Class: QgsPlotCanvas

Plot canvas is a class for displaying interactive 2d charts and plots.

Added in version 3.26.

Class Hierarchy

Base classes

QGraphicsView
QAbstractScrollArea
QFrame
QWidget
QObject
QPaintDevice

Subclasses

QgsElevationProfileCanvas

A canvas for elevation profiles.

Methods

setTool	Sets the interactive tool currently being used on the canvas.
tool	Returns the currently active tool.
unsetTool	Unset the current tool.

Virtual Methods

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

centerPlotOn	Centers the plot on the plot point corresponding to x, y in canvas units.
crs	Returns the coordinate reference system (CRS) for map coordinates used by the canvas.
panContentsBy	Pans the plot contents by dx, dy in canvas units.
refresh	Updates and redraws the plot.
scalePlot	Scales the plot by a specified scale factor.
snapToPlot	Snap a canvas point to the plot
toCanvasCoordinates	Converts a point in map coordinates to the associated canvas point.
toMapCoordinates	Converts a point on the canvas to the associated map coordinate.
wheelZoom	Zoom plot from a mouse wheel event.
zoomToRect	Zooms the plot to the specified rect in canvas units.

Signals

contextMenuAboutToShow	Emitted before the canvas context menu will be shown.
plotAreaChanged	Emitted whenever the visible area of the plot is changed.
toolChanged	Emitted when the plot tool is changed.
willBeDeleted	Emitted in the destructor when the canvas is about to be deleted, but is still in a perfectly valid state.

class qgis.gui.QgsPlotCanvas

Bases: QGraphicsView

__init__(parent: QWidget | None = None)

Constructor for QgsPlotCanvas, with the specified parent widget.

Parameters:

parent (Optional[QWidget] = None)

virtual centerPlotOn(self, x: float, y: float)

Centers the plot on the plot point corresponding to x, y in canvas units.

The default implementation does nothing.

Parameters:

• x (float)

• y (float)

signal contextMenuAboutToShow(menu: QMenu, event: QgsPlotMouseEvent)

Emitted before the canvas context menu will be shown. Can be used to extend the context menu.

Parameters:

• menu (QMenu)

• event (QgsPlotMouseEvent)

virtual crs(self) → QgsCoordinateReferenceSystem

Returns the coordinate reference system (CRS) for map coordinates used by the canvas.

May return an invalid CRS if no CRS is associated with the canvas.

Return type:

QgsCoordinateReferenceSystem

virtual panContentsBy(self, dx: float, dy: float)

Pans the plot contents by dx, dy in canvas units.

The default implementation does nothing.

Parameters:

• dx (float)

• dy (float)

signal plotAreaChanged

Emitted whenever the visible area of the plot is changed.

virtual refresh(self)

Updates and redraws the plot.

virtual scalePlot(self, factor: float)

Scales the plot by a specified scale factor.

The default implementation does nothing.

Parameters:

factor (float)

setTool(self, tool: QgsPlotTool | None)

Sets the interactive tool currently being used on the canvas.

Parameters:

tool (Optional[QgsPlotTool])

virtual snapToPlot(self, point: QPoint) → QgsPointXY

Snap a canvas point to the plot

Returns an empty point if snapping was not possible.

Parameters:

point (QPoint) – point in canvas coordinates

Return type:

QgsPointXY

virtual toCanvasCoordinates(self, point: QgsPoint) → QgsPointXY

Converts a point in map coordinates to the associated canvas point.

May return an empty point if the map point cannot be converted to a canvas point.

Parameters:

point (QgsPoint)

Return type:

QgsPointXY

virtual toMapCoordinates(self, point: QgsPointXY) → QgsPoint

Converts a point on the canvas to the associated map coordinate.

May return an empty point if the canvas point cannot be converted to a map point.

Parameters:

point (QgsPointXY)

Return type:

QgsPoint

tool(self) → QgsPlotTool | None

Returns the currently active tool.

Return type:

Optional[QgsPlotTool]

signal toolChanged(newTool: QgsPlotTool)

Emitted when the plot tool is changed.

Parameters:

newTool (QgsPlotTool)

unsetTool(self, tool: QgsPlotTool | None)

Unset the current tool.

This is called from destructor of plot tools to make sure that this map tool won’t be used any more.

You don’t have to call it manually, QgsPlotTool takes care of it.

Parameters:

tool (Optional[QgsPlotTool])

virtual wheelZoom(self, event: QWheelEvent | None)

Zoom plot from a mouse wheel event.

The default implementation does nothing.

Parameters:

event (Optional[QWheelEvent])

signal willBeDeleted

Emitted in the destructor when the canvas is about to be deleted, but is still in a perfectly valid state.

virtual zoomToRect(self, rect: QRectF)

Zooms the plot to the specified rect in canvas units.

The default implementation does nothing.

Parameters:

rect (QRectF)