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QgsMapRendererJob Class Reference

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

#include <qgsmaprendererjob.h>

Inheritance diagram for QgsMapRendererJob:
Inheritance graph
[legend]

Classes

struct  Error

Public Types

typedef QList< ErrorErrors

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 QgsLabelingResultstakeLabelingResults ()=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
QgsMapRendererCachemCache
QStringList mRequestedGeomCacheForLayers
 list of layer IDs for which the geometry cache should be updated
QMap< QString, QgsGeometryCachemGeometryCaches
 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, ...)

  1. create QgsMapRendererJob subclass with QgsMapSettings instance
  2. connect to job's finished() signal
  3. call start(). Map rendering will start in background, the function immediately returns
  4. 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:

Note
added in 2.4

Member Typedef Documentation

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: