Stop using QgsMapLayer's setCacheImage()

That caching mechanism is too coarse - it is expected that there is only one map renderer.
Instead, caching would need to be done on higher level, e.g. in QgsMapCanvas

src/app/legend/qgslegend.cpp

@@ -2802,7 +2802,6 @@ void QgsLegend::legendLayerZoomNative()
     QgsDebugMsg( "Raster units per pixel  : " + QString::number( layer->rasterUnitsPerPixelX() ) );
     QgsDebugMsg( "MapUnitsPerPixel before : " + QString::number( mMapCanvas->mapUnitsPerPixel() ) );
 
-    layer->setCacheImage( NULL );
     if ( mMapCanvas->hasCrsTransformEnabled() )
     {
       // get legth of central canvas pixel width in source raster crs
@@ -2842,7 +2841,6 @@ void QgsLegend::legendLayerStretchUsingCurrentExtent()
     myRectangle = mMapCanvas->mapSettings().outputExtentToLayerExtent( layer, mMapCanvas->extent() );
     layer->setContrastEnhancement( contrastEnhancementAlgorithm, QgsRaster::ContrastEnhancementMinMax, myRectangle );
 
-    layer->setCacheImage( NULL );
     refreshLayerSymbology( layer->id() );
     mMapCanvas->refresh();
   }

src/app/qgisapp.cpp

@@ -5815,8 +5815,6 @@ void QgisApp::copyFeatures( QgsFeatureStore & featureStore )
 
 void QgisApp::refreshMapCanvas()
 {
-  //clear all caches first
-  QgsMapLayerRegistry::instance()->clearAllLayerCaches();
   //reload cached provider data
   QgsMapLayerRegistry::instance()->reloadAllLayers();
   //then refresh
@@ -6856,7 +6854,6 @@ void QgisApp::histogramStretch( bool visibleAreaOnly, QgsRaster::ContrastEnhance
 
   myRasterLayer->setContrastEnhancement( QgsContrastEnhancement::StretchToMinimumMaximum, theLimits, myRectangle );
 
-  myRasterLayer->setCacheImage( NULL );
   mMapCanvas->refresh();
 }
 
@@ -6913,7 +6910,6 @@ void QgisApp::adjustBrightnessContrast( int delta, bool updateBrightness )
     brightnessFilter->setContrast( brightnessFilter->contrast() + delta );
   }
 
-  myRasterLayer->setCacheImage( NULL );
   mMapCanvas->refresh();
 }
 

src/app/qgsrasterlayerproperties.cpp

@@ -930,9 +930,6 @@ void QgsRasterLayerProperties::apply()
   // update symbology
   emit refreshLegend( mRasterLayer->id(), false );
 
-  //no need to delete the old one, maplayer will do it if needed
-  mRasterLayer->setCacheImage( 0 );
-
   //make sure the layer is redrawn
   mRasterLayer->triggerRepaint();
 

src/app/qgsvectorlayerproperties.cpp

@@ -532,9 +532,6 @@ void QgsVectorLayerProperties::apply()
   // update symbology
   emit refreshLegend( layer->id(), QgsLegendItem::DontChange );
 
-  //no need to delete the old one, maplayer will do it if needed
-  layer->setCacheImage( 0 );
-
   layer->triggerRepaint();
   // notify the project we've made a change
   QgsProject::instance()->dirty( true );

src/core/qgsmaplayer.cpp

@@ -1341,7 +1341,6 @@ void QgsMapLayer::setValid( bool valid )
 
 void QgsMapLayer::clearCacheImage()
 {
-  setCacheImage( 0 );
 }
 
 QString QgsMapLayer::metadata()

src/core/qgsmaplayer.h

@@ -360,12 +360,12 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** Return pointer to layer's undo stack */
     QUndoStack* undoStack();
 
-    /** \note Deprecated from 2.1 - returns NULL */
-    QImage *cacheImage() { return 0; }
-    /** \note Deprecated from 2.1 - does nothing */
-    void setCacheImage( QImage * ) {}
-    /** @note Deprecated from 2.1 - does nothing */
-    virtual void onCacheImageDelete() {}
+    /** @deprecated since 2.1 - returns NULL */
+    Q_DECL_DEPRECATED QImage *cacheImage() { return 0; }
+    /** @deprecated since 2.1 - does nothing */
+    Q_DECL_DEPRECATED void setCacheImage( QImage * ) {}
+    /** @deprecated since 2.1 - does nothing */
+    Q_DECL_DEPRECATED virtual void onCacheImageDelete() {}
 
   public slots:
 
@@ -386,7 +386,8 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
     /** Clear cached image
      * added in 1.5 */
-    void clearCacheImage();
+    //! @deprecated in 2.1 - does nothing
+    Q_DECL_DEPRECATED void clearCacheImage();
 
     /** \brief Obtain Metadata for this layer */
     virtual QString metadata();

src/core/qgsmaplayerregistry.cpp

@@ -151,16 +151,9 @@ void QgsMapLayerRegistry::removeAllMapLayers()
   mMapLayers.clear();
 } // QgsMapLayerRegistry::removeAllMapLayers()
 
-//Added in QGIS 1.4
 void QgsMapLayerRegistry::clearAllLayerCaches()
 {
-  QMap<QString, QgsMapLayer *>::iterator it;
-  for ( it = mMapLayers.begin(); it != mMapLayers.end() ; ++it )
-  {
-    //the map layer will take care of deleting the QImage
-    it.value()->setCacheImage( 0 );
-  }
-} // QgsMapLayerRegistry::clearAllLayerCaches()
+}
 
 void QgsMapLayerRegistry::reloadAllLayers()
 {

src/core/qgsmaplayerregistry.h

@@ -150,7 +150,8 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
      *
      * @note Added in QGIS 1.4
      */
-    void clearAllLayerCaches();
+    //! @deprecated since 2.1 - does nothing
+    Q_DECL_DEPRECATED void clearAllLayerCaches();
 
     /**
      * Reload all provider data caches (currently used for WFS and WMS providers)

src/core/qgsmaprenderer.cpp

@@ -329,18 +329,6 @@ void QgsMapRenderer::render( QPainter* painter, double* forceWidthScale )
   if ( mLabelingEngine )
     mLabelingEngine->init( this );
 
-  // know we know if this render is just a repeat of the last time, we
-  // can clear caches if it has changed
-  if ( !mySameAsLastFlag )
-  {
-    //clear the cache pixmap if we changed resolution / extent
-    QSettings mySettings;
-    if ( mySettings.value( "/qgis/enable_render_caching", false ).toBool() )
-    {
-      QgsMapLayerRegistry::instance()->clearAllLayerCaches();
-    }
-  }
-
   // render all layers in the stack, starting at the base
   QListIterator<QString> li( mLayerSet );
   li.toBack();
@@ -439,58 +427,7 @@ void QgsMapRenderer::render( QPainter* painter, double* forceWidthScale )
         scaleRaster = true;
       }
 
-      // Force render of layers that are being edited
-      // or if there's a labeling engine that needs the layer to register features
-      if ( ml->type() == QgsMapLayer::VectorLayer )
-      {
-        QgsVectorLayer* vl = qobject_cast<QgsVectorLayer *>( ml );
-        if ( vl->isEditable() ||
-             ( mRenderContext.labelingEngine() && mRenderContext.labelingEngine()->willUseLayer( vl ) ) )
-        {
-          ml->setCacheImage( 0 );
-        }
-      }
-
       QSettings mySettings;
-      bool useRenderCaching = false;
-      if ( ! split )//render caching does not yet cater for split extents
-      {
-        if ( mySettings.value( "/qgis/enable_render_caching", false ).toBool() )
-        {
-          useRenderCaching = true;
-          if ( !mySameAsLastFlag || ml->cacheImage() == 0 )
-          {
-            QgsDebugMsg( "Caching enabled but layer redraw forced by extent change or empty cache" );
-            QImage * mypImage = new QImage( mRenderContext.painter()->device()->width(),
-                                            mRenderContext.painter()->device()->height(), QImage::Format_ARGB32 );
-            if ( mypImage->isNull() )
-            {
-              QgsDebugMsg( "insufficient memory for image " + QString::number( mRenderContext.painter()->device()->width() ) + "x" + QString::number( mRenderContext.painter()->device()->height() ) );
-              emit drawError( ml );
-              painter->end(); // drawError is not caught by anyone, so we end painting to notify caller
-              return;
-            }
-            mypImage->fill( 0 );
-            ml->setCacheImage( mypImage ); //no need to delete the old one, maplayer does it for you
-            QPainter * mypPainter = new QPainter( ml->cacheImage() );
-            // Changed to enable anti aliasing by default in QGIS 1.7
-            if ( mySettings.value( "/qgis/enable_anti_aliasing", true ).toBool() )
-            {
-              mypPainter->setRenderHint( QPainter::Antialiasing );
-            }
-            mRenderContext.setPainter( mypPainter );
-          }
-          else if ( mySameAsLastFlag )
-          {
-            //draw from cached image
-            QgsDebugMsg( "Caching enabled --- drawing layer from cached image" );
-            mypContextPainter->drawImage( 0, 0, *( ml->cacheImage() ) );
-            disconnect( ml, SIGNAL( drawingProgress( int, int ) ), this, SLOT( onDrawingProgress( int, int ) ) );
-            //short circuit as there is nothing else to do...
-            continue;
-          }
-        }
-      }
 
       // If we are drawing with an alternative blending mode then we need to render to a separate image
       // before compositing this on the map. This effectively flattens the layer and prevents
@@ -500,8 +437,7 @@ void QgsMapRenderer::render( QPainter* painter, double* forceWidthScale )
       if (( mRenderContext.useAdvancedEffects() ) && ( ml->type() == QgsMapLayer::VectorLayer ) )
       {
         QgsVectorLayer* vl = qobject_cast<QgsVectorLayer *>( ml );
-        if (( !useRenderCaching )
-            && (( vl->blendMode() != QPainter::CompositionMode_SourceOver )
+        if ( (( vl->blendMode() != QPainter::CompositionMode_SourceOver )
                 || ( vl->featureBlendMode() != QPainter::CompositionMode_SourceOver )
                 || ( vl->layerTransparency() != 0 ) ) )
         {
@@ -589,17 +525,7 @@ void QgsMapRenderer::render( QPainter* painter, double* forceWidthScale )
         }
       }
 
-      if ( useRenderCaching )
-      {
-        // composite the cached image into our view and then clean up from caching
-        // by reinstating the painter as it was swapped out for caching renders
-        delete mRenderContext.painter();
-        mRenderContext.setPainter( mypContextPainter );
-        //draw from cached image that we created further up
-        if ( ml->cacheImage() )
-          mypContextPainter->drawImage( 0, 0, *( ml->cacheImage() ) );
-      }
-      else if ( flattenedLayer )
+      if ( flattenedLayer )
       {
         // If we flattened this layer for alternate blend modes, composite it now
         delete mRenderContext.painter();

src/core/qgsvectorlayer.cpp

@@ -133,7 +133,6 @@ QgsVectorLayer::QgsVectorLayer( QString vectorLayerPath,
     , mDiagramLayerSettings( 0 )
     , mValidExtent( false )
     , mSymbolFeatureCounted( false )
-    , mCurrentRendererContext( 0 )
 
 {
   mActions = new QgsAttributeAction( this );
@@ -388,8 +387,6 @@ void QgsVectorLayer::drawRendererV2( QgsFeatureIterator &fit, QgsRenderContext&
   if ( !hasGeometryType() )
     return;
 
-  mCurrentRendererContext = &rendererContext;
-
   QSettings settings;
   bool vertexMarkerOnlyForSelection = settings.value( "/qgis/digitizing/marker_only_for_selected", false ).toBool();
 
@@ -441,8 +438,6 @@ void QgsVectorLayer::drawRendererV2( QgsFeatureIterator &fit, QgsRenderContext&
   }
 
   stopRendererV2( rendererContext, NULL );
-
-  mCurrentRendererContext = NULL;
 }
 
 void QgsVectorLayer::drawRendererV2Levels( QgsFeatureIterator &fit, QgsRenderContext& rendererContext, bool labeling )
@@ -647,7 +642,6 @@ void QgsVectorLayer::select( const QgsFeatureId& fid )
 {
   mSelectedFeatureIds.insert( fid );
 
-  setCacheImage( 0 );
   emit selectionChanged( QgsFeatureIds() << fid, QgsFeatureIds(), false );
 }
 
@@ -655,7 +649,6 @@ void QgsVectorLayer::select( const QgsFeatureIds& featureIds )
 {
   mSelectedFeatureIds.unite( featureIds );
 
-  setCacheImage( 0 );
   emit selectionChanged( featureIds, QgsFeatureIds(), false );
 }
 
@@ -663,7 +656,6 @@ void QgsVectorLayer::deselect( const QgsFeatureId fid )
 {
   mSelectedFeatureIds.remove( fid );
 
-  setCacheImage( 0 );
   emit selectionChanged( QgsFeatureIds(), QgsFeatureIds() << fid, false );
 }
 
@@ -671,7 +663,6 @@ void QgsVectorLayer::deselect( const QgsFeatureIds& featureIds )
 {
   mSelectedFeatureIds.subtract( featureIds );
 
-  setCacheImage( 0 );
   emit selectionChanged( QgsFeatureIds(), featureIds, false );
 }
 
@@ -715,8 +706,6 @@ void QgsVectorLayer::modifySelection( QgsFeatureIds selectIds, QgsFeatureIds des
   mSelectedFeatureIds -= deselectIds;
   mSelectedFeatureIds += selectIds;
 
-  setCacheImage( 0 );
-
   emit selectionChanged( selectIds, deselectIds - intersectingIds, false );
 }
 
@@ -1127,9 +1116,6 @@ bool QgsVectorLayer::setSubsetString( QString subset )
   mDataSource = mDataProvider->dataSourceUri();
   updateExtents();
 
-  if ( res )
-    setCacheImage( 0 );
-
   return res;
 }
 
@@ -1252,8 +1238,6 @@ bool QgsVectorLayer::deleteSelectedFeatures()
     deleteFeature( fid );  // removes from selection
   }
 
-  // invalidate cache
-  setCacheImage( 0 );
   triggerRepaint();
   updateExtents();
 
@@ -2572,9 +2556,6 @@ bool QgsVectorLayer::commitChanges()
   updateFields();
   mDataProvider->updateExtents();
 
-  //clear the cache image so markers don't appear anymore on next draw
-  setCacheImage( 0 );
-
   return success;
 }
 
@@ -2616,9 +2597,6 @@ bool QgsVectorLayer::rollBack( bool deleteBuffer )
     mCache->deleteCachedGeometries();
   }
 
-  // invalidate the cache so the layer updates properly to show its original
-  // after the rollback
-  setCacheImage( 0 );
   return true;
 }
 
@@ -2642,9 +2620,6 @@ void QgsVectorLayer::setSelectedFeatures( const QgsFeatureIds& ids )
     }
   }
 
-  // invalidate cache
-  setCacheImage( 0 );
-
   emit selectionChanged( ids, deselectedFeatures, true );
 }
 
@@ -3763,12 +3738,6 @@ QString QgsVectorLayer::metadata()
   return myMetadata;
 }
 
-void QgsVectorLayer::onCacheImageDelete()
-{
-  if ( mCurrentRendererContext )
-    mCurrentRendererContext->setRenderingStopped( true );
-}
-
 void QgsVectorLayer::invalidateSymbolCountedFlag()
 {
   mSymbolFeatureCounted = false;

src/core/qgsvectorlayer.h

@@ -1418,12 +1418,6 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
       @note added in 1.7 */
     void checkJoinLayerRemove( QString theLayerId );
 
-    /**
-     * @brief Is called when the cache image is being deleted. Overwrite and use to clean up.
-     * @note added in 2.0
-     */
-    virtual void onCacheImageDelete();
-
   protected slots:
     void invalidateSymbolCountedFlag();
 
@@ -1575,8 +1569,6 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     /** Pointer to data provider derived from the abastract base class QgsDataProvider */
     QgsVectorDataProvider *mDataProvider;
 
-    QgsFeatureIterator mProviderIterator;
-
     /** index of the primary label field */
     QString mDisplayField;
 
@@ -1696,8 +1688,6 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     // Feature counts for each renderer symbol
     QMap<QgsSymbolV2*, long> mSymbolFeatureCountMap;
 
-    QgsRenderContext* mCurrentRendererContext;
-
     friend class QgsVectorLayerFeatureIterator;
 };
 

src/plugins/georeferencer/qgsgeorefplugingui.cpp

@@ -633,7 +633,6 @@ void QgsGeorefPluginGui::showGeorefConfigDialog()
 void QgsGeorefPluginGui::fullHistogramStretch()
 {
   mLayer->setContrastEnhancement( QgsContrastEnhancement::StretchToMinimumMaximum );
-  mLayer->setCacheImage( NULL );
   mCanvas->refresh();
 }
 
@@ -642,7 +641,6 @@ void QgsGeorefPluginGui::localHistogramStretch()
   QgsRectangle rectangle = mIface->mapCanvas()->mapSettings().outputExtentToLayerExtent( mLayer, mIface->mapCanvas()->extent() );
 
   mLayer->setContrastEnhancement( QgsContrastEnhancement::StretchToMinimumMaximum, QgsRaster::ContrastEnhancementMinMax, rectangle );
-  mLayer->setCacheImage( NULL );
   mCanvas->refresh();
 }