Bug 62500 – Editing SVGs will cause assertions

• Component: HTML Editing
• Status: RESOLVED FIXED

[Nikolas Zimmermann]

Editing SVGs will cause assertions. Try the linked URL, which is an example given from Ryosuke on IRC.

Play around with editing on, delete the "X", by placing the caret after the "X" and pressing <delete>.
/Users/nzimmermann/Coding/WebKit/Source/WebCore/rendering/svg/SVGRenderSupport.cpp(75) : static void WebCore::SVGRenderSupport::mapLocalToContainer(const WebCore::RenderObject*, WebCore::RenderBoxModelObject*, bool, bool, WebCore::TransformState&)
1   WebCore::SVGRenderSupport::mapLocalToContainer(WebCore::RenderObject const*, WebCore::RenderBoxModelObject*, bool, bool, WebCore::TransformState&)
2   WebCore::RenderSVGText::mapLocalToContainer(WebCore::RenderBoxModelObject*, bool, bool, WebCore::TransformState&) const
3   WebCore::RenderObject::mapLocalToContainer(WebCore::RenderBoxModelObject*, bool, bool, WebCore::TransformState&) const
4   WebCore::RenderObject::localToAbsolute(WebCore::FloatPoint const&, bool, bool) const
5   WebCore::VisiblePosition::xOffsetForVerticalNavigation() const
6   WebCore::FrameSelection::xPosForVerticalArrowNavigation(WebCore::FrameSelection::EPositionType)
7   WebCore::FrameSelection::modify(WebCore::FrameSelection::EAlteration, WebCore::SelectionDirection, WebCore::TextGranularity, bool)
8   WebCore::TypingCommand::deleteKeyPressed(WebCore::TextGranularity, bool)
9   WebCore::TypingCommand::doApply()
10  WebCore::EditCommand::apply()
11  WebCore::TypingCommand::deleteKeyPressed(WebCore::Document*, unsigned int, WebCore::TextGranularity)
12  WebCore::Editor::deleteWithDirection(WebCore::SelectionDirection, WebCore::TextGranularity, bool, bool)
13  WebCore::executeDeleteBackward(WebCore::Frame*, WebCore::Event*, WebCore::EditorCommandSource, WTF::String const&)
14  WebCore::Editor::Command::execute(WTF::String const&, WebCore::Event*) const
15  WebCore::Editor::Command::execute(WebCore::Event*) const

See the comment in VisiblePosition::xOffsetForVerticalNavigation:

    // This ignores transforms on purpose, for now. Vertical navigation is done
    // without consulting transforms, so that 'up' in transformed text is 'up'
    // relative to the text, not absolute 'up'.
    return renderer->localToAbsolute(localRect.location()).x();

Each call to localToAbsolute with useTransform=false, will cause an assertion for SVG.

VisiblePosition nextLinePosition(const VisiblePosition &visiblePosition, int x) in visible_units.cpp is affected as well:
        // FIXME: Can be wrong for multi-column layout and with transforms.
        FloatPoint absPos = containingBlock->localToAbsolute(FloatPoint());

...
An important step towards supporting editing in SVG, is making editing work under CSS transforms perfectly.
Everytime where localToAbsolute is called with useTrafos=false, there's a potential bug - it just needs a testcase that triggers the code with CSS transform used on the <div> that's edited, no SVG involved at all.
Maybe Ryosuke can come up with some? :-)

[Ahmad Saleem]

https://src.chromium.org/viewvc/blink?view=revision&revision=158002

[EWS]

Committed 257691@main (99962e54b060): <https://commits.webkit.org/257691@main>

Reviewed commits have been landed. Closing PR #7386 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/103218466>