Merge pull request #4111 from nyalldawson/refresh_layers

[FEATURE] Allow layers to be automatically refreshed at a specified interval

python/core/qgsmaplayer.sip

@@ -603,6 +603,11 @@ class QgsMapLayer : QObject
      */
     bool hasScaleBasedVisibility() const;
 
+    bool hasAutoRefreshEnabled() const;
+    int autoRefreshInterval() const;
+    void setAutoRefreshInterval( int interval );
+    void setAutoRefreshEnabled( bool enabled );
+
   public slots:
 
     /** Event handler for when a coordinate transform fails due to bad vertex error */
@@ -634,13 +639,7 @@ class QgsMapLayer : QObject
      */
     void setScaleBasedVisibility( const bool enabled );
 
-    /**
-     * Will advice the map canvas (and any other interested party) that this layer requires to be repainted.
-     * Will emit a repaintRequested() signal.
-     *
-     * @note in 2.6 function moved from vector/raster subclasses to QgsMapLayer
-     */
-    void triggerRepaint();
+    void triggerRepaint( bool deferredUpdate = false );
 
     /** \brief Obtain Metadata for this layer */
     virtual QString metadata() const;
@@ -687,10 +686,7 @@ class QgsMapLayer : QObject
     /** Emit a signal that layer's CRS has been reset */
     void crsChanged();
 
-    /** By emitting this signal the layer tells that either appearance or content have been changed
-     * and any view showing the rendered layer should refresh itself.
-     */
-    void repaintRequested();
+    void repaintRequested( bool deferredUpdate = false );
 
     /** This is used to send a request that any mapcanvas using this layer update its extents */
     void recalculateExtents() const;
@@ -739,6 +735,8 @@ class QgsMapLayer : QObject
      */
     void willBeDeleted();
 
+    void autoRefreshIntervalChanged( int interval );
+
   protected:
     /** Set the extent */
     virtual void setExtent( const QgsRectangle &rect );

src/app/qgisapp.cpp

@@ -10408,7 +10408,7 @@ void QgisApp::layersWereAdded( const QList<QgsMapLayer *>& theLayers )
 
     if ( provider )
     {
-      connect( provider, &QgsDataProvider::dataChanged, layer, &QgsMapLayer::triggerRepaint );
+      connect( provider, &QgsDataProvider::dataChanged, layer, [layer] { layer->triggerRepaint(); } );
       connect( provider, &QgsDataProvider::dataChanged, mMapCanvas, &QgsMapCanvas::refresh );
     }
   }

src/app/qgsrasterlayerproperties.cpp

@@ -139,6 +139,8 @@ QgsRasterLayerProperties::QgsRasterLayerProperties( QgsMapLayer* lyr, QgsMapCanv
   // enable or disable Build Pyramids button depending on selection in pyramid list
   connect( lbxPyramidResolutions, SIGNAL( itemSelectionChanged() ), this, SLOT( toggleBuildPyramidsButton() ) );
 
+  connect( mRefreshLayerCheckBox, &QCheckBox::toggled, mRefreshLayerIntervalSpinBox, &QDoubleSpinBox::setEnabled );
+
   // set up the scale based layer visibility stuff....
   mScaleRangeWidget->setMapCanvas( mMapCanvas );
   chkUseScaleDependentRendering->setChecked( lyr->hasScaleBasedVisibility() );
@@ -713,6 +715,10 @@ void QgsRasterLayerProperties::sync()
     leNoDataValue->insert( QLatin1String( "" ) );
   }
 
+  mRefreshLayerCheckBox->setChecked( mRasterLayer->hasAutoRefreshEnabled() );
+  mRefreshLayerIntervalSpinBox->setEnabled( mRasterLayer->hasAutoRefreshEnabled() );
+  mRefreshLayerIntervalSpinBox->setValue( mRasterLayer->autoRefreshInterval() / 1000.0 );
+
   populateTransparencyTable( mRasterLayer->renderer() );
 
   QgsDebugMsg( "populate colormap tab" );
@@ -940,6 +946,9 @@ void QgsRasterLayerProperties::apply()
   mRasterLayer->setMaximumScale( 1.0 / mScaleRangeWidget->minimumScale() );
   mRasterLayer->setMinimumScale( 1.0 / mScaleRangeWidget->maximumScale() );
 
+  mRasterLayer->setAutoRefreshInterval( mRefreshLayerIntervalSpinBox->value() * 1000.0 );
+  mRasterLayer->setAutoRefreshEnabled( mRefreshLayerCheckBox->isChecked() );
+
   //update the legend pixmap
   // pixmapLegend->setPixmap( mRasterLayer->legendAsPixmap() );
   // pixmapLegend->setScaledContents( true );

src/app/qgsvectorlayerproperties.cpp

@@ -322,6 +322,9 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
   }
 
   mLayersDependenciesTreeView->setModel( mLayersDependenciesTreeModel.get() );
+
+  connect( mRefreshLayerCheckBox, &QCheckBox::toggled, mRefreshLayerIntervalSpinBox, &QDoubleSpinBox::setEnabled );
+
 } // QgsVectorLayerProperties ctor
 
 
@@ -446,6 +449,10 @@ void QgsVectorLayerProperties::syncToLayer()
 
   mForceRasterCheckBox->setChecked( mLayer->renderer() && mLayer->renderer()->forceRasterRender() );
 
+  mRefreshLayerCheckBox->setChecked( mLayer->hasAutoRefreshEnabled() );
+  mRefreshLayerIntervalSpinBox->setEnabled( mLayer->hasAutoRefreshEnabled() );
+  mRefreshLayerIntervalSpinBox->setValue( mLayer->autoRefreshInterval() / 1000.0 );
+
   // load appropriate symbology page (V1 or V2)
   updateSymbologyPage();
 
@@ -583,6 +590,9 @@ void QgsVectorLayerProperties::apply()
   if ( mLayer->renderer() )
     mLayer->renderer()->setForceRasterRender( mForceRasterCheckBox->isChecked() );
 
+  mLayer->setAutoRefreshInterval( mRefreshLayerIntervalSpinBox->value() * 1000.0 );
+  mLayer->setAutoRefreshEnabled( mRefreshLayerCheckBox->isChecked() );
+
   mOldJoins = mLayer->vectorJoins();
 
   //save variables

src/browser/qgsbrowser.cpp

@@ -439,7 +439,7 @@ void QgsBrowser::updateCurrentTab()
       QgsRasterLayer *rlayer = qobject_cast< QgsRasterLayer * >( mLayer );
       if ( rlayer )
       {
-        connect( rlayer->dataProvider(), &QgsRasterDataProvider::dataChanged, rlayer, &QgsRasterLayer::triggerRepaint );
+        connect( rlayer->dataProvider(), &QgsRasterDataProvider::dataChanged, rlayer, [rlayer] { rlayer->triggerRepaint(); } );
         connect( rlayer->dataProvider(), &QgsRasterDataProvider::dataChanged, mapCanvas, &QgsMapCanvas::refresh );
       }
     }

src/core/qgsmaplayer.cpp

@@ -83,6 +83,7 @@ QgsMapLayer::QgsMapLayer( QgsMapLayer::LayerType type,
   mScaleBasedVisibility = false;
 
   connect( mStyleManager, &QgsMapLayerStyleManager::currentStyleChanged, this, &QgsMapLayer::styleChanged );
+  connect( &mRefreshTimer, &QTimer::timeout, this, [=] { triggerRepaint( true ); } );
 }
 
 QgsMapLayer::~QgsMapLayer()
@@ -420,6 +421,9 @@ bool QgsMapLayer::readLayerXml( const QDomElement& layerElement, const QgsProjec
   setMinimumScale( layerElement.attribute( QStringLiteral( "minimumScale" ) ).toDouble() );
   setMaximumScale( layerElement.attribute( QStringLiteral( "maximumScale" ) ).toDouble() );
 
+  setAutoRefreshInterval( layerElement.attribute( QStringLiteral( "autoRefreshTime" ), 0 ).toInt() );
+  setAutoRefreshEnabled( layerElement.attribute( QStringLiteral( "autoRefreshEnabled" ), QStringLiteral( "0" ) ).toInt() );
+
   QDomNode extentNode = layerElement.namedItem( QStringLiteral( "extent" ) );
   if ( !extentNode.isNull() )
   {
@@ -537,6 +541,9 @@ bool QgsMapLayer::writeLayerXml( QDomElement& layerElement, QDomDocument& docume
     layerElement.appendChild( QgsXmlUtils::writeRectangle( mExtent, document ) );
   }
 
+  layerElement.setAttribute( QStringLiteral( "autoRefreshTime" ), QString::number( mRefreshTimer.interval() ) );
+  layerElement.setAttribute( QStringLiteral( "autoRefreshEnabled" ), mRefreshTimer.isActive() ? 1 : 0 );
+
   // ID
   QDomElement layerId = document.createElement( QStringLiteral( "id" ) );
   QDomText layerIdText = document.createTextNode( id() );
@@ -857,6 +864,40 @@ bool QgsMapLayer::hasScaleBasedVisibility() const
   return mScaleBasedVisibility;
 }
 
+bool QgsMapLayer::hasAutoRefreshEnabled() const
+{
+  return mRefreshTimer.isActive();
+}
+
+int QgsMapLayer::autoRefreshInterval() const
+{
+  return mRefreshTimer.interval();
+}
+
+void QgsMapLayer::setAutoRefreshInterval( int interval )
+{
+  if ( interval <= 0 )
+  {
+    mRefreshTimer.stop();
+    mRefreshTimer.setInterval( 0 );
+  }
+  else
+  {
+    mRefreshTimer.setInterval( interval );
+  }
+  emit autoRefreshIntervalChanged( mRefreshTimer.isActive() ? mRefreshTimer.interval() : 0 );
+}
+
+void QgsMapLayer::setAutoRefreshEnabled( bool enabled )
+{
+  if ( !enabled )
+    mRefreshTimer.stop();
+  else if ( mRefreshTimer.interval() > 0 )
+    mRefreshTimer.start();
+
+  emit autoRefreshIntervalChanged( mRefreshTimer.isActive() ? mRefreshTimer.interval() : 0 );
+}
+
 void QgsMapLayer::setMinimumScale( double scale )
 {
   mMinScale = scale;
@@ -1591,9 +1632,9 @@ QgsMapLayerStyleManager* QgsMapLayer::styleManager() const
   return mStyleManager;
 }
 
-void QgsMapLayer::triggerRepaint()
+void QgsMapLayer::triggerRepaint( bool deferredUpdate )
 {
-  emit repaintRequested();
+  emit repaintRequested( deferredUpdate );
 }
 
 QString QgsMapLayer::metadata() const

src/core/qgsmaplayer.h

@@ -53,6 +53,7 @@ class CORE_EXPORT QgsMapLayer : public QObject
     Q_OBJECT
 
     Q_PROPERTY( QString name READ name WRITE setName NOTIFY nameChanged )
+    Q_PROPERTY( int autoRefreshInterval READ autoRefreshInterval WRITE setAutoRefreshInterval NOTIFY autoRefreshIntervalChanged )
 
   public:
 
@@ -646,6 +647,44 @@ class CORE_EXPORT QgsMapLayer : public QObject
      */
     bool hasScaleBasedVisibility() const;
 
+    /**
+     * Returns true if auto refresh is enabled for the layer.
+     * @note added in QGIS 3.0
+     * @see autoRefreshInterval()
+     * @see setAutoRefreshEnabled()
+     */
+    bool hasAutoRefreshEnabled() const;
+
+    /**
+     * Returns the auto refresh interval (in milliseconds). Note that
+     * auto refresh is only active when hasAutoRefreshEnabled() is true.
+     * @note added in QGIS 3.0
+     * @see autoRefreshEnabled()
+     * @see setAutoRefreshInterval()
+     */
+    int autoRefreshInterval() const;
+
+    /**
+     * Sets the auto refresh interval (in milliseconds) for the layer. This
+     * will cause the layer to be automatically redrawn on a matching interval.
+     * Note that auto refresh must be enabled by calling setAutoRefreshEnabled().
+     *
+     * Note that auto refresh triggers deferred repaints of the layer. Any map
+     * canvas must be refreshed separately in order to view the refreshed layer.
+     * @note added in QGIS 3.0
+     * @see autoRefreshInterval()
+     * @see setAutoRefreshEnabled()
+     */
+    void setAutoRefreshInterval( int interval );
+
+    /**
+     * Sets whether auto refresh is enabled for the layer.
+     * @note added in QGIS 3.0
+     * @see hasAutoRefreshEnabled()
+     * @see setAutoRefreshInterval()
+     */
+    void setAutoRefreshEnabled( bool enabled );
+
   public slots:
 
     //! Event handler for when a coordinate transform fails due to bad vertex error
@@ -678,12 +717,14 @@ class CORE_EXPORT QgsMapLayer : public QObject
     void setScaleBasedVisibility( const bool enabled );
 
     /**
-     * Will advice the map canvas (and any other interested party) that this layer requires to be repainted.
+     * Will advise the map canvas (and any other interested party) that this layer requires to be repainted.
      * Will emit a repaintRequested() signal.
+     * If \a deferredUpdate is true then the layer will only be repainted when the canvas is next
+     * re-rendered, and will not trigger any canvas redraws itself.
      *
      * @note in 2.6 function moved from vector/raster subclasses to QgsMapLayer
      */
-    void triggerRepaint();
+    void triggerRepaint( bool deferredUpdate = false );
 
     //! \brief Obtain Metadata for this layer
     virtual QString metadata() const;
@@ -732,8 +773,10 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
     /** By emitting this signal the layer tells that either appearance or content have been changed
      * and any view showing the rendered layer should refresh itself.
+     * If \a deferredUpdate is true then the layer will only be repainted when the canvas is next
+     * re-rendered, and will not trigger any canvas redraws itself.
      */
-    void repaintRequested();
+    void repaintRequested( bool deferredUpdate = false );
 
     //! This is used to send a request that any mapcanvas using this layer update its extents
     void recalculateExtents() const;
@@ -782,6 +825,13 @@ class CORE_EXPORT QgsMapLayer : public QObject
      */
     void willBeDeleted();
 
+    /**
+     * Emitted when the auto refresh interval changes.
+     * @see setAutoRefreshInterval()
+     * @note added in QGIS 3.0
+     */
+    void autoRefreshIntervalChanged( int interval );
+
   protected:
     //! Set the extent
     virtual void setExtent( const QgsRectangle &rect );
@@ -916,6 +966,10 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
     //! Manager of multiple styles available for a layer (may be null)
     QgsMapLayerStyleManager* mStyleManager;
+
+    //! Timer for triggering automatic refreshes of the layer
+    QTimer mRefreshTimer;
+
 };
 
 Q_DECLARE_METATYPE( QgsMapLayer* )

src/core/qgsvectorlayer.cpp

@@ -164,7 +164,7 @@ QgsVectorLayer::QgsVectorLayer( const QString& vectorLayerPath,
     setDataSource( vectorLayerPath, baseName, providerKey, loadDefaultStyleFlag );
   }
 
-  connect( this, &QgsVectorLayer::selectionChanged, this, &QgsVectorLayer::repaintRequested );
+  connect( this, &QgsVectorLayer::selectionChanged, this, [=] { emit repaintRequested(); } );
   connect( QgsProject::instance()->relationManager(), &QgsRelationManager::relationsLoaded, this, &QgsVectorLayer::onRelationsLoaded );
 
   // Default simplify drawing settings