676291 - Unicode characters rendered with excessive height and depth in Firefox in Windows

Status: RESOLVED DUPLICATE of bug 598900

(Core :: Layout: Text and Fonts, defect)

Description

[Neil Bartholomew]

Attachment: unicode-test.html - This file contains a simple example illustrating and explaining the problem

User Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20110429 Iceweasel/3.5.16 (like Firefox/3.5.16)
Build ID: 20110429081653

Steps to reproduce:

I used Unicode Greek Letters, e.g.

Comment 1

[Neil Bartholomew]

It appears that my original submission may have been truncated at the first occurrence of a Unicode Greek character, which is unfortunate because those characters are essential to the problem being reported. Just in case the full original report did not get uploaded due to the Unicode characters, here is a summary:

When Greek Unicode characters are used, Firefox (either 3.6 or 5) in Windows (either XP or Win7) gives these characters an excessive height and depth, resulting in very large line spacing around the line containing these characters. These characters are rendered correctly in Firefox (either version) in both MacOS and Linux, as well as Internet Explorer 8 in Windows 7. The problem appears only in Firefox in Windows.

Comment 2

[Neil Bartholomew]

A further clarification: The Greek characters referred to are (as with the ones in the previously attached sample file) Greek characters for use in mathematics which appear in Unicode Plane 1, such as 𝜓 (psi) or 𝛼 (alpha), NOT the Greek characters intended for writing Greek text which appear in Unicode Plane 0, such as α (alpha) or δ (delta).

Comment 3

[Neil Bartholomew]

And finally, one more clarification: The same behavior is observed when the entities (such as 𝜓 or 𝛼) are used, as when the actual Unicode characters are used.

Comment 4

[WADA:World Anti-bad-Duping Agency]

Do you install "Cambria Math" font in your MS Win? 
If yes, does problem occur when "Cambria Math" is used by Firefox on Win?

Get NSPR log with winfonts:5 on MS Win.
> SET NSPR_LOG_MODULES=winfonts:5
If "Cambria Math" is used, dup of Bug 598900.

Comment 5

[Jonathan Kew [:jfkthame]]

If you use an Aurora or Nightly build (i.e. prerelease of Firefox 7 or 8), you can install the fontinfo extension (https://addons.mozilla.org/en-US/firefox/addon/fontinfo/). Then select one of the problematic characters, right-click, and choose Show Fonts in Selection from the context menu.

This will almost certainly confirm that Cambria Math is being used to display those characters, which results in much larger line spacing because of the greater vertical extent of (some glyphs in) that font.

Comment 6

[Mihaela Velimiroviciu (:mihaelav)]

Build identifier: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:9.0a1) Gecko/20110912 Firefox/9.0a1
OS: Windows 7 64 bit

Verified on latest nightly build using the attached test page and the issue is reproducible: there is extra space above and bellow the line containing Greek character. 
The font used to display the text is Times New Roman.

If DirectWrite rendering is used (gfx.font_rendering.directwrite.enabled is set to true in about:config) the text is displayed correctly, witn no extra spacing between lines.

Marking as DUPLICATE to bug #598900 since it looks like a GDI related issue.