Fix image sometimes scrolling by 1px when clicking inside viewport

The max rounding error is +-0.5 so sometimes the rounding error alone caused a movement even if zero new change was requested.
jdpurcell · Dec 31, 2024 · 0a7cd33 · 0a7cd33
1 parent b22e3e0
commit 0a7cd33
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/src/scrollhelper.cpp b/src/scrollhelper.cpp
@@ -53,8 +53,8 @@ void ScrollHelper::move(QPointF delta)
         scrollDeltaY = calculateScrollDelta(scrollLocation.y(), vMin, vMax, scrollDeltaY);
     }
     scrollLocation += QPointF(scrollDeltaX, scrollDeltaY);
-    int scrollValueX = qRound(scrollLocation.x());
-    int scrollValueY = qRound(scrollLocation.y());
+    int scrollValueX = qAbs(scrollLocation.x()) == 0.5 ? 0 : qRound(scrollLocation.x());
+    int scrollValueY = qAbs(scrollLocation.y()) == 0.5 ? 0 : qRound(scrollLocation.y());
     lastMoveRoundingError = QPointF(scrollLocation.x() - scrollValueX, scrollLocation.y() - scrollValueY);
     int overscrollDistanceX =
         p.shouldConstrain && scrollValueX < hMin ? scrollValueX - hMin :