QgsMapRendererCache Class Reference

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

#include <qgsmaprenderercache.h>

Public Member Functions
	QgsMapRendererCache ()
QImage	cacheImage (QString layerId)
	get cached image for the specified layer ID. Returns null image if it is not cached.
void	clear ()
	invalidate the cache contents
void	clearCacheImage (QString layerId)
	remove layer from the cache
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

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

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

Definition at line 37 of file qgsmaprenderercache.h.

Constructor & Destructor Documentation

QgsMapRendererCache::QgsMapRendererCache

(

)

Definition at line 21 of file qgsmaprenderercache.cpp.

Member Function Documentation

QImage QgsMapRendererCache::cacheImage

(

QString

layerId

)

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

Definition at line 80 of file qgsmaprenderercache.cpp.

void QgsMapRendererCache::clear

(

)

invalidate the cache contents

Definition at line 26 of file qgsmaprenderercache.cpp.

void QgsMapRendererCache::clearCacheImage

(

QString

layerId

)

remove layer from the cache

Definition at line 93 of file qgsmaprenderercache.cpp.

void QgsMapRendererCache::clearInternal ( )

protected

invalidate cache contents (without locking)

Definition at line 32 of file qgsmaprenderercache.cpp.

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

Definition at line 49 of file qgsmaprenderercache.cpp.

void QgsMapRendererCache::layerRequestedRepaint ( )

protectedslot

remove layer (that emitted the signal) from the cache

Definition at line 86 of file qgsmaprenderercache.cpp.

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

set cached image for the specified layer ID

Definition at line 67 of file qgsmaprenderercache.cpp.

Member Data Documentation

QMap<QString, QImage> QgsMapRendererCache::mCachedImages

protected

Definition at line 72 of file qgsmaprenderercache.h.

QgsRectangle QgsMapRendererCache::mExtent

protected

Definition at line 70 of file qgsmaprenderercache.h.

QMutex QgsMapRendererCache::mMutex

protected

Definition at line 69 of file qgsmaprenderercache.h.

double QgsMapRendererCache::mScale

protected

Definition at line 71 of file qgsmaprenderercache.h.

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

• /tmp/buildd/qgis-2.8.2+12wheezy/src/core/qgsmaprenderercache.h
• /tmp/buildd/qgis-2.8.2+12wheezy/src/core/qgsmaprenderercache.cpp