Avoid style dock flashing when editing layers

Also prevent a lot of duplicate style dock updates, and fix
the style dock losing connection to layer style changes

Author: nyalldawson

python/core/qgsmaplayer.sip

@@ -618,6 +618,11 @@ class QgsMapLayer : QObject
     /** Time stamp of data source in the moment when data/metadata were loaded by provider */
     virtual QDateTime timestamp() const;
 
+    /** Triggers an emission of the styleChanged() signal.
+     * @note added in QGIS 2.16
+     */
+    void emitStyleChanged();
+
   signals:
 
     //! @deprecated in 2.4 - not emitted anymore
@@ -649,9 +654,19 @@ class QgsMapLayer : QObject
     /** Signal emitted when the blend mode is changed, through QgsMapLayer::setBlendMode() */
     void blendModeChanged( QPainter::CompositionMode blendMode );
 
-    /** Signal emitted when renderer is changed */
+    /** Signal emitted when renderer is changed.
+     * @see styleChanged()
+    */
     void rendererChanged();
 
+    /** Signal emitted whenever a change affects the layer's style. Ie this may be triggered
+     * by renderer changes, label style changes, or other style changes such as blend
+     * mode or layer opacity changes.
+     * @note added in QGIS 2.16
+     * @see rendererChanged()
+    */
+    void styleChanged();
+
     /**
      * Signal emitted when legend of the layer has changed
      * @note added in 2.6

src/app/qgisapp.cpp

@@ -11345,10 +11345,14 @@ void QgisApp::showLayerProperties( QgsMapLayer *ml )
       vlp->addPropertiesPageFactory( factory );
     }
 
+    mMapStyleWidget->blockUpdates( true );
     if ( vlp->exec() )
     {
       activateDeactivateLayerRelatedActions( ml );
+      mMapStyleWidget->updateCurrentWidgetLayer();
     }
+    mMapStyleWidget->blockUpdates( false );
+
     delete vlp; // delete since dialog cannot be reused without updating code
   }
   else if ( ml->type() == QgsMapLayer::PluginLayer )

src/app/qgsapplayertreeviewmenuprovider.cpp

@@ -511,7 +511,7 @@ void QgsAppLayerTreeViewMenuProvider::setVectorSymbolColor( const QColor& color
     return;
 
   QString layerId = action->property( "layerId" ).toString();
-  QgsVectorLayer* layer = dynamic_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( layerId ) );
+  QgsVectorLayer* layer = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( layerId ) );
   if ( !layer )
     return;
 
@@ -545,6 +545,7 @@ void QgsAppLayerTreeViewMenuProvider::setVectorSymbolColor( const QColor& color
   }
 
   layer->triggerRepaint();
+  layer->emitStyleChanged();
   mView->refreshLayerSymbology( layer->id() );
 }
 
@@ -573,6 +574,10 @@ void QgsAppLayerTreeViewMenuProvider::editSymbolLegendNodeSymbol()
   if ( dlg.exec() )
   {
     node->setSymbol( symbol.take() );
+    if ( vlayer )
+    {
+      vlayer->emitStyleChanged();
+    }
   }
 }
 
@@ -596,4 +601,8 @@ void QgsAppLayerTreeViewMenuProvider::setSymbolLegendNodeColor( const QColor &co
   QgsSymbolV2* newSymbol = originalSymbol->clone();
   newSymbol->setColor( color );
   node->setSymbol( newSymbol );
+  if ( QgsVectorLayer* layer = qobject_cast<QgsVectorLayer*>( QgsMapLayerRegistry::instance()->mapLayer( layerId ) ) )
+  {
+    layer->emitStyleChanged();
+  }
 }

src/app/qgslayerstylingwidget.cpp

@@ -95,13 +95,37 @@ void QgsLayerStylingWidget::setPageFactories( QList<QgsLayerStylingPanelFactory
   mPageFactories.append( mStyleManagerFactory );
 }
 
+void QgsLayerStylingWidget::blockUpdates( bool blocked )
+{
+  if ( !mCurrentLayer )
+    return;
+
+  if ( blocked )
+  {
+    disconnect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  }
+  else
+  {
+    connect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  }
+}
+
 void QgsLayerStylingWidget::setLayer( QgsMapLayer *layer )
 {
+  if ( layer == mCurrentLayer )
+    return;
+
+  if ( mCurrentLayer )
+  {
+    disconnect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  }
+
   if ( !layer || !layer->isSpatial() )
   {
     mLayerCombo->setLayer( nullptr );
     mStackedWidget->setCurrentIndex( mNotSupportedPage );
     mLastStyleXml.clear();
+    mCurrentLayer = nullptr;
     return;
   }
 
@@ -112,9 +136,10 @@ void QgsLayerStylingWidget::setLayer( QgsMapLayer *layer )
   }
 
   mCurrentLayer = layer;
-  connect( mCurrentLayer, SIGNAL( repaintRequested() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  connect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
 
   int lastPage = mOptionsListWidget->currentIndex().row();
+  mOptionsListWidget->blockSignals( true );
   mOptionsListWidget->clear();
   mUserPages.clear();
   if ( layer->type() == QgsMapLayer::VectorLayer )
@@ -140,6 +165,7 @@ void QgsLayerStylingWidget::setLayer( QgsMapLayer *layer )
     }
   }
   mOptionsListWidget->addItem( new QListWidgetItem( QgsApplication::getThemeIcon( "mActionHistory.svg" ), "" ) );
+  mOptionsListWidget->blockSignals( false );
 
   if ( sameLayerType )
   {
@@ -164,7 +190,7 @@ void QgsLayerStylingWidget::apply()
   if ( !mCurrentLayer )
     return;
 
-  disconnect( mCurrentLayer, SIGNAL( repaintRequested() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  disconnect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
 
   QString undoName = "Style Change";
 
@@ -213,7 +239,7 @@ void QgsLayerStylingWidget::apply()
     mMapCanvas->clearCache();
     mMapCanvas->refresh();
   }
-  disconnect( mCurrentLayer, SIGNAL( repaintRequested() ), this, SLOT( updateCurrentWidgetLayer() ) );
+  connect( mCurrentLayer, SIGNAL( styleChanged() ), this, SLOT( updateCurrentWidgetLayer() ) );
 }
 
 void QgsLayerStylingWidget::autoApply()
@@ -374,8 +400,7 @@ void QgsLayerStylingWidget::layerAboutToBeRemoved( QgsMapLayer* layer )
   if ( layer == mCurrentLayer )
   {
     mAutoApplyTimer->stop();
-    mStackedWidget->setCurrentIndex( mNotSupportedPage );
-    mCurrentLayer = nullptr;
+    setLayer( nullptr );
   }
 }
 

src/app/qgslayerstylingwidget.h

@@ -72,6 +72,13 @@ class APP_EXPORT QgsLayerStylingWidget : public QWidget, private Ui::QgsLayerSty
 
     void setPageFactories( QList<QgsLayerStylingPanelFactory*> factories );
 
+    /** Sets whether updates of the styling widget are blocked. This can be called to prevent
+     * the widget being refreshed multiple times when a batch of layer style changes are
+     * about to be applied
+     * @param blocked set to true to block updates, or false to re-allow updates
+     */
+    void blockUpdates( bool blocked );
+
   signals:
     void styleChanged( QgsMapLayer* layer );
 
@@ -81,9 +88,10 @@ class APP_EXPORT QgsLayerStylingWidget : public QWidget, private Ui::QgsLayerSty
     void autoApply();
     void undo();
     void redo();
+    void updateCurrentWidgetLayer();
 
   private slots:
-    void updateCurrentWidgetLayer();
+
     void layerAboutToBeRemoved( QgsMapLayer* layer );
     void liveApplyToggled( bool value );
 

src/core/qgsmaplayer.cpp

@@ -147,6 +147,7 @@ void QgsMapLayer::setBlendMode( QPainter::CompositionMode blendMode )
 {
   mBlendMode = blendMode;
   emit blendModeChanged( blendMode );
+  emit styleChanged();
 }
 
 /** Read blend mode for layer */
@@ -1707,6 +1708,11 @@ QString QgsMapLayer::metadata()
   return QString();
 }
 
+void QgsMapLayer::emitStyleChanged()
+{
+  emit styleChanged();
+}
+
 void QgsMapLayer::setExtent( const QgsRectangle &r )
 {
   mExtent = r;

src/core/qgsmaplayer.h

@@ -638,6 +638,11 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** Time stamp of data source in the moment when data/metadata were loaded by provider */
     virtual QDateTime timestamp() const { return QDateTime() ; }
 
+    /** Triggers an emission of the styleChanged() signal.
+     * @note added in QGIS 2.16
+     */
+    void emitStyleChanged();
+
   signals:
 
     //! @deprecated in 2.4 - not emitted anymore
@@ -669,9 +674,19 @@ class CORE_EXPORT QgsMapLayer : public QObject
     /** Signal emitted when the blend mode is changed, through QgsMapLayer::setBlendMode() */
     void blendModeChanged( QPainter::CompositionMode blendMode );
 
-    /** Signal emitted when renderer is changed */
+    /** Signal emitted when renderer is changed.
+     * @see styleChanged()
+    */
     void rendererChanged();
 
+    /** Signal emitted whenever a change affects the layer's style. Ie this may be triggered
+     * by renderer changes, label style changes, or other style changes such as blend
+     * mode or layer opacity changes.
+     * @note added in QGIS 2.16
+     * @see rendererChanged()
+    */
+    void styleChanged();
+
     /**
      * Signal emitted when legend of the layer has changed
      * @note added in 2.6

src/core/qgspallabeling.cpp

@@ -1244,10 +1244,9 @@ void QgsPalLayerSettings::writeToLayer( QgsVectorLayer* layer )
   layer->setCustomProperty( "labeling/zIndex", zIndex );
 
   writeDataDefinedPropertyMap( layer, nullptr, dataDefinedProperties );
+  layer->emitStyleChanged();
 }
 
-
-
 void QgsPalLayerSettings::readXml( QDomElement& elem )
 {
   enabled = true;

src/core/qgsvectorlayer.cpp

@@ -659,6 +659,7 @@ void QgsVectorLayer::setDiagramRenderer( QgsDiagramRendererV2* r )
   delete mDiagramRenderer;
   mDiagramRenderer = r;
   emit rendererChanged();
+  emit styleChanged();
 }
 
 QGis::GeometryType QgsVectorLayer::geometryType() const
@@ -2964,6 +2965,7 @@ void QgsVectorLayer::setRendererV2( QgsFeatureRendererV2 *r )
     mSymbolFeatureCountMap.clear();
 
     emit rendererChanged();
+    emit styleChanged();
   }
 }
 
@@ -3469,6 +3471,7 @@ void QgsVectorLayer::setFeatureBlendMode( QPainter::CompositionMode featureBlend
 {
   mFeatureBlendMode = featureBlendMode;
   emit featureBlendModeChanged( featureBlendMode );
+  emit styleChanged();
 }
 
 /** Read blend mode for layer */
@@ -3482,6 +3485,7 @@ void QgsVectorLayer::setLayerTransparency( int layerTransparency )
 {
   mLayerTransparency = layerTransparency;
   emit layerTransparencyChanged( layerTransparency );
+  emit styleChanged();
 }
 
 /** Read transparency for layer */

src/core/raster/qgsrasterlayer.cpp

@@ -936,6 +936,7 @@ void QgsRasterLayer::setContrastEnhancement( QgsContrastEnhancement::ContrastEnh
   qDeleteAll( myEnhancements );
 
   emit repaintRequested();
+  emit styleChanged();
 }
 
 void QgsRasterLayer::setDefaultContrastEnhancement()
@@ -1076,6 +1077,7 @@ void QgsRasterLayer::setRenderer( QgsRasterRenderer* theRenderer )
   if ( !theRenderer ) { return; }
   mPipe.set( theRenderer );
   emit rendererChanged();
+  emit styleChanged();
 }
 
 void QgsRasterLayer::showProgress( int theValue )