[webkit-changes] [WebKit/WebKit] f7b4df: `InlineTextBox`es containing `Zero Width Joiner`, ...

[Vitaly Dyachkov]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: f7b4df2d3a2cacd74bf240875b9bd025570631ca
      https://github.com/WebKit/WebKit/commit/f7b4df2d3a2cacd74bf240875b9bd025570631ca
  Author: Vitaly Dyachkov <vitaly at igalia.com>
  Date:   2023-01-31 (Tue, 31 Jan 2023)

  Changed paths:
    M Source/WebCore/platform/graphics/WidthIterator.cpp

  Log Message:
  -----------
  `InlineTextBox`es containing `Zero Width Joiner`, `Zero Width Non-Joiner`, or `Zero Width No-Break Space` characters must not use simplified text measuring
https://bugs.webkit.org/show_bug.cgi?id=251009

Reviewed by Alan Baradlay.

When calculating the width of an InlineTexBox using simplified measuring,
we simply sum up the width of every glyph. Some fonts
(at least FreeType fonts) specify the non-zero width of
`Zero Width Joiner`, `Zero Width Non-Joiner`, and `Zero Width No-Break Space`.

Later, during the rendering, these glyphs are skipped causing
the `InlineTextBox`es to become wider than they should be.

Originally, `WidthIterator::characterCanUseSimplifiedTextMeasuring`
was returning `false` for these characters. It was flipped by
https://commits.webkit.org/241351@main along with `New Line`
and `Carriage Return`.

Fixes `css2.1/20110323/word-spacing-characters-003.htm` for WPE port.

* Source/WebCore/platform/graphics/WidthIterator.cpp:
(WebCore::WidthIterator::characterCanUseSimplifiedTextMeasuring):

Canonical link: https://commits.webkit.org/259618@main