From d39a6d80f63414a4e933ac2f859805635850942a Mon Sep 17 00:00:00 2001 From: Mitch Curtis Date: Tue, 24 Sep 2019 10:09:12 +0200 Subject: Tumbler: fix displacement calculation when wrap is false Use the position of the item and the currentItem in the calculation in order to get reliable results. This fixes the displacement being off by a small margin, which increased as the delegate height became smaller. Fixes: QTBUG-66799 Change-Id: Ieca5033fb4c0ed62f5965a21fcab7aa558bd40e6 Reviewed-by: Andy Shaw Reviewed-by: Mitch Curtis --- src/quicktemplates2/qquicktumbler.cpp | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/quicktemplates2/qquicktumbler.cpp b/src/quicktemplates2/qquicktumbler.cpp index 8b702c60..85c70b1b 100644 --- a/src/quicktemplates2/qquicktumbler.cpp +++ b/src/quicktemplates2/qquicktumbler.cpp @@ -949,9 +949,20 @@ void QQuickTumblerAttachedPrivate::calculateDisplacement() const qreal contentY = tumblerPrivate->viewContentY; const qreal delegateH = delegateHeight(tumbler); const qreal preferredHighlightBegin = tumblerPrivate->view->property("preferredHighlightBegin").toReal(); - // Tumbler's displacement goes from negative at the top to positive towards the bottom, so we must switch this around. - const qreal reverseDisplacement = (contentY + preferredHighlightBegin) / delegateH; - displacement = reverseDisplacement - index; + const qreal itemY = qobject_cast(parent)->y(); + qreal currentItemY = 0; + auto currentItem = tumblerPrivate->view->property("currentItem").value(); + if (currentItem) + currentItemY = currentItem->y(); + // Start from the y position of the current item. + const qreal topOfCurrentItemInViewport = currentItemY - contentY; + // Then, calculate the distance between it and the preferredHighlightBegin. + const qreal relativePositionToPreferredHighlightBegin = topOfCurrentItemInViewport - preferredHighlightBegin; + // Next, calculate the distance between us and the current item. + const qreal distanceFromCurrentItem = currentItemY - itemY; + const qreal displacementInPixels = distanceFromCurrentItem - relativePositionToPreferredHighlightBegin; + // Convert it from pixels to a floating point index. + displacement = displacementInPixels / delegateH; } emitIfDisplacementChanged(previousDisplacement, displacement); -- cgit v1.2.3