[FEATURE] Applied patch from #1974 to enable render caching capability in QGIS. This speeds up common operations such as layer re-ordering, changing symbology, WMS / WFS client, hiding / showing layers and opens the door for future enhancements such as threaded rendering and pre-compositing layer cache manipulation.

git-svn-id: http://svn.osgeo.org/qgis/trunk@11831 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: timlinux

python/core/qgsmaplayer.sip

@@ -252,6 +252,13 @@ public:
     /** Return pointer to layer's undo stack */
     QUndoStack* undoStack();
 
+    /** Get the QImage used for caching render operations
+     * @note This method was added in QGIS 1.4 **/
+    QImage * cacheImage() { return mpCacheImage; }
+    /** Set the QImage used for caching render operations 
+     * @note This method was added in QGIS 1.4 **/
+    void setCacheImage( QImage * thepImage ); 
+
 public slots:
 
     /** Event handler for when a coordinate transform fails due to bad vertex error */

python/core/qgsmaplayerregistry.sip

@@ -59,6 +59,14 @@ public:
  */
  void removeAllMapLayers();
 
+ /* Clears all layer caches, resetting them to zero and 
+ * freeing up any memory they may have been using. Layer
+ * caches are used to speed up rendering in certain situations
+ * see ticket #1974 for more details.
+ * @note this method was added in QGIS 1.4
+ */
+ void clearAllLayerCaches();
+
 signals:
 
     /** emitted when a layer is removed from the registry

src/app/qgisapp.cpp

@@ -4476,6 +4476,9 @@ void QgisApp::pasteTransformations()
 
 void QgisApp::refreshMapCanvas()
 {
+  //clear all caches first
+  QgsMapLayerRegistry::instance()->clearAllLayerCaches();
+  //then refresh
   mMapCanvas->refresh();
 }
 

src/app/qgsoptions.cpp

@@ -149,6 +149,7 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WFlags fl ) :
 
   //set the state of the checkboxes
   chkAntiAliasing->setChecked( settings.value( "/qgis/enable_anti_aliasing", false ).toBool() );
+  chkUseRenderCaching->setChecked( settings.value( "/qgis/enable_render_caching", false ).toBool() );
 
   // Slightly awkard here at the settings value is true to use QImage,
   // but the checkbox is true to use QPixmap
@@ -365,6 +366,7 @@ void QgsOptions::saveOptions()
   settings.setValue( "/qgis/addPostgisDC", cbxAddPostgisDC->isChecked() );
   settings.setValue( "/qgis/new_layers_visible", chkAddedVisibility->isChecked() );
   settings.setValue( "/qgis/enable_anti_aliasing", chkAntiAliasing->isChecked() );
+  settings.setValue( "/qgis/enable_render_caching", chkUseRenderCaching->isChecked() );
   settings.setValue( "/qgis/use_qimage_to_render", !( chkUseQPixmap->isChecked() ) );
   settings.setValue( "qgis/capitaliseLayerName", capitaliseCheckBox->isChecked() );
   settings.setValue( "qgis/askToSaveProjectChanges", chbAskToSaveProjectChanges->isChecked() );
@@ -530,7 +532,9 @@ void QgsOptions::on_chkAntiAliasing_stateChanged()
   // used (we we can. but it then doesn't do anti-aliasing, and this
   // will confuse people).
   if ( chkAntiAliasing->isChecked() )
+  {
     chkUseQPixmap->setChecked( false );
+  }
 
 }
 
@@ -540,7 +544,9 @@ void QgsOptions::on_chkUseQPixmap_stateChanged()
   // used (we we can. but it then doesn't do anti-aliasing, and this
   // will confuse people).
   if ( chkUseQPixmap->isChecked() )
+  {
     chkAntiAliasing->setChecked( false );
+  }
 
 }
 

src/app/qgsrasterlayerproperties.cpp

@@ -1439,6 +1439,9 @@ void QgsRasterLayerProperties::apply()
   // update symbology
   emit refreshLegend( mRasterLayer->getLayerID(), 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

@@ -658,6 +658,9 @@ void QgsVectorLayerProperties::apply()
   // update symbology
   emit refreshLegend( layer->getLayerID(), false );
 
+  //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

@@ -75,13 +75,18 @@ QgsMapLayer::QgsMapLayer( QgsMapLayer::LayerType type,
   mMinScale = 0;
   mMaxScale = 100000000;
   mScaleBasedVisibility = false;
+  mpCacheImage = 0;
 }
 
 
 
 QgsMapLayer::~QgsMapLayer()
 {
   delete mCRS;
+  if ( mpCacheImage ) 
+  { 
+    delete mpCacheImage; 
+  }  
 }
 
 QgsMapLayer::LayerType QgsMapLayer::type() const
@@ -729,3 +734,13 @@ QUndoStack* QgsMapLayer::undoStack()
 {
   return &mUndoStack;
 }
+
+void QgsMapLayer::setCacheImage( QImage * thepImage ) 
+{ 
+  QgsDebugMsg( "cache Image set!" );
+  if ( mpCacheImage ) 
+  { 
+    delete mpCacheImage; 
+  }  
+  mpCacheImage = thepImage; 
+}

src/core/qgsmaplayer.h

@@ -24,6 +24,7 @@
 
 #include <QObject>
 #include <QUndoStack>
+#include <QImage>
 
 #include "qgsrectangle.h"
 
@@ -263,6 +264,13 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** Return pointer to layer's undo stack */
     QUndoStack* undoStack();
 
+    /** Get the QImage used for caching render operations
+     * @note This method was added in QGIS 1.4 **/
+    QImage * cacheImage() { return mpCacheImage; }
+    /** Set the QImage used for caching render operations 
+     * @note This method was added in QGIS 1.4 **/
+    void setCacheImage( QImage * thepImage ); 
+
   public slots:
 
     /** Event handler for when a coordinate transform fails due to bad vertex error */
@@ -360,8 +368,13 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** A flag that tells us whether to use the above vars to restrict layer visibility */
     bool mScaleBasedVisibility;
 
+    /** Collection of undoable operations for this layer. **/
     QUndoStack mUndoStack;
 
+    /**QImage for caching of rendering operations
+     * @note This property was added in QGIS 1.4 **/
+    QImage * mpCacheImage;
+
 };
 
 #endif

src/core/qgsmaplayerregistry.cpp

@@ -118,6 +118,16 @@ void QgsMapLayerRegistry::removeAllMapLayers()
 
 } // 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()
 
 QMap<QString, QgsMapLayer*> & QgsMapLayerRegistry::mapLayers()
 {

src/core/qgsmaplayerregistry.h

@@ -82,6 +82,13 @@ class CORE_EXPORT QgsMapLayerRegistry : public QObject
     */
     void removeAllMapLayers();
 
+    /* Clears all layer caches, resetting them to zero and 
+     * freeing up any memory they may have been using. Layer
+     * caches are used to speed up rendering in certain situations
+     * see ticket #1974 for more details.
+     * @note this method was added in QGIS 1.4
+     */
+     void clearAllLayerCaches();
   signals:
 
     /** emitted when a layer is removed from the registry