qgslayertreeview.cpp

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/***************************************************************************
  qgslayertreeview.cpp
  --------------------------------------
  Date                 : May 2014
  Copyright            : (C) 2014 by Martin Dobias
  Email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgslayertreeview.h"
 
#include "qgsgui.h"
#include "qgslayertree.h"
#include "qgslayertreeembeddedwidgetregistry.h"
#include "qgslayertreemodel.h"
#include "qgslayertreemodellegendnode.h"
#include "qgslayertreeutils.h"
#include "qgslayertreeviewdefaultactions.h"
#include "qgsmaplayer.h"
#include "qgsmessagebar.h"
 
#include <QApplication>
#include <QContextMenuEvent>
#include <QHeaderView>
#include <QMenu>
#include <QMimeData>
#include <QScrollBar>
#include <QString>
 
#include "moc_qgslayertreeview.cpp"
 
using namespace Qt::StringLiterals;
 
#ifdef ENABLE_MODELTEST
#include "modeltest.h"
#endif
 
#include "qgslayertreeviewindicator.h"
#include "qgslayertreeviewitemdelegate.h"
 
 
QgsLayerTreeViewBase::QgsLayerTreeViewBase( QWidget *parent )
  : QTreeView( parent )
  , mBlockDoubleClickTimer( new QTimer( this ) )
{
  mBlockDoubleClickTimer->setSingleShot( true );
  mBlockDoubleClickTimer->setInterval( QApplication::doubleClickInterval() );
 
  setHeaderHidden( true );
 
  setDragEnabled( true );
  setAcceptDrops( true );
  setDropIndicatorShown( true );
  setEditTriggers( EditKeyPressed );
  setExpandsOnDoubleClick( false ); // normally used for other actions
 
  // Ensure legend graphics are scrollable
  header()->setStretchLastSection( false );
  header()->setSectionResizeMode( QHeaderView::ResizeToContents );
 
  // If vertically scrolling by item, legend graphics can get clipped
  setVerticalScrollMode( QAbstractItemView::ScrollPerPixel );
 
  setSelectionMode( ExtendedSelection );
  setDefaultDropAction( Qt::MoveAction );
 
  connect( this, &QTreeView::collapsed, this, &QgsLayerTreeViewBase::updateExpandedStateToNode );
  connect( this, &QTreeView::expanded, this, &QgsLayerTreeViewBase::updateExpandedStateToNode );
}
 
QgsLayerTreeViewBase::~QgsLayerTreeViewBase()
{
  delete mBlockDoubleClickTimer;
}
 
void QgsLayerTreeViewBase::mouseDoubleClickEvent( QMouseEvent *event )
{
  if ( mBlockDoubleClickTimer->isActive() )
    event->accept();
  else
    QTreeView::mouseDoubleClickEvent( event );
}
 
void QgsLayerTreeViewBase::setLayerTreeModel( QgsLayerTreeModel *model )
{
  if ( mLayerTreeModel )
  {
    disconnect( mLayerTreeModel->rootGroup(), &QgsLayerTreeNode::expandedChanged, this, &QgsLayerTreeViewBase::onExpandedChanged );
    disconnect( mLayerTreeModel, &QAbstractItemModel::modelReset, this, &QgsLayerTreeViewBase::onModelReset );
    disconnect( mLayerTreeModel, &QAbstractItemModel::dataChanged, this, &QgsLayerTreeViewBase::onDataChanged );
  }
 
  mLayerTreeModel = model;
 
  mLayerTreeModel->addTargetScreenProperties( QgsScreenProperties( screen() ) );
 
  connect( mLayerTreeModel->rootGroup(), &QgsLayerTreeNode::expandedChanged, this, &QgsLayerTreeViewBase::onExpandedChanged );
 
  connect( mLayerTreeModel, &QAbstractItemModel::modelReset, this, &QgsLayerTreeViewBase::onModelReset );
  connect( mLayerTreeModel, &QAbstractItemModel::dataChanged, this, &QgsLayerTreeViewBase::onDataChanged );
 
  updateExpandedStateFromNode( mLayerTreeModel->rootGroup() );
}
 
QgsLayerTreeModel *QgsLayerTreeViewBase::layerTreeModel() const
{
  return mLayerTreeModel;
}
 
void QgsLayerTreeViewBase::updateExpandedStateFromNode( QgsLayerTreeNode *node )
{
  const QModelIndex idx = node2index( node );
  setExpanded( idx, node->isExpanded() );
 
  const auto constChildren = node->children();
  for ( QgsLayerTreeNode *child : constChildren )
    updateExpandedStateFromNode( child );
}
 
QModelIndex QgsLayerTreeViewBase::viewIndexToLayerTreeModelIndex( const QModelIndex &index ) const
{
  // if no proxy in use, we already have a layer tree model index
  if ( model() == mLayerTreeModel )
    return index;
 
  if ( QAbstractProxyModel *proxy = qobject_cast< QAbstractProxyModel *>( model() ) )
  {
    return proxy->mapToSource( index );
  }
 
  return QModelIndex();
}
 
QModelIndex QgsLayerTreeViewBase::layerTreeModelIndexToViewIndex( const QModelIndex &index ) const
{
  // if no proxy in use, we already have a view index
  if ( model() == mLayerTreeModel )
    return index;
 
  if ( QAbstractProxyModel *proxy = qobject_cast< QAbstractProxyModel *>( model() ) )
  {
    return proxy->mapFromSource( index );
  }
 
  return QModelIndex();
}
 
void QgsLayerTreeViewBase::updateExpandedStateToNode( const QModelIndex &index )
{
  if ( QgsLayerTreeNode *node = index2node( index ) )
  {
    node->setExpanded( isExpanded( index ) );
  }
  else if ( QgsLayerTreeModelLegendNode *node = index2legendNode( index ) )
  {
    const QString ruleKey = node->data( static_cast<int>( QgsLayerTreeModelLegendNode::CustomRole::RuleKey ) ).toString();
    QStringList lst = node->layerNode()->customProperty( u"expandedLegendNodes"_s ).toStringList();
    const bool expanded = isExpanded( index );
    const bool isInList = lst.contains( ruleKey );
    if ( expanded && !isInList )
    {
      lst.append( ruleKey );
      node->layerNode()->setCustomProperty( u"expandedLegendNodes"_s, lst );
    }
    else if ( !expanded && isInList )
    {
      lst.removeAll( ruleKey );
      node->layerNode()->setCustomProperty( u"expandedLegendNodes"_s, lst );
    }
  }
}
 
void QgsLayerTreeViewBase::onExpandedChanged( QgsLayerTreeNode *node, bool expanded )
{
  const QModelIndex idx = node2index( node );
  if ( isExpanded( idx ) != expanded )
    setExpanded( idx, expanded );
}
 
void QgsLayerTreeViewBase::onModelReset()
{
  if ( !mLayerTreeModel )
    return;
  updateExpandedStateFromNode( mLayerTreeModel->rootGroup() );
  //checkModel();
}
 
void QgsLayerTreeViewBase::onDataChanged( const QModelIndex &, const QModelIndex &, const QVector<int> & )
{
  mBlockDoubleClickTimer->start();
}
 
QgsLayerTreeNode *QgsLayerTreeViewBase::index2node( const QModelIndex &index ) const
{
  if ( mLayerTreeModel )
    return mLayerTreeModel->index2node( viewIndexToLayerTreeModelIndex( index ) );
 
  return nullptr;
}
 
QModelIndex QgsLayerTreeViewBase::node2index( QgsLayerTreeNode *node ) const
{
  return layerTreeModelIndexToViewIndex( node2sourceIndex( node ) );
}
 
QModelIndex QgsLayerTreeViewBase::node2sourceIndex( QgsLayerTreeNode *node ) const
{
  if ( mLayerTreeModel )
    return mLayerTreeModel->node2index( node );
 
  return QModelIndex();
}
 
QgsLayerTreeModelLegendNode *QgsLayerTreeViewBase::index2legendNode( const QModelIndex &index ) const
{
  return QgsLayerTreeModel::index2legendNode( viewIndexToLayerTreeModelIndex( index ) );
}
 
QgsLayerTreeNode *QgsLayerTreeViewBase::currentNode() const
{
  if ( QItemSelectionModel *selectModel = selectionModel() )
    return index2node( selectModel->currentIndex() );
  else
    return nullptr;
}
 
QList<QgsLayerTreeNode *> QgsLayerTreeViewBase::selectedNodes( bool skipInternal ) const
{
  if ( !mLayerTreeModel )
    return {};
 
  QModelIndexList mapped;
  if ( QItemSelectionModel *selectModel = selectionModel() )
  {
    const QModelIndexList selected = selectModel->selectedIndexes();
    mapped.reserve( selected.size() );
    for ( const QModelIndex &index : selected )
      mapped << viewIndexToLayerTreeModelIndex( index );
  }
 
  return mLayerTreeModel->indexes2nodes( mapped, skipInternal );
}
 
 
QgsMapLayer *QgsLayerTreeViewBase::currentLayer() const
{
  return layerForIndex( currentIndex() );
}
 
QgsMapLayer *QgsLayerTreeViewBase::layerForIndex( const QModelIndex &index ) const
{
  // Check if model has been set and index is valid
  if ( mLayerTreeModel && index.isValid() )
  {
    if ( QgsLayerTreeNode *node = index2node( index ) )
    {
      if ( QgsLayerTree::isLayer( node ) )
        return QgsLayerTree::toLayer( node )->layer();
    }
    else
    {
      // possibly a legend node
      QgsLayerTreeModelLegendNode *legendNode = index2legendNode( index );
      if ( legendNode )
        return legendNode->layerNode()->layer();
    }
  }
  return nullptr;
}
 
QgsLayerTreeGroup *QgsLayerTreeViewBase::currentGroupNode() const
{
  QgsLayerTreeNode *node = currentNode();
  if ( QgsLayerTree::isGroup( node ) )
    return QgsLayerTree::toGroup( node );
  else if ( QgsLayerTree::isLayer( node ) )
  {
    QgsLayerTreeNode *parent = node->parent();
    if ( QgsLayerTree::isGroup( parent ) )
      return QgsLayerTree::toGroup( parent );
  }
 
  if ( QItemSelectionModel *selectModel = selectionModel() )
  {
    if ( QgsLayerTreeModelLegendNode *legendNode = index2legendNode( selectModel->currentIndex() ) )
    {
      QgsLayerTreeLayer *parent = legendNode->layerNode();
      if ( QgsLayerTree::isGroup( parent->parent() ) )
        return QgsLayerTree::toGroup( parent->parent() );
    }
  }
 
  return nullptr;
}
 
QList<QgsLayerTreeLayer *> QgsLayerTreeViewBase::selectedLayerNodes() const
{
  QList<QgsLayerTreeLayer *> layerNodes;
  const QList<QgsLayerTreeNode *> constSelectedNodes = selectedNodes();
  layerNodes.reserve( constSelectedNodes.size() );
  for ( QgsLayerTreeNode *node : constSelectedNodes )
  {
    if ( QgsLayerTree::isLayer( node ) )
      layerNodes << QgsLayerTree::toLayer( node );
  }
  return layerNodes;
}
 
QList<QgsMapLayer *> QgsLayerTreeViewBase::selectedLayers() const
{
  QList<QgsMapLayer *> list;
  const QList<QgsLayerTreeLayer *> constSelectedLayerNodes = selectedLayerNodes();
  list.reserve( constSelectedLayerNodes.size() );
  for ( QgsLayerTreeLayer *node : constSelectedLayerNodes )
  {
    if ( node->layer() )
      list << node->layer();
  }
  return list;
}
 
QModelIndex QgsLayerTreeViewBase::legendNode2index( QgsLayerTreeModelLegendNode *legendNode )
{
  return layerTreeModelIndexToViewIndex( legendNode2sourceIndex( legendNode ) );
}
 
QModelIndex QgsLayerTreeViewBase::legendNode2sourceIndex( QgsLayerTreeModelLegendNode *legendNode )
{
  if ( mLayerTreeModel )
    return mLayerTreeModel->legendNode2index( legendNode );
  return QModelIndex();
}
 
void QgsLayerTreeViewBase::setCurrentNode( QgsLayerTreeNode *node )
{
  if ( !node )
  {
    setCurrentIndex( QModelIndex() );
    return;
  }
 
  setCurrentIndex( node2index( node ) );
}
 
void QgsLayerTreeViewBase::setCurrentLayer( QgsMapLayer *layer )
{
  if ( !layer || !mLayerTreeModel )
  {
    setCurrentIndex( QModelIndex() );
    return;
  }
 
  QgsLayerTreeLayer *nodeLayer = mLayerTreeModel->rootGroup()->findLayer( layer->id() );
  if ( !nodeLayer )
    return;
 
  setCurrentNode( nodeLayer );
}
 
QgsLayerTreeModelLegendNode *QgsLayerTreeViewBase::currentLegendNode() const
{
  if ( QItemSelectionModel *selectModel = selectionModel() )
    return index2legendNode( selectModel->currentIndex() );
  else
    return nullptr;
}
 
QList<QgsLayerTreeModelLegendNode *> QgsLayerTreeViewBase::selectedLegendNodes() const
{
  QList<QgsLayerTreeModelLegendNode *> res;
  QItemSelectionModel *selectModel = selectionModel();
  if ( !mLayerTreeModel || !selectModel )
    return res;
 
  const QModelIndexList selected = selectModel->selectedIndexes();
  res.reserve( selected.size() );
  for ( const QModelIndex &index : selected )
  {
    const QModelIndex modelIndex = viewIndexToLayerTreeModelIndex( index );
    if ( QgsLayerTreeModelLegendNode *node = mLayerTreeModel->index2legendNode( modelIndex ) )
    {
      res.push_back( node );
    }
  }
 
  return res;
}
 
QList<QgsMapLayer *> QgsLayerTreeViewBase::selectedLayersRecursive() const
{
  QModelIndexList mapped;
  QItemSelectionModel *selectModel = selectionModel();
  if ( !mLayerTreeModel || !selectModel )
    return QList<QgsMapLayer *>();
 
  const QModelIndexList selected = selectModel->selectedIndexes();
  mapped.reserve( selected.size() );
  for ( const QModelIndex &index : selected )
  {
    mapped << viewIndexToLayerTreeModelIndex( index );
  }
 
  const QList<QgsLayerTreeNode *> nodes = mLayerTreeModel->indexes2nodes( mapped, false );
  const QSet<QgsMapLayer *> layersSet = QgsLayerTreeUtils::collectMapLayersRecursive( nodes );
  return qgis::setToList( layersSet );
}
 
static void expandAllLegendNodes( QgsLayerTreeLayer *nodeLayer, bool expanded, QgsLayerTreeModel *model )
{
  // for layers we also need to find out with legend nodes contain some children and make them expanded/collapsed
  // if we are collapsing, we just write out an empty list
  QStringList lst;
  if ( expanded )
  {
    const auto constLayerLegendNodes = model->layerLegendNodes( nodeLayer, true );
    for ( QgsLayerTreeModelLegendNode *legendNode : constLayerLegendNodes )
    {
      const QString parentKey = legendNode->data( static_cast<int>( QgsLayerTreeModelLegendNode::CustomRole::ParentRuleKey ) ).toString();
      if ( !parentKey.isEmpty() && !lst.contains( parentKey ) )
        lst << parentKey;
    }
  }
  nodeLayer->setCustomProperty( u"expandedLegendNodes"_s, lst );
}
 
static void expandAllNodes( QgsLayerTreeGroup *parent, bool expanded, QgsLayerTreeModel *model )
{
  const auto constChildren = parent->children();
  for ( QgsLayerTreeNode *node : constChildren )
  {
    node->setExpanded( expanded );
    if ( QgsLayerTree::isGroup( node ) )
      expandAllNodes( QgsLayerTree::toGroup( node ), expanded, model );
    else if ( QgsLayerTree::isLayer( node ) )
      expandAllLegendNodes( QgsLayerTree::toLayer( node ), expanded, model );
  }
}
 
void QgsLayerTreeViewBase::expandAllNodes()
{
  // unfortunately expandAll() does not emit expanded() signals
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
  ::expandAllNodes( layerModel->rootGroup(), true, layerModel );
  expandAll();
}
 
void QgsLayerTreeViewBase::collapseAllNodes()
{
  // unfortunately collapseAll() does not emit collapsed() signals
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
  ::expandAllNodes( layerModel->rootGroup(), false, layerModel );
  collapseAll();
}
 
QgsLayerTreeViewDefaultActions *QgsLayerTreeViewBase::defaultActions()
{
  if ( !mDefaultActions )
    mDefaultActions = new QgsLayerTreeViewDefaultActions( this );
  return mDefaultActions;
}
 
//
// QgsLayerTreeView
//
 
QgsLayerTreeView::QgsLayerTreeView( QWidget *parent )
  : QgsLayerTreeViewBase( parent )
{
  // we need a custom item delegate in order to draw indicators
  setItemDelegate( new QgsLayerTreeViewItemDelegate( this ) );
  setStyle( new QgsLayerTreeViewProxyStyle( this ) );
 
  setLayerMarkWidth( static_cast<int>( QFontMetricsF( font() ).horizontalAdvance( 'l' ) * Qgis::UI_SCALE_FACTOR ) );
 
  connect( horizontalScrollBar(), &QScrollBar::valueChanged, this, &QgsLayerTreeView::onHorizontalScroll );
}
 
QgsLayerTreeView::~QgsLayerTreeView()
{
  delete mMenuProvider;
}
 
void QgsLayerTreeView::setModel( QAbstractItemModel *model )
{
  QgsLayerTreeModel *treeModel = qobject_cast<QgsLayerTreeModel *>( model );
  if ( !treeModel )
    return;
 
  auto proxyModel = new QgsLayerTreeProxyModel( treeModel, this );
  proxyModel->setShowPrivateLayers( mShowPrivateLayers );
  proxyModel->setHideValidLayers( mHideValidLayers );
 
  setModel( treeModel, proxyModel );
}
 
void QgsLayerTreeView::setModel( QgsLayerTreeModel *treeModel, QgsLayerTreeProxyModel *proxyModel )
{
  if ( mMessageBar )
    connect( treeModel, &QgsLayerTreeModel::messageEmitted, this, [this]( const QString &message, Qgis::MessageLevel level = Qgis::MessageLevel::Info, int duration = 5 ) {
      Q_UNUSED( duration )
      mMessageBar->pushMessage( message, level );
    } );
 
  mProxyModel = proxyModel;
  connect( mProxyModel, &QAbstractItemModel::rowsInserted, this, &QgsLayerTreeView::modelRowsInserted );
  connect( mProxyModel, &QAbstractItemModel::rowsRemoved, this, &QgsLayerTreeView::modelRowsRemoved );
 
#ifdef ENABLE_MODELTEST
  new ModelTest( mProxyModel, this );
#endif
 
  QTreeView::setModel( mProxyModel );
  QgsLayerTreeViewBase::setLayerTreeModel( treeModel );
 
  connect( treeModel->rootGroup(), &QgsLayerTreeNode::customPropertyChanged, this, &QgsLayerTreeView::onCustomPropertyChanged );
 
  connect( selectionModel(), &QItemSelectionModel::currentChanged, this, &QgsLayerTreeView::onCurrentChanged );
 
  connect( treeModel, &QAbstractItemModel::dataChanged, this, &QgsLayerTreeView::onDataChanged );
 
  //checkModel();
}
 
void QgsLayerTreeView::setMenuProvider( QgsLayerTreeViewMenuProvider *menuProvider )
{
  delete mMenuProvider;
  mMenuProvider = menuProvider;
}
 
void QgsLayerTreeView::setLayerVisible( QgsMapLayer *layer, bool visible )
{
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layer || !layerModel )
    return;
  QgsLayerTreeLayer *nodeLayer = layerModel->rootGroup()->findLayer( layer->id() );
  if ( !nodeLayer )
    return;
  nodeLayer->setItemVisibilityChecked( visible );
}
 
void QgsLayerTreeView::contextMenuEvent( QContextMenuEvent *event )
{
  if ( !mMenuProvider )
    return;
 
  const QModelIndex idx = indexAt( event->pos() );
  if ( !idx.isValid() )
    setCurrentIndex( QModelIndex() );
 
  QMenu *menu = mMenuProvider->createContextMenu();
  if ( menu )
  {
    emit contextMenuAboutToShow( menu );
 
    if ( menu->actions().count() != 0 )
      menu->exec( mapToGlobal( event->pos() ) );
    delete menu;
  }
}
 
 
void QgsLayerTreeView::modelRowsInserted( const QModelIndex &index, int start, int end )
{
  QgsLayerTreeNode *parentNode = index2node( index );
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !parentNode || !layerModel )
    return;
 
  // Embedded widgets - replace placeholders in the model by actual widgets
  if ( layerModel->testFlag( QgsLayerTreeModel::UseEmbeddedWidgets ) && QgsLayerTree::isLayer( parentNode ) )
  {
    QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( parentNode );
    if ( QgsMapLayer *layer = nodeLayer->layer() )
    {
      const int widgetsCount = layer->customProperty( u"embeddedWidgets/count"_s, 0 ).toInt();
      QList<QgsLayerTreeModelLegendNode *> legendNodes = layerModel->layerLegendNodes( nodeLayer, true );
      for ( int i = 0; i < widgetsCount; ++i )
      {
        const QString providerId = layer->customProperty( u"embeddedWidgets/%1/id"_s.arg( i ) ).toString();
        if ( QgsLayerTreeEmbeddedWidgetProvider *provider = QgsGui::layerTreeEmbeddedWidgetRegistry()->provider( providerId ) )
        {
          const QModelIndex index = legendNode2index( legendNodes[i] );
          QWidget *wdgt = provider->createWidget( layer, i );
          // Since column is resized to contents, limit the expanded width of embedded
          //  widgets, if they are not already limited, e.g. have the default MAX value.
          // Else, embedded widget may grow very wide due to large legend graphics.
          // NOTE: This approach DOES NOT work right. It causes horizontal scroll
          //       bar to disappear if the embedded widget is expanded and part
          //       of the last layer in the panel, even if much wider legend items
          //       are expanded above it. The correct width-limiting method should
          //       be setting fixed-width, hidpi-aware embedded widget items in a
          //       layout and appending an expanding QSpacerItem to end. This ensures
          //       full width is always created in the column by the embedded widget.
          //       See QgsLayerTreeOpacityWidget
          //if ( wdgt->maximumWidth() == QWIDGETSIZE_MAX )
          //{
          //  wdgt->setMaximumWidth( 250 );
          //}
 
          setIndexWidget( index, wdgt );
        }
      }
    }
  }
 
 
  if ( QgsLayerTree::isLayer( parentNode ) )
  {
    // if ShowLegendAsTree flag is enabled in model, we may need to expand some legend nodes
    const QStringList expandedNodeKeys = parentNode->customProperty( u"expandedLegendNodes"_s ).toStringList();
    if ( expandedNodeKeys.isEmpty() )
      return;
 
    const auto constLayerLegendNodes = layerModel->layerLegendNodes( QgsLayerTree::toLayer( parentNode ), true );
    for ( QgsLayerTreeModelLegendNode *legendNode : constLayerLegendNodes )
    {
      const QString ruleKey = legendNode->data( static_cast<int>( QgsLayerTreeModelLegendNode::CustomRole::RuleKey ) ).toString();
      if ( expandedNodeKeys.contains( ruleKey ) )
        setExpanded( legendNode2index( legendNode ), true );
    }
    return;
  }
 
  QList<QgsLayerTreeNode *> children = parentNode->children();
  for ( int i = start; i <= end && i < children.count(); ++i )
  {
    updateExpandedStateFromNode( children[i] );
  }
 
  // make sure we still have correct current layer
  onCurrentChanged();
}
 
void QgsLayerTreeView::modelRowsRemoved()
{
  // make sure we still have correct current layer
  onCurrentChanged();
}
 
void QgsLayerTreeView::onCurrentChanged()
{
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
 
  QgsMapLayer *layerCurrent = layerForIndex( currentIndex() );
  const QString layerCurrentID = layerCurrent ? layerCurrent->id() : QString();
  if ( mCurrentLayerID == layerCurrentID )
    return;
 
  // update the current index in model (the item will be underlined)
  QModelIndex proxyModelNodeLayerIndex;
  if ( layerCurrent )
  {
    QgsLayerTreeLayer *nodeLayer = layerModel->rootGroup()->findLayer( layerCurrentID );
    if ( nodeLayer )
      proxyModelNodeLayerIndex = node2index( nodeLayer );
  }
 
  if ( !proxyModelNodeLayerIndex.isValid() )
  {
    mCurrentLayerID = QString();
    layerModel->setCurrentIndex( QModelIndex() );
  }
  else
  {
    mCurrentLayerID = layerCurrentID;
    layerModel->setCurrentIndex( mProxyModel->mapToSource( proxyModelNodeLayerIndex ) );
  }
 
  //checkModel();
 
  emit currentLayerChanged( layerCurrent );
}
 
void QgsLayerTreeView::onCustomPropertyChanged( QgsLayerTreeNode *node, const QString &key )
{
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( key != "expandedLegendNodes"_L1 || !QgsLayerTree::isLayer( node ) || !layerModel )
    return;
 
  const QSet<QString> expandedLegendNodes = qgis::listToSet( node->customProperty( u"expandedLegendNodes"_s ).toStringList() );
 
  const QList<QgsLayerTreeModelLegendNode *> legendNodes = layerModel->layerLegendNodes( QgsLayerTree::toLayer( node ), true );
  for ( QgsLayerTreeModelLegendNode *legendNode : legendNodes )
  {
    const QString key = legendNode->data( static_cast<int>( QgsLayerTreeModelLegendNode::CustomRole::RuleKey ) ).toString();
    if ( !key.isEmpty() )
      setExpanded( legendNode2index( legendNode ), expandedLegendNodes.contains( key ) );
  }
}
 
void QgsLayerTreeView::addIndicator( QgsLayerTreeNode *node, QgsLayerTreeViewIndicator *indicator )
{
  if ( !mIndicators[node].contains( indicator ) )
  {
    mIndicators[node].append( indicator );
    connect( indicator, &QgsLayerTreeViewIndicator::changed, this, [this] {
      update();
      viewport()->repaint();
    } );
    update();
    viewport()->repaint(); //update() does not automatically trigger a repaint()
  }
}
 
void QgsLayerTreeView::removeIndicator( QgsLayerTreeNode *node, QgsLayerTreeViewIndicator *indicator )
{
  mIndicators[node].removeOne( indicator );
  update();
}
 
QList<QgsLayerTreeViewIndicator *> QgsLayerTreeView::indicators( QgsLayerTreeNode *node ) const
{
  return mIndicators.value( node );
}

QStringList QgsLayerTreeView::viewOnlyCustomProperties()
{
  return QStringList() << u"expandedLegendNodes"_s;
}
 
void QgsLayerTreeView::refreshLayerSymbology( const QString &layerId )
{
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
  QgsLayerTreeLayer *nodeLayer = layerModel->rootGroup()->findLayer( layerId );
  if ( nodeLayer )
    layerModel->refreshLayerLegend( nodeLayer );
}
 
 
void QgsLayerTreeView::setMessageBar( QgsMessageBar *messageBar )
{
  if ( mMessageBar == messageBar )
    return;
 
  mMessageBar = messageBar;
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
 
  if ( mMessageBar )
    connect( layerModel, &QgsLayerTreeModel::messageEmitted, this, [this]( const QString &message, Qgis::MessageLevel level = Qgis::MessageLevel::Info, int duration = 5 ) {
      Q_UNUSED( duration )
      mMessageBar->pushMessage( message, level );
    } );
}
 
void QgsLayerTreeView::setShowPrivateLayers( bool showPrivate )
{
  if ( !mProxyModel )
    return;
 
  mShowPrivateLayers = showPrivate;
  mProxyModel->setShowPrivateLayers( showPrivate );
}
 
void QgsLayerTreeView::setHideValidLayers( bool hideValid )
{
  if ( !mProxyModel )
    return;
 
  mHideValidLayers = hideValid;
  mProxyModel->setHideValidLayers( mHideValidLayers );
}
 
bool QgsLayerTreeView::showPrivateLayers() const
{
  return mShowPrivateLayers;
}
 
bool QgsLayerTreeView::hideValidLayers() const
{
  return mHideValidLayers;
}
 
void QgsLayerTreeView::mouseReleaseEvent( QMouseEvent *event )
{
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
 
  // we need to keep last mouse position in order to know whether to emit an indicator's clicked() signal
  // (the item delegate needs to know which indicator has been clicked)
  mLastReleaseMousePos = event->pos();
 
  const QgsLayerTreeModel::Flags oldFlags = layerModel->flags();
  if ( event->modifiers() & Qt::ControlModifier )
    layerModel->setFlags( oldFlags | QgsLayerTreeModel::ActionHierarchical );
  else
    layerModel->setFlags( oldFlags & ~QgsLayerTreeModel::ActionHierarchical );
  QTreeView::mouseReleaseEvent( event );
  layerModel->setFlags( oldFlags );
}
 
void QgsLayerTreeView::keyPressEvent( QKeyEvent *event )
{
  if ( event->key() == Qt::Key_Space )
  {
    const QList<QgsLayerTreeNode *> constSelectedNodes = selectedNodes();
 
    if ( !constSelectedNodes.isEmpty() )
    {
      const bool isFirstNodeChecked = constSelectedNodes[0]->itemVisibilityChecked();
      for ( QgsLayerTreeNode *node : constSelectedNodes )
      {
        node->setItemVisibilityChecked( !isFirstNodeChecked );
      }
 
      // if we call the original keyPress handler, the current item will be checked to the original state yet again
      return;
    }
  }
 
  QgsLayerTreeModel *layerModel = layerTreeModel();
  if ( !layerModel )
    return;
  const QgsLayerTreeModel::Flags oldFlags = layerModel->flags();
  if ( event->modifiers() & Qt::ControlModifier )
    layerModel->setFlags( oldFlags | QgsLayerTreeModel::ActionHierarchical );
  else
    layerModel->setFlags( oldFlags & ~QgsLayerTreeModel::ActionHierarchical );
  QTreeView::keyPressEvent( event );
  layerModel->setFlags( oldFlags );
}
 
void QgsLayerTreeView::dragEnterEvent( QDragEnterEvent *event )
{
  if ( event->mimeData()->hasUrls() || event->mimeData()->hasFormat( u"application/x-vnd.qgis.qgis.uri"_s ) )
  {
    // the mime data are coming from layer tree, so ignore that, do not import those layers again
    if ( !event->mimeData()->hasFormat( u"application/qgis.layertreemodeldata"_s ) )
    {
      event->accept();
      return;
    }
  }
  QTreeView::dragEnterEvent( event );
}
 
void QgsLayerTreeView::dragMoveEvent( QDragMoveEvent *event )
{
  if ( event->mimeData()->hasUrls() || event->mimeData()->hasFormat( u"application/x-vnd.qgis.qgis.uri"_s ) )
  {
    // the mime data are coming from layer tree, so ignore that, do not import those layers again
    if ( !event->mimeData()->hasFormat( u"application/qgis.layertreemodeldata"_s ) )
    {
      event->accept();
      return;
    }
  }
  QTreeView::dragMoveEvent( event );
}
 
void QgsLayerTreeView::dropEvent( QDropEvent *event )
{
  if ( event->mimeData()->hasUrls() || event->mimeData()->hasFormat( u"application/x-vnd.qgis.qgis.uri"_s ) )
  {
    // the mime data are coming from layer tree, so ignore that, do not import those layers again
    if ( !event->mimeData()->hasFormat( u"application/qgis.layertreemodeldata"_s ) )
    {
      event->accept();
 
      QModelIndex index = indexAt( event->pos() );
      if ( index.isValid() )
      {
        setCurrentIndex( index );
      }
 
      emit datasetsDropped( event );
      return;
    }
  }
  if ( event->keyboardModifiers() & Qt::AltModifier || event->keyboardModifiers() & Qt::ControlModifier )
  {
    event->accept();
  }
  QTreeView::dropEvent( event );
}
 
void QgsLayerTreeView::resizeEvent( QResizeEvent *event )
{
  // Since last column is resized to content (instead of stretched), the active
  // selection rectangle ends at width of widest visible item in tree,
  // regardless of which item is selected. This causes layer indicators to
  // become 'inactive' (not clickable and no tool tip) unless their rectangle
  // enters the view item's selection (active) rectangle.
  // Always resetting the minimum section size relative to the viewport ensures
  // the view item's selection rectangle extends to the right edge of the
  // viewport, which allows indicators to become active again.
  header()->setMinimumSectionSize( viewport()->width() );
  QTreeView::resizeEvent( event );
}
 
void QgsLayerTreeView::onHorizontalScroll( int value )
{
  Q_UNUSED( value )
  viewport()->update();
}
 
void QgsLayerTreeView::onDataChanged( const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles )
{
  Q_UNUSED( topLeft )
  Q_UNUSED( bottomRight )
 
  // If an item is resized asynchronously (e.g. wms legend)
  // The items below will need to be shifted vertically.
  // This doesn't happen automatically, unless the viewport update is triggered.
 
  if ( roles.contains( Qt::SizeHintRole ) )
    viewport()->update();
 
  //checkModel();
}
 
#if 0
// for model debugging
void QgsLayerTreeView::checkModel()
{
  std::function<void( QgsLayerTreeNode *, int )> debug;
  debug = [ & ]( QgsLayerTreeNode * node, int depth )
  {
    if ( depth == 1 )
      qDebug() << "----------------------------------------------";
 
    qDebug() << depth << node->name() << node2index( node ) << layerTreeModel()->rowCount( node2sourceIndex( node ) ) << mProxyModel->rowCount( node2index( node ) );
    Q_ASSERT( node == index2node( node2index( node ) ) );
    Q_ASSERT( node == layerTreeModel()->index2node( node2sourceIndex( node ) ) );
    Q_ASSERT( layerTreeModel()->rowCount( node2sourceIndex( node ) ) == mProxyModel->rowCount( node2index( node ) ) );
 
    for ( int i = 0; i < mProxyModel->rowCount( node2index( node ) ); i++ )
    {
      QgsLayerTreeNode *childNode { index2node( mProxyModel->index( i, 0, node2index( node ) ) ) };
      if ( childNode )
        debug( childNode, depth + 1 );
      else
        qDebug() << "Warning no child node!";
    }
  };
  debug( layerTreeModel()->rootGroup(), 1 );
}
#endif
 
QgsLayerTreeProxyModel *QgsLayerTreeView::proxyModel() const
{
  return mProxyModel;
}
 
QgsLayerTreeProxyModel::QgsLayerTreeProxyModel( QgsLayerTreeModel *treeModel, QObject *parent )
  : QSortFilterProxyModel( parent )
  , mLayerTreeModel( treeModel )
{
  setSourceModel( treeModel );
}
 
void QgsLayerTreeProxyModel::setFilterText( const QString &filterText )
{
  if ( filterText == mFilterText )
    return;
 
  mFilterText = filterText;
  invalidateFilter();
}
 
bool QgsLayerTreeProxyModel::filterAcceptsRow( int sourceRow, const QModelIndex &sourceParent ) const
{
  QgsLayerTreeNode *node = mLayerTreeModel->index2node( mLayerTreeModel->index( sourceRow, 0, sourceParent ) );
  return nodeShown( node );
}
 
bool QgsLayerTreeProxyModel::nodeShown( QgsLayerTreeNode *node ) const
{
  if ( !node )
    return true;
 
  if ( node->nodeType() == QgsLayerTreeNode::NodeGroup )
  {
    return true;
  }
  else
  {
    QgsMapLayer *layer = QgsLayerTree::toLayer( node )->layer();
    if ( !layer )
      return true;
    if ( !mFilterText.isEmpty() && !layer->name().contains( mFilterText, Qt::CaseInsensitive ) )
      return false;
    if ( !mShowPrivateLayers && layer->flags().testFlag( QgsMapLayer::LayerFlag::Private ) )
    {
      return false;
    }
    if ( mHideValidLayers && layer->isValid() )
      return false;
 
    return true;
  }
}
 
bool QgsLayerTreeProxyModel::showPrivateLayers() const
{
  return mShowPrivateLayers;
}
 
void QgsLayerTreeProxyModel::setShowPrivateLayers( bool showPrivate )
{
  if ( showPrivate == mShowPrivateLayers )
    return;
 
  mShowPrivateLayers = showPrivate;
  invalidateFilter();
}
 
bool QgsLayerTreeProxyModel::hideValidLayers() const
{
  return mHideValidLayers;
}
 
void QgsLayerTreeProxyModel::setHideValidLayers( bool hideValid )
{
  if ( hideValid == mHideValidLayers )
    return;
 
  mHideValidLayers = hideValid;
  invalidateFilter();
}