QGIS API Documentation  2.5.0-Master
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Properties Friends Macros Groups Pages
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
[legend]
Collaboration diagram for QgsMapRendererCache:
Collaboration graph
[legend]

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

Definition at line 37 of file qgsmaprenderercache.h.

Constructor & Destructor Documentation

QgsMapRendererCache::QgsMapRendererCache ( )

Definition at line 21 of file qgsmaprenderercache.cpp.

References clear().

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.

References mCachedImages, and mMutex.

Referenced by QgsMapRendererJob::prepareJobs().

void QgsMapRendererCache::clear ( )

invalidate the cache contents

Definition at line 26 of file qgsmaprenderercache.cpp.

References clearInternal(), and mMutex.

Referenced by QgsMapCanvas::clearCache(), and QgsMapRendererCache().

void QgsMapRendererCache::clearCacheImage ( QString  layerId)
void QgsMapRendererCache::clearInternal ( )
protected

invalidate cache contents (without locking)

Definition at line 32 of file qgsmaprenderercache.cpp.

References QgsMapLayerRegistry::instance(), layerRequestedRepaint(), QgsMapLayerRegistry::mapLayer(), mCachedImages, mExtent, mScale, and QgsRectangle::setMinimal().

Referenced by clear(), and init().

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.

References clearInternal(), mExtent, mMutex, and mScale.

Referenced by QgsMapRendererJob::prepareJobs().

void QgsMapRendererCache::layerRequestedRepaint ( )
protectedslot

remove layer (that emitted the signal) from the cache

Definition at line 86 of file qgsmaprenderercache.cpp.

References clearCacheImage(), and QgsMapLayer::id().

Referenced by clearCacheImage(), clearInternal(), and setCacheImage().

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

set cached image for the specified layer ID

Definition at line 67 of file qgsmaprenderercache.cpp.

References QgsMapLayerRegistry::instance(), layerRequestedRepaint(), QgsMapLayerRegistry::mapLayer(), mCachedImages, and mMutex.

Referenced by QgsMapRendererJob::cleanupJobs().

Member Data Documentation

QMap<QString, QImage> QgsMapRendererCache::mCachedImages
protected

Definition at line 72 of file qgsmaprenderercache.h.

Referenced by cacheImage(), clearCacheImage(), clearInternal(), and setCacheImage().

QgsRectangle QgsMapRendererCache::mExtent
protected

Definition at line 70 of file qgsmaprenderercache.h.

Referenced by clearInternal(), and init().

QMutex QgsMapRendererCache::mMutex
protected

Definition at line 69 of file qgsmaprenderercache.h.

Referenced by cacheImage(), clear(), clearCacheImage(), init(), and setCacheImage().

double QgsMapRendererCache::mScale
protected

Definition at line 71 of file qgsmaprenderercache.h.

Referenced by clearInternal(), and init().


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