tdf#130857 qt weld: Implement TreeView tooltip handling

Handle the QEvent::ToolTip event for the
QTreeView's viewport. Retrieve the tooltip
for the item using weld::TreeView::signal_query_tooltip
and display it if it's non-empty.

This makes the file path of the corresponding template
show up when hovering over an item in the
"File" -> "Templates" -> "Manage Templates" dialog
with the list view mode enabled with
SAL_VCL_QT_USE_WELDED_WIDGETS=1, in a WIP branch
where support for that dialog using native Qt widgets
is declared.

Change-Id: Ia849a9fa6506ffbd2d74be00600e0a694f1b9efd
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/190317
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

Author: michaelweghorn

vcl/inc/qt5/QtInstanceTreeView.hxx

@@ -209,6 +209,8 @@ public:
     static void setColumnRoles(QTreeView& rTreeView,
                                const QList<QList<Qt::ItemDataRole>>& rDataRoles);
 
+    virtual bool eventFilter(QObject* pObject, QEvent* pEvent) override;
+
 private:
     QModelIndex modelIndex(int nRow, int nCol = 0,
                            const QModelIndex& rParentIndex = QModelIndex()) const;
@@ -221,6 +223,8 @@ private:
 
     void setImage(const weld::TreeIter& rIter, const QPixmap& rPixmap, int nCol);
 
+    bool handleToolTipEvent(const QHelpEvent* pEvent);
+
 private Q_SLOTS:
     void handleActivated();
     void handleDataChanged(const QModelIndex& rTopLeft, const QModelIndex& rBottomRight,

vcl/qt5/QtInstanceTreeView.cxx

@@ -13,6 +13,7 @@
 #include <vcl/qt/QtUtils.hxx>
 
 #include <QtWidgets/QHeaderView>
+#include <QtWidgets/QToolTip>
 
 // role used for the ID in the QStandardItem
 constexpr int ROLE_ID = Qt::UserRole + 1000;
@@ -43,6 +44,9 @@ QtInstanceTreeView::QtInstanceTreeView(QTreeView* pTreeView)
             &QtInstanceTreeView::handleSelectionChanged);
     connect(m_pModel, &QSortFilterProxyModel::dataChanged, this,
             &QtInstanceTreeView::handleDataChanged);
+
+    assert(m_pTreeView->viewport());
+    m_pTreeView->viewport()->installEventFilter(this);
 }
 
 void QtInstanceTreeView::insert(const weld::TreeIter* pParent, int nPos, const OUString* pStr,
@@ -1097,6 +1101,14 @@ void QtInstanceTreeView::setColumnRoles(QTreeView& rTreeView,
     rTreeView.setProperty(PROPERTY_COLUMN_ROLES, QVariant::fromValue(rDataRoles));
 }
 
+bool QtInstanceTreeView::eventFilter(QObject* pObject, QEvent* pEvent)
+{
+    if (pEvent->type() == QEvent::ToolTip && pObject == m_pTreeView->viewport())
+        return handleToolTipEvent(static_cast<QHelpEvent*>(pEvent));
+
+    return QtInstanceWidget::eventFilter(pObject, pEvent);
+}
+
 QModelIndex QtInstanceTreeView::modelIndex(int nRow, int nCol,
                                            const QModelIndex& rParentIndex) const
 {
@@ -1158,6 +1170,23 @@ void QtInstanceTreeView::setImage(const weld::TreeIter& rIter, const QPixmap& rP
     });
 }
 
+bool QtInstanceTreeView::handleToolTipEvent(const QHelpEvent* pHelpEvent)
+{
+    QModelIndex aIndex = m_pTreeView->indexAt(pHelpEvent->pos());
+    if (!aIndex.isValid())
+        return false;
+
+    SolarMutexGuard g;
+    const QtInstanceTreeIter aIter(aIndex);
+    const QString sToolTip = toQString(signal_query_tooltip(aIter));
+    if (sToolTip.isEmpty())
+        return false;
+
+    QToolTip::showText(pHelpEvent->globalPos(), sToolTip, m_pTreeView,
+                       m_pTreeView->visualRect(aIndex));
+    return true;
+}
+
 void QtInstanceTreeView::handleActivated()
 {
     SolarMutexGuard g;