Include hidden headers in trees and tables consistently

There was a disagreement between the a11y plugin and QTreeView
whether the horizontal header should have been exposed or not.
When the header was hidden, this resulted in that we sent an event
with a child id that was wrong, or in worst case higher than
QAI::childrenCount(). This was the reason we got the warning
output as described in the task.

With this commit, we consistently *expose* hidden headers both for
QTreeView and QTableView, but ensure that their state().invisible is
set to true instead.
This makes it consistent with how hidden cells are exposed.

This also fixes a bug in QTableViewPrivate::accessibleTable2Index
where we always added 1 to the index, which was spotted while
writing the test.

Task-number:  QTBUG-33247

Change-Id: Ifd1f83d56296dd071424fdb81fce7628bc24fe0a
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

3 files changed, 14 insertions, 6 deletions

diff --git a/src/widgets/itemviews/qtableview_p.h b/src/widgets/itemviews/qtableview_p.h
index d36dcd2c3a..74eb7b7728 100644
--- a/src/widgets/itemviews/qtableview_p.h
+++ b/src/widgets/itemviews/qtableview_p.h
@@ -170,8 +170,9 @@ public:
     }
 
     inline int accessibleTable2Index(const QModelIndex &index) const {
-        return (index.row() + (horizontalHeader ? 1 : 0)) * (index.model()->columnCount() + (verticalHeader ? 1 : 0))
-            + index.column() + (verticalHeader ? 1 : 0) + 1;
+        const int vHeader = verticalHeader ? 1 : 0;
+        return (index.row() + (horizontalHeader ? 1 : 0)) * (index.model()->columnCount() + vHeader)
+            + index.column() + vHeader;
     }
 
     int sectionSpanEndLogical(const QHeaderView *header, int logical, int span) const;
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index b5f1b12365..204a6c923f 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -3912,9 +3912,8 @@ void QTreeView::currentChanged(const QModelIndex &current, const QModelIndex &pr
     }
 #ifndef QT_NO_ACCESSIBILITY
     if (QAccessible::isActive() && current.isValid()) {
-        int entry = (visualIndex(current) + (header()?1:0))*current.model()->columnCount()+current.column();
         QAccessibleEvent event(this, QAccessible::Focus);
-        event.setChild(entry);
+        event.setChild(accessibleTree2Index(current));
         QAccessible::updateAccessibility(&event);
     }
 #endif
@@ -3932,7 +3931,7 @@ void QTreeView::selectionChanged(const QItemSelection &selected,
         // ### does not work properly for selection ranges.
         QModelIndex sel = selected.indexes().value(0);
         if (sel.isValid()) {
-            int entry = (visualIndex(sel) + (header()?1:0))*sel.model()->columnCount()+sel.column();
+            int entry = accessibleTree2Index(sel);
             Q_ASSERT(entry >= 0);
             QAccessibleEvent event(this, QAccessible::Selection);
             event.setChild(entry);
@@ -3940,7 +3939,7 @@ void QTreeView::selectionChanged(const QItemSelection &selected,
         }
         QModelIndex desel = deselected.indexes().value(0);
         if (desel.isValid()) {
-            int entry = (visualIndex(desel) + (header()?1:0))*desel.model()->columnCount()+desel.column();
+            int entry = accessibleTree2Index(desel);
             Q_ASSERT(entry >= 0);
             QAccessibleEvent event(this, QAccessible::SelectionRemove);
             event.setChild(entry);
@@ -3957,6 +3956,13 @@ int QTreeView::visualIndex(const QModelIndex &index) const
     return d->viewIndex(index);
 }
 
+int QTreeView::accessibleTree2Index(const QModelIndex &index) const
+{
+    // Note that this will include the header, even if its hidden.
+    return (visualIndex(index) + (header() ? 1 : 0)) * index.model()->columnCount() + index.column();
+}
+
+
 QT_END_NAMESPACE
 
 #include "moc_qtreeview.cpp"
diff --git a/src/widgets/itemviews/qtreeview.h b/src/widgets/itemviews/qtreeview.h
index d9c6cd9269..a29e9b64b0 100644
--- a/src/widgets/itemviews/qtreeview.h
+++ b/src/widgets/itemviews/qtreeview.h
@@ -224,6 +224,7 @@ private:
     friend class QAccessibleTree;
     friend class QAccessibleTableCell;
     int visualIndex(const QModelIndex &index) const;
+    int accessibleTree2Index(const QModelIndex &index) const;
 
     Q_DECLARE_PRIVATE(QTreeView)
     Q_DISABLE_COPY(QTreeView)