haikuwebkit/LayoutTests/fast/scrolling/rtl-scrollbars-initial-posi...

<!DOCTYPE html>
<div style="width: 100px; height: 100px; direction: rtl; overflow: scroll;">
  <div style="width: 192px; height: 192px; border: 4px solid black;"></div>
</div>
Fix initial horizontal scrollbar position when vertical scrollbar is on the left. https://bugs.webkit.org/show_bug.cgi?id=224409 Reviewed by Darin Adler. Source/WebCore: Scrollable elements that place their vertical scrollbar on the left (e.g. when they're `direction: rtl` or when the OS language is RTL and the relevant setting to always follow OS scrollbar side is used) have an incorrect scroll origin, which leads to creating a horizontal scrollbar with an incorrect initial offset. This is because RenderLayerScrollableArea::computeScrollDimensions runs prior to the scrollbars being created. So whenever we start or stop having a (non-overlay) vertical scrollbar on the left, we need to recompute the scroll origin and fix up the horizontal scrollbar's offset. Tests: fast/scrolling/rtl-scrollbars-initial-position-dynamic.html fast/scrolling/rtl-scrollbars-initial-position.html * rendering/RenderLayerScrollableArea.cpp: (WebCore::RenderLayerScrollableArea::computeScrollDimensions): (WebCore::RenderLayerScrollableArea::computeScrollOrigin): Split this out of computeScrollDimensions so we can call it from updateScrollbarsAfterLayout and updateScrollbarsAfterStyleChange, and have it ask the horizontal scrollbar to update its offset. We could condition this on the scroll origin actually having changed, but that's going to be a similar check that Scrollbar::offsetDidChange does to ensure the offset value did indeed change. We don't want to condition this on shouldPlaceBlockDirectionScrollbarOnLeft(), since that's dependent on the current style, and we may be reacting to a style change removed the vertical scrollbar on the left. (WebCore::RenderLayerScrollableArea::updateScrollbarsAfterLayout): (WebCore::RenderLayerScrollableArea::updateScrollbarsAfterStyleChange): * rendering/RenderLayerScrollableArea.h: LayoutTests: * fast/scrolling/rtl-scrollbars-initial-position-dynamic-expected.html: Added. * fast/scrolling/rtl-scrollbars-initial-position-dynamic.html: Added. * fast/scrolling/rtl-scrollbars-initial-position-expected.html: Added. * fast/scrolling/rtl-scrollbars-initial-position.html: Added. Canonical link: https://commits.webkit.org/236382@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@275811 268f45cc-cd09-0410-ab3c-d52691b4dbfc 2021-04-11 22:53:50 +00:00			`<!DOCTYPE html>`
			`<div style="width: 100px; height: 100px; direction: rtl; overflow: scroll;">`
			`<div style="width: 192px; height: 192px; border: 4px solid black;"></div>`
			`</div>`