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

#include <qgsmaprendererjob.h>

Inheritance diagram for QgsMapRendererJob:

Classes
struct	Error

Public Types
typedef QList< Error >	Errors

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

Public Member Functions
	QgsMapRendererJob (const QgsMapSettings &settings)
virtual	~QgsMapRendererJob ()
virtual void	start ()=0
	Start the rendering job and immediately return.
virtual void	cancel ()=0
	Stop the rendering job - does not return until the job has terminated.
virtual void	waitForFinished ()=0
	Block until the job has finished.
virtual bool	isActive () const =0
	Tell whether the rendering job is currently running in background.
virtual QgsLabelingResults *	takeLabelingResults ()=0
	Get pointer to internal labeling engine (in order to get access to the results)
Errors	errors () const
	List of errors that happened during the rendering job - available when the rendering has been finished.
void	setCache (QgsMapRendererCache *cache)
	Assign a cache to be used for reading and storing rendered images of individual layers.
void	setRequestedGeometryCacheForLayers (const QStringList &layerIds)
	Set which vector layers should be cached while rendering.
int	renderingTime () const
	Find out how log it took to finish the job (in miliseconds)

Protected Member Functions
LayerRenderJobs	prepareJobs (QPainter painter, QgsPalLabeling labelingEngine)
void	cleanupJobs (LayerRenderJobs &jobs)
bool	needTemporaryImage (QgsMapLayer *ml)
void	updateLayerGeometryCaches ()
	called when rendering has finished to update all layers' geometry caches

Static Protected Member Functions
static bool	reprojectToLayerExtent (const QgsCoordinateTransform *ct, bool layerCrsGeographic, QgsRectangle &extent, QgsRectangle &r2)
	Convenience function to project an extent into the layer source CRS, but also split it into two extents if it crosses the +/- 180 degree line.
static QImage	composeImage (const QgsMapSettings &settings, const LayerRenderJobs &jobs)
static void	drawLabeling (const QgsMapSettings &settings, QgsRenderContext &renderContext, QgsPalLabeling labelingEngine, QPainter painter)
static void	drawOldLabeling (const QgsMapSettings &settings, QgsRenderContext &renderContext)
static void	drawNewLabeling (const QgsMapSettings &settings, QgsRenderContext &renderContext, QgsPalLabeling *labelingEngine)

Protected Attributes
QgsMapSettings	mSettings
Errors	mErrors
QgsMapRendererCache *	mCache
QStringList	mRequestedGeomCacheForLayers
	list of layer IDs for which the geometry cache should be updated
QMap< QString, QgsGeometryCache >	mGeometryCaches
	map of geometry caches
QTime	mRenderingStart
int	mRenderingTime

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

Note: added in 2.4

Member Typedef Documentation

typedef QList<Error> QgsMapRendererJob::Errors

Constructor & Destructor Documentation

QgsMapRendererJob::QgsMapRendererJob ( const QgsMapSettings & settings )

virtual QgsMapRendererJob::~QgsMapRendererJob ( )

inlinevirtual

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.

void QgsMapRendererJob::cleanupJobs ( LayerRenderJobs & jobs )

protected

Note: not available in python bindings

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

staticprotected

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

staticprotected

void QgsMapRendererJob::drawNewLabeling	(	const QgsMapSettings &	settings,
		QgsRenderContext &	renderContext,
		QgsPalLabeling *	labelingEngine
	)

staticprotected

void QgsMapRendererJob::drawOldLabeling	(	const QgsMapSettings &	settings,
		QgsRenderContext &	renderContext
	)

staticprotected

QgsMapRendererJob::Errors QgsMapRendererJob::errors ( ) const

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

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.

bool QgsMapRendererJob::needTemporaryImage ( QgsMapLayer * ml )

protected

LayerRenderJobs QgsMapRendererJob::prepareJobs	(	QPainter *	painter,
		QgsPalLabeling *	labelingEngine
	)

protected

Note: not available in python bindings

int QgsMapRendererJob::renderingTime ( ) const

inline

Find out how log it took to finish the job (in miliseconds)

bool QgsMapRendererJob::reprojectToLayerExtent	(	const QgsCoordinateTransform *	ct,
		bool	layerCrsGeographic,
		QgsRectangle &	extent,
		QgsRectangle &	r2
	)

staticprotected

Convenience function to project an extent into the layer source CRS, but also split it into two extents if it crosses the +/- 180 degree line.

Modifies the given extent to be in the source CRS coordinates, and if it was split, returns true, and also sets the contents of the r2 parameter

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::setRequestedGeometryCacheForLayers ( const QStringList & layerIds )

inline

Set which vector layers should be cached while rendering.

Note: The way how geometries are cached is really suboptimal - this method may be removed in future releases

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

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

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

void QgsMapRendererJob::updateLayerGeometryCaches ( )

protected

called when rendering has finished to update all layers' geometry caches

virtual void QgsMapRendererJob::waitForFinished ( )

pure virtual

Block until the job has finished.

Implemented in QgsMapRendererCustomPainterJob, QgsMapRendererSequentialJob, and QgsMapRendererParallelJob.

Member Data Documentation

QgsMapRendererCache* QgsMapRendererJob::mCache

protected

Errors QgsMapRendererJob::mErrors

protected

QMap<QString, QgsGeometryCache> QgsMapRendererJob::mGeometryCaches

protected

map of geometry caches

QTime QgsMapRendererJob::mRenderingStart

protected

int QgsMapRendererJob::mRenderingTime

protected

QStringList QgsMapRendererJob::mRequestedGeomCacheForLayers

protected

list of layer IDs for which the geometry cache should be updated

QgsMapSettings QgsMapRendererJob::mSettings

protected

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

/tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaprendererjob.h
/tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaprenderercustompainterjob.cpp
/tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaprendererjob.cpp

Classes

Public Types

Signals

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation