[FEATURE] Layer tree embedded widgets

python/core/qgsdataitem.sip

@@ -75,7 +75,7 @@ class QgsDataItem : QObject
 
     /** Create children. Children are not expected to have parent set.
      * This method MUST BE THREAD SAFE. */
-    virtual QVector<QgsDataItem*> createChildren();
+    virtual QVector<QgsDataItem*> createChildren() /Factory/;
 
     enum State
     {

python/gui/gui.sip

@@ -192,6 +192,8 @@
 %Include auth/qgsauthtrustedcasdialog.sip
 
 %Include layertree/qgscustomlayerorderwidget.sip
+%Include layertree/qgslayertreeembeddedconfigwidget.sip
+%Include layertree/qgslayertreeembeddedwidgetregistry.sip
 %Include layertree/qgslayertreemapcanvasbridge.sip
 %Include layertree/qgslayertreeview.sip
 %Include layertree/qgslayertreeviewdefaultactions.sip

python/gui/layertree/qgslayertreeembeddedconfigwidget.sip

@@ -0,0 +1,22 @@
+
+/** \ingroup gui
+ * \class QgsLayerTreeEmbeddedConfigWidget
+ * A widget to configure layer tree embedded widgets for a particular map layer.
+ * @note introduced in QGIS 2.16
+ */
+class QgsLayerTreeEmbeddedConfigWidget : public QWidget
+{
+%TypeHeaderCode
+#include <qgslayertreeembeddedconfigwidget.h>
+%End
+
+  public:
+    QgsLayerTreeEmbeddedConfigWidget( QWidget* parent /TransferThis/ = nullptr );
+
+    //! Initialize widget with a map layer
+    void setLayer( QgsMapLayer* layer );
+
+    //! Store changes made in the widget to the layer
+    void applyToLayer();
+
+};

python/gui/layertree/qgslayertreeembeddedwidgetregistry.sip

@@ -0,0 +1,72 @@
+
+/** \ingroup gui
+ * \class QgsLayerTreeEmbeddedWidgetProvider
+ * Provider interface to be implemented in order to introduce new kinds of embedded widgets for use in layer tree.
+ * Embedded widgets are assigned per individual map layers and they are shown before any legend entries.
+ * @see QgsLayerTreeEmbeddedWidgetRegistry
+ * @note introduced in QGIS 2.16
+ */
+class QgsLayerTreeEmbeddedWidgetProvider
+{
+%TypeHeaderCode
+#include <qgslayertreeembeddedwidgetregistry.h>
+%End
+
+  public:
+    virtual ~QgsLayerTreeEmbeddedWidgetProvider();
+
+    //! Unique name of the provider (among other providers)
+    virtual QString id() const = 0;
+
+    //! Human readable name - may be translatable with tr()
+    virtual QString name() const = 0;
+
+    //! Factory to create widgets. The returned widget is owned by the caller.
+    //! The widgetIndex argument may be used to identify which widget is being
+    //! created (useful when using multiple widgets from the same provider for one layer).
+    virtual QWidget* createWidget( QgsMapLayer* layer, int widgetIndex ) = 0 /Factory/;
+
+    //! Whether it makes sense to use this widget for a particular layer
+    virtual bool supportsLayer( QgsMapLayer* layer ) = 0;
+};
+
+/** \ingroup gui
+ * \class QgsLayerTreeEmbeddedWidgetRegistry
+ * Registry of widgets that may be embedded into layer tree view.
+ * Embedded widgets are assigned per individual map layers and they are shown before any legend entries.
+ * Layer tree must have UseEmbeddedWidgets flag enabled in order to show assigned widgets.
+ *
+ * @see QgsLayerTreeEmbeddedWidgetRegistry
+ * @note introduced in QGIS 2.16
+ */
+class QgsLayerTreeEmbeddedWidgetRegistry
+{
+%TypeHeaderCode
+#include <qgslayertreeembeddedwidgetregistry.h>
+%End
+
+  public:
+
+    /** Means of accessing canonical single instance  */
+    static QgsLayerTreeEmbeddedWidgetRegistry* instance();
+
+    ~QgsLayerTreeEmbeddedWidgetRegistry();
+
+    /** Return list of all registered providers */
+    QStringList providers() const;
+
+    /** Get provider object from the provider's ID */
+    QgsLayerTreeEmbeddedWidgetProvider* provider( const QString& providerId ) const;
+
+    /** Register a provider, takes ownership of the object.
+     * Returns true on success, false if the provider is already registered. */
+    bool addProvider( QgsLayerTreeEmbeddedWidgetProvider* provider /Transfer/ );
+
+    /** Unregister a provider, the provider object is deleted.
+     * Returns true on success, false if the provider was not registered. */
+    bool removeProvider( const QString& providerId );
+
+  protected:
+    //! Protected constructor - use instance() to access the registry.
+    QgsLayerTreeEmbeddedWidgetRegistry();
+};

src/app/qgisapp.cpp

@@ -2815,6 +2815,7 @@ void QgisApp::initLayerTreeView()
   model->setFlag( QgsLayerTreeModel::AllowNodeRename );
   model->setFlag( QgsLayerTreeModel::AllowNodeChangeVisibility );
   model->setFlag( QgsLayerTreeModel::ShowLegendAsTree );
+  model->setFlag( QgsLayerTreeModel::UseEmbeddedWidgets );
   model->setAutoCollapseLegendNodes( 10 );
 
   mLayerTreeView->setModel( model );

src/app/qgsrasterlayerproperties.cpp

@@ -797,6 +797,12 @@ void QgsRasterLayerProperties::sync()
 
   mLayerLegendUrlLineEdit->setText( mRasterLayer->legendUrl() );
   mLayerLegendUrlFormatComboBox->setCurrentIndex( mLayerLegendUrlFormatComboBox->findText( mRasterLayer->legendUrlFormat() ) );
+
+  /*
+   * Legend Tab
+   */
+  mLegendConfigEmbeddedWidget->setLayer( mRasterLayer );
+
 } // QgsRasterLayerProperties::sync()
 
 /*
@@ -806,6 +812,11 @@ void QgsRasterLayerProperties::sync()
  */
 void QgsRasterLayerProperties::apply()
 {
+  /*
+   * Legend Tab
+   */
+  mLegendConfigEmbeddedWidget->applyToLayer();
+
   QgsDebugMsg( "apply processing symbology tab" );
   /*
    * Symbology Tab

src/app/qgsvectorlayerproperties.cpp

@@ -251,6 +251,9 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
   diagLayout->addWidget( diagramPropertiesDialog );
   mDiagramFrame->setLayout( diagLayout );
 
+  // Legend tab
+  mLegendConfigEmbeddedWidget->setLayer( mLayer );
+
   // WMS Name as layer short name
   mLayerShortNameLineEdit->setText( mLayer->shortName() );
   // WMS Name validator
@@ -535,6 +538,9 @@ void QgsVectorLayerProperties::apply()
     labelingDialog->writeSettingsToLayer();
   }
 
+  // apply legend settings
+  mLegendConfigEmbeddedWidget->applyToLayer();
+
   //
   // Set up sql subset query if applicable
   //

src/core/layertree/qgslayertreemodel.cpp

@@ -33,6 +33,27 @@
 #include "qgsvectorlayer.h"
 
 
+/** In order to support embedded widgets in layer tree view, the model
+ * generates one placeholder legend node for each embedded widget.
+ * The placeholder will be replaced by an embedded widget in QgsLayerTreeView
+ */
+class EmbeddedWidgetLegendNode : public QgsLayerTreeModelLegendNode
+{
+  public:
+    EmbeddedWidgetLegendNode( QgsLayerTreeLayer* nodeL )
+        : QgsLayerTreeModelLegendNode( nodeL )
+    {
+    }
+
+    virtual QVariant data( int role ) const override
+    {
+      Q_UNUSED( role );
+      return QVariant();
+    }
+};
+
+
+
 QgsLayerTreeModel::QgsLayerTreeModel( QgsLayerTreeGroup* rootNode, QObject *parent )
     : QAbstractItemModel( parent )
     , mRootNode( rootNode )
@@ -1169,9 +1190,20 @@ void QgsLayerTreeModel::addLegendToLayer( QgsLayerTreeLayer* nodeL )
   // apply filtering defined in layer node's custom properties (reordering, filtering, custom labels)
   QgsMapLayerLegendUtils::applyLayerNodeProperties( nodeL, lstNew );
 
+  if ( testFlag( UseEmbeddedWidgets ) )
+  {
+    // generate placeholder legend nodes that will be replaced by widgets in QgsLayerTreeView
+    int widgetsCount = ml->customProperty( "embeddedWidgets/count", 0 ).toInt();
+    while ( widgetsCount > 0 )
+    {
+      lstNew.insert( 0, new EmbeddedWidgetLegendNode( nodeL ) );
+      --widgetsCount;
+    }
+  }
+
   QList<QgsLayerTreeModelLegendNode*> filteredLstNew = filterLegendNodes( lstNew );
 
-  bool isEmbedded = filteredLstNew.count() == 1 && filteredLstNew[0]->isEmbeddedInParent();
+  bool hasOnlyEmbedded = filteredLstNew.count() == 1 && filteredLstNew[0]->isEmbeddedInParent();
 
   Q_FOREACH ( QgsLayerTreeModelLegendNode* n, lstNew )
   {
@@ -1190,11 +1222,11 @@ void QgsLayerTreeModel::addLegendToLayer( QgsLayerTreeLayer* nodeL )
 
   int count = data.tree ? data.tree->children[nullptr].count() : filteredLstNew.count();
 
-  if ( ! isEmbedded ) beginInsertRows( node2index( nodeL ), 0, count - 1 );
+  if ( ! hasOnlyEmbedded ) beginInsertRows( node2index( nodeL ), 0, count - 1 );
 
   mLegend[nodeL] = data;
 
-  if ( ! isEmbedded ) endInsertRows();
+  if ( ! hasOnlyEmbedded ) endInsertRows();
 
   if ( hasStyleOverride )
     ml->styleManager()->restoreOverrideStyle();
@@ -1291,17 +1323,19 @@ int QgsLayerTreeModel::legendNodeRowCount( QgsLayerTreeModelLegendNode* node ) c
 
 int QgsLayerTreeModel::legendRootRowCount( QgsLayerTreeLayer* nL ) const
 {
-  if ( legendEmbeddedInParent( nL ) )
-    return 0;
-
   if ( !mLegend.contains( nL ) )
     return 0;
 
   const LayerLegendData& data = mLegend[nL];
   if ( data.tree )
     return data.tree->children[nullptr].count();
 
-  return data.activeNodes.count();
+  int count = data.activeNodes.count();
+
+  if ( legendEmbeddedInParent( nL ) )
+    count--;  // one item less -- it is embedded in parent
+
+  return count;
 }
 
 
@@ -1365,14 +1399,29 @@ Qt::ItemFlags QgsLayerTreeModel::legendNodeFlags( QgsLayerTreeModelLegendNode* n
 
 bool QgsLayerTreeModel::legendEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const
 {
+  return legendNodeEmbeddedInParent( nodeLayer );
+}
+
+QgsLayerTreeModelLegendNode* QgsLayerTreeModel::legendNodeEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const
+{
+  // legend node embedded in parent does not have to be the first one...
+  // there could be extra legend nodes generated for embedded widgets
   const LayerLegendData& data = mLegend[nodeLayer];
-  return data.activeNodes.count() == 1 && data.activeNodes[0]->isEmbeddedInParent();
+  Q_FOREACH ( QgsLayerTreeModelLegendNode* legendNode, data.activeNodes )
+  {
+    if ( legendNode->isEmbeddedInParent() )
+      return legendNode;
+  }
+  return nullptr;
 }
 
 
 QIcon QgsLayerTreeModel::legendIconEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const
 {
-  return QIcon( qvariant_cast<QPixmap>( mLegend[nodeLayer].activeNodes[0]->data( Qt::DecorationRole ) ) );
+  QgsLayerTreeModelLegendNode* legendNode = legendNodeEmbeddedInParent( nodeLayer );
+  if ( !legendNode )
+    return QIcon();
+  return QIcon( qvariant_cast<QPixmap>( legendNode->data( Qt::DecorationRole ) ) );
 }
 
 

src/core/layertree/qgslayertreemodel.h

@@ -80,6 +80,7 @@ class CORE_EXPORT QgsLayerTreeModel : public QAbstractItemModel
       ShowRasterPreviewIcon      = 0x0002,  //!< Will use real preview of raster layer as icon (may be slow)
       ShowLegendAsTree           = 0x0004,  //!< For legends that support it, will show them in a tree instead of a list (needs also ShowLegend). Added in 2.8
       DeferredLegendInvalidation = 0x0008,  //!< defer legend model invalidation
+      UseEmbeddedWidgets         = 0x0010,  //!< Layer nodes may optionally include extra embedded widgets (if used in QgsLayerTreeView). Added in 2.16
 
       // behavioral flags
       AllowNodeReorder           = 0x1000,  //!< Allow reordering with drag'n'drop
@@ -276,6 +277,8 @@ class CORE_EXPORT QgsLayerTreeModel : public QAbstractItemModel
     QVariant legendNodeData( QgsLayerTreeModelLegendNode* node, int role ) const;
     Qt::ItemFlags legendNodeFlags( QgsLayerTreeModelLegendNode* node ) const;
     bool legendEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const;
+    /** Return legend node that may be embbeded in parent (i.e. its icon will be used for layer's icon). */
+    QgsLayerTreeModelLegendNode* legendNodeEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const;
     QIcon legendIconEmbeddedInParent( QgsLayerTreeLayer* nodeLayer ) const;
     void legendCleanup();
     void legendInvalidateMapBasedData();

src/gui/CMakeLists.txt

@@ -153,6 +153,9 @@ SET(QGIS_GUI_SRCS
   editorwidgets/qgsvaluerelationwidgetfactory.cpp
 
   layertree/qgscustomlayerorderwidget.cpp
+  layertree/qgslayertreeembeddedconfigwidget.cpp
+  layertree/qgslayertreeembeddedwidgetregistry.cpp
+  layertree/qgslayertreeembeddedwidgetsimpl.cpp
   layertree/qgslayertreemapcanvasbridge.cpp
   layertree/qgslayertreeview.cpp
   layertree/qgslayertreeviewdefaultactions.cpp
@@ -574,6 +577,8 @@ SET(QGIS_GUI_MOC_HDRS
   editorwidgets/qgsvaluerelationwidgetwrapper.h
 
   layertree/qgscustomlayerorderwidget.h
+  layertree/qgslayertreeembeddedconfigwidget.h
+  layertree/qgslayertreeembeddedwidgetsimpl.h
   layertree/qgslayertreemapcanvasbridge.h
   layertree/qgslayertreeview.h
   layertree/qgslayertreeviewdefaultactions.h
@@ -669,6 +674,9 @@ SET(QGIS_GUI_HDRS
   editorwidgets/qgsvaluemapwidgetfactory.h
   editorwidgets/qgsvaluerelationwidgetfactory.h
 
+  layertree/qgslayertreeembeddedconfigwidget.h
+  layertree/qgslayertreeembeddedwidgetregistry.h
+
   raster/qgsrasterrendererwidget.h
 )