Supported Symbology¶

Bridge uses the bridge-style library to export QGIS simbology into other formats such as SLD (used when uploading to GeoServer), MapServer files, or MapboxGL.

Below you can find a list of supported elements that are know to be correctly converted from QGIS to SLD, along with additional information about limitations of the conversion between these two formats.

Common settings¶

This section describes general elements that are common to most types of layers and symbologies

Drawing order (symbol levels)¶

You can use symbol levels in QGIS to define the order used to render symbol layers, and they will be correctly converted to z-levels in SLD.

Size units¶

Size values can be used in milimeters, pixels, points, or real world meters. In this last case, expressions cannot be used, only fixed values.

Notice that it’s, however, a safer option to use pixels instead of milimeters (which are the default unit in QGIS), since pixels is the assumed unit for formats like SLD, and, therefore, no conversion is needed.

Expressions¶

Expressions are supported wherever QGIS allows to use data-defined values. They must be created using QGIS expression language (Python custom functions are not supported). Not all functions available in QGIS can be used, since there’s not an equivalent for all of them in GeoServer. The following is a list of the QGIS functions that can be used:

radians, degrees, floor, ceil, area, buffer, centroid,
if, bounds, distance, convex_hull, end_point, start_point,
x, y, concat, substr, lower, upper, replace, exterior_ring,
intersects, overlaps, touches, within, relates, crosses,
disjoint, geom_from_wkt, perimeter, union, acos, asin, atan,
atan2, sin, cos, tan, ln, title, translate, min, max

Certain parameters accept expressions, but those are not supported by Bridge when converting to SLD:

Colors
Parameters selected from drop down lists
Offset values
Expressions are not supported for size measurements, when those measures are not expressed in pixels or mm (that is, if you are using map units or real word meters for a size that changes with the current map scale)

Blending modes¶

Blending modes are supported at the layer level.

Vector Layers¶

The supported elements for styling vector layers are detailed in this section.

Supported renderers¶

The following renderers are supported for vector layers:

Single symbol

Categorized

Graduated

Heatmap
The following limitation must be considered:
- Radius must be expressed in pixels
- Expression are not supported for the weight parameter
Rule-based
- Nested rules are supported.
- ELSE rule is supported, but it might behave incorrectly in the SLD version if the layer has labeling, since QGIS consider labeling to be a separate part of the symbology, while SLD considers it as another symbolizer
- To know more about the supported expressiosn that can be used in rules filters, see the Expressions section

Supported symbology elements for points symbols¶

The following symbol layer types are supported for rendering points:

Simple marker
Below is a list of the parameters that are supported:
- Size
- Fill Color
- Stroke Color
- Stroke style
- Stroke width
- Join style
- Rotation
- Offset
SVG marker
Below is a list of the parameters that are supported:
- Size
- Fill Color
- Stroke Color
- Stroke width
- Rotation
- Offset
- SVG image
Raster image marker
Below is a list of the parameters that are supported:
- Size
- Rotation
- File
Font marker
Below is a list of the parameters that are supported:
- Size
- Fill Color
- Font
Geometry generator

Supported symbology elements for line symbols¶

The following symbol layer types are supported for rendering lines:

Simple line
Below is a list of the parameters that are supported:
- Color
- Stroke width
- Stroke style
- Join style
- Cap style
- Offset
Marker line:
Below is a list of the parameters that are supported:
- Marker placement: only with interval mode is supported
- Offset along line
As marker, you can use simple markers, SVG markers and raster image markers, with the restrictions mentioned in the corresponding section about supported symbology for point symbols.
Geometry generator

Supported symbology elements for polygon symbols¶

The following symbol layer types are supported for rendering polygons:

Simple fill
Below is a list of the parameters that are supported:
- Size
- Fill Color
- Fill style: only solid, no brush, horizontal, vertical, cross
- Stroke Color
- Stroke style
- Stroke width
- Join style
- Rotation
Point pattern fill
Below is a list of the parameters that are supported:
- Horizontal distance
- Vertical distance
As marker, you can use simple markers, SVG markers and raster image markers, with the restrictions mentioned in the corresponding section about supported symbology for point symbols.
Line pattern fill
Below is a list of the parameters that are supported:
- Rotation: Angle will be rounded to a multiple of 45 degrees
- Spacing
Outline: Simple line

See the section on supported symbology for simple lines
Outline: Marker line

See the section on supported symbology for marker lines
Geometry generator