[webkit-changes] [WebKit/WebKit] 18268b: Writing suggestions show in the wrong place when t...

[Wenson Hsieh]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 18268bbc067da5473c03a0896409d1ba1b71f8e0
      https://github.com/WebKit/WebKit/commit/18268bbc067da5473c03a0896409d1ba1b71f8e0
  Author: Wenson Hsieh <wenson_hsieh at apple.com>
  Date:   2024-10-13 (Sun, 13 Oct 2024)

  Changed paths:
    A LayoutTests/editing/input/cocoa/inline-predictions-in-text-with-leading-whitespace-expected.html
    A LayoutTests/editing/input/cocoa/inline-predictions-in-text-with-leading-whitespace.html
    M Source/WebCore/editing/Editor.cpp

  Log Message:
  -----------
  Writing suggestions show in the wrong place when the text node contains leading non-visible whitespace
https://bugs.webkit.org/show_bug.cgi?id=281403
rdar://137237226

Reviewed by Richard Robinson.

In the case where writing suggestions are inserted within a text node with leading whitespace, we
end up inserting the generated renderer (representing the suggested text) at the wrong offset within
the text node.

This happens because `WritingSuggestionData::offset()` is incorrect when we set up the suggested
text renderer in `RenderTreeUpdater::GeneratedContent::updateWritingSuggestionsRenderer`. This
offset is in turn computed in `Editor::setWritingSuggestion`, where we use `characterCount` to get
the number of characters between the start of the text node and the caret position. The problem with
this approach is that `characterCount` ignores non-rendered whitespace, but the result is then used
to index into the text node's data, which includes non-rendered whitespace, when determining whether
(or how) to split up the existing text node to insert writing suggestions. As a result, the writing
suggestions renderer is incorrectly offset by an amount equal to the number of non-rendered
whitespace characters at the start of the text node.

To fix this, we use the `endOffset()` of the selection range, after verifying that the selection
range is both (1) collapsed, and (2) an offset within a text node. The current implementation of
writing suggestions doesn't work properly unless these conditions are met anyways, so it's safe to
enforce this and simply use the end offset relative to the containing text.

* LayoutTests/editing/input/cocoa/inline-predictions-in-text-with-leading-whitespace-expected.html: Added.
* LayoutTests/editing/input/cocoa/inline-predictions-in-text-with-leading-whitespace.html: Added.

Add a layout test to exercise the change, by verifying that inserting a writing suggestion after the
end of `<div contenteditable>To </div>` results in the same behavior as inserting the same
suggestion after the end of `<div contenteditable>   To </div>`.

* Source/WebCore/editing/Editor.cpp:
(WebCore::Editor::setWritingSuggestion):

Canonical link: https://commits.webkit.org/285107@main



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