Unify header-based scroll offsets in itemviews

This is a spin-off of 00b11cc.

Change-Id: I042f066bdb1d248a04473d4b0a31002330a73907
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

4 files changed, 21 insertions, 30 deletions

diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 0dbf0a6a76..d95e693126 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -3540,6 +3540,19 @@ int QHeaderViewPrivate::adjustedVisualIndex(int visualIndex) const
     return visualIndex;
 }
 
+void QHeaderViewPrivate::setScrollOffset(const QScrollBar *scrollBar, QAbstractItemView::ScrollMode scrollMode)
+{
+    Q_Q(QHeaderView);
+    if (scrollMode == QAbstractItemView::ScrollPerItem) {
+        if (scrollBar->maximum() > 0 && scrollBar->value() == scrollBar->maximum())
+            q->setOffsetToLastSection();
+        else
+            q->setOffsetToSectionPosition(scrollBar->value());
+    } else {
+        q->setOffset(scrollBar->value());
+    }
+}
+
 #ifndef QT_NO_DATASTREAM
 void QHeaderViewPrivate::write(QDataStream &out) const
 {
diff --git a/src/widgets/itemviews/qheaderview_p.h b/src/widgets/itemviews/qheaderview_p.h
index 7fda0c8873..de9321530c 100644
--- a/src/widgets/itemviews/qheaderview_p.h
+++ b/src/widgets/itemviews/qheaderview_p.h
@@ -341,6 +341,7 @@ public:
     // other
     int viewSectionSizeHint(int logical) const;
     int adjustedVisualIndex(int visualIndex) const;
+    void setScrollOffset(const QScrollBar *scrollBar, QAbstractItemView::ScrollMode scrollMode);
 
 #ifndef QT_NO_DATASTREAM
     void write(QDataStream &out) const;
diff --git a/src/widgets/itemviews/qtableview.cpp b/src/widgets/itemviews/qtableview.cpp
index 471f8b149c..e581188f0a 100644
--- a/src/widgets/itemviews/qtableview.cpp
+++ b/src/widgets/itemviews/qtableview.cpp
@@ -1126,15 +1126,7 @@ void QTableView::doItemsLayout()
 {
     Q_D(QTableView);
     QAbstractItemView::doItemsLayout();
-    if (verticalScrollMode() == QAbstractItemView::ScrollPerItem) {
-        const int max = verticalScrollBar()->maximum();
-        if (max > 0 && verticalScrollBar()->value() == max)
-            d->verticalHeader->setOffsetToLastSection();
-        else
-            d->verticalHeader->setOffsetToSectionPosition(verticalScrollBar()->value());
-    } else {
-        d->verticalHeader->setOffset(verticalScrollBar()->value());
-    }
+    d->verticalHeader->d_func()->setScrollOffset(verticalScrollBar(), verticalScrollMode());
     if (!d->verticalHeader->updatesEnabled())
         d->verticalHeader->setUpdatesEnabled(true);
 }
@@ -1271,29 +1263,19 @@ void QTableView::scrollContentsBy(int dx, int dy)
 
     dx = isRightToLeft() ? -dx : dx;
     if (dx) {
+        int oldOffset = d->horizontalHeader->offset();
+        d->horizontalHeader->d_func()->setScrollOffset(horizontalScrollBar(), horizontalScrollMode());
         if (horizontalScrollMode() == QAbstractItemView::ScrollPerItem) {
-            int oldOffset = d->horizontalHeader->offset();
-            if (horizontalScrollBar()->value() == horizontalScrollBar()->maximum())
-                d->horizontalHeader->setOffsetToLastSection();
-            else
-                d->horizontalHeader->setOffsetToSectionPosition(horizontalScrollBar()->value());
             int newOffset = d->horizontalHeader->offset();
             dx = isRightToLeft() ? newOffset - oldOffset : oldOffset - newOffset;
-        } else {
-            d->horizontalHeader->setOffset(horizontalScrollBar()->value());
         }
     }
     if (dy) {
+        int oldOffset = d->verticalHeader->offset();
+        d->verticalHeader->d_func()->setScrollOffset(verticalScrollBar(), verticalScrollMode());
         if (verticalScrollMode() == QAbstractItemView::ScrollPerItem) {
-            int oldOffset = d->verticalHeader->offset();
-            if (verticalScrollBar()->value() == verticalScrollBar()->maximum())
-                d->verticalHeader->setOffsetToLastSection();
-            else
-                d->verticalHeader->setOffsetToSectionPosition(verticalScrollBar()->value());
             int newOffset = d->verticalHeader->offset();
             dy = oldOffset - newOffset;
-        } else {
-            d->verticalHeader->setOffset(verticalScrollBar()->value());
         }
     }
     d->scrollContentsBy(dx, dy);
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index dd450daaea..0977f7a2c1 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -2401,16 +2401,11 @@ void QTreeView::scrollContentsBy(int dx, int dy)
 
     dx = isRightToLeft() ? -dx : dx;
     if (dx) {
+        int oldOffset = d->header->offset();
+        d->header->d_func()->setScrollOffset(horizontalScrollBar(), horizontalScrollMode());
         if (horizontalScrollMode() == QAbstractItemView::ScrollPerItem) {
-            int oldOffset = d->header->offset();
-            if (horizontalScrollBar()->value() == horizontalScrollBar()->maximum())
-                d->header->setOffsetToLastSection();
-            else
-                d->header->setOffsetToSectionPosition(horizontalScrollBar()->value());
             int newOffset = d->header->offset();
             dx = isRightToLeft() ? newOffset - oldOffset : oldOffset - newOffset;
-        } else {
-            d->header->setOffset(horizontalScrollBar()->value());
         }
     }