1 files changed, 27 insertions, 12 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index ad7be840d0..edfb5c0f57 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -54,6 +54,7 @@
 #include <private/qabstractitemview_p.h>
 #include <private/qabstractitemmodel_p.h>
 #include <private/qguiapplication_p.h>
+#include <private/qscrollbar_p.h>
 #ifndef QT_NO_ACCESSIBILITY
 #include <qaccessible.h>
 #endif
@@ -427,6 +428,11 @@ void QAbstractItemViewPrivate::_q_scrollerStateChanged()
     \since 4.2
     \enum QAbstractItemView::ScrollMode
 
+    Describes how the scrollbar should behave. When setting the scroll mode
+    to ScrollPerPixel the single step size will adjust automatically unless
+    it was set explicitly using \l{QAbstractSlider::}{setSingleStep()}.
+    The automatic adjustment can be restored by setting the single step size to -1.
+
     \value ScrollPerItem    The view will scroll the contents one item at a time.
     \value ScrollPerPixel   The view will scroll the contents one pixel at a time.
 */
@@ -758,7 +764,7 @@ void QAbstractItemView::setSelectionModel(QItemSelectionModel *selectionModel)
     Q_ASSERT(selectionModel);
     Q_D(QAbstractItemView);
 
-    if (selectionModel->model() != d->model) {
+    if (Q_UNLIKELY(selectionModel->model() != d->model)) {
         qWarning("QAbstractItemView::setSelectionModel() failed: "
                  "Trying to set a selection model, which works on "
                  "a different model than the view.");
@@ -1113,7 +1119,7 @@ void QAbstractItemView::reset()
 void QAbstractItemView::setRootIndex(const QModelIndex &index)
 {
     Q_D(QAbstractItemView);
-    if (index.isValid() && index.model() != d->model) {
+    if (Q_UNLIKELY(index.isValid() && index.model() != d->model)) {
         qWarning("QAbstractItemView::setRootIndex failed : index must be from the currently set model");
         return;
     }
@@ -1166,9 +1172,9 @@ void QAbstractItemView::selectAll()
 void QAbstractItemView::edit(const QModelIndex &index)
 {
     Q_D(QAbstractItemView);
-    if (!d->isIndexValid(index))
+    if (Q_UNLIKELY(!d->isIndexValid(index)))
         qWarning("edit: index was invalid");
-    if (!edit(index, AllEditTriggers, 0))
+    if (Q_UNLIKELY(!edit(index, AllEditTriggers, 0)))
         qWarning("edit: editing failed");
 }
 
@@ -1235,6 +1241,10 @@ void QAbstractItemView::setVerticalScrollMode(ScrollMode mode)
         return;
     QModelIndex topLeft = indexAt(QPoint(0, 0));
     d->verticalScrollMode = mode;
+    if (mode == ScrollPerItem)
+        verticalScrollBar()->d_func()->itemviewChangeSingleStep(1); // setSingleStep(-1) => step with 1
+    else
+        verticalScrollBar()->setSingleStep(-1); // Ensure that the view can update single step
     updateGeometries(); // update the scroll bars
     scrollTo(topLeft, QAbstractItemView::PositionAtTop);
 }
@@ -1257,7 +1267,13 @@ QAbstractItemView::ScrollMode QAbstractItemView::verticalScrollMode() const
 void QAbstractItemView::setHorizontalScrollMode(ScrollMode mode)
 {
     Q_D(QAbstractItemView);
+    if (mode == d->horizontalScrollMode)
+        return;
     d->horizontalScrollMode = mode;
+    if (mode == ScrollPerItem)
+        horizontalScrollBar()->d_func()->itemviewChangeSingleStep(1); // setSingleStep(-1) => step with 1
+    else
+        horizontalScrollBar()->setSingleStep(-1); // Ensure that the view can update single step
     updateGeometries(); // update the scroll bars
 }
 
@@ -4274,9 +4290,8 @@ QModelIndex QAbstractItemViewPrivate::indexForEditor(QWidget *editor) const
 
 void QAbstractItemViewPrivate::removeEditor(QWidget *editor)
 {
-   QEditorIndexHash::iterator it = editorIndexHash.find(editor);
-    if (it != editorIndexHash.end())
-    {
+    const auto it = editorIndexHash.constFind(editor);
+    if (it != editorIndexHash.cend()) {
         indexEditorHash.remove(it.value());
         editorIndexHash.erase(it);
     }
@@ -4335,11 +4350,11 @@ QItemViewPaintPairs QAbstractItemViewPrivate::draggablePaintPairs(const QModelIn
     QRect &rect = *r;
     const QRect viewportRect = viewport->rect();
     QItemViewPaintPairs ret;
-    for (int i = 0; i < indexes.count(); ++i) {
-        const QModelIndex &index = indexes.at(i);
+    for (const auto &index : indexes) {
         const QRect current = q->visualRect(index);
         if (current.intersects(viewportRect)) {
-            ret += qMakePair(current, index);
+            QItemViewPaintPair p = { current, index };
+            ret += p;
             rect |= current;
         }
     }
@@ -4359,8 +4374,8 @@ QPixmap QAbstractItemViewPrivate::renderToPixmap(const QModelIndexList &indexes,
     QStyleOptionViewItem option = viewOptionsV1();
     option.state |= QStyle::State_Selected;
     for (int j = 0; j < paintPairs.count(); ++j) {
-        option.rect = paintPairs.at(j).first.translated(-r->topLeft());
-        const QModelIndex &current = paintPairs.at(j).second;
+        option.rect = paintPairs.at(j).rect.translated(-r->topLeft());
+        const QModelIndex &current = paintPairs.at(j).index;
         adjustViewOptionsForIndex(&option, current);
         delegateForIndex(current)->paint(&painter, option, current);
     }