[api] Optionally allow items in QgsMapLayerModel to be reordered via …

…drag and drop
qgis · Jun 9, 2020 · 154a499 · 154a499
1 parent 9e23fb9
commit 154a499
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Showing 4 changed files with 454 additions and 26 deletions.
diff --git a/python/core/auto_generated/qgsmaplayermodel.sip.in b/python/core/auto_generated/qgsmaplayermodel.sip.in
@@ -10,7 +10,6 @@
 
 
 
-
 class QgsMapLayerModel : QAbstractItemModel
 {
 %Docstring
@@ -36,19 +35,43 @@ The QgsMapLayerModel class is a model to display layers in widgets.
       AdditionalRole,
     };
 
-    explicit QgsMapLayerModel( QObject *parent /TransferThis/ = 0 );
+    explicit QgsMapLayerModel( QObject *parent /TransferThis/ = 0, QgsProject *project = 0 );
 %Docstring
 QgsMapLayerModel creates a model to display layers in widgets.
+
+If a specific ``project`` is not specified then the QgsProject.instance() project will be used to
+populate the model.
 %End
 
-    explicit QgsMapLayerModel( const QList<QgsMapLayer *> &layers, QObject *parent = 0 );
+    explicit QgsMapLayerModel( const QList<QgsMapLayer *> &layers, QObject *parent = 0, QgsProject *project = 0 );
 %Docstring
 QgsMapLayerModel creates a model to display a specific list of layers in a widget.
+
+If a specific ``project`` is not specified then the QgsProject.instance() project will be used to
+populate the model.
 %End
 
     void setItemsCheckable( bool checkable );
 %Docstring
 setItemsCheckable defines if layers should be selectable in the widget
+%End
+
+    void setItemsCanBeReordered( bool allow );
+%Docstring
+Sets whether items in the model can be reordered via drag and drop.
+
+.. seealso:: :py:func:`itemsCanBeReordered`
+
+.. versionadded:: 3.14
+%End
+
+    bool itemsCanBeReordered() const;
+%Docstring
+Returns ``True`` if items in the model can be reordered via drag and drop.
+
+.. seealso:: :py:func:`setItemsCanBeReordered`
+
+.. versionadded:: 3.14
 %End
 
     void checkAll( Qt::CheckState checkState );
@@ -147,12 +170,25 @@ Returns the list of additional (non map layer) items included at the end of the
 
     virtual QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const;
 
-
-
     virtual bool setData( const QModelIndex &index, const QVariant &value, int role = Qt::EditRole );
 
     virtual Qt::ItemFlags flags( const QModelIndex &index ) const;
 
+    virtual bool insertRows( int row, int count, const QModelIndex &parent = QModelIndex() );
+
+    virtual bool removeRows( int row, int count, const QModelIndex &parent = QModelIndex() );
+
+    virtual QStringList mimeTypes() const;
+
+    virtual bool canDropMimeData( const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent ) const;
+
+    virtual QMimeData *mimeData( const QModelIndexList &indexes ) const;
+
+    virtual bool dropMimeData( const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent );
+
+    virtual Qt::DropActions supportedDropActions() const;
+
+
 
     static QIcon iconForLayer( QgsMapLayer *layer );
 %Docstring
@@ -167,6 +203,7 @@ Returns the icon corresponding to a specified map ``layer``.
 
   protected:
 
+
 };
 
 /************************************************************************

diff --git a/src/core/qgsmaplayermodel.cpp b/src/core/qgsmaplayermodel.cpp
@@ -21,27 +21,38 @@
 #include "qgsapplication.h"
 #include "qgsvectorlayer.h"
 
-
-QgsMapLayerModel::QgsMapLayerModel( const QList<QgsMapLayer *> &layers, QObject *parent )
+QgsMapLayerModel::QgsMapLayerModel( const QList<QgsMapLayer *> &layers, QObject *parent, QgsProject *project )
   : QAbstractItemModel( parent )
+  , mProject( project ? project : QgsProject::instance() )
 {
-  connect( QgsProject::instance(), static_cast < void ( QgsProject::* )( const QStringList & ) >( &QgsProject::layersWillBeRemoved ), this, &QgsMapLayerModel::removeLayers );
+  connect( mProject, static_cast < void ( QgsProject::* )( const QStringList & ) >( &QgsProject::layersWillBeRemoved ), this, &QgsMapLayerModel::removeLayers );
   addLayers( layers );
 }
 
-QgsMapLayerModel::QgsMapLayerModel( QObject *parent )
+QgsMapLayerModel::QgsMapLayerModel( QObject *parent, QgsProject *project )
   : QAbstractItemModel( parent )
+  , mProject( project ? project : QgsProject::instance() )
 {
-  connect( QgsProject::instance(), &QgsProject::layersAdded, this, &QgsMapLayerModel::addLayers );
-  connect( QgsProject::instance(), static_cast < void ( QgsProject::* )( const QStringList & ) >( &QgsProject::layersWillBeRemoved ), this, &QgsMapLayerModel::removeLayers );
-  addLayers( QgsProject::instance()->mapLayers().values() );
+  connect( mProject, &QgsProject::layersAdded, this, &QgsMapLayerModel::addLayers );
+  connect( mProject, static_cast < void ( QgsProject::* )( const QStringList & ) >( &QgsProject::layersWillBeRemoved ), this, &QgsMapLayerModel::removeLayers );
+  addLayers( mProject->mapLayers().values() );
 }
 
 void QgsMapLayerModel::setItemsCheckable( bool checkable )
 {
   mItemCheckable = checkable;
 }
 
+void QgsMapLayerModel::setItemsCanBeReordered( bool allow )
+{
+  mCanReorder = allow;
+}
+
+bool QgsMapLayerModel::itemsCanBeReordered() const
+{
+  return mCanReorder;
+}
+
 void QgsMapLayerModel::checkAll( Qt::CheckState checkState )
 {
   QMap<QString, Qt::CheckState>::iterator i = mLayersChecked.begin();
@@ -138,8 +149,7 @@ void QgsMapLayerModel::removeLayers( const QStringList &layerIds )
   if ( mAllowEmpty )
     offset++;
 
-  const auto constLayerIds = layerIds;
-  for ( const QString &layerId : constLayerIds )
+  for ( const QString &layerId : layerIds )
   {
     QModelIndex startIndex = index( 0, 0 );
     QModelIndexList list = match( startIndex, LayerIdRole, layerId, 1 );
@@ -340,20 +350,145 @@ Qt::ItemFlags QgsMapLayerModel::flags( const QModelIndex &index ) const
 {
   if ( !index.isValid() )
   {
-    return nullptr;
+    if ( mCanReorder )
+      return Qt::ItemIsDropEnabled;
+    else
+      return nullptr;
   }
 
   bool isEmpty = index.row() == 0 && mAllowEmpty;
   int additionalIndex = index.row() - ( mAllowEmpty ? 1 : 0 ) - mLayers.count();
 
   Qt::ItemFlags flags = Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+
+  if ( mCanReorder && !isEmpty && additionalIndex < 0 )
+  {
+    flags |= Qt::ItemIsDragEnabled;
+  }
+
   if ( mItemCheckable && !isEmpty && additionalIndex < 0 )
   {
     flags |= Qt::ItemIsUserCheckable;
   }
   return flags;
 }
 
+bool QgsMapLayerModel::insertRows( int row, int count, const QModelIndex &parent )
+{
+  if ( parent.isValid() )
+    return false;
+
+  int offset = 0;
+  if ( mAllowEmpty )
+    offset++;
+
+  beginInsertRows( parent, row, row + count - 1 );
+  for ( int i = row; i < row + count; ++i )
+    mLayers.insert( i - offset, nullptr );
+  endInsertRows();
+
+  return true;
+}
+
+bool QgsMapLayerModel::removeRows( int row, int count, const QModelIndex &parent )
+{
+  if ( parent.isValid() || row < 0 )
+    return false;
+
+  int offset = 0;
+  if ( mAllowEmpty )
+  {
+    if ( row == 0 )
+      return false;
+
+    offset++;
+  }
+
+  if ( row - offset > mLayers.count() - 1 )
+  {
+    return false;
+  }
+
+  beginRemoveRows( parent, row, row + count - 1 );
+  for ( int i = 0; i != count; ++i )
+    mLayers.removeAt( row - offset );
+  endRemoveRows();
+
+  return true;
+}
+
+QStringList QgsMapLayerModel::mimeTypes() const
+{
+  QStringList types;
+  types << QStringLiteral( "application/qgis.layermodeldata" );
+  return types;
+}
+
+bool QgsMapLayerModel::canDropMimeData( const QMimeData *data, Qt::DropAction action, int, int, const QModelIndex & ) const
+{
+  if ( !mCanReorder || action != Qt::MoveAction || !data->hasFormat( QStringLiteral( "application/qgis.layermodeldata" ) ) )
+    return false;
+  return true;
+}
+
+QMimeData *QgsMapLayerModel::mimeData( const QModelIndexList &indexes ) const
+{
+  std::unique_ptr< QMimeData > mimeData = qgis::make_unique< QMimeData >();
+
+  QByteArray encodedData;
+  QDataStream stream( &encodedData, QIODevice::WriteOnly );
+
+  for ( const QModelIndex &index : indexes )
+  {
+    if ( index.isValid() )
+    {
+      QString text = data( index, LayerIdRole ).toString();
+      stream << text;
+    }
+  }
+  mimeData->setData( QStringLiteral( "application/qgis.layermodeldata" ), encodedData );
+  return mimeData.release();
+}
+
+bool QgsMapLayerModel::dropMimeData( const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent )
+{
+  if ( !canDropMimeData( data, action, row, column, parent ) || row < 0 )
+    return false;
+
+  if ( action == Qt::IgnoreAction )
+    return true;
+  else if ( action != Qt::MoveAction )
+    return false;
+
+  QByteArray encodedData = data->data( QStringLiteral( "application/qgis.layermodeldata" ) );
+  QDataStream stream( &encodedData, QIODevice::ReadOnly );
+  QStringList newItems;
+  int rows = 0;
+
+  while ( !stream.atEnd() )
+  {
+    QString text;
+    stream >> text;
+    newItems << text;
+    ++rows;
+  }
+
+  insertRows( row, rows, QModelIndex() );
+  for ( const QString &text : qgis::as_const( newItems ) )
+  {
+    QModelIndex idx = index( row, 0, QModelIndex() );
+    setData( idx, text, LayerIdRole );
+    row++;
+  }
+
+  return true;
+}
+
+Qt::DropActions QgsMapLayerModel::supportedDropActions() const
+{
+  return Qt::MoveAction;
+}
+
 QIcon QgsMapLayerModel::iconForLayer( QgsMapLayer *layer )
 {
   switch ( layer->type() )
@@ -415,15 +550,34 @@ QIcon QgsMapLayerModel::iconForLayer( QgsMapLayer *layer )
 
 bool QgsMapLayerModel::setData( const QModelIndex &index, const QVariant &value, int role )
 {
+  if ( !index.isValid() )
+    return false;
+
   bool isEmpty = index.row() == 0 && mAllowEmpty;
   int additionalIndex = index.row() - ( mAllowEmpty ? 1 : 0 ) - mLayers.count();
 
-  if ( role == Qt::CheckStateRole && !isEmpty && additionalIndex < 0 )
+  switch ( role )
   {
-    QgsMapLayer *layer = static_cast<QgsMapLayer *>( index.internalPointer() );
-    mLayersChecked[layer->id()] = ( Qt::CheckState )value.toInt();
-    emit dataChanged( index, index );
-    return true;
+    case Qt::CheckStateRole:
+    {
+      if ( !isEmpty && additionalIndex < 0 )
+      {
+        QgsMapLayer *layer = static_cast<QgsMapLayer *>( index.internalPointer() );
+        mLayersChecked[layer->id()] = ( Qt::CheckState )value.toInt();
+        emit dataChanged( index, index );
+        return true;
+      }
+      break;
+    }
+
+    case LayerIdRole:
+      if ( !isEmpty && additionalIndex < 0 )
+      {
+        mLayers[index.row() - ( mAllowEmpty ? 1 : 0 )] = mProject->mapLayer( value.toString() );
+        emit dataChanged( index, index );
+        return true;
+      }
+      break;
   }
 
   return false;