File indexing completed on 2024-12-22 04:40:11

 /*
     SPDX-FileCopyrightText: 2007-2009 Sergio Pistone <sergio_pistone@yahoo.com.ar>
     SPDX-FileCopyrightText: 2010-2022 Mladen Milinkovic <max@smoothware.net>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "treeview.h"
 
 #include <QTimer>
 #include <QScrollBar>
 
 TreeView::TreeView(QWidget *parent) :
     QTreeView(parent),
     m_updateGeometriesTimer(new QTimer(this)),
     m_currentModelRows(-1),
     m_instantGeometryUpdate(0)
 {
     // NOTE: The updateGeometries() methods takes forever to execute (around 100ms
     // for a view with more that 1 thousand items, and more as more items are added).
     // The culprit is the updateGeometries() method in QHeaderView which takes a lot
     // of time when there are columns with ResizeToContents mode set.
     // To workaround this, we reimplement the updateGeometries method to (re)start a
     // timer that invoques the real work only on timeout (reported as BUG 234368 at Qt).
     // To further refine our hack, we only delay the geometries update when the model's
     // "has rows" (imaginary) property hasn't changed since last geometries update.
     // This works very well in our case because the columns with ResizeToContents enabled
     // have items of the same size and so their geometries only change with "has rows" state.
 
     m_updateGeometriesTimer->setInterval(200);
     m_updateGeometriesTimer->setSingleShot(true);
 
     connect(m_updateGeometriesTimer, &QTimer::timeout, this, &TreeView::onUpdateGeometriesTimeout);
 }
 
 TreeView::~TreeView()
 {}
 
 void
 TreeView::setModel(QAbstractItemModel *newModel)
 {
     if(model()) {
         disconnect(model(), &QAbstractItemModel::dataChanged, viewport(), QOverload<>::of(&QWidget::update));
         disconnect(model(), &QAbstractItemModel::rowsAboutToBeInserted, this, &TreeView::onRowsAboutToBeInserted);
         disconnect(model(), &QAbstractItemModel::rowsAboutToBeRemoved, this, &TreeView::onRowsAboutToBeRemoved);
     }
 
     QTreeView::setModel(newModel);
 
     if(newModel) {
         m_currentModelRows = newModel->rowCount();
         connect(newModel, &QAbstractItemModel::dataChanged, viewport(), QOverload<>::of(&QWidget::update));
         connect(newModel, &QAbstractItemModel::rowsAboutToBeInserted, this, &TreeView::onRowsAboutToBeInserted);
         connect(newModel, &QAbstractItemModel::rowsAboutToBeRemoved, this, &TreeView::onRowsAboutToBeRemoved);
     } else {
         m_currentModelRows = -1;
     }
 }
 
 void
 TreeView::onRowsAboutToBeInserted(const QModelIndex &parent, int start, int end)
 {
     if(!parent.isValid()) {
         m_instantGeometryUpdate = m_currentModelRows == 0 ? 1 : 0;
         m_currentModelRows += end - start + 1;
     }
 }
 
 void
 TreeView::onRowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
 {
     if(!parent.isValid()) {
         m_currentModelRows -= end - start + 1;
         m_instantGeometryUpdate = m_currentModelRows == 0 ? 1 : 0;
     }
 }
 
 void
 TreeView::updateGeometries()
 {
     if(m_instantGeometryUpdate--)
         QTreeView::updateGeometries();
     else
         m_updateGeometriesTimer->start();
 }
 
 void
 TreeView::onUpdateGeometriesTimeout()
 {
     QTreeView::updateGeometries();
 }