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Public Member Functions | Protected Slots | Protected Member Functions | Protected Attributes | List of all members
QgsMapRendererCache Class Reference

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

#include <qgsmaprenderercache.h>

Inheritance diagram for QgsMapRendererCache:
Inheritance graph
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Public Member Functions

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

Protected Slots

void layerRequestedRepaint ()
 remove layer (that emitted the signal) from the cache More...
 

Protected Member Functions

void clearInternal ()
 invalidate cache contents (without locking) More...
 

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: