QHeaderView - Fix auto-scroll on manual move on sections

This patch fixes the manual move of sections when auto scroll is on.
It is done in QAbstractItemView::doAutoScroll by letting the
qheaderView use its parents scrollbars if they are childs of a
QTableView or QTreeView.

Task-number: QTBUG-993
Task-number: QTBUG-1103

Change-Id: I70d999d9a07c3566e42d01cc5ebb47a69a83d9d4
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

2 files changed, 21 insertions, 0 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index 8ba078ffd3..57c3b44aaa 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -55,6 +55,9 @@
 #include <qdatetime.h>
 #include <qlineedit.h>
 #include <qspinbox.h>
+#include <qtreeview.h>
+#include <qtableview.h>
+#include <qheaderview.h>
 #include <qstyleditemdelegate.h>
 #include <private/qabstractitemview_p.h>
 #include <private/qabstractitemmodel_p.h>
@@ -3749,6 +3752,22 @@ void QAbstractItemView::doAutoScroll()
     QScrollBar *verticalScroll = verticalScrollBar();
     QScrollBar *horizontalScroll = horizontalScrollBar();
 
+    // QHeaderView does not (normally) have scrollbars
+    // It needs to use its parents scroll instead
+    QHeaderView *hv = qobject_cast<QHeaderView*>(this);
+    if (hv) {
+        QAbstractScrollArea *parent = qobject_cast<QAbstractScrollArea*>(parentWidget());
+        if (parent) {
+            if (hv->orientation() == Qt::Horizontal) {
+                if (!hv->horizontalScrollBar() || !hv->horizontalScrollBar()->isVisible())
+                    horizontalScroll = parent->horizontalScrollBar();
+            } else {
+                if (!hv->verticalScrollBar() || !hv->verticalScrollBar()->isVisible())
+                    verticalScroll = parent->verticalScrollBar();
+            }
+        }
+    }
+
     int verticalStep = verticalScroll->pageStep();
     int horizontalStep = horizontalScroll->pageStep();
     if (d->autoScrollCount < qMax(verticalStep, horizontalStep))
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index dc80a4b81f..6326b497c5 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -2333,6 +2333,8 @@ void QHeaderView::mouseMoveEvent(QMouseEvent *e)
             return;
         }
         case QHeaderViewPrivate::MoveSection: {
+            if (d->shouldAutoScroll(e->pos()))
+                d->startAutoScroll();
             if (qAbs(pos - d->firstPos) >= QApplication::startDragDistance()
                 || !d->sectionIndicator->isHidden()) {
                 int visual = visualIndexAt(pos);