Bug 194498 – [FreeType] Unable to render some Hebrew characters

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Alberto Garcia]

WebKitGTK is unable to render some Hebrew characters, displaying square boxes instead.

Here's the link to the test case:

   http://bibleconsultants.nl/downloads/webkit2gtk/resources.html

Here's what it's supposed to look like:

   http://bibleconsultants.nl/downloads/webkit2gtk/right-rendering.png

And here's how it appears on WebKitGTK:

   http://bibleconsultants.nl/downloads/webkit2gtk/wrong-rendering.png

The problem seems to be that some of those characters are decomposed (i.e combinations of two or more characters). The W3C validator does indeed emit a warning saying that "Text run is not in Unicode Normalization Form C", but that doesn't seem to be a requirement for HTML and it should be possible to display the text correctly.

I reproduced this problem with WebKitGTK 2.22.6, and master seems to be affected as well.

Other tests (using Debian stretch packages):

  - Chromium 71.0.3578.80 also fails.
  - Firefox-ESR 60.5.0 works fine.
  - Chrome 71.0.3578.98 works fine.

Other apps (Gedit, gnome-terminal, ...) seem to work fine as well.

[Alberto Garcia]

Created attachment 361673 [details]
Test case

Here's a simpler version of the text case.

[Alberto Garcia]

Created attachment 361674 [details]
Test case (NFC normalization)

Here's the same file as before but normalized using Unicode NFC.

This one can be displayed correctly.

[Michael Catanzaro]

Note this affects many languages, not just Hebrew.

[Alberto Garcia]

(In reply to Michael Catanzaro from comment #3)
> Note this affects many languages, not just Hebrew.

Yes, most certainly, but this is the test case we have.

[Carlos Garcia Campos]

Created attachment 361789 [details]
Patch

[Alberto Garcia]

(In reply to Carlos Garcia Campos from comment #5)
> Created attachment 361789 [details]
> Patch

I tried it in the 2.22.x branch, I confirm that it fixes this issue.

[Michael Catanzaro]

Comment on attachment 361789 [details]
Patch

D'oh!

It's frustrating that so many ICU APIs have to be called twice in a row to be used safely, instead of just allocating the buffer for us. Oh well.

[Carlos Garcia Campos]

Committed r241402: <https://trac.webkit.org/changeset/241402>

[Carlos Garcia Campos]

*** Bug 184448 has been marked as a duplicate of this bug. ***