=iqGVDLMz2u8