Abstract base class for map rendering implementations. More...

#include <qgsmaprendererjob.h>

Inheritance diagram for QgsMapRendererJob:

[legend]

Classes
struct	Error

Public Types
typedef QList< QgsMapRendererJob::Error >	Errors

Signals
void	finished ()
	emitted when asynchronous rendering is finished (or canceled). More...

void	renderingLayersFinished ()
	Emitted when the layers are rendered. More...

Public Member Functions
	QgsMapRendererJob (const QgsMapSettings &settings)

virtual void	cancel ()=0
	Stop the rendering job - does not return until the job has terminated. More...

virtual void	cancelWithoutBlocking ()=0
	Triggers cancellation of the rendering job without blocking. More...

Errors	errors () const
	List of errors that happened during the rendering job - available when the rendering has been finished. More...

const QgsFeatureFilterProvider *	featureFilterProvider () const
	Returns the feature filter provider used by the QgsRenderContext of each LayerRenderJob. More...

virtual bool	isActive () const =0
	Tell whether the rendering job is currently running in background. More...

const QgsMapSettings &	mapSettings () const
	Returns map settings with which this job was started. More...

QHash< QgsMapLayer *, int >	perLayerRenderingTime () const
	Returns the render time (in ms) per layer. More...

int	renderingTime () const
	Returns the total time it took to finish the job (in milliseconds). More...

void	setCache (QgsMapRendererCache *cache)
	Assign a cache to be used for reading and storing rendered images of individual layers. More...

void	setFeatureFilterProvider (const QgsFeatureFilterProvider *f)
	Set the feature filter provider used by the QgsRenderContext of each LayerRenderJob. More...

virtual void	start ()=0
	Start the rendering job and immediately return. More...

virtual QgsLabelingResults *	takeLabelingResults ()=0
	Gets pointer to internal labeling engine (in order to get access to the results). More...

virtual bool	usedCachedLabels () const =0
	Returns true if the render job was able to use a cached labeling solution. More...

virtual void	waitForFinished ()=0
	Block until the job has finished. More...

Static Public Attributes
static const QString	LABEL_CACHE_ID
	QgsMapRendererCache ID string for cached label image. More...

Protected Member Functions
void	cleanupJobs (LayerRenderJobs &jobs)

void	cleanupLabelJob (LabelRenderJob &job)
	Handles clean up tasks for a label job, including deletion of images and storing cached label results. More...

void	logRenderingTime (const LayerRenderJobs &jobs, const LabelRenderJob &labelJob)

LayerRenderJobs	prepareJobs (QPainter painter, QgsLabelingEngine labelingEngine2)

bool	prepareLabelCache () const
	Prepares the cache for storing the result of labeling. More...

LabelRenderJob	prepareLabelingJob (QPainter painter, QgsLabelingEngine labelingEngine2, bool canUseLabelCache=true)
	Prepares a labeling job. More...

Static Protected Member Functions
static QImage	composeImage (const QgsMapSettings &settings, const LayerRenderJobs &jobs, const LabelRenderJob &labelJob)

static Q_DECL_DEPRECATED void	drawLabeling (const QgsMapSettings &settings, QgsRenderContext &renderContext, QgsLabelingEngine labelingEngine2, QPainter painter)

static void	drawLabeling (QgsRenderContext &renderContext, QgsLabelingEngine labelingEngine2, QPainter painter)

Protected Attributes
QgsMapRendererCache *	mCache = nullptr

Errors	mErrors

QHash< QgsWeakMapLayerPointer, int >	mPerLayerRenderingTime
	Render time (in ms) per layer, by layer ID. More...

QTime	mRenderingStart

int	mRenderingTime = 0

QgsMapSettings	mSettings

Detailed Description

Abstract base class for map rendering implementations.

The API is designed in a way that rendering is done asynchronously, therefore the caller is not blocked while the rendering is in progress. Non-blocking operation is quite important because the rendering can take considerable amount of time.

Common use case: 0. prepare QgsMapSettings with rendering configuration (extent, layer, map size, ...)

create QgsMapRendererJob subclass with QgsMapSettings instance
connect to job's finished() signal
call start(). Map rendering will start in background, the function immediately returns
at some point, slot connected to finished() signal is called, map rendering is done

It is possible to cancel the rendering job while it is active by calling cancel() function.

The following subclasses are available:

QgsMapRendererSequentialJob - renders map in one background thread to an image
QgsMapRendererParallelJob - renders map in multiple background threads to an image
QgsMapRendererCustomPainterJob - renders map with given QPainter in one background thread

Since: QGIS 2.4

Definition at line 115 of file qgsmaprendererjob.h.

Member Typedef Documentation

typedef QList<QgsMapRendererJob::Error> QgsMapRendererJob::Errors

Definition at line 190 of file qgsmaprendererjob.h.

Constructor & Destructor Documentation

QgsMapRendererJob::QgsMapRendererJob ( const QgsMapSettings & settings )

Member Function Documentation

virtual void QgsMapRendererJob::cancel ( )

pure virtual

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

Does nothing if the rendering is not active.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

virtual void QgsMapRendererJob::cancelWithoutBlocking ( )

pure virtual

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.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

void QgsMapRendererJob::cleanupJobs ( LayerRenderJobs & jobs )

protected

Note: not available in Python bindings

void QgsMapRendererJob::cleanupLabelJob ( LabelRenderJob & job )

protected

Handles clean up tasks for a label job, including deletion of images and storing cached label results.

Note: not available in Python bindings

Since: QGIS 3.0

static QImage QgsMapRendererJob::composeImage	(	const QgsMapSettings &	settings,
		const LayerRenderJobs &	jobs,
		const LabelRenderJob &	labelJob
	)

staticprotected

Note: not available in Python bindings

void QgsMapRendererJob::drawLabeling	(	const QgsMapSettings &	settings,
		QgsRenderContext &	renderContext,
		QgsLabelingEngine *	labelingEngine2,
		QPainter *	painter
	)

staticprotected

Note: not available in Python bindings

Deprecated:: Will be removed in QGIS 4.0

Definition at line 341 of file qgsmaprenderercustompainterjob.cpp.

void QgsMapRendererJob::drawLabeling	(	QgsRenderContext &	renderContext,
		QgsLabelingEngine *	labelingEngine2,
		QPainter *	painter
	)

staticprotected

Note: not available in Python bindings

Definition at line 321 of file qgsmaprenderercustompainterjob.cpp.

Errors QgsMapRendererJob::errors ( ) const

List of errors that happened during the rendering job - available when the rendering has been finished.

const QgsFeatureFilterProvider* QgsMapRendererJob::featureFilterProvider ( ) const

inline

Returns the feature filter provider used by the QgsRenderContext of each LayerRenderJob.

Since: QGIS 3.0

Definition at line 177 of file qgsmaprendererjob.h.

void QgsMapRendererJob::finished ( )

signal

emitted when asynchronous rendering is finished (or canceled).

virtual bool QgsMapRendererJob::isActive ( ) const

pure virtual

Tell whether the rendering job is currently running in background.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

void QgsMapRendererJob::logRenderingTime	(	const LayerRenderJobs &	jobs,
		const LabelRenderJob &	labelJob
	)

protected

Note: not available in Python bindings

const QgsMapSettings& QgsMapRendererJob::mapSettings ( ) const

Returns map settings with which this job was started.

Returns: A QgsMapSettings instance with render settings

Since: QGIS 2.8

QHash< QgsMapLayer *, int > QgsMapRendererJob::perLayerRenderingTime ( ) const

Returns the render time (in ms) per layer.

Note: Not available in Python bindings.

Since: QGIS 3.0

LayerRenderJobs QgsMapRendererJob::prepareJobs	(	QPainter *	painter,
		QgsLabelingEngine *	labelingEngine2
	)

protected

Note: not available in Python bindings

bool QgsMapRendererJob::prepareLabelCache ( ) const

protected

Prepares the cache for storing the result of labeling.

Returns false if the render cannot use cached labels and should not cache the result.

Note: not available in Python bindings

LabelRenderJob QgsMapRendererJob::prepareLabelingJob	(	QPainter *	painter,
		QgsLabelingEngine *	labelingEngine2,
		bool	canUseLabelCache = `true`
	)

protected

Prepares a labeling job.

Note: not available in Python bindings

Since: QGIS 3.0

void QgsMapRendererJob::renderingLayersFinished ( )

signal

Emitted when the layers are rendered.

Rendering labels is not yet done. If the fully rendered layer including labels is required use finished() instead.

Since: QGIS 3.0

int QgsMapRendererJob::renderingTime ( ) const

inline

Returns the total time it took to finish the job (in milliseconds).

See also: perLayerRenderingTime()

Definition at line 206 of file qgsmaprendererjob.h.

void QgsMapRendererJob::setCache ( QgsMapRendererCache * cache )

Assign a cache to be used for reading and storing rendered images of individual layers.

Does not take ownership of the object.

void QgsMapRendererJob::setFeatureFilterProvider ( const QgsFeatureFilterProvider * f )

inline

Set the feature filter provider used by the QgsRenderContext of each LayerRenderJob.

Ownership is not transferred and the provider must not be deleted before the render job.

Since: QGIS 3.0

Definition at line 170 of file qgsmaprendererjob.h.

virtual void QgsMapRendererJob::start ( )

pure virtual

Start the rendering job and immediately return.

Does nothing if the rendering is already in progress.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

virtual QgsLabelingResults* QgsMapRendererJob::takeLabelingResults ( )

pure virtual

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()

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

virtual bool QgsMapRendererJob::usedCachedLabels ( ) const

pure virtual

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()

Since: QGIS 3.0

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

virtual void QgsMapRendererJob::waitForFinished ( )

pure virtual

Block until the job has finished.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

Member Data Documentation

const QString QgsMapRendererJob::LABEL_CACHE_ID

static

QgsMapRendererCache ID string for cached label image.

Note: not available in Python bindings

Definition at line 226 of file qgsmaprendererjob.h.

QgsMapRendererCache* QgsMapRendererJob::mCache = nullptr

protected

Definition at line 248 of file qgsmaprendererjob.h.

Errors QgsMapRendererJob::mErrors

protected

Definition at line 246 of file qgsmaprendererjob.h.

QHash< QgsWeakMapLayerPointer, int > QgsMapRendererJob::mPerLayerRenderingTime

protected

Render time (in ms) per layer, by layer ID.

Definition at line 253 of file qgsmaprendererjob.h.

QTime QgsMapRendererJob::mRenderingStart

protected

Definition at line 245 of file qgsmaprendererjob.h.

int QgsMapRendererJob::mRenderingTime = 0

protected

Definition at line 250 of file qgsmaprendererjob.h.

QgsMapSettings QgsMapRendererJob::mSettings

protected

Definition at line 244 of file qgsmaprendererjob.h.

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

/build/qgis-3.4.15+24xenial/src/core/qgsmaprendererjob.h
/build/qgis-3.4.15+24xenial/src/core/qgsmaprenderercustompainterjob.cpp

Classes

Public Types

Signals

Public Member Functions

Static Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation