Map canvas is a class for displaying all GIS data types on a canvas. More...

#include <qgsmapcanvas.h>

Inheritance diagram for QgsMapCanvas:

[legend]

Classes
class	CanvasProperties
	Deprecated to be deleted, stuff from here should be moved elsewhere. More...

Public Slots
void	layerStateChange ()
	This slot is connected to the visibility change of one or more layers.

void	readProject (const QDomDocument &)
	called to read map canvas settings from project

void	redrawAllLayers ()
	Clears all cached images and redraws all layers.

void	refresh ()
	Repaints the canvas map.

void	refreshAllLayers ()
	Reload all layers (including refreshing layer properties from their data sources), clears the cache and refreshes the canvas.

void	saveAsImage (const QString &fileName, QPixmap *QPixmap=nullptr, const QString &="PNG")
	Save the contents of the map canvas to disk as an image.

void	selectionChangedSlot ()
	Receives signal about selection change, and pass it on with layer info.

void	setMagnificationFactor (double factor, const QgsPointXY *center=nullptr)
	Sets the factor of magnification to apply to the map canvas.

void	setRenderFlag (bool flag)
	Sets whether a user has disabled canvas renders via the GUI.

void	setScaleLocked (bool isLocked)
	Lock the scale, so zooming can be performed using magnication.

void	setZoomResolutions (const QList< double > &resolutions)
	Set a list of resolutions (map units per pixel) to which to "snap to" when zooming the map.

void	setZRange (const QgsDoubleRange &range)
	Sets the range of z-values which will be visible in the map.

void	stopRendering ()
	stop rendering (if there is any right now)

void	writeProject (QDomDocument &)
	called to write map canvas settings to project

void	zoomIn ()
	Zoom in with fixed factor.

double	zoomInFactor () const
	Returns the zoom in factor.

void	zoomOut ()
	Zoom out with fixed factor.

double	zoomOutFactor () const
	Returns the zoom in factor.

const QList< double > &	zoomResolutions () const

void	zoomToSelected (const QList< QgsMapLayer * > &layers)
	Zoom to the combined extent of the selected features of all provided (vector) layers.

void	zoomToSelected (QgsMapLayer *layer=nullptr)
	Zoom to the extent of the selected features of provided map layer.

QgsDoubleRange	zRange () const
	Returns the range of z-values which will be visible in the map.

Signals
void	canvasColorChanged ()
	Emitted when canvas background color changes.

void	contextMenuAboutToShow (QMenu menu, QgsMapMouseEvent event)
	Emitted before the map canvas context menu will be shown.

void	currentLayerChanged (QgsMapLayer *layer)
	Emitted when the current layer is changed.

void	destinationCrsChanged ()
	Emitted when map CRS has changed.

void	extentsChanged ()
	Emitted when the extents of the map change.

void	keyPressed (QKeyEvent *e)
	Emit key press event.

void	keyReleased (QKeyEvent *e)
	Emit key release event.

void	layersChanged ()
	Emitted when a new set of layers has been received.

void	layerStyleOverridesChanged ()
	Emitted when the configuration of overridden layer styles changes.

void	magnificationChanged (double magnification)
	Emitted when the scale of the map changes.

void	mapCanvasRefreshed ()
	Emitted when canvas finished a refresh request.

void	mapRefreshCanceled ()
	Emitted when the pending map refresh has been canceled.

void	mapToolSet (QgsMapTool newTool, QgsMapTool oldTool)
	Emit map tool changed with the old tool.

void	messageEmitted (const QString &title, const QString &message, Qgis::MessageLevel level=Qgis::MessageLevel::Info)
	emit a message (usually to be displayed in a message bar)

void	panDistanceBearingChanged (double distance, Qgis::DistanceUnit unit, double bearing)
	Emitted whenever the distance or bearing of an in-progress panning operation is changed.

void	renderComplete (QPainter *painter)
	Emitted when the canvas has rendered.

void	renderErrorOccurred (const QString &error, QgsMapLayer *layer)
	Emitted whenever an error is encountered during a map render operation.

void	renderStarting ()
	Emitted when the canvas is about to be rendered.

void	rotationChanged (double rotation)
	Emitted when the rotation of the map changes.

void	scaleChanged (double scale)
	Emitted when the scale of the map changes.

void	scaleLockChanged (bool locked)
	Emitted when the scale locked state of the map changes.

void	selectionChanged (QgsMapLayer *layer)
	Emitted when selection in any layer gets changed.

void	tapAndHoldGestureOccurred (const QgsPointXY &mapPoint, QTapAndHoldGesture *gesture)
	Emitted whenever a tap and hold gesture occurs at the specified map point.

void	temporalRangeChanged ()
	Emitted when the map canvas temporal range changes.

void	themeChanged (const QString &theme)
	Emitted when the canvas has been assigned a different map theme.

void	transformContextChanged ()
	Emitted when the canvas transform context is changed.

void	xyCoordinates (const QgsPointXY &p)
	Emits current mouse position.

void	zoomLastStatusChanged (bool available)
	Emitted when zoom last status changed.

void	zoomNextStatusChanged (bool available)
	Emitted when zoom next status changed.

void	zRangeChanged ()
	Emitted when the map canvas z (elevation) range changes.

Public Member Functions
	QgsMapCanvas (QWidget *parent=nullptr)
	Constructor.

	~QgsMapCanvas () override

void	addOverlayWidget (QWidget *widget, Qt::Edge edge)
	Adds an overlay widget to the layout, which will be bound to the specified edge.

bool	allowInteraction (QgsMapCanvasInteractionBlocker::Interaction interaction) const
	Returns `true` if the specified interaction is currently permitted on the canvas.

QList< QgsMapCanvasAnnotationItem * >	annotationItems () const
	Returns a list of all annotation items in the canvas.

bool	annotationsVisible () const
	Returns `true` if annotations are visible within the map canvas.

bool	antiAliasingEnabled () const
	`true` if antialiasing is enabled

QgsMapRendererCache *	cache ()
	Returns the map renderer cache, if caching is enabled.

void	cancelJobs ()
	Cancel any rendering job, in a blocking way.

QColor	canvasColor () const
	Read property of QColor bgColor.

QgsPointXY	center () const
	Gets map center, in geographical coordinates.

void	clearCache ()
	Make sure to remove any rendered images from cache (does nothing if cache is not enabled)

void	clearExtentHistory ()
	Clears the list of extents and sets current extent as first item.

QgsExpressionContext	createExpressionContext () const override
	This method needs to be reimplemented in all classes which implement this interface and return an expression context.

QgsMapLayer *	currentLayer ()
	returns current layer (set by legend widget)

QgsExpressionContextScope *	defaultExpressionContextScope () const
	Creates a new scope which contains default variables and functions relating to the map canvas.

void	enableAntiAliasing (bool flag)
	used to determine if anti-aliasing is enabled or not

void	enableMapTileRendering (bool flag)
	sets map tile rendering flag

QgsExpressionContextScope &	expressionContextScope ()
	Returns a reference to the expression context scope for the map canvas.

const QgsExpressionContextScope &	expressionContextScope () const
	Returns a const reference to the expression context scope for the map canvas.

QgsRectangle	extent () const
	Returns the current zoom extent of the map canvas.

Qgis::MapCanvasFlags	flags () const
	Returns flags which control how the map canvas behaves.

void	flashFeatureIds (QgsVectorLayer *layer, const QgsFeatureIds &ids, const QColor &startColor=QColor(255, 0, 0, 255), const QColor &endColor=QColor(255, 0, 0, 0), int flashes=3, int duration=500)
	Causes a set of features with matching ids from a vector layer to flash within the canvas.

void	flashGeometries (const QList< QgsGeometry > &geometries, const QgsCoordinateReferenceSystem &crs=QgsCoordinateReferenceSystem(), const QColor &startColor=QColor(255, 0, 0, 255), const QColor &endColor=QColor(255, 0, 0, 0), int flashes=3, int duration=500)
	Causes a set of geometries to flash within the canvas.

void	freeze (bool frozen=true)
	Freezes/thaws the map canvas.

QgsRectangle	fullExtent () const
	Returns the combined extent for all layers on the map canvas.

const QgsMapToPixel *	getCoordinateTransform ()
	Gets the current coordinate transform.

void	installInteractionBlocker (QgsMapCanvasInteractionBlocker *blocker)
	Installs an interaction blocker onto the canvas, which may prevent certain map canvas interactions from occurring.

bool	isCachingEnabled () const
	Check whether images of rendered layers are curerently being cached.

bool	isDrawing ()
	Find out whether rendering is in progress.

bool	isFrozen () const
	Returns `true` if canvas is frozen.

bool	isParallelRenderingEnabled () const
	Check whether the layers are rendered in parallel or sequentially.

const QgsLabelingEngineSettings &	labelingEngineSettings () const
	Returns global labeling engine settings from the internal map settings.

const QgsLabelingResults *	labelingResults (bool allowOutdatedResults=true) const
	Gets access to the labeling results (may be `nullptr`).

QgsMapLayer *	layer (const QString &id)
	Returns the map layer with the matching ID, or `nullptr` if no layers could be found.

QgsMapLayer *	layer (int index)
	Returns the map layer at position index in the layer stack.

int	layerCount () const
	Returns number of layers on the map.

template<typename T >
QVector< T >	layers () const
	Returns a list of registered map layers with a specified layer type.

QList< QgsMapLayer * >	layers (bool expandGroupLayers=false) const
	Returns the list of layers shown within the map canvas.

QMap< QString, QString >	layerStyleOverrides () const
	Returns the stored overrides of styles for layers.

double	magnificationFactor () const
	Returns the magnification factor.

QgsMapSettings &	mapSettings ()
	Returns a reference to the map settings used for map rendering.

const QgsMapSettings &	mapSettings () const
	Gets access to properties used for map rendering.

QgsMapTool *	mapTool () const
	Returns the currently active tool.

Qgis::DistanceUnit	mapUnits () const
	Convenience function for returning the current canvas map units.

double	mapUnitsPerPixel () const
	Returns the mapUnitsPerPixel (map units per pixel) for the canvas.

int	mapUpdateInterval () const
	Find out how often map preview should be updated while it is being rendered (in milliseconds)

QPoint	mouseLastXY ()
	returns last position of mouse cursor

void	panAction (QMouseEvent *event)
	Called when mouse is moving and pan is activated.

void	panActionEnd (QPoint releasePoint)
	Ends pan action and redraws the canvas.

void	panActionStart (QPoint releasePoint)
	Starts a pan action.

void	panToFeatureIds (QgsVectorLayer *layer, const QgsFeatureIds &ids, bool alwaysRecenter=true)
	Centers canvas extent to feature ids.

void	panToSelected (const QList< QgsMapLayer * > &layers)
	Pan to the combined extent of the selected features of all provided (vector) layers.

void	panToSelected (QgsMapLayer *layer=nullptr)
	Pan to the selected features of current ayer keeping same extent.

bool	previewJobsEnabled () const
	Returns `true` if canvas map preview jobs (low priority render jobs which render portions of the view just outside of the canvas extent, to allow preview of these out-of-canvas areas when panning or zooming out the map) are enabled for the canvas.

QgsPreviewEffect::PreviewMode	previewMode () const
	Returns the current preview mode for the map canvas.

bool	previewModeEnabled () const
	Returns whether a preview mode is enabled for the map canvas.

QgsProject *	project ()
	Returns the project linked to this canvas.

QgsRectangle	projectExtent () const
	Returns the associated project's full extent, in the canvas' CRS.

void	removeInteractionBlocker (QgsMapCanvasInteractionBlocker *blocker)
	Removes an interaction blocker from the canvas.

const QgsRenderedItemResults *	renderedItemResults (bool allowOutdatedResults=true) const
	Gets access to the rendered item results (may be `nullptr`), which includes the results of rendering annotation items in the canvas map.

bool	renderFlag () const
	Returns `true` if canvas render is disabled as a result of user disabling renders via the GUI.

double	rotation () const
	Gets the current map canvas rotation in clockwise degrees.

double	scale () const
	Returns the last reported scale of the canvas.

bool	scaleLocked () const
	Returns whether the scale is locked, so zooming can be performed using magnication.

QColor	selectionColor () const
	Returns color for selected features.

void	setAnnotationsVisible (bool visible)
	Sets whether annotations are visible in the canvas.

void	setCachingEnabled (bool enabled)
	Set whether to cache images of rendered layers.

void	setCanvasColor (const QColor &_newVal)
	Write property of QColor bgColor.

void	setCenter (const QgsPointXY &center)
	Set the center of the map canvas, in geographical coordinates.

void	setCurrentLayer (QgsMapLayer *layer)

void	setCustomDropHandlers (const QVector< QPointer< QgsCustomDropHandler > > &handlers)
	Sets a list of custom drop handlers to use when drop events occur on the canvas.

void	setDestinationCrs (const QgsCoordinateReferenceSystem &crs)
	Sets destination coordinate reference system.

void	setExpressionContextScope (const QgsExpressionContextScope &scope)
	Sets an expression context scope for the map canvas.

void	setExtent (const QgsRectangle &r, bool magnified=false)
	Sets the extent of the map canvas to the specified rectangle.

void	setFlags (Qgis::MapCanvasFlags flags)
	Sets flags which control how the map canvas behaves.

void	setLabelingEngineSettings (const QgsLabelingEngineSettings &settings)
	Sets global labeling engine settings in the internal map settings.

void	setLayers (const QList< QgsMapLayer * > &layers)
	Sets the list of layers that should be shown in the canvas.

void	setLayerStyleOverrides (const QMap< QString, QString > &overrides)
	Sets the stored overrides of styles for rendering layers.

void	setMapController (QgsAbstract2DMapController *controller)
	Sets the input controller device to use for controlling the canvas.

void	setMapSettingsFlags (Qgis::MapSettingsFlags flags)
	Resets the flags for the canvas' map settings.

void	setMapTool (QgsMapTool *mapTool, bool clean=false)
	Sets the map tool currently being used on the canvas.

void	setMapUpdateInterval (int timeMilliseconds)
	Set how often map preview should be updated while it is being rendered (in milliseconds)

void	setParallelRenderingEnabled (bool enabled)
	Set whether the layers are rendered in parallel or sequentially.

void	setPreviewJobsEnabled (bool enabled)
	Sets whether canvas map preview jobs (low priority render jobs which render portions of the view just outside of the canvas extent, to allow preview of these out-of-canvas areas when panning or zooming out the map) are enabled for the canvas.

void	setPreviewMode (QgsPreviewEffect::PreviewMode mode)
	Sets a preview mode for the map canvas.

void	setPreviewModeEnabled (bool previewEnabled)
	Enables a preview mode for the map canvas.

void	setProject (QgsProject *project)
	Sets the project linked to this canvas.

bool	setReferencedExtent (const QgsReferencedRectangle &extent)
	Sets the canvas to the specified extent.

void	setRotation (double degrees)
	Set the rotation of the map canvas in clockwise degrees.

void	setSegmentationTolerance (double tolerance)
	Sets the segmentation tolerance applied when rendering curved geometries.

void	setSegmentationToleranceType (QgsAbstractGeometry::SegmentationToleranceType type)
	Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)

void	setSelectionColor (const QColor &color)
	Set color of selected vector features.

void	setSnappingUtils (QgsSnappingUtils *utils)
	Assign an instance of snapping utils to the map canvas.

void	setTemporalController (QgsTemporalController *controller)
	Sets the temporal controller for this canvas.

void	setTemporalRange (const QgsDateTimeRange &range)
	Set datetime range for the map canvas.

void	setTheme (const QString &theme)
	Sets a map theme to show in the canvas.

void	setWheelFactor (double factor)
	Sets wheel zoom factor (should be greater than 1)

QgsSnappingUtils *	snappingUtils () const
	Returns snapping utility class that is associated with map canvas.

const QgsTemporalController *	temporalController () const
	Gets access to the temporal controller that will be used to update the canvas temporal range.

const QgsDateTimeRange &	temporalRange () const
	Returns map canvas datetime range.

QString	theme () const
	Returns the map's theme shown in the canvas, if set.

void	unsetMapTool (QgsMapTool *mapTool)
	Unset the current map tool or last non zoom tool.

void	updateScale ()
	Emits signal scaleChanged to update scale in main window.

void	waitWhileRendering ()
	Blocks until the rendering job has finished.

void	zoomByFactor (double scaleFactor, const QgsPointXY *center=nullptr, bool ignoreScaleLock=false)
	Zoom with the factor supplied.

void	zoomScale (double scale, bool ignoreScaleLock=false)
	Zooms the canvas to a specific scale.

void	zoomToFeatureExtent (QgsRectangle &rect)
	Zooms to feature extent.

void	zoomToFeatureIds (QgsVectorLayer *layer, const QgsFeatureIds &ids)
	Set canvas extent to the bounding box of a set of features.

void	zoomToFullExtent ()
	Zoom to the full extent of all layers currently visible in the canvas.

void	zoomToNextExtent ()
	Zoom to the next extent (view)

void	zoomToPreviousExtent ()
	Zoom to the previous extent (view)

void	zoomToProjectExtent ()
	Zoom to the full extent the project associated with this canvas.

void	zoomWithCenter (int x, int y, bool zoomIn)
	Zooms in/out with a given center.

Public Member Functions inherited from QgsExpressionContextGenerator
virtual	~QgsExpressionContextGenerator ()=default

Protected Slots
void	updateCanvasItemPositions ()
	called on resize or changed extent to notify canvas items to change their rectangle

Protected Member Functions
void	dragEnterEvent (QDragEnterEvent *e) override

void	dropEvent (QDropEvent *event) override

void	emitExtentsChanged ()
	Emits the extentsChanged signal when appropriate.

bool	event (QEvent *e) override

void	keyPressEvent (QKeyEvent *e) override

void	keyReleaseEvent (QKeyEvent *e) override

void	mouseDoubleClickEvent (QMouseEvent *e) override

void	mouseMoveEvent (QMouseEvent *e) override

void	mousePressEvent (QMouseEvent *e) override

void	mouseReleaseEvent (QMouseEvent *e) override

void	moveCanvasContents (bool reset=false)
	called when panning is in action, reset indicates end of panning

void	paintEvent (QPaintEvent *e) override

void	resizeEvent (QResizeEvent *e) override

void	showEvent (QShowEvent *event) override

bool	viewportEvent (QEvent *event) override

void	wheelEvent (QWheelEvent *e) override

Protected Attributes
std::unique_ptr< CanvasProperties >	mCanvasProperties
	Handle pattern for implementation object.

Properties
bool	previewJobsEnabled

QString	theme

Friends
class	TestQgsMapCanvas

Detailed Description

Map canvas is a class for displaying all GIS data types on a canvas.

Definition at line 92 of file qgsmapcanvas.h.

Constructor & Destructor Documentation

◆ QgsMapCanvas()

QgsMapCanvas::QgsMapCanvas ( QWidget * parent = nullptr )

Constructor.

Definition at line 129 of file qgsmapcanvas.cpp.

◆ ~QgsMapCanvas()

QgsMapCanvas::~QgsMapCanvas ( )

override

Definition at line 258 of file qgsmapcanvas.cpp.

Member Function Documentation

◆ addOverlayWidget()

void QgsMapCanvas::addOverlayWidget	(	QWidget *	widget,
		Qt::Edge	edge
	)

Adds an overlay widget to the layout, which will be bound to the specified edge.

The widget will always float above the map canvas.

Note: Widgets on the left and right edges will always be positioned first, with top and bottom edge widgets expanding to take the remaining horizontal space.

Since: QGIS 3.38

Definition at line 289 of file qgsmapcanvas.cpp.

◆ allowInteraction()

bool QgsMapCanvas::allowInteraction ( QgsMapCanvasInteractionBlocker::Interaction interaction ) const

Returns true if the specified interaction is currently permitted on the canvas.

Since: QGIS 3.14

Definition at line 1399 of file qgsmapcanvas.cpp.

◆ annotationItems()

QList< QgsMapCanvasAnnotationItem * > QgsMapCanvas::annotationItems ( ) const

Returns a list of all annotation items in the canvas.

Definition at line 3507 of file qgsmapcanvas.cpp.

◆ annotationsVisible()

bool QgsMapCanvas::annotationsVisible ( ) const

inline

Returns true if annotations are visible within the map canvas.

See also: setAnnotationsVisible()

Definition at line 808 of file qgsmapcanvas.h.

◆ antiAliasingEnabled()

bool QgsMapCanvas::antiAliasingEnabled ( ) const

true if antialiasing is enabled

Definition at line 343 of file qgsmapcanvas.cpp.

◆ cache()

QgsMapRendererCache * QgsMapCanvas::cache ( )

Returns the map renderer cache, if caching is enabled.

See also: isCachingEnabled(); setCachingEnabled()

Since: QGIS 3.32

Definition at line 680 of file qgsmapcanvas.cpp.

◆ cancelJobs()

void QgsMapCanvas::cancelJobs ( )

Cancel any rendering job, in a blocking way.

Used for application closing.

Note: not available in Python bindings

Definition at line 294 of file qgsmapcanvas.cpp.

◆ canvasColor()

QColor QgsMapCanvas::canvasColor ( ) const

Read property of QColor bgColor.

Definition at line 2885 of file qgsmapcanvas.cpp.

◆ canvasColorChanged

void QgsMapCanvas::canvasColorChanged ( )

signal

Emitted when canvas background color changes.

◆ center()

QgsPointXY QgsMapCanvas::center ( ) const

Gets map center, in geographical coordinates.

Definition at line 1651 of file qgsmapcanvas.cpp.

◆ clearCache()

void QgsMapCanvas::clearCache ( )

Make sure to remove any rendered images from cache (does nothing if cache is not enabled)

Definition at line 669 of file qgsmapcanvas.cpp.

◆ clearExtentHistory()

void QgsMapCanvas::clearExtentHistory ( )

Clears the list of extents and sets current extent as first item.

Definition at line 1743 of file qgsmapcanvas.cpp.

◆ contextMenuAboutToShow

void QgsMapCanvas::contextMenuAboutToShow	(	QMenu *	menu,
		QgsMapMouseEvent *	event
	)

signal

Emitted before the map canvas context menu will be shown.

Can be used to extend the context menu.

Since: QGIS 3.16

◆ createExpressionContext()

QgsExpressionContext QgsMapCanvas::createExpressionContext ( ) const

overridevirtual

This method needs to be reimplemented in all classes which implement this interface and return an expression context.

Implements QgsExpressionContextGenerator.

Definition at line 718 of file qgsmapcanvas.cpp.

◆ currentLayer()

QgsMapLayer * QgsMapCanvas::currentLayer ( )

returns current layer (set by legend widget)

Definition at line 706 of file qgsmapcanvas.cpp.

◆ currentLayerChanged

void QgsMapCanvas::currentLayerChanged ( QgsMapLayer * layer )

signal

Emitted when the current layer is changed.

◆ defaultExpressionContextScope()

QgsExpressionContextScope * QgsMapCanvas::defaultExpressionContextScope ( ) const

Creates a new scope which contains default variables and functions relating to the map canvas.

See also: expressionContextScope(); setExpressionContextScope()

Since: QGIS 3.4

Definition at line 711 of file qgsmapcanvas.cpp.

◆ destinationCrsChanged

void QgsMapCanvas::destinationCrsChanged ( )

signal

Emitted when map CRS has changed.

◆ dragEnterEvent()

void QgsMapCanvas::dragEnterEvent ( QDragEnterEvent * e )

overrideprotected

Definition at line 3392 of file qgsmapcanvas.cpp.

◆ dropEvent()

void QgsMapCanvas::dropEvent ( QDropEvent * event )

overrideprotected

Definition at line 3155 of file qgsmapcanvas.cpp.

◆ emitExtentsChanged()

void QgsMapCanvas::emitExtentsChanged ( )

protected

Emits the extentsChanged signal when appropriate.

Since: QGIS 3.30

Definition at line 3195 of file qgsmapcanvas.cpp.

◆ enableAntiAliasing()

void QgsMapCanvas::enableAntiAliasing ( bool flag )

used to determine if anti-aliasing is enabled or not

Definition at line 337 of file qgsmapcanvas.cpp.

◆ enableMapTileRendering()

void QgsMapCanvas::enableMapTileRendering ( bool flag )

sets map tile rendering flag

Definition at line 348 of file qgsmapcanvas.cpp.

◆ event()

bool QgsMapCanvas::event ( QEvent * e )

overrideprotected

Definition at line 3445 of file qgsmapcanvas.cpp.

◆ expressionContextScope() [1/2]

QgsExpressionContextScope & QgsMapCanvas::expressionContextScope ( )

inline

Returns a reference to the expression context scope for the map canvas.

This scope is injected into the expression context used for rendering the map, and can be used to apply specific variable overrides for expression evaluation for the map canvas render.

See also: setExpressionContextScope(); defaultExpressionContextScope()

Definition at line 767 of file qgsmapcanvas.h.

◆ expressionContextScope() [2/2]

const QgsExpressionContextScope & QgsMapCanvas::expressionContextScope ( ) const

inline

Returns a const reference to the expression context scope for the map canvas.

See also: setExpressionContextScope(); defaultExpressionContextScope()

Note: not available in Python bindings

Definition at line 775 of file qgsmapcanvas.h.

◆ extent()

QgsRectangle QgsMapCanvas::extent ( ) const

Returns the current zoom extent of the map canvas.

Definition at line 1520 of file qgsmapcanvas.cpp.

◆ extentsChanged

void QgsMapCanvas::extentsChanged ( )

signal

Emitted when the extents of the map change.

◆ flags()

Qgis::MapCanvasFlags QgsMapCanvas::flags ( ) const

Returns flags which control how the map canvas behaves.

See also: setFlags()

Since: QGIS 3.40

Definition at line 417 of file qgsmapcanvas.cpp.

◆ flashFeatureIds()

void QgsMapCanvas::flashFeatureIds	(	QgsVectorLayer *	layer,
		const QgsFeatureIds &	ids,
		const QColor &	startColor = `QColor( 255, 0, 0, 255 )`,
		const QColor &	endColor = `QColor( 255, 0, 0, 0 )`,
		int	flashes = `3`,
		int	duration = `500`
	)

Causes a set of features with matching ids from a vector layer to flash within the canvas.

The startColor and endColor can be specified, along with the number of flashes and duration of each flash (in milliseconds).

Note: If the features or geometries are already available, flashGeometries() is much more efficient.

See also: flashGeometries()

Definition at line 2204 of file qgsmapcanvas.cpp.

◆ flashGeometries()

void QgsMapCanvas::flashGeometries	(	const QList< QgsGeometry > &	geometries,
		const QgsCoordinateReferenceSystem &	crs = `QgsCoordinateReferenceSystem()`,
		const QColor &	startColor = `QColor( 255, 0, 0, 255 )`,
		const QColor &	endColor = `QColor( 255, 0, 0, 0 )`,
		int	flashes = `3`,
		int	duration = `500`
	)

Causes a set of geometries to flash within the canvas.

If crs is a valid coordinate reference system, the geometries will be automatically transformed from this CRS to the canvas CRS.

The startColor and endColor can be specified, along with the number of flashes and duration of each flash (in milliseconds).

See also: flashFeatureIds()

Definition at line 2227 of file qgsmapcanvas.cpp.

◆ freeze()

void QgsMapCanvas::freeze ( bool frozen = true )

Freezes/thaws the map canvas.

This is used to prevent the canvas from responding to events while layers are being added/removed etc.

Parameters

frozen Boolean specifying if the canvas should be frozen (true) or thawed (false). Default is true.

See also: isFrozen(); setRenderFlag()

Note: freeze() should be used to programmatically halt map updates, while setRenderFlag() should only be used when users disable rendering via GUI.

Definition at line 2940 of file qgsmapcanvas.cpp.

◆ fullExtent()

QgsRectangle QgsMapCanvas::fullExtent ( ) const

Returns the combined extent for all layers on the map canvas.

This method returns the combined extent for all layers which are currently visible in the map canvas. The returned extent will be in the same CRS as the map canvas.

See also: projectExtent()

Definition at line 1525 of file qgsmapcanvas.cpp.

◆ getCoordinateTransform()

const QgsMapToPixel * QgsMapCanvas::getCoordinateTransform ( )

Gets the current coordinate transform.

Definition at line 398 of file qgsmapcanvas.cpp.

◆ installInteractionBlocker()

void QgsMapCanvas::installInteractionBlocker ( QgsMapCanvasInteractionBlocker * blocker )

Installs an interaction blocker onto the canvas, which may prevent certain map canvas interactions from occurring.

The caller retains ownership of blocker, and must correctly call removeInteractionBlocker() before deleting the object.

See also: allowInteraction(); removeInteractionBlocker()

Since: QGIS 3.14

Definition at line 1389 of file qgsmapcanvas.cpp.

◆ isCachingEnabled()

bool QgsMapCanvas::isCachingEnabled ( ) const

Check whether images of rendered layers are curerently being cached.

See also: setCachingEnabled(); cache()

Definition at line 664 of file qgsmapcanvas.cpp.

◆ isDrawing()

bool QgsMapCanvas::isDrawing ( )

Find out whether rendering is in progress.

Definition at line 391 of file qgsmapcanvas.cpp.

◆ isFrozen()

bool QgsMapCanvas::isFrozen ( ) const

Returns true if canvas is frozen.

See also: freeze(); renderFlag()

Note: isFrozen() should be used to determine whether map updates have been halted programmatically, while renderFlag() should be used to determine whether a user has disabled rendering via GUI.

Definition at line 2945 of file qgsmapcanvas.cpp.

◆ isParallelRenderingEnabled()

bool QgsMapCanvas::isParallelRenderingEnabled ( ) const

Check whether the layers are rendered in parallel or sequentially.

Definition at line 690 of file qgsmapcanvas.cpp.

◆ keyPressed

void QgsMapCanvas::keyPressed ( QKeyEvent * e )

signal

Emit key press event.

◆ keyPressEvent()

void QgsMapCanvas::keyPressEvent ( QKeyEvent * e )

overrideprotected

Definition at line 2306 of file qgsmapcanvas.cpp.

◆ keyReleased

void QgsMapCanvas::keyReleased ( QKeyEvent * e )

signal

Emit key release event.

◆ keyReleaseEvent()

void QgsMapCanvas::keyReleaseEvent ( QKeyEvent * e )

overrideprotected

Definition at line 2406 of file qgsmapcanvas.cpp.

◆ labelingEngineSettings()

const QgsLabelingEngineSettings & QgsMapCanvas::labelingEngineSettings ( ) const

Returns global labeling engine settings from the internal map settings.

Definition at line 3538 of file qgsmapcanvas.cpp.

◆ labelingResults()

const QgsLabelingResults * QgsMapCanvas::labelingResults ( bool allowOutdatedResults = true ) const

Gets access to the labeling results (may be nullptr).

Since QGIS 3.20, if the allowOutdatedResults flag is false then outdated labeling results (e.g. as a result of an ongoing canvas render) will not be returned, and instead nullptr will be returned.

Definition at line 625 of file qgsmapcanvas.cpp.

◆ layer() [1/2]

QgsMapLayer * QgsMapCanvas::layer ( const QString & id )

Returns the map layer with the matching ID, or nullptr if no layers could be found.

This method searches both layers associated with the map canvas (see layers()) and layers from the QgsProject associated with the canvas (which is current the QgsProject::instance()). It can be used to resolve layer IDs to layers which may be visible in the canvas, but not associated with a QgsProject.

Since: QGIS 3.22

Definition at line 362 of file qgsmapcanvas.cpp.

◆ layer() [2/2]

QgsMapLayer * QgsMapCanvas::layer ( int index )

Returns the map layer at position index in the layer stack.

Definition at line 353 of file qgsmapcanvas.cpp.

◆ layerCount()

int QgsMapCanvas::layerCount ( ) const

Returns number of layers on the map.

Definition at line 2924 of file qgsmapcanvas.cpp.

◆ layers() [1/2]

template<typename T >

QVector< T > QgsMapCanvas::layers ( ) const

inline

Returns a list of registered map layers with a specified layer type.

Note: not available in Python bindings

Since: QGIS 3.40

Definition at line 534 of file qgsmapcanvas.h.

◆ layers() [2/2]

QList< QgsMapLayer * > QgsMapCanvas::layers ( bool expandGroupLayers = false ) const

Returns the list of layers shown within the map canvas.

Since QGIS 3.24, if the expandGroupLayers option is true then group layers will be converted to all their child layers.

See also: setLayers()

Definition at line 2929 of file qgsmapcanvas.cpp.

◆ layersChanged

void QgsMapCanvas::layersChanged ( )

signal

Emitted when a new set of layers has been received.

◆ layerStateChange

void QgsMapCanvas::layerStateChange ( )

slot

This slot is connected to the visibility change of one or more layers.

Definition at line 2934 of file qgsmapcanvas.cpp.

◆ layerStyleOverrides()

QMap< QString, QString > QgsMapCanvas::layerStyleOverrides ( ) const

Returns the stored overrides of styles for layers.

See also: setLayerStyleOverrides().

Definition at line 2960 of file qgsmapcanvas.cpp.

◆ layerStyleOverridesChanged

void QgsMapCanvas::layerStyleOverridesChanged ( )

signal

Emitted when the configuration of overridden layer styles changes.

◆ magnificationChanged

void QgsMapCanvas::magnificationChanged ( double magnification )

signal

Emitted when the scale of the map changes.

◆ magnificationFactor()

double QgsMapCanvas::magnificationFactor ( ) const

Returns the magnification factor.

Definition at line 332 of file qgsmapcanvas.cpp.

◆ mapCanvasRefreshed

void QgsMapCanvas::mapCanvasRefreshed ( )

signal

Emitted when canvas finished a refresh request.

◆ mapRefreshCanceled

void QgsMapCanvas::mapRefreshCanceled ( )

signal

Emitted when the pending map refresh has been canceled.

Since: QGIS 3.18

◆ mapSettings() [1/2]

QgsMapSettings & QgsMapCanvas::mapSettings ( )

Returns a reference to the map settings used for map rendering.

Note: Not available in Python bindings.

Since: QGIS 3.34

Definition at line 512 of file qgsmapcanvas.cpp.

◆ mapSettings() [2/2]

const QgsMapSettings & QgsMapCanvas::mapSettings ( ) const

Gets access to properties used for map rendering.

Definition at line 507 of file qgsmapcanvas.cpp.

◆ mapTool()

QgsMapTool * QgsMapCanvas::mapTool ( ) const

Returns the currently active tool.

Definition at line 3091 of file qgsmapcanvas.cpp.

◆ mapToolSet

void QgsMapCanvas::mapToolSet	(	QgsMapTool *	newTool,
		QgsMapTool *	oldTool
	)

signal

Emit map tool changed with the old tool.

◆ mapUnits()

Qgis::DistanceUnit QgsMapCanvas::mapUnits ( ) const

Convenience function for returning the current canvas map units.

The map units are dictated by the canvas' destinationCrs() map units.

Definition at line 2955 of file qgsmapcanvas.cpp.

◆ mapUnitsPerPixel()

double QgsMapCanvas::mapUnitsPerPixel ( ) const

Returns the mapUnitsPerPixel (map units per pixel) for the canvas.

Definition at line 2950 of file qgsmapcanvas.cpp.

◆ mapUpdateInterval()

int QgsMapCanvas::mapUpdateInterval ( ) const

Find out how often map preview should be updated while it is being rendered (in milliseconds)

Definition at line 700 of file qgsmapcanvas.cpp.

◆ messageEmitted

void QgsMapCanvas::messageEmitted	(	const QString &	title,
		const QString &	message,
		Qgis::MessageLevel	level = `Qgis::MessageLevel::Info`
	)

signal

emit a message (usually to be displayed in a message bar)

◆ mouseDoubleClickEvent()

void QgsMapCanvas::mouseDoubleClickEvent ( QMouseEvent * e )

overrideprotected

Definition at line 2438 of file qgsmapcanvas.cpp.

◆ mouseLastXY()

QPoint QgsMapCanvas::mouseLastXY ( )

returns last position of mouse cursor

Definition at line 3201 of file qgsmapcanvas.cpp.

◆ mouseMoveEvent()

void QgsMapCanvas::mouseMoveEvent ( QMouseEvent * e )

overrideprotected

Definition at line 2771 of file qgsmapcanvas.cpp.

◆ mousePressEvent()

void QgsMapCanvas::mousePressEvent ( QMouseEvent * e )

overrideprotected

Definition at line 2521 of file qgsmapcanvas.cpp.

◆ mouseReleaseEvent()

void QgsMapCanvas::mouseReleaseEvent ( QMouseEvent * e )

overrideprotected

Definition at line 2574 of file qgsmapcanvas.cpp.

◆ moveCanvasContents()

void QgsMapCanvas::moveCanvasContents ( bool reset = false )

protected

called when panning is in action, reset indicates end of panning

Definition at line 3146 of file qgsmapcanvas.cpp.

◆ paintEvent()

void QgsMapCanvas::paintEvent ( QPaintEvent * e )

overrideprotected

Definition at line 2651 of file qgsmapcanvas.cpp.

◆ panAction()

void QgsMapCanvas::panAction ( QMouseEvent * event )

Called when mouse is moving and pan is activated.

Definition at line 3129 of file qgsmapcanvas.cpp.

◆ panActionEnd()

void QgsMapCanvas::panActionEnd ( QPoint releasePoint )

Ends pan action and redraws the canvas.

Definition at line 3101 of file qgsmapcanvas.cpp.

◆ panActionStart()

void QgsMapCanvas::panActionStart ( QPoint releasePoint )

Starts a pan action.

Note: Not available in Python bindings

Since: QGIS 3.12

Definition at line 3120 of file qgsmapcanvas.cpp.

◆ panDistanceBearingChanged

void QgsMapCanvas::panDistanceBearingChanged	(	double	distance,
		Qgis::DistanceUnit	unit,
		double	bearing
	)

signal

Emitted whenever the distance or bearing of an in-progress panning operation is changed.

This signal will be emitted during a pan operation as the user moves the map, giving the total distance and bearing between the map position at the start of the pan and the current pan position.

Since: QGIS 3.12

◆ panToFeatureIds()

void QgsMapCanvas::panToFeatureIds	(	QgsVectorLayer *	layer,
		const QgsFeatureIds &	ids,
		bool	alwaysRecenter = `true`
	)

Centers canvas extent to feature ids.

Parameters

layer	the vector layer
ids	the feature ids
alwaysRecenter	if `false`, the canvas is recentered only if the bounding box is not contained within the current extent

Definition at line 2013 of file qgsmapcanvas.cpp.

◆ panToSelected() [1/2]

void QgsMapCanvas::panToSelected ( const QList< QgsMapLayer * > & layers )

Pan to the combined extent of the selected features of all provided (vector) layers.

Parameters

layers A list of layers

Since: QGIS 3.18

Definition at line 2131 of file qgsmapcanvas.cpp.

◆ panToSelected() [2/2]

void QgsMapCanvas::panToSelected ( QgsMapLayer * layer = nullptr )

Pan to the selected features of current ayer keeping same extent.

Definition at line 2071 of file qgsmapcanvas.cpp.

◆ previewJobsEnabled()

bool QgsMapCanvas::previewJobsEnabled ( ) const

Returns true if canvas map preview jobs (low priority render jobs which render portions of the view just outside of the canvas extent, to allow preview of these out-of-canvas areas when panning or zooming out the map) are enabled for the canvas.

See also: setPreviewJobsEnabled()

Definition at line 1051 of file qgsmapcanvas.cpp.

◆ previewMode()

QgsPreviewEffect::PreviewMode QgsMapCanvas::previewMode ( ) const

Returns the current preview mode for the map canvas.

This setting only has an effect if previewModeEnabled is true.

Returns: preview mode for map canvas

See also: setPreviewMode; previewModeEnabled

Definition at line 3236 of file qgsmapcanvas.cpp.

◆ previewModeEnabled()

bool QgsMapCanvas::previewModeEnabled ( ) const

Returns whether a preview mode is enabled for the map canvas.

Returns: true if a preview mode is currently enabled

See also: setPreviewModeEnabled; previewMode

Definition at line 3216 of file qgsmapcanvas.cpp.

◆ project()

QgsProject * QgsMapCanvas::project ( )

Returns the project linked to this canvas.

The returned value may be nullptr.

Since: QGIS 3.14

Definition at line 3096 of file qgsmapcanvas.cpp.

◆ projectExtent()

QgsRectangle QgsMapCanvas::projectExtent ( ) const

Returns the associated project's full extent, in the canvas' CRS.

This method returns the full extent for the project associated with this canvas. Unlike fullExtent(), this method does NOT consider which layers are actually visible in the map canvas.

See also: fullExtent()

Since: QGIS 3.20

Definition at line 1530 of file qgsmapcanvas.cpp.

◆ readProject

void QgsMapCanvas::readProject ( const QDomDocument & doc )

slot

called to read map canvas settings from project

Definition at line 3262 of file qgsmapcanvas.cpp.

◆ redrawAllLayers

void QgsMapCanvas::redrawAllLayers ( )

slot

Clears all cached images and redraws all layers.

Note: Unlike refreshAllLayers(), this does NOT reload layers themselves, and accordingly is more "lightweight". Use this method when only an update of the layer's renderers is required.

Since: QGIS 3.10

Definition at line 3480 of file qgsmapcanvas.cpp.

◆ refresh

void QgsMapCanvas::refresh ( )

slot

Repaints the canvas map.

Definition at line 735 of file qgsmapcanvas.cpp.

◆ refreshAllLayers

void QgsMapCanvas::refreshAllLayers ( )

slot

Reload all layers (including refreshing layer properties from their data sources), clears the cache and refreshes the canvas.

Note: Consider using the less expensive redrawAllLayers() method if a layer reload from the data provider is not required.

Definition at line 3468 of file qgsmapcanvas.cpp.

◆ removeInteractionBlocker()

void QgsMapCanvas::removeInteractionBlocker ( QgsMapCanvasInteractionBlocker * blocker )

Removes an interaction blocker from the canvas.

See also: allowInteraction(); installInteractionBlocker()

Since: QGIS 3.14

Definition at line 1394 of file qgsmapcanvas.cpp.

◆ renderComplete

void QgsMapCanvas::renderComplete ( QPainter * painter )

signal

Emitted when the canvas has rendered.

Passes a pointer to the painter on which the map was drawn. This is useful for plugins that wish to draw on the map after it has been rendered. Passing the painter allows plugins to work when the map is being rendered onto a pixmap other than the mapCanvas own pixmap member.

anything related to rendering progress is not visible outside of map canvas
additional drawing shall be done directly within the renderer job or independently as a map canvas item

◆ renderedItemResults()

const QgsRenderedItemResults * QgsMapCanvas::renderedItemResults ( bool allowOutdatedResults = true ) const

Gets access to the rendered item results (may be nullptr), which includes the results of rendering annotation items in the canvas map.

If the allowOutdatedResults flag is false then outdated rendered item results (e.g. as a result of an ongoing canvas render) will not be returned, and instead nullptr will be returned.

Since: QGIS 3.22

Definition at line 633 of file qgsmapcanvas.cpp.

◆ renderErrorOccurred

void QgsMapCanvas::renderErrorOccurred	(	const QString &	error,
		QgsMapLayer *	layer
	)

signal

Emitted whenever an error is encountered during a map render operation.

The layer argument indicates the associated map layer, if available.

Since: QGIS 3.10.0

◆ renderFlag()

bool QgsMapCanvas::renderFlag ( ) const

inline

Returns true if canvas render is disabled as a result of user disabling renders via the GUI.

See also: setRenderFlag(); isFrozen()

Note: isFrozen() should be used to determine whether map updates have been halted programmatically, while renderFlag() should be used to determine whether a user has disabled rendering via GUI.

Definition at line 571 of file qgsmapcanvas.h.

◆ renderStarting

void QgsMapCanvas::renderStarting ( )

signal

Emitted when the canvas is about to be rendered.

◆ resizeEvent()

void QgsMapCanvas::resizeEvent ( QResizeEvent * e )

overrideprotected

Definition at line 2622 of file qgsmapcanvas.cpp.

◆ rotation()

double QgsMapCanvas::rotation ( ) const

Gets the current map canvas rotation in clockwise degrees.

Definition at line 1662 of file qgsmapcanvas.cpp.

◆ rotationChanged

void QgsMapCanvas::rotationChanged ( double rotation )

signal

Emitted when the rotation of the map changes.

◆ saveAsImage

void QgsMapCanvas::saveAsImage	(	const QString &	fileName,
		QPixmap *	QPixmap = `nullptr`,
		const QString &	format = `"PNG"`
	)

slot

Save the contents of the map canvas to disk as an image.

Definition at line 1454 of file qgsmapcanvas.cpp.

◆ scale()

double QgsMapCanvas::scale ( ) const

Returns the last reported scale of the canvas.

The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

Definition at line 386 of file qgsmapcanvas.cpp.

◆ scaleChanged

void QgsMapCanvas::scaleChanged ( double scale )

signal

Emitted when the scale of the map changes.

◆ scaleLockChanged

void QgsMapCanvas::scaleLockChanged ( bool locked )

signal

Emitted when the scale locked state of the map changes.

Parameters

locked true if the scale is locked

See also: setScaleLocked

Since: QGIS 3.18

◆ scaleLocked()

bool QgsMapCanvas::scaleLocked ( ) const

inline

Returns whether the scale is locked, so zooming can be performed using magnication.

See also: setScaleLocked()

Definition at line 665 of file qgsmapcanvas.h.

◆ selectionChanged

void QgsMapCanvas::selectionChanged ( QgsMapLayer * layer )

signal

Emitted when selection in any layer gets changed.

Note: Since QGIS 3.28 this signal is emitted for multiple layer types, including QgsVectorLayer and QgsVectorTileLayer

◆ selectionChangedSlot

void QgsMapCanvas::selectionChangedSlot ( )

slot

Receives signal about selection change, and pass it on with layer info.

Definition at line 3381 of file qgsmapcanvas.cpp.

◆ selectionColor()

QColor QgsMapCanvas::selectionColor ( ) const

Returns color for selected features.

Definition at line 2919 of file qgsmapcanvas.cpp.

◆ setAnnotationsVisible()

void QgsMapCanvas::setAnnotationsVisible ( bool visible )

Sets whether annotations are visible in the canvas.

See also: annotationsVisible()

Definition at line 3523 of file qgsmapcanvas.cpp.

◆ setCachingEnabled()

void QgsMapCanvas::setCachingEnabled ( bool enabled )

Set whether to cache images of rendered layers.

See also: isCachingEnabled(); cache()

Definition at line 641 of file qgsmapcanvas.cpp.

◆ setCanvasColor()

void QgsMapCanvas::setCanvasColor ( const QColor & _newVal )

Write property of QColor bgColor.

Definition at line 2860 of file qgsmapcanvas.cpp.

◆ setCenter()

void QgsMapCanvas::setCenter ( const QgsPointXY & center )

Set the center of the map canvas, in geographical coordinates.

Definition at line 1636 of file qgsmapcanvas.cpp.

◆ setCurrentLayer()

void QgsMapCanvas::setCurrentLayer ( QgsMapLayer * layer )

Definition at line 377 of file qgsmapcanvas.cpp.

◆ setCustomDropHandlers()

void QgsMapCanvas::setCustomDropHandlers ( const QVector< QPointer< QgsCustomDropHandler > > & handlers )

Sets a list of custom drop handlers to use when drop events occur on the canvas.

Note: Not available in Python bindings

Since: QGIS 3.10

Definition at line 1061 of file qgsmapcanvas.cpp.

◆ setDestinationCrs()

void QgsMapCanvas::setDestinationCrs ( const QgsCoordinateReferenceSystem & crs )

Sets destination coordinate reference system.

Definition at line 517 of file qgsmapcanvas.cpp.

◆ setExpressionContextScope()

void QgsMapCanvas::setExpressionContextScope ( const QgsExpressionContextScope & scope )

inline

Sets an expression context scope for the map canvas.

This scope is injected into the expression context used for rendering the map, and can be used to apply specific variable overrides for expression evaluation for the map canvas render. This method will overwrite the existing expression context scope for the canvas.

Parameters

scope new expression context scope

See also: expressionContextScope(); defaultExpressionContextScope()

Definition at line 758 of file qgsmapcanvas.h.

◆ setExtent()

void QgsMapCanvas::setExtent	(	const QgsRectangle &	r,
		bool	magnified = `false`
	)

Sets the extent of the map canvas to the specified rectangle.

The magnified argument dictates whether existing canvas constraints such as a scale lock should be respected or not during the operation. If magnified is true then an existing scale lock constraint will be applied. This means that the final visible canvas extent may not match the specified extent.

If magnified is false then scale lock settings will be ignored, and the specified rectangle will ALWAYS be visible in the canvas.

Definition at line 1548 of file qgsmapcanvas.cpp.

◆ setFlags()

void QgsMapCanvas::setFlags ( Qgis::MapCanvasFlags flags )

Sets flags which control how the map canvas behaves.

See also: flags()

Since: QGIS 3.40

Definition at line 412 of file qgsmapcanvas.cpp.

◆ setLabelingEngineSettings()

void QgsMapCanvas::setLabelingEngineSettings ( const QgsLabelingEngineSettings & settings )

Sets global labeling engine settings in the internal map settings.

Definition at line 3533 of file qgsmapcanvas.cpp.

◆ setLayers()

void QgsMapCanvas::setLayers ( const QList< QgsMapLayer * > & layers )

Sets the list of layers that should be shown in the canvas.

If the map canvas has been associated with a map theme via a call to setTheme(), then any calls to setLayers() are ignored. It is necessary to first clear the theme association by calling setTheme() with an empty string before setLayers() calls can be made.

See also: layers()

Definition at line 403 of file qgsmapcanvas.cpp.

◆ setLayerStyleOverrides()

void QgsMapCanvas::setLayerStyleOverrides ( const QMap< QString, QString > & overrides )

Sets the stored overrides of styles for rendering layers.

If the map canvas has been associated with a map theme via a call to setTheme(), then any calls to setLayerStyleOverrides() are ignored. It is necessary to first clear the theme association by calling setTheme() with an empty string before setLayerStyleOverrides() calls can be made.

See also: layerStyleOverrides()

Definition at line 2965 of file qgsmapcanvas.cpp.

◆ setMagnificationFactor

void QgsMapCanvas::setMagnificationFactor	(	double	factor,
		const QgsPointXY *	center = `nullptr`
	)

slot

Sets the factor of magnification to apply to the map canvas.

Indeed, we increase/decrease the DPI of the map settings according to this factor in order to render marker point, labels, ... bigger.

Parameters

factor	The factor of magnification
center	Optional point to re-center the map

Definition at line 316 of file qgsmapcanvas.cpp.

◆ setMapController()

void QgsMapCanvas::setMapController ( QgsAbstract2DMapController * controller )

Sets the input controller device to use for controlling the canvas.

Ownership of controller is transferred to the canvas.

Since: QGIS 3.34

Definition at line 1409 of file qgsmapcanvas.cpp.

◆ setMapSettingsFlags()

void QgsMapCanvas::setMapSettingsFlags ( Qgis::MapSettingsFlags flags )

Resets the flags for the canvas' map settings.

Definition at line 618 of file qgsmapcanvas.cpp.

◆ setMapTool()

void QgsMapCanvas::setMapTool	(	QgsMapTool *	mapTool,
		bool	clean = `false`
	)

Sets the map tool currently being used on the canvas.

Definition at line 2803 of file qgsmapcanvas.cpp.

◆ setMapUpdateInterval()

void QgsMapCanvas::setMapUpdateInterval ( int timeMilliseconds )

Set how often map preview should be updated while it is being rendered (in milliseconds)

Definition at line 695 of file qgsmapcanvas.cpp.

◆ setParallelRenderingEnabled()

void QgsMapCanvas::setParallelRenderingEnabled ( bool enabled )

Set whether the layers are rendered in parallel or sequentially.

Definition at line 685 of file qgsmapcanvas.cpp.

◆ setPreviewJobsEnabled()

void QgsMapCanvas::setPreviewJobsEnabled ( bool enabled )

Sets whether canvas map preview jobs (low priority render jobs which render portions of the view just outside of the canvas extent, to allow preview of these out-of-canvas areas when panning or zooming out the map) are enabled for the canvas.

See also: previewJobsEnabled()

Definition at line 1056 of file qgsmapcanvas.cpp.

◆ setPreviewMode()

void QgsMapCanvas::setPreviewMode ( QgsPreviewEffect::PreviewMode mode )

Sets a preview mode for the map canvas.

This setting only has an effect if previewModeEnabled is true.

Parameters

mode	preview mode for the canvas

See also: previewMode; setPreviewModeEnabled; previewModeEnabled

Definition at line 3226 of file qgsmapcanvas.cpp.

◆ setPreviewModeEnabled()

void QgsMapCanvas::setPreviewModeEnabled ( bool previewEnabled )

Enables a preview mode for the map canvas.

Parameters

previewEnabled set to true to enable a preview mode

See also: setPreviewMode

Definition at line 3206 of file qgsmapcanvas.cpp.

◆ setProject()

void QgsMapCanvas::setProject ( QgsProject * project )

Sets the project linked to this canvas.

Since: QGIS 3.14

Definition at line 2849 of file qgsmapcanvas.cpp.

◆ setReferencedExtent()

bool QgsMapCanvas::setReferencedExtent ( const QgsReferencedRectangle & extent )

Sets the canvas to the specified extent.

Returns: true if the zoom was successful.

Exceptions

QgsCsException if a transformation error occurred.

Since: QGIS 3.10

Definition at line 1617 of file qgsmapcanvas.cpp.

◆ setRenderFlag

void QgsMapCanvas::setRenderFlag ( bool flag )

slot

Sets whether a user has disabled canvas renders via the GUI.

Parameters

flag	set to `false` to indicate that user has disabled renders

See also: renderFlag(); freeze()

Note: freeze() should be used to programmatically halt map updates, while setRenderFlag() should only be used when users disable rendering via GUI.

Definition at line 2996 of file qgsmapcanvas.cpp.

◆ setRotation()

void QgsMapCanvas::setRotation ( double degrees )

Set the rotation of the map canvas in clockwise degrees.

Definition at line 1667 of file qgsmapcanvas.cpp.

◆ setScaleLocked

void QgsMapCanvas::setScaleLocked ( bool isLocked )

slot

Lock the scale, so zooming can be performed using magnication.

See also: scaleLocked()

Definition at line 2762 of file qgsmapcanvas.cpp.

◆ setSegmentationTolerance()

void QgsMapCanvas::setSegmentationTolerance ( double tolerance )

Sets the segmentation tolerance applied when rendering curved geometries.

Parameters

tolerance the segmentation tolerance

Definition at line 3497 of file qgsmapcanvas.cpp.

◆ setSegmentationToleranceType()

void QgsMapCanvas::setSegmentationToleranceType ( QgsAbstractGeometry::SegmentationToleranceType type )

Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)

Parameters

type	the segmentation tolerance typename

Definition at line 3502 of file qgsmapcanvas.cpp.

◆ setSelectionColor()

void QgsMapCanvas::setSelectionColor ( const QColor & color )

Set color of selected vector features.

Definition at line 2890 of file qgsmapcanvas.cpp.

◆ setSnappingUtils()

void QgsMapCanvas::setSnappingUtils ( QgsSnappingUtils * utils )

Assign an instance of snapping utils to the map canvas.

The instance is not owned by the canvas, so it is possible to use one instance in multiple canvases.

For main canvas in QGIS, do not associate a different instance from the existing one (it is updated from the project's snapping configuration).

Definition at line 3257 of file qgsmapcanvas.cpp.

◆ setTemporalController()

void QgsMapCanvas::setTemporalController ( QgsTemporalController * controller )

Sets the temporal controller for this canvas.

The controller will be used to update the canvas' temporal range.

Since: QGIS 3.14

Definition at line 570 of file qgsmapcanvas.cpp.

◆ setTemporalRange()

void QgsMapCanvas::setTemporalRange ( const QgsDateTimeRange & range )

Set datetime range for the map canvas.

The temporalRangeChanged() signal will be emitted if the temporal range has been changed.

Note: Calling setTemporalRange() does not automatically trigger a map refresh.

See also: temporalRange()

Since: QGIS 3.14

Definition at line 1367 of file qgsmapcanvas.cpp.

◆ setTheme()

void QgsMapCanvas::setTheme ( const QString & theme )

Sets a map theme to show in the canvas.

The theme name must match a theme present in the associated project's QgsMapThemeCollection.

When the canvas is associated to a map theme, it will automatically follow the layer selection and layer styles from that theme. Calls to setLayers() or setLayerStyleOverrides() will have no effect, and canvases associated with a QgsLayerTreeMapCanvasBridge will no longer synchronize their state with the layer tree. In these cases it is necessary to call setTheme() with an empty string to clear the theme association and allow map updates with setLayers(), setLayerStyleOverrides(), or via QgsLayerTreeMapCanvasBridge.

If an empty string is passed then the current theme association will be cleared.

See also: theme()

Definition at line 2975 of file qgsmapcanvas.cpp.

◆ setWheelFactor()

void QgsMapCanvas::setWheelFactor ( double factor )

Sets wheel zoom factor (should be greater than 1)

Definition at line 2722 of file qgsmapcanvas.cpp.

◆ setZoomResolutions

void QgsMapCanvas::setZoomResolutions ( const QList< double > & resolutions )

inlineslot

Set a list of resolutions (map units per pixel) to which to "snap to" when zooming the map.

Parameters

resolutions A list of resolutions

Since: QGIS 3.12

Definition at line 1004 of file qgsmapcanvas.h.

◆ setZRange

void QgsMapCanvas::setZRange ( const QgsDoubleRange & range )

slot

Sets the range of z-values which will be visible in the map.

See also: zRange(); zRangeChanged()

Since: QGIS 3.18

Definition at line 1949 of file qgsmapcanvas.cpp.

◆ showEvent()

void QgsMapCanvas::showEvent ( QShowEvent * event )

overrideprotected

Definition at line 3189 of file qgsmapcanvas.cpp.

◆ snappingUtils()

QgsSnappingUtils * QgsMapCanvas::snappingUtils ( ) const

Returns snapping utility class that is associated with map canvas.

If no snapping utils instance has been associated previously, an internal will be created for convenience (so map tools do not need to test for existence of the instance).

Main canvas in QGIS returns an instance which is always up-to-date with the project's snapping configuration.

Definition at line 3246 of file qgsmapcanvas.cpp.

◆ stopRendering

void QgsMapCanvas::stopRendering ( )

slot

stop rendering (if there is any right now)

Definition at line 1438 of file qgsmapcanvas.cpp.

◆ tapAndHoldGestureOccurred

void QgsMapCanvas::tapAndHoldGestureOccurred	(	const QgsPointXY &	mapPoint,
		QTapAndHoldGesture *	gesture
	)

signal

Emitted whenever a tap and hold gesture occurs at the specified map point.

Since: QGIS 3.12

◆ temporalController()

const QgsTemporalController * QgsMapCanvas::temporalController ( ) const

Gets access to the temporal controller that will be used to update the canvas temporal range.

Since: QGIS 3.14

Definition at line 613 of file qgsmapcanvas.cpp.

◆ temporalRange()

const QgsDateTimeRange & QgsMapCanvas::temporalRange ( ) const

Returns map canvas datetime range.

See also: setTemporalRange()

Since: QGIS 3.14

Definition at line 1384 of file qgsmapcanvas.cpp.

◆ temporalRangeChanged

void QgsMapCanvas::temporalRangeChanged ( )

signal

Emitted when the map canvas temporal range changes.

Since: QGIS 3.14

◆ theme()

QString QgsMapCanvas::theme ( ) const

inline

Returns the map's theme shown in the canvas, if set.

See also: setTheme()

Definition at line 620 of file qgsmapcanvas.h.

◆ themeChanged

void QgsMapCanvas::themeChanged ( const QString & theme )

signal

Emitted when the canvas has been assigned a different map theme.

See also: setTheme()

◆ transformContextChanged

void QgsMapCanvas::transformContextChanged ( )

signal

Emitted when the canvas transform context is changed.

◆ unsetMapTool()

void QgsMapCanvas::unsetMapTool ( QgsMapTool * mapTool )

Unset the current map tool or last non zoom tool.

This is called from destructor of map tools to make sure that this map tool won't be used any more. You don't have to call it manually, QgsMapTool takes care of it.

Definition at line 2836 of file qgsmapcanvas.cpp.

◆ updateCanvasItemPositions

void QgsMapCanvas::updateCanvasItemPositions ( )

protectedslot

called on resize or changed extent to notify canvas items to change their rectangle

Definition at line 2658 of file qgsmapcanvas.cpp.

◆ updateScale()

void QgsMapCanvas::updateScale ( )

Emits signal scaleChanged to update scale in main window.

Definition at line 1679 of file qgsmapcanvas.cpp.

◆ viewportEvent()

bool QgsMapCanvas::viewportEvent ( QEvent * event )

overrideprotected

Definition at line 3430 of file qgsmapcanvas.cpp.

◆ waitWhileRendering()

void QgsMapCanvas::waitWhileRendering ( )

Blocks until the rendering job has finished.

In almost all cases you do NOT want to call this, as it will hang the UI until the rendering job is complete. It's included in API solely for unit testing and standalone Python scripts.

Definition at line 3489 of file qgsmapcanvas.cpp.

◆ wheelEvent()

void QgsMapCanvas::wheelEvent ( QWheelEvent * e )

overrideprotected

Definition at line 2676 of file qgsmapcanvas.cpp.

◆ writeProject

void QgsMapCanvas::writeProject ( QDomDocument & doc )

slot

called to write map canvas settings to project

Definition at line 3330 of file qgsmapcanvas.cpp.

◆ xyCoordinates

void QgsMapCanvas::xyCoordinates ( const QgsPointXY & p )

signal

Emits current mouse position.

Note: changed in 1.3

◆ zoomByFactor()

void QgsMapCanvas::zoomByFactor	(	double	scaleFactor,
		const QgsPointXY *	center = `nullptr`,
		bool	ignoreScaleLock = `false`
	)

Zoom with the factor supplied.

Factor > 1 zooms out, interval (0,1) zooms in If point is given, re-center on it.

If ignoreScaleLock is set to true, then any existing constraint on the map scale of the canvas will be ignored during the zoom operation.

Definition at line 3365 of file qgsmapcanvas.cpp.

◆ zoomIn

void QgsMapCanvas::zoomIn ( )

slot

Zoom in with fixed factor.

Definition at line 2727 of file qgsmapcanvas.cpp.

◆ zoomInFactor

double QgsMapCanvas::zoomInFactor ( ) const

slot

Returns the zoom in factor.

Definition at line 3698 of file qgsmapcanvas.cpp.

◆ zoomLastStatusChanged

void QgsMapCanvas::zoomLastStatusChanged ( bool available )

signal

Emitted when zoom last status changed.

◆ zoomNextStatusChanged

void QgsMapCanvas::zoomNextStatusChanged ( bool available )

signal

Emitted when zoom next status changed.

◆ zoomOut

void QgsMapCanvas::zoomOut ( )

slot

Zoom out with fixed factor.

Definition at line 2733 of file qgsmapcanvas.cpp.

◆ zoomOutFactor

double QgsMapCanvas::zoomOutFactor ( ) const

slot

Returns the zoom in factor.

Definition at line 3711 of file qgsmapcanvas.cpp.

◆ zoomResolutions

const QList< double > & QgsMapCanvas::zoomResolutions ( ) const

inlineslot

Returns: List of resolutions to which to "snap to" when zooming the map

See also: setZoomResolutions()

Since: QGIS 3.12

Definition at line 1021 of file qgsmapcanvas.h.

◆ zoomScale()

void QgsMapCanvas::zoomScale	(	double	scale,
		bool	ignoreScaleLock = `false`
	)

Zooms the canvas to a specific scale.

The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

If ignoreScaleLock is set to true, then any existing constraint on the map scale of the canvas will be ignored during the zoom operation.

Definition at line 2739 of file qgsmapcanvas.cpp.

◆ zoomToFeatureExtent()

void QgsMapCanvas::zoomToFeatureExtent ( QgsRectangle & rect )

Zooms to feature extent.

Adds a small margin around the extent and does a pan if rect is empty (point extent)

Definition at line 1965 of file qgsmapcanvas.cpp.

◆ zoomToFeatureIds()

void QgsMapCanvas::zoomToFeatureIds	(	QgsVectorLayer *	layer,
		const QgsFeatureIds &	ids
	)

Set canvas extent to the bounding box of a set of features.

Parameters

layer	the vector layer
ids	the feature ids

Definition at line 1989 of file qgsmapcanvas.cpp.

◆ zoomToFullExtent()

void QgsMapCanvas::zoomToFullExtent ( )

Zoom to the full extent of all layers currently visible in the canvas.

See also: zoomToProjectExtent()

Definition at line 1685 of file qgsmapcanvas.cpp.

◆ zoomToNextExtent()

void QgsMapCanvas::zoomToNextExtent ( )

Zoom to the next extent (view)

Definition at line 1728 of file qgsmapcanvas.cpp.

◆ zoomToPreviousExtent()

void QgsMapCanvas::zoomToPreviousExtent ( )

Zoom to the previous extent (view)

Definition at line 1712 of file qgsmapcanvas.cpp.

◆ zoomToProjectExtent()

void QgsMapCanvas::zoomToProjectExtent ( )

Zoom to the full extent the project associated with this canvas.

This method zooms to the full extent for the project associated with this canvas. Unlike zoomToFullExtent(), this method does NOT consider which layers are actually visible in the map canvas.

Since: QGIS 3.20

Definition at line 1698 of file qgsmapcanvas.cpp.

◆ zoomToSelected [1/2]

void QgsMapCanvas::zoomToSelected ( const QList< QgsMapLayer * > & layers )

slot

Zoom to the combined extent of the selected features of all provided (vector) layers.

Parameters

layers A list of layers

Since: QGIS 3.18

Definition at line 1868 of file qgsmapcanvas.cpp.

◆ zoomToSelected [2/2]

void QgsMapCanvas::zoomToSelected ( QgsMapLayer * layer = nullptr )

slot

Zoom to the extent of the selected features of provided map layer.

Parameters

layer optionally specify different than current layer

Definition at line 1787 of file qgsmapcanvas.cpp.

◆ zoomWithCenter()

void QgsMapCanvas::zoomWithCenter	(	int	x,
		int	y,
		bool	zoomIn
	)

Zooms in/out with a given center.

Definition at line 2744 of file qgsmapcanvas.cpp.

◆ zRange

QgsDoubleRange QgsMapCanvas::zRange ( ) const

slot

Returns the range of z-values which will be visible in the map.

See also: setZRange(); zRangeChanged()

Since: QGIS 3.18

Definition at line 1944 of file qgsmapcanvas.cpp.

◆ zRangeChanged

void QgsMapCanvas::zRangeChanged ( )

signal

Emitted when the map canvas z (elevation) range changes.

See also: zRange(); setZRange()

Since: QGIS 3.18

Friends And Related Symbol Documentation

◆ TestQgsMapCanvas

friend class TestQgsMapCanvas

friend

Definition at line 1574 of file qgsmapcanvas.h.

Member Data Documentation

◆ mCanvasProperties

std::unique_ptr<CanvasProperties> QgsMapCanvas::mCanvasProperties

protected

Handle pattern for implementation object.

Definition at line 1272 of file qgsmapcanvas.h.

Property Documentation

◆ previewJobsEnabled

bool QgsMapCanvas::previewJobsEnabled

readwrite

Definition at line 106 of file qgsmapcanvas.h.

◆ theme

QString QgsMapCanvas::theme

readwrite

Definition at line 105 of file qgsmapcanvas.h.

The documentation for this class was generated from the following files:

/build/qgis-3.41.0+git20241116+25ec5511245+99sid/src/gui/qgsmapcanvas.h
/build/qgis-3.41.0+git20241116+25ec5511245+99sid/src/gui/qgsmapcanvas.cpp

Classes

Public Slots

Signals

Public Member Functions

Protected Slots

Protected Member Functions

Protected Attributes

Properties

Friends

Detailed Description

Constructor & Destructor Documentation

◆ QgsMapCanvas()

◆ ~QgsMapCanvas()

Member Function Documentation

◆ addOverlayWidget()

◆ allowInteraction()

◆ annotationItems()

◆ annotationsVisible()

◆ antiAliasingEnabled()

◆ cache()

◆ cancelJobs()

◆ canvasColor()

◆ canvasColorChanged

◆ center()

◆ clearCache()

◆ clearExtentHistory()

◆ contextMenuAboutToShow

◆ createExpressionContext()

◆ currentLayer()

◆ currentLayerChanged

◆ defaultExpressionContextScope()

◆ destinationCrsChanged

◆ dragEnterEvent()

◆ dropEvent()

◆ emitExtentsChanged()

◆ enableAntiAliasing()

◆ enableMapTileRendering()

◆ event()

◆ expressionContextScope() [1/2]

◆ expressionContextScope() [2/2]

◆ extent()

◆ extentsChanged

◆ flags()

◆ flashFeatureIds()

◆ flashGeometries()

◆ freeze()

◆ fullExtent()

◆ getCoordinateTransform()

◆ installInteractionBlocker()

◆ isCachingEnabled()

◆ isDrawing()

◆ isFrozen()

◆ isParallelRenderingEnabled()

◆ keyPressed

◆ keyPressEvent()

◆ keyReleased

◆ keyReleaseEvent()

◆ labelingEngineSettings()

◆ labelingResults()

◆ layer() [1/2]

◆ layer() [2/2]

◆ layerCount()

◆ layers() [1/2]

◆ layers() [2/2]

◆ layersChanged

◆ layerStateChange

◆ layerStyleOverrides()

◆ layerStyleOverridesChanged

◆ magnificationChanged

◆ magnificationFactor()

◆ mapCanvasRefreshed

◆ mapRefreshCanceled

◆ mapSettings() [1/2]

◆ mapSettings() [2/2]

◆ mapTool()

◆ mapToolSet

◆ mapUnits()

◆ mapUnitsPerPixel()

◆ mapUpdateInterval()

◆ messageEmitted