Class: QgsMapCanvasItem

An abstract class for items that can be placed on the map canvas.

Class Hierarchy

Base classes

QGraphicsItem

Subclasses

QgsAdvancedDigitizingCanvasItem	Draws the graphical elements of the CAD tools (QgsAdvancedDigitizingDockWidget) on the map canvas.
QgsGeometryRubberBand	A rubberband class for QgsAbstractGeometry (considering curved geometries).
QgsHighlight	Highlights features on the map.
QgsMapCanvasAnnotationItem	An interactive map canvas item which displays a QgsAnnotation.
QgsRubberBand	Responsible for drawing transient features (e.g. digitizing lines) on the map.
QgsSnapToGridCanvasItem	Shows a grid on the map canvas given a spatial resolution.
QgsVertexMarker	A map canvas item for marking vertices of features using e.g. circles or ‘x’.

Abstract Methods

paint

function to be implemented by derived classes

Methods

rect	returns canvas item rectangle in map units
setRect	sets canvas item rectangle in map units
setRenderContextVariables	Sets render context parameters
toCanvasCoordinates	transformation from map coordinates to screen coordinates
toMapCoordinates	transformation from screen coordinates to map coordinates
updateCanvas	schedules map canvas for repaint

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsMapCanvasItem. See the FAQ for more details.

updatePosition

called on changed extent or resize event to update position of the item

class qgis.gui.QgsMapCanvasItem

Bases: QGraphicsItem

__init__(mapCanvas: QgsMapCanvas | None)

protected constructor: cannot be constructed directly

Parameters:

mapCanvas (Optional[QgsMapCanvas])

abstract paint(self, painter: QPainter | None)

function to be implemented by derived classes

Parameters:

painter (Optional[QPainter])

abstract paint(self, painter: QPainter | None, option: QStyleOptionGraphicsItem | None, widget: QWidget | None = None)

Parameters:

• painter (Optional[QPainter])

• option (Optional[QStyleOptionGraphicsItem])

• widget (Optional[QWidget] = None)

rect(self) → QgsRectangle

returns canvas item rectangle in map units

Return type:

QgsRectangle

setRect(self, r: QgsRectangle, resetRotation: bool = True)

sets canvas item rectangle in map units

Parameters:

• r (QgsRectangle)

• resetRotation (bool = True)

setRenderContextVariables(self, p: QPainter | None, context: QgsRenderContext) → bool

Sets render context parameters

Parameters:

• p (Optional[QPainter]) – painter for rendering

• context (QgsRenderContext) – out: configured context

Return type:

bool

Returns:

True in case of success

toCanvasCoordinates(self, point: QgsPointXY) → QPointF

transformation from map coordinates to screen coordinates

Parameters:

point (QgsPointXY)

Return type:

QPointF

toMapCoordinates(self, point: QPoint) → QgsPointXY

transformation from screen coordinates to map coordinates

Parameters:

point (QPoint)

Return type:

QgsPointXY

updateCanvas(self)

schedules map canvas for repaint

virtual updatePosition(self)

called on changed extent or resize event to update position of the item