Fix support for setCacheImage() to enforce refresh of a layer

python/core/qgsmaplayer.sip

@@ -209,12 +209,12 @@ class QgsMapLayer : QObject
 
         Layer definitions can be used to load a layer and styling all from a single file.
     */
-    QDomDocument asLayerDefinition ( );
+    QDomDocument asLayerDefinition( );
 
     /** Creates a new layer from a layer defininition document
     */
     static QgsMapLayer* fromLayerDefinition( QDomDocument& document );
-    static QgsMapLayer* fromLayerDefinitionFile(const QString qlrfile );
+    static QgsMapLayer* fromLayerDefinitionFile( const QString qlrfile );
 
     /** Set a custom property for layer. Properties are stored in a map and saved in project file.
      *  @note Added in v1.4 */
@@ -355,7 +355,7 @@ class QgsMapLayer : QObject
 
     /** @deprecated since 2.4 - returns NULL */
     QImage *cacheImage() /Deprecated/;
-    /** @deprecated since 2.4 - does nothing */
+    /** @deprecated since 2.4 - caches listen to repaintRequested() signal to invalidate the cached image */
     void setCacheImage( QImage * thepImage /Transfer/ ) /Deprecated/;
     /** @deprecated since 2.4 - does nothing */
     virtual void onCacheImageDelete() /Deprecated/;
@@ -377,7 +377,8 @@ class QgsMapLayer : QObject
     void toggleScaleBasedVisibility( bool theVisibilityFlag );
     bool hasScaleBasedVisibility() const;
 
-    /** @deprecated since 2.4 - does nothing */
+    /** Clear cached image
+     *  @deprecated in 2.4 - caches listen to repaintRequested() signal to invalidate the cached image */
     void clearCacheImage() /Deprecated/;
 
     /** \brief Obtain Metadata for this layer */

src/core/qgsmaplayer.cpp

@@ -1402,8 +1402,14 @@ void QgsMapLayer::setValid( bool valid )
   mValid = valid;
 }
 
+void QgsMapLayer::setCacheImage( QImage * )
+{
+  emit repaintRequested();
+}
+
 void QgsMapLayer::clearCacheImage()
 {
+  emit repaintRequested();
 }
 
 QString QgsMapLayer::metadata()

src/core/qgsmaplayer.h

@@ -222,12 +222,12 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
         Layer definitions can be used to load a layer and styling all from a single file.
     */
-    QDomDocument asLayerDefinition ( );
+    QDomDocument asLayerDefinition( );
 
     /** Creates a new layer from a layer defininition document
     */
     static QgsMapLayer* fromLayerDefinition( QDomDocument& document );
-    static QgsMapLayer* fromLayerDefinitionFile(const QString qlrfile );
+    static QgsMapLayer* fromLayerDefinitionFile( const QString qlrfile );
 
     /** Set a custom property for layer. Properties are stored in a map and saved in project file.
      *  @note Added in v1.4 */
@@ -370,8 +370,8 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
     /** @deprecated since 2.4 - returns NULL */
     Q_DECL_DEPRECATED QImage *cacheImage() { return 0; }
-    /** @deprecated since 2.4 - does nothing */
-    Q_DECL_DEPRECATED void setCacheImage( QImage * ) {}
+    /** @deprecated since 2.4 - caches listen to repaintRequested() signal to invalidate the cached image */
+    Q_DECL_DEPRECATED void setCacheImage( QImage * );
     /** @deprecated since 2.4 - does nothing */
     Q_DECL_DEPRECATED virtual void onCacheImageDelete() {}
 
@@ -393,8 +393,7 @@ class CORE_EXPORT QgsMapLayer : public QObject
     bool hasScaleBasedVisibility() const;
 
     /** Clear cached image
-     * added in 1.5 */
-    //! @deprecated in 2.4 - does nothing
+     *  @deprecated in 2.4 - caches listen to repaintRequested() signal to invalidate the cached image */
     Q_DECL_DEPRECATED void clearCacheImage();
 
     /** \brief Obtain Metadata for this layer */

src/core/qgsmaprenderercache.cpp

@@ -1,6 +1,8 @@
 
 #include "qgsmaprenderercache.h"
 
+#include "qgsmaplayerregistry.h"
+#include "qgsmaplayer.h"
 
 QgsMapRendererCache::QgsMapRendererCache()
 {
@@ -10,8 +12,23 @@ QgsMapRendererCache::QgsMapRendererCache()
 void QgsMapRendererCache::clear()
 {
   QMutexLocker lock( &mMutex );
+  clearInternal();
+}
+
+void QgsMapRendererCache::clearInternal()
+{
   mExtent.setMinimal();
   mScale = 0;
+
+  // make sure we are disconnected from all layers
+  foreach ( QString layerId, mCachedImages.keys() )
+  {
+    QgsMapLayer* layer = QgsMapLayerRegistry::instance()->mapLayer( layerId );
+    if ( layer )
+    {
+      disconnect( layer, SIGNAL( repaintRequested() ), this, SLOT( layerRequestedRepaint() ) );
+    }
+  }
   mCachedImages.clear();
 }
 
@@ -24,13 +41,12 @@ bool QgsMapRendererCache::init( QgsRectangle extent, double scale )
        scale == mScale )
     return true;
 
+  clearInternal();
+
   // set new params
   mExtent = extent;
   mScale = scale;
 
-  // invalidate cache
-  mCachedImages.clear();
-
   return false;
 }
 
@@ -38,6 +54,13 @@ void QgsMapRendererCache::setCacheImage( QString layerId, const QImage& img )
 {
   QMutexLocker lock( &mMutex );
   mCachedImages[layerId] = img;
+
+  // connect to the layer to listen to layer's repaintRequested() signals
+  QgsMapLayer* layer = QgsMapLayerRegistry::instance()->mapLayer( layerId );
+  if ( layer )
+  {
+    connect( layer, SIGNAL( repaintRequested() ), this, SLOT( layerRequestedRepaint() ) );
+  }
 }
 
 QImage QgsMapRendererCache::cacheImage( QString layerId )
@@ -46,10 +69,22 @@ QImage QgsMapRendererCache::cacheImage( QString layerId )
   return mCachedImages.value( layerId );
 }
 
-void QgsMapRendererCache::layerDataChanged()
+void QgsMapRendererCache::layerRequestedRepaint()
 {
-  // TODO!
-  qDebug( "nothing here yet" );
+  QgsMapLayer* layer = qobject_cast<QgsMapLayer*>( sender() );
+  if ( layer )
+    clearCacheImage( layer->id() );
 }
 
+void QgsMapRendererCache::clearCacheImage( QString layerId )
+{
+  QMutexLocker lock( &mMutex );
 
+  mCachedImages.remove( layerId );
+
+  QgsMapLayer* layer = QgsMapLayerRegistry::instance()->mapLayer( layerId );
+  if ( layer )
+  {
+    disconnect( layer, SIGNAL( repaintRequested() ), this, SLOT( layerRequestedRepaint() ) );
+  }
+}

src/core/qgsmaprenderercache.h

@@ -11,7 +11,11 @@
 /**
  * This class is responsible for keeping cache of rendered images of individual layers.
  *
- * The class is thread-safe (multiple classes can access the same instance safely).
+ * 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
  */
@@ -35,9 +39,16 @@ class CORE_EXPORT QgsMapRendererCache : public QObject
     //! get cached image for the specified layer ID. Returns null image if it is not cached.
     QImage cacheImage( QString layerId );
 
-  public slots:
+    //! remove layer from the cache
+    void clearCacheImage( QString layerId );
+
+  protected slots:
     //! remove layer (that emitted the signal) from the cache
-    void layerDataChanged();
+    void layerRequestedRepaint();
+
+  protected:
+    //! invalidate cache contents (without locking)
+    void clearInternal();
 
   protected:
     QMutex mMutex;

src/core/qgsmaprendererjob.cpp

@@ -589,7 +589,7 @@ LayerRenderJobs QgsMapRendererJob::prepareJobs( QPainter* painter, QgsPalLabelin
     {
       QgsVectorLayer* vl = qobject_cast<QgsVectorLayer *>( ml );
       if ( vl->isEditable() || ( labelingEngine && labelingEngine->willUseLayer( vl ) ) )
-        mCache->setCacheImage( ml->id(), QImage() );
+        mCache->clearCacheImage( ml->id() );
     }
 
     layerJobs.append( LayerRenderJob() );

src/gui/qgsmapcanvas.cpp

@@ -380,7 +380,7 @@ void QgsMapCanvas::setLayerSet( QList<QgsMapCanvasLayer> &layers )
       // Add check if vector layer when disconnecting from selectionChanged slot
       // Ticket #811 - racicot
       QgsMapLayer *currentLayer = layer( i );
-      disconnect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( layerRequestedRepaint() ) );
+      disconnect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
       QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
       if ( isVectLyr )
       {
@@ -395,7 +395,7 @@ void QgsMapCanvas::setLayerSet( QList<QgsMapCanvasLayer> &layers )
       // Add check if vector layer when connecting to selectionChanged slot
       // Ticket #811 - racicot
       QgsMapLayer *currentLayer = layer( i );
-      connect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( layerRequestedRepaint() ) );
+      connect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
       QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
       if ( isVectLyr )
       {
@@ -681,18 +681,6 @@ void QgsMapCanvas::refreshMap()
   mMapUpdateTimer.start();
 }
 
-void QgsMapCanvas::layerRequestedRepaint()
-{
-  // make sure to clear the cached image
-  if ( mCache )
-  {
-    QgsMapLayer* layer = qobject_cast<QgsMapLayer*>( sender() );
-    if ( layer )
-      mCache->setCacheImage( layer->id(), QImage() );
-  }
-
-  refresh();
-}
 
 void QgsMapCanvas::rendererJobFinished()
 {

src/gui/qgsmapcanvas.h

@@ -382,9 +382,6 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
 
     void refreshMap();
 
-    //! Layer says something has changed that affects its appearance
-    void layerRequestedRepaint();
-
   signals:
     /** Let the owner know how far we are with render operations */
     //! @deprecated since 2.4 - already unused in 2.0 anyway