DolphinView: Conform to global scroll speed

One scroll with the mouse wheel is supposed to scroll the view by
QApplication::wheelScrollLines, however previous to this commit Dolphin
scrolled the view by QApplication::wheelScrollLines^2 instead, which
was wrong and way too much.

This commit fixes this by defining one line height as the height of the
current default font. This value is multiplied by
QApplication::wheelScrollLines to determine the scroll amount per mouse
wheel scroll.

In details view mode however, where there really are rows to go by,
this commit makes sure to always scroll by full rows. The number of
rows to scroll is determined by rounding up from the scroll amount used
in the other view modes.

Co-authored-by: Felix Ernst

1 files changed, 1 insertions, 9 deletions

diff --git a/src/kitemviews/kitemlistcontainer.cpp b/src/kitemviews/kitemlistcontainer.cpp
index 128140e2e..3ec56e5f1 100644
--- a/src/kitemviews/kitemlistcontainer.cpp
+++ b/src/kitemviews/kitemlistcontainer.cpp
@@ -286,7 +286,6 @@ void KItemListContainer::updateScrollOffsetScrollBar()
 
     KItemListSmoothScroller *smoothScroller = nullptr;
     QScrollBar *scrollOffsetScrollBar = nullptr;
-    int singleStep = 0;
     int pageStep = 0;
     int maximum = 0;
     if (view->scrollOrientation() == Qt::Vertical) {
@@ -296,13 +295,6 @@ void KItemListContainer::updateScrollOffsetScrollBar()
         }
         scrollOffsetScrollBar = verticalScrollBar();
 
-        // Don't scroll super fast when using a wheel mouse:
-        // We want to consider one "line" to be the text label which has a
-        // roughly fixed height rather than using the height of the icon which
-        // may be very tall
-        const QFontMetrics metrics(font());
-        singleStep = metrics.height() * QApplication::wheelScrollLines();
-
         // We cannot use view->size().height() because this height might
         // include the header widget, which is not part of the scrolled area.
         pageStep = view->verticalPageStep();
@@ -318,11 +310,11 @@ void KItemListContainer::updateScrollOffsetScrollBar()
             return;
         }
         scrollOffsetScrollBar = horizontalScrollBar();
-        singleStep = view->itemSize().width();
         pageStep = view->size().width();
         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
     }
 
+    const int singleStep = view->scrollSingleStep();
     const int value = view->scrollOffset();
     if (smoothScroller->requestScrollBarUpdate(maximum)) {
         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0) || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;