[FEATURE] Change of ergonomy of the visibility of layers inside groups

See qgis/QGIS-Enhancement-Proposals#86

- Checking/unchecking a group doesn't change the check state of its children.
A node is visible if and only if it is checked and all its parents too.
- There is no more a semi-checked state for a group
- Ctrl-clic on a unchecked group will check the group and all its descendants.
- Ctrl-clic on a unchecked layer will check the lager and all its parents.
- Ctrl-clic on a checked group will uncheck the group and all its descendants.
- Ctrl-clic on a checked layer will uncheck the layer and all its parents.
- Those actions are available in contextual menu items in the tree view.
- Invisible layers because they or their parent(s) is unchecked are greyed out.

doc/api_break.dox

@@ -687,6 +687,13 @@ QgsCptCitySelectionItem        {#qgis_api_break_3_0_QgsCptCitySelectionItem}
 
 - parseXML() has been renamed to parseXml()
 
+
+QgsCustomLayerOrderWidget        {#qgis_api_break_3_0_QgsCustomLayerOrderWidget}
+-------------------------
+
+- the signature of the visibilityChanged() signal is changed to visibilityChanged( QgsLayerTreeNode *node )
+
+
 QgsCRSCache        {#qgis_api_break_3_0_QgsCRSCache}
 -----------
 
@@ -1059,12 +1066,16 @@ QgsLayerTreeGroup        {#qgis_api_break_3_0_QgsLayerTreeGroup}
 -----------------
 
 - readChildrenFromXML() has been renamed to readChildrenFromXml()
-
+- isVisible() is moved to QgsLayerTreeNode
+- setVisible() is replaced by QgsLayerTreeNode::setItemVisibilityChecked()
+- protected methods updateVisibilityFromChildren() and updateChildVisibility() removed
 
 QgsLayerTreeLayer        {#qgis_api_break_3_0_QgsLayerTreeLayer}
 -----------------
 
 - setLayerName(), layerName() were renamed to setName(), name()
+- isVisible() is moved to QgsLayerTreeNode
+- setVisible() is replaced by QgsLayerTreeNode::setItemVisibilityChecked()
 
 
 QgsLayerTreeModel        {#qgis_api_break_3_0_QgsLayerTreeMode}
@@ -1090,7 +1101,7 @@ QgsLayerTreeNode        {#qgis_api_break_3_0_QgsLayerTreeNode}
 
 - readCommonXML() has been renamed to readCommonXml()
 - writeCommonXML() has been renamed to writeCommonXml()
-
+- the signature of the visibilityChanged() signal is changed to visibilityChanged( QgsLayerTreeNode *node )
 
 QgsLimitedRandomColorRampDialog        {#qgis_api_break_3_0_QgsLimitedRandomRampDialog}
 -------------------------------

python/core/layertree/qgslayertreegroup.sip

@@ -71,11 +71,6 @@ class QgsLayerTreeGroup : QgsLayerTreeNode
     //! Return a clone of the group. The children are cloned too.
     virtual QgsLayerTreeGroup* clone() const /Factory/;
 
-    //! Return the check state of the group node
-    Qt::CheckState isVisible() const;
-    //! Set check state of the group node - will also update children
-    void setVisible( Qt::CheckState state );
-
     //! Return whether the group is mutually exclusive (only one child can be checked at a time)
     //! @note added in 2.12
     bool isMutuallyExclusive() const;
@@ -86,14 +81,10 @@ class QgsLayerTreeGroup : QgsLayerTreeNode
     void setIsMutuallyExclusive( bool enabled, int initialChildIndex = -1 );
 
   protected slots:
-    void layerDestroyed();
     void nodeVisibilityChanged( QgsLayerTreeNode* node );
 
   protected:
-    //! Set check state of this group from its children
-    void updateVisibilityFromChildren();
-    //! Set check state of children (when this group's check state changes) - if not mutually exclusive
-    void updateChildVisibility();
+
     //! Set check state of children - if mutually exclusive
     void updateChildVisibilityMutuallyExclusive();
 

python/core/layertree/qgslayertreelayer.sip

@@ -38,9 +38,6 @@ class QgsLayerTreeLayer : QgsLayerTreeNode
     //! @note added in 3.0
     void setName( const QString& n );
 
-    Qt::CheckState isVisible() const;
-    void setVisible( Qt::CheckState visible );
-
     static QgsLayerTreeLayer* readXml( QDomElement& element ) /Factory/;
     virtual void writeXml( QDomElement& parentElement );
 

python/core/layertree/qgslayertreemodel.sip

@@ -61,6 +61,7 @@ class QgsLayerTreeModel : QAbstractItemModel
       AllowNodeRename,            //!< Allow renaming of groups and layers
       AllowNodeChangeVisibility,  //!< Allow user to set node visibility with a check box
       AllowLegendChangeState,     //!< Allow check boxes for legend nodes (if supported by layer's legend)
+      ActionHierarchical,         //!< Check/uncheck action has consequences on children (or parents for leaf node)
     };
     typedef QFlags<QgsLayerTreeModel::Flag> Flags;
 

python/core/layertree/qgslayertreenode.sip

@@ -94,6 +94,34 @@ class QgsLayerTreeNode : QObject
     //! Create a copy of the node. Returns new instance
     virtual QgsLayerTreeNode *clone() const = 0 /Factory/;
 
+    //! Returns whether a node is really visible (ie checked and all its ancestors checked as well)
+    //! @note added in 3.0
+    bool isVisible() const;
+
+    //! Returns whether a node is checked (independantly of its ancestors or children)
+    //! @note added in 3.0
+    bool itemVisibilityChecked() const;
+
+    //! Check or uncheck a node (independantly of its ancestors or children)
+    //! @note added in 3.0
+    void setItemVisibilityChecked( bool checked );
+
+    //! Check or uncheck a node and all its children (taking into account exclusion rules)
+    //! @note added in 3.0
+    virtual void setItemVisibilityCheckedRecursive( bool checked );
+
+    //! Check or uncheck a node and all its parents
+    //! @note added in 3.0
+    void setItemVisibilityCheckedParentRecursive( bool checked );
+
+    //! Return whether this node is checked and all its children.
+    //! @note added in 3.0
+    bool isItemVisibilityCheckedRecursive() const;
+
+    //! Return whether this node is unchecked and all its children.
+    //! @note added in 3.0
+    bool isItemVisibilityUncheckedRecursive() const;
+
     //! Return whether the node should be shown as expanded or collapsed in GUI
     bool isExpanded() const;
     //! Set whether the node should be shown as expanded or collapsed in GUI
@@ -121,7 +149,7 @@ class QgsLayerTreeNode : QObject
     //! Emitted when one or more nodes has been removed from a node within the tree
     void removedChildren( QgsLayerTreeNode *node, int indexFrom, int indexTo );
     //! Emitted when check state of a node within the tree has been changed
-    void visibilityChanged( QgsLayerTreeNode *node, Qt::CheckState state );
+    void visibilityChanged( QgsLayerTreeNode *node );
     //! Emitted when a custom property of a node within the tree has been changed or removed
     void customPropertyChanged( QgsLayerTreeNode *node, const QString& key );
     //! Emitted when the collapsed/expanded state of a node within the tree has been changed

python/gui/layertree/qgscustomlayerorderwidget.sip

@@ -20,7 +20,8 @@ class QgsCustomLayerOrderWidget : QWidget
   protected slots:
     void bridgeHasCustomLayerOrderChanged( bool state );
     void bridgeCustomLayerOrderChanged( const QStringList& order );
-    void nodeVisibilityChanged( QgsLayerTreeNode* node, Qt::CheckState state );
+    //! Slot triggered when the ivsibility of a node changes
+    void nodeVisibilityChanged( QgsLayerTreeNode* node );
 
     void modelUpdated();
 };

python/gui/layertree/qgslayertreeviewdefaultactions.sip

@@ -20,6 +20,15 @@ class QgsLayerTreeViewDefaultActions : QObject
     QAction* actionRenameGroupOrLayer( QObject* parent = 0 ) /Factory/;
     QAction* actionShowFeatureCount( QObject* parent = 0 ) /Factory/;
 
+    //! Action to check a group and all its children
+    QAction* actionCheckAndAllChildren( QObject* parent = nullptr );
+
+    //! Action to uncheck a group and all its children
+    QAction* actionUncheckAndAllChildren( QObject* parent = nullptr );
+
+    //! Action to check a group and all its parents
+    QAction* actionCheckAndAllParents( QObject* parent = nullptr );
+
     QAction* actionZoomToLayer( QgsMapCanvas* canvas, QObject* parent = 0 ) /Factory/;
     QAction* actionZoomToGroup( QgsMapCanvas* canvas, QObject* parent = 0 ) /Factory/;
     // TODO: zoom to selected

src/app/dwg/qgsdwgimportdialog.cpp

@@ -422,7 +422,7 @@ void QgsDwgImportDialog::createGroup( QgsLayerTreeGroup *group, QString name, QS
   if ( !layerGroup->children().isEmpty() )
   {
     layerGroup->setExpanded( false );
-    layerGroup->setVisible( visible ? Qt::Checked : Qt::Unchecked );
+    layerGroup->setItemVisibilityChecked( visible );
   }
   else
   {

src/app/qgisapp.cpp

@@ -2808,7 +2808,7 @@ void QgisApp::setupConnections()
            this, SLOT( markDirty() ) );
   connect( mLayerTreeView->layerTreeModel()->rootGroup(), SIGNAL( removedChildren( QgsLayerTreeNode*, int, int ) ),
            this, SLOT( updateNewLayerInsertionPoint() ) );
-  connect( mLayerTreeView->layerTreeModel()->rootGroup(), SIGNAL( visibilityChanged( QgsLayerTreeNode*, Qt::CheckState ) ),
+  connect( mLayerTreeView->layerTreeModel()->rootGroup(), SIGNAL( visibilityChanged( QgsLayerTreeNode* ) ),
            this, SLOT( markDirty() ) );
   connect( mLayerTreeView->layerTreeModel()->rootGroup(), SIGNAL( customPropertyChanged( QgsLayerTreeNode*, QString ) ),
            this, SLOT( markDirty() ) );
@@ -5759,19 +5759,16 @@ void QgisApp::stopRendering()
 void QgisApp::hideAllLayers()
 {
   QgsDebugMsg( "hiding all layers!" );
+  mLayerTreeView->layerTreeModel()->rootGroup()->setItemVisibilityCheckedRecursive( false );
 
-  Q_FOREACH ( QgsLayerTreeLayer* nodeLayer, mLayerTreeView->layerTreeModel()->rootGroup()->findLayers() )
-    nodeLayer->setVisible( Qt::Unchecked );
 }
 
 
 // reimplements method from base (gui) class
 void QgisApp::showAllLayers()
 {
   QgsDebugMsg( "Showing all layers!" );
-
-  Q_FOREACH ( QgsLayerTreeLayer* nodeLayer, mLayerTreeView->layerTreeModel()->rootGroup()->findLayers() )
-    nodeLayer->setVisible( Qt::Checked );
+  mLayerTreeView->layerTreeModel()->rootGroup()->setItemVisibilityCheckedRecursive( true );
 }
 
 //reimplements method from base (gui) class
@@ -5781,10 +5778,7 @@ void QgisApp::hideSelectedLayers()
 
   Q_FOREACH ( QgsLayerTreeNode* node, mLayerTreeView->selectedNodes() )
   {
-    if ( QgsLayerTree::isGroup( node ) )
-      QgsLayerTree::toGroup( node )->setVisible( Qt::Unchecked );
-    else if ( QgsLayerTree::isLayer( node ) )
-      QgsLayerTree::toLayer( node )->setVisible( Qt::Unchecked );
+    node->setItemVisibilityChecked( false );
   }
 }
 
@@ -5796,7 +5790,7 @@ void QgisApp::hideDeselectedLayers()
   {
     if ( selectedLayerNodes.contains( nodeLayer ) )
       continue;
-    nodeLayer->setVisible( Qt::Unchecked );
+    nodeLayer->setItemVisibilityChecked( false );
   }
 }
 
@@ -5807,10 +5801,12 @@ void QgisApp::showSelectedLayers()
 
   Q_FOREACH ( QgsLayerTreeNode* node, mLayerTreeView->selectedNodes() )
   {
-    if ( QgsLayerTree::isGroup( node ) )
-      QgsLayerTree::toGroup( node )->setVisible( Qt::Checked );
-    else if ( QgsLayerTree::isLayer( node ) )
-      QgsLayerTree::toLayer( node )->setVisible( Qt::Checked );
+    QgsLayerTreeNode* nodeIter = node;
+    while ( nodeIter )
+    {
+      nodeIter->setItemVisibilityChecked( true );
+      nodeIter = nodeIter->parent();
+    }
   }
 }
 
@@ -8373,7 +8369,7 @@ void QgisApp::layerSubsetString()
         // hide the old layer
         QgsLayerTreeLayer* vLayerTreeLayer = QgsProject::instance()->layerTreeRoot()->findLayer( vlayer->id() );
         if ( vLayerTreeLayer )
-          vLayerTreeLayer->setVisible( Qt::Unchecked );
+          vLayerTreeLayer->setItemVisibilityChecked( false );
         vlayer = newLayer;
       }
       else
@@ -8663,7 +8659,7 @@ void QgisApp::duplicateLayers( const QList<QgsMapLayer *>& lyrList )
     QgsLayerTreeLayer* nodeDupLayer = parentGroup->insertLayer( parentGroup->children().indexOf( nodeSelectedLyr ) + 1, dupLayer );
 
     // always set duplicated layers to not visible so layer can be configured before being turned on
-    nodeDupLayer->setVisible( Qt::Unchecked );
+    nodeDupLayer->setItemVisibilityChecked( false );
 
     // duplicate the layer style
     QString errMsg;

src/app/qgsapplayertreeviewmenuprovider.cpp

@@ -80,6 +80,10 @@ QMenu* QgsAppLayerTreeViewMenuProvider::createContextMenu()
 
       menu->addAction( actions->actionMutuallyExclusiveGroup( menu ) );
 
+      menu->addAction( actions->actionCheckAndAllChildren( menu ) );
+
+      menu->addAction( actions->actionUncheckAndAllChildren( menu ) );
+
       if ( mView->selectedNodes( true ).count() >= 2 )
         menu->addAction( actions->actionGroupSelected( menu ) );
 
@@ -125,6 +129,8 @@ QMenu* QgsAppLayerTreeViewMenuProvider::createContextMenu()
         if ( !layer->isInScaleRange( mCanvas->scale() ) )
           menu->addAction( tr( "Zoom to &Visible Scale" ), QgisApp::instance(), SLOT( zoomToLayerScale() ) );
 
+        menu->addAction( actions->actionCheckAndAllParents( menu ) );
+
         // set layer crs
         menu->addAction( QgsApplication::getThemeIcon( QStringLiteral( "/mActionSetCRS.png" ) ), tr( "Set Layer CRS" ), QgisApp::instance(), SLOT( setLayerCrs() ) );
 

src/app/qgsvectorlayerproperties.cpp

@@ -309,7 +309,7 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
   // use visibility as selection
   mLayersDependenciesTreeModel->setFlag( QgsLayerTreeModel::AllowNodeChangeVisibility );
 
-  mLayersDependenciesTreeGroup->setVisible( Qt::Unchecked );
+  mLayersDependenciesTreeGroup->setItemVisibilityChecked( false );
 
   QSet<QString> dependencySources;
   Q_FOREACH ( const QgsMapLayerDependency& dep, mLayer->dependencies() )
@@ -318,7 +318,7 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
   }
   Q_FOREACH ( QgsLayerTreeLayer* layer, mLayersDependenciesTreeGroup->findLayers() )
   {
-    layer->setVisible( dependencySources.contains( layer->layerId() ) ? Qt::Checked : Qt::Unchecked );
+    layer->setItemVisibilityChecked( dependencySources.contains( layer->layerId() ) );
   }
 
   mLayersDependenciesTreeView->setModel( mLayersDependenciesTreeModel.data() );