QgsMapRendererCache Class Reference

This class is responsible for keeping cache of rendered images of individual layers. More...

#include <qgsmaprenderercache.h>

Public Member Functions
	QgsMapRendererCache ()
void	clear ()
	invalidate the cache contents
bool	init (QgsRectangle extent, double scale)
	initialize cache: set new parameters and erase cache if parameters have changed
void	setCacheImage (QString layerId, const QImage &img)
	set cached image for the specified layer ID
QImage	cacheImage (QString layerId)
	get cached image for the specified layer ID. Returns null image if it is not cached.
void	clearCacheImage (QString layerId)
	remove layer from the cache

Protected Slots
void	layerRequestedRepaint ()
	remove layer (that emitted the signal) from the cache

Protected Member Functions
void	clearInternal ()
	invalidate cache contents (without locking)

Protected Attributes
QMutex	mMutex
QgsRectangle	mExtent
double	mScale
QMap< QString, QImage >	mCachedImages

Detailed Description

This class is responsible for keeping cache of rendered images of individual layers.

Once a layer has rendered image stored in the cache (using setCacheImage(...)), the cache listens to repaintRequested() signals from layer. If triggered, the cache removes the rendered image (and disconnects from the layer).

The class is thread-safe (multiple classes can access the same instance safely).

Note

added in 2.4

Constructor & Destructor Documentation

QgsMapRendererCache::QgsMapRendererCache

(

)

Member Function Documentation

QImage QgsMapRendererCache::cacheImage

(

QString

layerId

)

get cached image for the specified layer ID. Returns null image if it is not cached.

void QgsMapRendererCache::clear

(

)

invalidate the cache contents

void QgsMapRendererCache::clearCacheImage

(

QString

layerId

)

remove layer from the cache

void QgsMapRendererCache::clearInternal ( )

protected

invalidate cache contents (without locking)

bool QgsMapRendererCache::init	(	QgsRectangle	extent,
		double	scale
	)

initialize cache: set new parameters and erase cache if parameters have changed

Returns

flag whether the parameters are the same as last time

void QgsMapRendererCache::layerRequestedRepaint ( )

protectedslot

remove layer (that emitted the signal) from the cache

void QgsMapRendererCache::setCacheImage	(	QString	layerId,
		const QImage &	img
	)

set cached image for the specified layer ID

Member Data Documentation

QMap<QString, QImage> QgsMapRendererCache::mCachedImages

protected

QgsRectangle QgsMapRendererCache::mExtent

protected

QMutex QgsMapRendererCache::mMutex

protected

double QgsMapRendererCache::mScale

protected

---

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

• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaprenderercache.h
• /tmp/buildd/qgis-2.6.0+wheezy1/src/core/qgsmaprenderercache.cpp