QgsMapRendererCustomPainterJob Class Reference

Job implementation that renders everything sequentially using a custom painter. More...

#include <qgsmaprenderercustompainterjob.h>

Inheritance diagram for QgsMapRendererCustomPainterJob:

Public Member Functions
	QgsMapRendererCustomPainterJob (const QgsMapSettings &settings, QPainter *painter)
	~QgsMapRendererCustomPainterJob () override
void	cancel () override
	Stop the rendering job - does not return until the job has terminated.
void	cancelWithoutBlocking () override
	Triggers cancellation of the rendering job without blocking.
bool	isActive () const override
	Tell whether the rendering job is currently running in background.
const std::vector< LayerRenderJob > &	jobs () const
void	prepare ()
	Prepares the job for rendering synchronously in a background thread.
void	renderPrepared ()
	Render a pre-prepared job.
void	renderSynchronously ()
	Render the map synchronously in this thread.
QgsLabelingResults *	takeLabelingResults () override
	Gets pointer to internal labeling engine (in order to get access to the results).
bool	usedCachedLabels () const override
	Returns true if the render job was able to use a cached labeling solution.
void	waitForFinished () override
	Block until the job has finished.
void	waitForFinishedWithEventLoop (QEventLoop::ProcessEventsFlags flags=QEventLoop::AllEvents)
	Wait for the job to be finished - and keep the thread's event loop running while waiting.
Public Member Functions inherited from QgsMapRendererAbstractCustomPainterJob
	QgsMapRendererAbstractCustomPainterJob (const QgsMapSettings &settings)
	Constructor for QgsMapRendererAbstractCustomPainterJob, using the given map settings.
Public Member Functions inherited from QgsMapRendererJob
	QgsMapRendererJob (const QgsMapSettings &settings)
	~QgsMapRendererJob () override
Errors	errors () const
	List of errors that happened during the rendering job - available when the rendering has been finished.
const QgsFeatureFilterProvider *	featureFilterProvider () const
	Returns the feature filter provider used by the QgsRenderContext of each LayerRenderJob.
QgsLabelingEngineFeedback *	labelingEngineFeedback ()
	Returns the associated labeling engine feedback object.
QgsLabelSink *	labelSink () const
	Returns the label sink associated to this rendering job.
QStringList	layersRedrawnFromCache () const
	Returns a list of the layer IDs for all layers which were redrawn from cached images.
const QgsMapSettings &	mapSettings () const
	Returns map settings with which this job was started.
QHash< QgsMapLayer *, int >	perLayerRenderingTime () const
	Returns the render time (in ms) per layer.
int	renderingTime () const
	Returns the total time it took to finish the job (in milliseconds).
void	setCache (QgsMapRendererCache *cache)
	Assign a cache to be used for reading and storing rendered images of individual layers.
void	setFeatureFilterProvider (const QgsFeatureFilterProvider *f)
	Set the feature filter provider used by the QgsRenderContext of each LayerRenderJob.
void	setLabelSink (QgsLabelSink *sink)
	Assigns the label sink which will take over responsibility for handling labels during the rendering job.
void	setLayerRenderingTimeHints (const QHash< QString, int > &hints)
	Sets approximate render times (in ms) for map layers.
void	start ()
	Start the rendering job and immediately return.
QgsRenderedItemResults *	takeRenderedItemResults ()
	Takes the rendered item results from the map render job and returns them.

Additional Inherited Members
Public Types inherited from QgsMapRendererJob
typedef QList< QgsMapRendererJob::Error >	Errors
Signals inherited from QgsMapRendererJob
void	finished ()
	emitted when asynchronous rendering is finished (or canceled).
void	layerRendered (const QString &layerId)
	Emitted when a layer has completed rendering.
void	layerRenderingStarted (const QString &layerId)
	Emitted just before rendering starts for a particular layer.
void	renderingLayersFinished ()
	Emitted when the layers are rendered.
Static Public Attributes inherited from QgsMapRendererJob
static const QString	ELEVATION_MAP_CACHE_PREFIX
	QgsMapRendererCache prefix string for cached elevation map image.
static const QString	LABEL_CACHE_ID
	QgsMapRendererCache ID string for cached label image.
static const QString	LABEL_PREVIEW_CACHE_ID
	QgsMapRendererCache ID string for cached label image during preview compositions only.
static const QgsSettingsEntryBool *	settingsLogCanvasRefreshEvent = new QgsSettingsEntryBool( QStringLiteral( "logCanvasRefreshEvent" ), QgsSettingsTree::sTreeMap, false )
	Settings entry log canvas refresh event.
static const QgsSettingsEntryString *	settingsMaskBackend = new QgsSettingsEntryString( QStringLiteral( "mask-backend" ), QgsSettingsTree::sTreeMap, QString(), QStringLiteral( "Backend engine to use for selective masking" ) )
	Settings entry for mask painting backend engine.
Protected Member Functions inherited from QgsMapRendererAbstractCustomPainterJob
void	preparePainter (QPainter *painter, const QColor &backgroundColor=Qt::transparent)
	Prepares the given painter ready for a map render.
Protected Member Functions inherited from QgsMapRendererJob
void	cleanupJobs (std::vector< LayerRenderJob > &jobs)
void	cleanupLabelJob (LabelRenderJob &job)
	Handles clean up tasks for a label job, including deletion of images and storing cached label results.
void	cleanupSecondPassJobs (std::vector< LayerRenderJob > &jobs)
void	initSecondPassJobs (std::vector< LayerRenderJob > &secondPassJobs, LabelRenderJob &labelJob) const
	Initialize secondPassJobs according to what have been rendered (mask clipping path e.g.) in first pass jobs and labelJob.
void	logRenderingTime (const std::vector< LayerRenderJob > &jobs, const std::vector< LayerRenderJob > &secondPassJobs, const LabelRenderJob &labelJob)
QList< QPointer< QgsMapLayer > >	participatingLabelLayers (QgsLabelingEngine *engine)
	Returns a list of the layers participating in the map labeling.
std::vector< LayerRenderJob >	prepareJobs (QPainter *painter, QgsLabelingEngine *labelingEngine2, bool deferredPainterSet=false)
	Creates a list of layer rendering jobs and prepares them for later render.
bool	prepareLabelCache () const
	Prepares the cache for storing the result of labeling.
LabelRenderJob	prepareLabelingJob (QPainter *painter, QgsLabelingEngine *labelingEngine2, bool canUseLabelCache=true)
	Prepares a labeling job.
std::vector< LayerRenderJob >	prepareSecondPassJobs (std::vector< LayerRenderJob > &firstPassJobs, LabelRenderJob &labelJob)
	Prepares jobs for a second pass, if selective masks exist (from labels or symbol layers).
Static Protected Member Functions inherited from QgsMapRendererJob
static QImage	composeImage (const QgsMapSettings &settings, const std::vector< LayerRenderJob > &jobs, const LabelRenderJob &labelJob, const QgsMapRendererCache *cache=nullptr)
static void	composeSecondPass (std::vector< LayerRenderJob > &secondPassJobs, LabelRenderJob &labelJob, bool forceVector=false)
	Compose second pass images into first pass images.
static Q_DECL_DEPRECATED void	drawLabeling (const QgsMapSettings &settings, QgsRenderContext &renderContext, QgsLabelingEngine *labelingEngine2, QPainter *painter)
static void	drawLabeling (QgsRenderContext &renderContext, QgsLabelingEngine *labelingEngine2, QPainter *painter)
static QgsElevationMap	layerElevationToBeComposed (const QgsMapSettings &settings, const LayerRenderJob &job, const QgsMapRendererCache *cache)
static QImage	layerImageToBeComposed (const QgsMapSettings &settings, const LayerRenderJob &job, const QgsMapRendererCache *cache)
Protected Attributes inherited from QgsMapRendererJob
QList< QPointer< QgsMapLayer > >	mAdditionalLabelLayers
	Additional layers participating in labeling problem.
QgsMapRendererCache *	mCache = nullptr
Errors	mErrors
QHash< QString, int >	mLayerRenderingTimeHints
	Approximate expected layer rendering time per layer, by layer ID.
QStringList	mLayersRedrawnFromCache
QHash< QgsWeakMapLayerPointer, int >	mPerLayerRenderingTime
	Render time (in ms) per layer, by layer ID.
bool	mRecordRenderingTime = true
	true if layer rendering time should be recorded.
std::unique_ptr< QgsRenderedItemResults >	mRenderedItemResults
QElapsedTimer	mRenderingStart
int	mRenderingTime = 0
QgsMapSettings	mSettings

Detailed Description

Job implementation that renders everything sequentially using a custom painter.

Also supports synchronous rendering in main thread for cases when rendering in background is not an option because of some technical limitations (e.g. printing to printer on some platforms).

Definition at line 62 of file qgsmaprenderercustompainterjob.h.

Constructor & Destructor Documentation

QgsMapRendererCustomPainterJob()

QgsMapRendererCustomPainterJob::QgsMapRendererCustomPainterJob	(	const QgsMapSettings &	settings,
		QPainter *	painter
	)

Definition at line 63 of file qgsmaprenderercustompainterjob.cpp.

~QgsMapRendererCustomPainterJob()

QgsMapRendererCustomPainterJob::~QgsMapRendererCustomPainterJob ( )

override

Definition at line 72 of file qgsmaprenderercustompainterjob.cpp.

Member Function Documentation

cancel()

void QgsMapRendererCustomPainterJob::cancel ( )

overridevirtual

Stop the rendering job - does not return until the job has terminated.

Does nothing if the rendering is not active.

Implements QgsMapRendererJob.

Definition at line 132 of file qgsmaprenderercustompainterjob.cpp.

cancelWithoutBlocking()

void QgsMapRendererCustomPainterJob::cancelWithoutBlocking ( )

overridevirtual

Triggers cancellation of the rendering job without blocking.

The render job will continue to operate until it is able to cancel, at which stage the finished() signal will be emitted. Does nothing if the rendering is not active.

Implements QgsMapRendererJob.

Definition at line 156 of file qgsmaprenderercustompainterjob.cpp.

isActive()

bool QgsMapRendererCustomPainterJob::isActive ( ) const

overridevirtual

Tell whether the rendering job is currently running in background.

Implements QgsMapRendererJob.

Definition at line 190 of file qgsmaprenderercustompainterjob.cpp.

jobs()

const std::vector< LayerRenderJob > & QgsMapRendererCustomPainterJob::jobs ( ) const

inline

Note

not available in Python bindings

Definition at line 77 of file qgsmaprenderercustompainterjob.h.

prepare()

void QgsMapRendererCustomPainterJob::prepare

(

)

Prepares the job for rendering synchronously in a background thread.

Must be called from the main thread.

This is an alternative to ordinary API (using start() + waiting for finished() signal), and an alternative to renderSynchronously() (which should only ever be called from the main thread).

See also

renderPrepared()

Since

QGIS 3.10

Definition at line 225 of file qgsmaprenderercustompainterjob.cpp.

renderPrepared()

void QgsMapRendererCustomPainterJob::renderPrepared

(

)

Render a pre-prepared job.

Can be safely called in a background thread.

Must be preceded by a call to prepare()

This is an alternative to ordinary API (using start() + waiting for finished() signal), and an alternative to renderSynchronously() (which should only ever be called from the main thread).

Since

QGIS 3.10

Definition at line 233 of file qgsmaprenderercustompainterjob.cpp.

renderSynchronously()

void QgsMapRendererCustomPainterJob::renderSynchronously

(

)

Render the map synchronously in this thread.

The function does not return until the map is completely rendered.

This is an alternative to ordinary API (using start() + waiting for finished() signal). Users are discouraged to use this method unless they have a strong reason for doing it. The synchronous rendering blocks the main thread, making the application unresponsive. Also, it is not possible to cancel rendering while it is in progress.

Definition at line 217 of file qgsmaprenderercustompainterjob.cpp.

takeLabelingResults()

QgsLabelingResults * QgsMapRendererCustomPainterJob::takeLabelingResults ( )

overridevirtual

Gets pointer to internal labeling engine (in order to get access to the results).

This should not be used if cached labeling was redrawn - see usedCachedLabels().

See also

usedCachedLabels()

Implements QgsMapRendererJob.

Definition at line 200 of file qgsmaprenderercustompainterjob.cpp.

usedCachedLabels()

bool QgsMapRendererCustomPainterJob::usedCachedLabels ( ) const

overridevirtual

Returns true if the render job was able to use a cached labeling solution.

If so, any previously stored labeling results (see takeLabelingResults()) should be retained.

See also

takeLabelingResults()

Implements QgsMapRendererJob.

Definition at line 195 of file qgsmaprenderercustompainterjob.cpp.

waitForFinished()

void QgsMapRendererCustomPainterJob::waitForFinished ( )

overridevirtual

Block until the job has finished.

Implements QgsMapRendererJob.

Definition at line 173 of file qgsmaprenderercustompainterjob.cpp.

waitForFinishedWithEventLoop()

void QgsMapRendererCustomPainterJob::waitForFinishedWithEventLoop

(

QEventLoop::ProcessEventsFlags

flags = QEventLoop::AllEvents

)

Wait for the job to be finished - and keep the thread's event loop running while waiting.

With a call to waitForFinished(), the waiting is done with a synchronization primitive and does not involve processing of messages. That may cause issues to code which requires some events to be handled in the main thread. Some plugins hooking into the rendering pipeline may require this in order to work properly - for example, OpenLayers plugin which uses a QWebPage in the main thread.

Ideally the "wait for finished" method should not be used at all. The code triggering rendering should not need to actively wait for rendering to finish.

Definition at line 209 of file qgsmaprenderercustompainterjob.cpp.

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

• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/maprenderer/qgsmaprenderercustompainterjob.h
• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/maprenderer/qgsmaprenderercustompainterjob.cpp