[Webkit-unassigned] [Bug 108323] New: Improve the logic in WebCore::scrollOffsetForFixedPosition()

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=108323

           Summary: Improve the logic in
                    WebCore::scrollOffsetForFixedPosition()
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: anilsson at rim.com
                CC: tonikitoo at webkit.org, kenneth at webkit.org


The code in WebCore::scrollOffsetForFixedPosition() is correct if the layout viewport is equal in size to the visual viewport. In desktop ports of WebKit, these are always equal.

However, there are features in WebCore::ScrollView to separate these two, a strategy popular with mobile ports of WebKit.

virtual void ScrollView::setFixedVisibleContentRect(const IntRect& visibleContentRect)

and

void ScrollView::setFixedLayoutSize(const IntSize&)
void ScrollView::setUseFixedLayout(bool enable)

can be used to cause the visual viewport and the layout viewport to differ. In that case, WebCore::scrollOffsetForFixedPosition() can return incorrect results for RTL pages, causing left property to be broken with position:fixed elements.

See also my comments https://bugs.webkit.org/show_bug.cgi?id=59204 for some background.

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.