Class: QgsLineSymbol

A line symbol type, for rendering LineString and MultiLineString geometries.

Class Hierarchy

Base classes

QgsSymbol

Abstract base class for all rendered symbols.

Methods

dataDefinedWidth	Returns data defined width for whole symbol (including all symbol layers).
renderPolyline	Renders the symbol along the line joining points, using the given render context.
setDataDefinedWidth	Set data defined width for whole symbol (including all symbol layers).
setWidth	Sets the width for the whole line symbol.
setWidthUnit	Sets the width units for the whole symbol (including all symbol layers).
width	Returns the estimated width for the whole symbol, which is the maximum width of all marker symbol layers in the symbol.

Static Methods

createSimple

Create a line symbol with one symbol layer: SimpleLine with specified properties.

class qgis.core.QgsLineSymbol

Bases: QgsSymbol

__init__(layers: Iterable[QgsSymbolLayer] = [])

Constructor for QgsLineSymbol, with the specified list of initial symbol layers.

Ownership of the layers are transferred to the symbol.

Parameters:

layers (Iterable[QgsSymbolLayer] = [])

static createSimple(properties: Dict[str, Any]) → QgsLineSymbol | None

Create a line symbol with one symbol layer: SimpleLine with specified properties. This is a convenience method for easier creation of line symbols.

Parameters:

properties (Dict[str, Any])

Return type:

Optional[QgsLineSymbol]

dataDefinedWidth(self) → QgsProperty

Returns data defined width for whole symbol (including all symbol layers).

Return type:

QgsProperty

Returns:

data defined width, or invalid property if size is not set at the line level. Caller takes responsibility for deleting the returned object.

See also

setDataDefinedWidth()

renderPolyline(self, points: QPolygonF, f: QgsFeature | None, context: QgsRenderContext, layer: int = -1, selected: bool = False)

Renders the symbol along the line joining points, using the given render context.

The f argument is used to pass the feature currently being rendered (when available).

If only a single symbol layer from the symbol should be rendered, it should be specified in the layer argument. A layer of -1 indicates that all symbol layers should be rendered.

If selected is True then the symbol will be drawn using the “selected feature” style and colors instead of the symbol’s normal style.

Parameters:

• points (QPolygonF)

• f (Optional[QgsFeature])

• context (QgsRenderContext)

• layer (int = -1)

• selected (bool = False)

setDataDefinedWidth(self, property: QgsProperty)

Set data defined width for whole symbol (including all symbol layers).

See also

dataDefinedWidth()

Parameters:

property (QgsProperty)

setWidth(self, width: float)

Sets the width for the whole line symbol. Individual symbol layer sizes will be scaled to maintain their current relative size to the whole symbol size.

See also

width()

Parameters:

width (float)

setWidthUnit(self, unit: Qgis.RenderUnit)

Sets the width units for the whole symbol (including all symbol layers).

Parameters:

unit (Qgis.RenderUnit) – size units

Added in version 3.16.

width(self) → float

Returns the estimated width for the whole symbol, which is the maximum width of all marker symbol layers in the symbol.

Warning

This returned value is inaccurate if the symbol consists of multiple symbol layers with different width units. Use the overload accepting a QgsRenderContext argument instead for accurate sizes in this case.

See also

setWidth()

Return type:

float

width(self, context: QgsRenderContext) → float

Returns the symbol width, in painter units. This is the maximum width of all marker symbol layers in the symbol.

This method returns an accurate width by calculating the actual rendered width of each symbol layer using the provided render context.

See also

setWidth()

Added in version 3.4.5.

Parameters:

context (QgsRenderContext)

Return type:

float