1639450 - clicking on scrollbar track after pinch zoom on scroll frame without overflow does not scroll at all

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect, P3)

Comment 1

[Timothy Nikkel (:tnikkel)]

This is how the scrolling happens from clicking on the scrollbar track

• frame #0: 0x00000001062ea6cb XULmozilla::ScrollFrameHelper::ScrollToWithOrigin(this=0x0000000136302260, aScrollPosition=nsPoint @ 0x00007ffeefbfcff8, aMode=Smooth, aOrigin=0x000000010ac80a94, aRange=0x00007ffeefbfd098, aSnap=DISABLE_SNAP) at nsGfxScrollFrame.cpp:2281:15 [opt] frame #1: 0x00000001062e62d4 XULmozilla::ScrollFrameHelper::ScrollBy(this=0x0000000136302260, aDelta=nsIntPoint @ 0x00007fa60abdcab0, aUnit=PAGES, aMode=Smooth, aOverflow=0x00007ffeefbfd100, aOrigin=<unavailable>, aMomentum=NOT_MOMENTUM, aSnap=ENABLE_SNAP) at nsGfxScrollFrame.cpp:4349:3 [opt]
  frame #2: 0x000000010633e493 XULnon-virtual thunk to nsHTMLScrollFrame::ScrollByPage(nsScrollbarFrame*, int, nsIScrollbarMediator::ScrollSnapMode) [inlined] mozilla::ScrollFrameHelper::ScrollByUnit(this=<unavailable>, aScrollbar=<unavailable>, aMode=Smooth, aDirection=<unavailable>, aUnit=PAGES, aSnap=<unavailable>) at nsGfxScrollFrame.cpp:1549:3 [opt] frame #3: 0x000000010633e451 XULnon-virtual thunk to nsHTMLScrollFrame::ScrollByPage(nsScrollbarFrame*, int, nsIScrollbarMediator::ScrollSnapMode) [inlined] mozilla::ScrollFrameHelper::ScrollByPage(this=<unavailable>, aScrollbar=<unavailable>, aDirection=<unavailable>, aSnap=<unavailable>) at nsGfxScrollFrame.cpp:1453 [opt]
  frame #4: 0x000000010633e451 XULnon-virtual thunk to nsHTMLScrollFrame::ScrollByPage(nsScrollbarFrame*, int, nsIScrollbarMediator::ScrollSnapMode) [inlined] nsHTMLScrollFrame::ScrollByPage(this=<unavailable>, aScrollbar=<unavailable>, aDirection=<unavailable>, aSnap=<unavailable>) at nsGfxScrollFrame.h:1077 [opt] frame #5: 0x000000010633e448 XULnon-virtual thunk to nsHTMLScrollFrame::ScrollByPage(nsScrollbarFrame*, int, nsIScrollbarMediator::ScrollSnapMode) at nsGfxScrollFrame.h:0 [opt]
  frame #6: 0x00000001064b7071 XUL`nsSliderFrame::PageScroll(this=0x0000000136302818, aChange=1) at nsSliderFrame.cpp:1427:10 [opt]

The problem is that ScrollToWithOrigin and ScrollToImpl clamp the requested scroll position to the layout scroll range. Changing that looks like it might be an involved fix, possibly pulling in bug 1543485.

Comment 2

[Botond Ballo [:botond]]

Perhaps some of the relevant functions (e.g. ScrollByPage) could take an option to scroll the visual viewport (via nsIPresShell::ScrollToVisual()) rather than the layout viewport?

Comment 3

[Timothy Nikkel (:tnikkel)]

Yeah, something like that is needed.

Comment 4

[Kris Taeleman (:ktaeleman)]

Interacting with scrollbars works now after 1657822