Allow showing additional items in QgsMapLayerComboBox

These may represent additional layers such as layers which
are not included in the map layer registry, or paths to
layers which have not yet been loaded into QGIS.

python/core/qgsmaplayermodel.sip

@@ -20,6 +20,7 @@ class QgsMapLayerModel : QAbstractItemModel
       LayerIdRole, /*!< Stores the map layer ID */
       LayerRole, /*!< Stores pointer to the map layer itself */
       IsEmptyRole, //!< True if index corresponds to the empty (not set) value
+      IsAdditionalRole, //!< True if index corresponds to an additional (non map layer) item
     };
 
     /**
@@ -68,6 +69,22 @@ class QgsMapLayerModel : QAbstractItemModel
      */
     bool showCrs() const;
 
+    /**
+     * Sets a list of additional (non map layer) items to include at the end of the model.
+     * These may represent additional layers such as layers which are not included in the map
+     * layer registry, or paths to layers which have not yet been loaded into QGIS.
+     * @see additionalItems()
+     * @note added in QGIS 3.0
+     */
+    void setAdditionalItems( const QStringList& items );
+
+    /**
+     * Return the list of additional (non map layer) items included at the end of the model.
+     * @see setAdditionalItems()
+     * @note added in QGIS 3.0
+     */
+    QStringList additionalItems() const;
+
     /**
      * @brief layersChecked returns the list of layers which are checked (or unchecked)
      */

python/gui/qgsmaplayercombobox.sip

@@ -56,6 +56,22 @@ class QgsMapLayerComboBox : QComboBox
      */
     bool showCrs() const;
 
+    /**
+     * Sets a list of additional (non map layer) items to include at the end of the combobox.
+     * These may represent additional layers such as layers which are not included in the map
+     * layer registry, or paths to layers which have not yet been loaded into QGIS.
+     * @see additionalItems()
+     * @note added in QGIS 3.0
+     */
+    void setAdditionalItems( const QStringList& items );
+
+    /**
+     * Return the list of additional (non map layer) items included at the end of the combo box.
+     * @see setAdditionalItems()
+     * @note added in QGIS 3.0
+     */
+    QStringList additionalItems() const;
+
     /** Returns the current layer selected in the combo box.
      * @see layer
      */

src/core/qgsmaplayermodel.cpp

@@ -108,8 +108,37 @@ QModelIndex QgsMapLayerModel::indexFromLayer( QgsMapLayer *layer ) const
   return index( r, 0 );
 }
 
+void QgsMapLayerModel::setAdditionalItems( const QStringList& items )
+{
+  if ( items == mAdditionalItems )
+    return;
+
+  int offset = 0;
+  if ( mAllowEmpty )
+    offset++;
+
+  offset += mLayers.count();
+
+  //remove existing
+  if ( !mAdditionalItems.isEmpty() )
+  {
+    beginRemoveRows( QModelIndex(), offset, offset + mAdditionalItems.count() - 1 );
+    mAdditionalItems.clear();
+    endRemoveRows();
+  }
+
+  //add new
+  beginInsertRows( QModelIndex(), offset, offset + items.count() - 1 );
+  mAdditionalItems = items;
+  endInsertRows();
+}
+
 void QgsMapLayerModel::removeLayers( const QStringList& layerIds )
 {
+  int offset = 0;
+  if ( mAllowEmpty )
+    offset++;
+
   Q_FOREACH ( const QString& layerId, layerIds )
   {
     QModelIndex startIndex = index( 0, 0 );
@@ -119,7 +148,7 @@ void QgsMapLayerModel::removeLayers( const QStringList& layerIds )
       QModelIndex index = list[0];
       beginRemoveRows( QModelIndex(), index.row(), index.row() );
       mLayersChecked.remove( layerId );
-      mLayers.removeAt( index.row() );
+      mLayers.removeAt( index.row() - offset );
       endRemoveRows();
     }
   }
@@ -171,7 +200,7 @@ int QgsMapLayerModel::rowCount( const QModelIndex &parent ) const
   if ( parent.isValid() )
     return 0;
 
-  return ( mAllowEmpty ? 1 : 0 ) + mLayers.length();
+  return ( mAllowEmpty ? 1 : 0 ) + mLayers.length() + mAdditionalItems.count();
 }
 
 int QgsMapLayerModel::columnCount( const QModelIndex &parent ) const
@@ -183,16 +212,20 @@ int QgsMapLayerModel::columnCount( const QModelIndex &parent ) const
 
 QVariant QgsMapLayerModel::data( const QModelIndex &index, int role ) const
 {
-  bool isEmpty = index.row() == 0 && mAllowEmpty;
-
   if ( !index.isValid() )
     return QVariant();
 
+  bool isEmpty = index.row() == 0 && mAllowEmpty;
+  int additionalIndex = index.row() - ( mAllowEmpty ? 1 : 0 ) - mLayers.count();
+
   if ( role == Qt::DisplayRole )
   {
     if ( index.row() == 0 && mAllowEmpty )
       return QVariant();
 
+    if ( additionalIndex >= 0 )
+      return mAdditionalItems.at( additionalIndex );
+
     QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
     if ( !layer )
       return QVariant();
@@ -209,7 +242,7 @@ QVariant QgsMapLayerModel::data( const QModelIndex &index, int role ) const
 
   if ( role == LayerIdRole )
   {
-    if ( isEmpty )
+    if ( isEmpty || additionalIndex >= 0 )
       return QVariant();
 
     QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
@@ -218,7 +251,7 @@ QVariant QgsMapLayerModel::data( const QModelIndex &index, int role ) const
 
   if ( role == LayerRole )
   {
-    if ( isEmpty )
+    if ( isEmpty || additionalIndex >= 0 )
       return QVariant();
 
     return QVariant::fromValue<QgsMapLayer*>( static_cast<QgsMapLayer*>( index.internalPointer() ) );
@@ -227,9 +260,12 @@ QVariant QgsMapLayerModel::data( const QModelIndex &index, int role ) const
   if ( role == IsEmptyRole )
     return isEmpty;
 
+  if ( role == IsAdditionalRole )
+    return additionalIndex >= 0;
+
   if ( role == Qt::CheckStateRole && mItemCheckable )
   {
-    if ( isEmpty )
+    if ( isEmpty || additionalIndex >= 0 )
       return QVariant();
 
     QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
@@ -238,7 +274,7 @@ QVariant QgsMapLayerModel::data( const QModelIndex &index, int role ) const
 
   if ( role == Qt::DecorationRole )
   {
-    if ( isEmpty )
+    if ( isEmpty || additionalIndex >= 0 )
       return QVariant();
 
     QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
@@ -315,9 +351,10 @@ Qt::ItemFlags QgsMapLayerModel::flags( const QModelIndex &index ) const
   }
 
   bool isEmpty = index.row() == 0 && mAllowEmpty;
+  int additionalIndex = index.row() - ( mAllowEmpty ? 1 : 0 ) - mLayers.count();
 
   Qt::ItemFlags flags = Qt::ItemIsEnabled | Qt::ItemIsSelectable;
-  if ( mItemCheckable && !isEmpty )
+  if ( mItemCheckable && !isEmpty && additionalIndex < 0 )
   {
     flags |= Qt::ItemIsUserCheckable;
   }
@@ -328,8 +365,9 @@ Qt::ItemFlags QgsMapLayerModel::flags( const QModelIndex &index ) const
 bool QgsMapLayerModel::setData( const QModelIndex &index, const QVariant &value, int role )
 {
   bool isEmpty = index.row() == 0 && mAllowEmpty;
+  int additionalIndex = index.row() - ( mAllowEmpty ? 1 : 0 ) - mLayers.count();
 
-  if ( role == Qt::CheckStateRole && !isEmpty )
+  if ( role == Qt::CheckStateRole && !isEmpty && additionalIndex < 0 )
   {
     QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
     mLayersChecked[layer->id()] = ( Qt::CheckState )value.toInt();

src/core/qgsmaplayermodel.h

@@ -36,6 +36,7 @@ class CORE_EXPORT QgsMapLayerModel : public QAbstractItemModel
     Q_PROPERTY( bool allowEmptyLayer READ allowEmptyLayer WRITE setAllowEmptyLayer )
     Q_PROPERTY( bool showCrs READ showCrs WRITE setShowCrs )
     Q_PROPERTY( bool itemsCheckable READ itemsCheckable WRITE setItemsCheckable )
+    Q_PROPERTY( QStringList additionalItems READ additionalItems WRITE setAdditionalItems )
 
   public:
 
@@ -45,6 +46,7 @@ class CORE_EXPORT QgsMapLayerModel : public QAbstractItemModel
       LayerIdRole = Qt::UserRole + 1, //!< Stores the map layer ID
       LayerRole, //!< Stores pointer to the map layer itself
       IsEmptyRole, //!< True if index corresponds to the empty (not set) value
+      IsAdditionalRole, //!< True if index corresponds to an additional (non map layer) item
     };
 
     /**
@@ -107,6 +109,22 @@ class CORE_EXPORT QgsMapLayerModel : public QAbstractItemModel
      */
     QModelIndex indexFromLayer( QgsMapLayer* layer ) const;
 
+    /**
+     * Sets a list of additional (non map layer) items to include at the end of the model.
+     * These may represent additional layers such as layers which are not included in the map
+     * layer registry, or paths to layers which have not yet been loaded into QGIS.
+     * @see additionalItems()
+     * @note added in QGIS 3.0
+     */
+    void setAdditionalItems( const QStringList& items );
+
+    /**
+     * Return the list of additional (non map layer) items included at the end of the model.
+     * @see setAdditionalItems()
+     * @note added in QGIS 3.0
+     */
+    QStringList additionalItems() const { return mAdditionalItems; }
+
   protected slots:
     void removeLayers( const QStringList& layerIds );
     void addLayers( const QList<QgsMapLayer*>& layers );
@@ -138,6 +156,7 @@ class CORE_EXPORT QgsMapLayerModel : public QAbstractItemModel
 
     bool mAllowEmpty;
     bool mShowCrs;
+    QStringList mAdditionalItems;
 };
 
 #endif // QGSMAPLAYERMODEL_H

src/core/qgsmaplayerproxymodel.cpp

@@ -78,7 +78,8 @@ bool QgsMapLayerProxyModel::filterAcceptsRow( int source_row, const QModelIndex
 
   QModelIndex index = sourceModel()->index( source_row, 0, source_parent );
 
-  if ( sourceModel()->data( index, QgsMapLayerModel::IsEmptyRole ).toBool() )
+  if ( sourceModel()->data( index, QgsMapLayerModel::IsEmptyRole ).toBool()
+       || sourceModel()->data( index, QgsMapLayerModel::IsAdditionalRole ).toBool() )
     return true;
 
   QgsMapLayer* layer = static_cast<QgsMapLayer*>( index.internalPointer() );
@@ -133,6 +134,15 @@ bool QgsMapLayerProxyModel::lessThan( const QModelIndex &left, const QModelIndex
   else if ( sourceModel()->data( right, QgsMapLayerModel::IsEmptyRole ).toBool() )
     return false;
 
+  // additional rows are always last
+  bool leftAdditional = sourceModel()->data( left, QgsMapLayerModel::IsAdditionalRole ).toBool();
+  bool rightAdditional = sourceModel()->data( right, QgsMapLayerModel::IsAdditionalRole ).toBool();
+
+  if ( leftAdditional && !rightAdditional )
+    return false;
+  else if ( rightAdditional && !leftAdditional )
+    return true;
+
   // default mode is alphabetical order
   QString leftStr = sourceModel()->data( left ).toString();
   QString rightStr = sourceModel()->data( right ).toString();

src/gui/qgsmaplayercombobox.cpp

@@ -48,6 +48,16 @@ bool QgsMapLayerComboBox::showCrs() const
   return mProxyModel->sourceLayerModel()->showCrs();
 }
 
+void QgsMapLayerComboBox::setAdditionalItems( const QStringList& items )
+{
+  mProxyModel->sourceLayerModel()->setAdditionalItems( items );
+}
+
+QStringList QgsMapLayerComboBox::additionalItems() const
+{
+  return mProxyModel->sourceLayerModel()->additionalItems();
+}
+
 void QgsMapLayerComboBox::setLayer( QgsMapLayer *layer )
 {
   if ( !layer )

src/gui/qgsmaplayercombobox.h

@@ -83,6 +83,22 @@ class GUI_EXPORT QgsMapLayerComboBox : public QComboBox
      */
     bool showCrs() const;
 
+    /**
+     * Sets a list of additional (non map layer) items to include at the end of the combobox.
+     * These may represent additional layers such as layers which are not included in the map
+     * layer registry, or paths to layers which have not yet been loaded into QGIS.
+     * @see additionalItems()
+     * @note added in QGIS 3.0
+     */
+    void setAdditionalItems( const QStringList& items );
+
+    /**
+     * Return the list of additional (non map layer) items included at the end of the combo box.
+     * @see setAdditionalItems()
+     * @note added in QGIS 3.0
+     */
+    QStringList additionalItems() const;
+
     /** Returns the current layer selected in the combo box.
      * @see layer
      */