Gui: Expand group after selection

This commit ensures that after selecting item the group is automatically
expanded. User can force expansion by explcitly clicking expand button,
groups expanded that way will stay expanded unless user collapses them.
Otherwise non-active group will be collapsed automatically.

src/Gui/DlgPreferencesImp.cpp

@@ -53,10 +53,12 @@
 #include "Tools.h"
 #include "WidgetFactory.h"
 
+#include <QDesktopWidget>
 
 using namespace Gui::Dialog;
 
-QWidget* PreferencesPageItem::getWidget() const {
+QWidget* PreferencesPageItem::getWidget() const
+{
     return _widget;
 }
 
@@ -70,6 +72,16 @@ void PreferencesPageItem::setWidget(QWidget* widget)
     _widget->setProperty(PropertyName, QVariant::fromValue(this));
 }
 
+bool PreferencesPageItem::isExpanded() const
+{
+    return _expanded;
+}
+
+void PreferencesPageItem::setExpanded(bool expanded)
+{
+    _expanded = expanded;
+}
+
 Q_DECLARE_METATYPE(PreferencesPageItem*);
 
 const int DlgPreferencesImp::GroupNameRole = Qt::UserRole + 1;
@@ -110,6 +122,14 @@ DlgPreferencesImp::DlgPreferencesImp(QWidget* parent, Qt::WindowFlags fl)
             &QTreeView::clicked,
             this,
             &DlgPreferencesImp::onPageSelected);
+    connect(ui->groupsTreeView,
+            &QTreeView::expanded,
+            this,
+            &DlgPreferencesImp::onGroupExpanded);
+    connect(ui->groupsTreeView,
+            &QTreeView::collapsed,
+            this,
+            &DlgPreferencesImp::onGroupCollapsed);
     connect(ui->buttonReset,
             &QPushButton::clicked,
             this,
@@ -217,6 +237,7 @@ PreferencesPageItem* DlgPreferencesImp::createGroup(const std::string &groupName
     item->setTextAlignment(Qt::AlignLeft | Qt::AlignVCenter);
     item->setFlags(Qt::ItemIsSelectable | Qt::ItemIsEnabled);
     item->setWidget(groupPages);
+    item->setSelectable(false);
 
     _model.invisibleRootItem()->appendRow(item);
 
@@ -671,20 +692,50 @@ QModelIndex findRootIndex(const QModelIndex& index)
 
 void DlgPreferencesImp::onPageSelected(const QModelIndex& index)
 {
-    auto root = findRootIndex(index);
+    auto* currentItem = static_cast<PreferencesPageItem*>(_model.itemFromIndex(index));
 
-    auto* groupItem = static_cast<PreferencesPageItem*>(_model.itemFromIndex(root));
+    if (currentItem->hasChildren()) {
+        auto pageIndex = currentItem->child(0)->index();
+
+        ui->groupsTreeView->selectionModel()->select(pageIndex, QItemSelectionModel::ClearAndSelect);
+
+        onPageSelected(pageIndex);
+
+        return;
+    }
+
+    auto groupIndex = findRootIndex(index);
+
+    auto* groupItem = static_cast<PreferencesPageItem*>(_model.itemFromIndex(groupIndex));
     auto* pagesStackWidget = static_cast<QStackedWidget*>(groupItem->getWidget());
 
     ui->groupWidgetStack->setCurrentWidget(groupItem->getWidget());
 
-    if (index != root) {
+    if (index != groupIndex) {
         pagesStackWidget->setCurrentIndex(index.row());
     }
 
     updatePageDependentLabels();
 }
 
+void DlgPreferencesImp::onGroupExpanded(const QModelIndex& index)
+{
+    auto root = findRootIndex(index);
+
+    auto* groupItem = static_cast<PreferencesPageItem*>(_model.itemFromIndex(root));
+
+    groupItem->setExpanded(true);
+}
+
+void DlgPreferencesImp::onGroupCollapsed(const QModelIndex& index)
+{
+    auto root = findRootIndex(index);
+
+    auto* groupItem = static_cast<PreferencesPageItem*>(_model.itemFromIndex(root));
+
+    groupItem->setExpanded(false);
+}
+
 void DlgPreferencesImp::onStackWidgetChange(int index)
 {
     auto stack = qobject_cast<QStackedWidget*>(sender());
@@ -697,6 +748,30 @@ void DlgPreferencesImp::onStackWidgetChange(int index)
     if (auto selected = stack->widget(index)) {
         selected->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
     }
+
+    auto currentItem = getCurrentPage();
+
+    if (!currentItem) {
+        return;
+    }
+
+    ui->groupsTreeView->selectionModel()->select(currentItem->index(), QItemSelectionModel::ClearAndSelect);
+
+    auto root = _model.invisibleRootItem();
+    for (int i = 0; i < root->rowCount(); i++) {
+        auto currentGroup = static_cast<PreferencesPageItem*>(root->child(i));
+
+        if (!currentGroup->isExpanded()) {
+            ui->groupsTreeView->collapse(currentGroup->index());
+        }
+    }
+
+    auto parentItem = currentItem;
+    while ((parentItem = static_cast<PreferencesPageItem*>(parentItem->parent()))) {
+        bool wasExpanded = parentItem->isExpanded();
+        ui->groupsTreeView->expand(parentItem->index());
+        parentItem->setExpanded(wasExpanded);
+    }
 }
 
 void DlgPreferencesImp::changeEvent(QEvent *e)