QTreeView: fix crash when starting a drag with hidden columns.

Crash was introduced by d639105759491 (pre-Qt-4.8 only)

Task-number: QTBUG-15834
Merge-request: MR-2725

(cherry picked from qt4 commit fd25323de7b5d5f3e0ffb1bd81ea4d251e071566)

Change-Id: I59959d3ba4c9bcb0d39bdbe58432817bbbfdd9f1
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 1a1dc85ae6..368be3a6c8 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1388,11 +1388,19 @@ void QTreeViewPrivate::adjustViewOptionsForIndex(QStyleOptionViewItemV4 *option,
     option->showDecorationSelected = (selectionBehavior & QTreeView::SelectRows)
                                      || option->showDecorationSelected;
 
-    QVector<int> logicalIndices;
-    QVector<QStyleOptionViewItemV4::ViewItemPosition> viewItemPosList; // vector of left/middle/end for each logicalIndex
+    QVector<int> logicalIndices; // index = visual index of visible columns only. data = logical index.
+    QVector<QStyleOptionViewItemV4::ViewItemPosition> viewItemPosList; // vector of left/middle/end for each logicalIndex, visible columns only.
     calcLogicalIndices(&logicalIndices, &viewItemPosList);
-    int logicalIndex = header->logicalIndex(current.column());
-    option->viewItemPosition = viewItemPosList.at(logicalIndex);
+
+    int columnIndex = 0;
+    for (int visualIndex = 0; visualIndex < current.column(); ++visualIndex) {
+        int logicalIndex = header->logicalIndex(visualIndex);
+        if (!header->isSectionHidden(logicalIndex)) {
+            ++columnIndex;
+        }
+    }
+
+    option->viewItemPosition = viewItemPosList.at(columnIndex);
 }