Bug 116051 – PlatformLayer containing scrollbars does not disappear when setting overflow:hidden on page root, until resize.

• Component: New Bugs
• Status: RESOLVED FIXED

[Jer Noble]

Layer containing scrollbars does not disappear when setting overflow:hidden on page root, until resize.

[Jer Noble]

Created attachment 201620 [details]
Patch

[Build Bot]

Comment on attachment 201620 [details]
Patch

Attachment 201620 [details] did not pass mac-wk2-ews (mac-wk2):
Output: http://webkit-queues.appspot.com/results/464500

New failing tests:
compositing/contents-opaque/body-background-painted.html
animations/3d/matrix-transform-type-animation.html
animations/3d/state-at-end-event-transform.html
compositing/backing/no-backing-for-clip-overlap.html
accessibility/image-map2.html
animations/additive-transform-animations.html
compositing/contents-opaque/background-color.html
compositing/bounds-in-flipped-writing-mode.html
accessibility/lists.html
compositing/layers-inside-overflow-scroll.html
accessibility/deleting-iframe-destroys-axcache.html
compositing/animation/state-at-end-event-transform-layer.html
compositing/sibling-positioning.html
compositing/generated-content.html
compositing/self-painting-layers.html
animations/3d/change-transform-in-end-event.html
compositing/animation/busy-indicator.html
compositing/tiled-layers-hidpi.html
accessibility/plugin.html
compositing/columns/composited-in-paginated.html
compositing/color-matching/pdf-image-match.html
compositing/contents-opaque/body-background-skipped.html
compositing/contents-opaque/background-clip.html
compositing/compositing-visible-descendant.html
compositing/overflow-trumps-transform-style.html
compositing/color-matching/image-color-matching.html
compositing/backing/no-backing-for-clip.html
compositing/backing/no-backing-for-clip-overhang.html
compositing/backing/no-backing-for-perspective.html
compositing/clip-child-by-non-stacking-ancestor.html

[Build Bot]

Created attachment 201673 [details]
Archive of layout-test-results from webkit-ews-09 for mac-mountainlion-wk2

The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews.
Bot: webkit-ews-09  Port: mac-mountainlion-wk2  Platform: Mac OS X 10.8.2

[Radar WebKit Bug Importer]

<rdar://problem/14294042>

[Jer Noble]

The WK1 and WK2 results are different because of this section of ScrollView.cpp, ScrollView::setScrollbarModes(...):

    if (platformWidget())
        platformSetScrollbarModes();
    else
        updateScrollbars(scrollOffset());

WK1 takes the first branch, and WK2 the second.  The second branch hits this new code, and (correctly) resizes the document to account for the vertical scrollbar which is forced on in FrameView.cpp, FrameView::layout(...):

                    // Set the initial vMode to AlwaysOn if we're auto.
                    if (vMode == ScrollbarAuto)
                        setVerticalScrollbarMode(ScrollbarAlwaysOn); // This causes a vertical scrollbar to appear.
                    // Set the initial hMode to AlwaysOff if we're auto.
                    if (hMode == ScrollbarAuto)
                        setHorizontalScrollbarMode(ScrollbarAlwaysOff); // This causes a horizontal scrollbar to disappear.

[Jer Noble]

So it seems to me that this patch fixes an underlying bug in WebKitTestRunner: the size of the content area is not being updated when scrollbars are added or removed.

[Jer Noble]

Created attachment 220544 [details]
Patch

[Jer Noble]

That area of code has changed quite a bit since the original patch was reviewed.  The new fix is much smaller and more targeted.

[Jer Noble]

Committed r161457: <http://trac.webkit.org/changeset/161457>