Bug 18335 – Pango font backend unable to display japanese properly

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Mike Hommey]

(and I guess this applies mostly to anything that is not ASCII)

The interesting thing is that it works better when using LANG=ja_JP.UTF-8.

Anyways, with LANG=en_US.UTF8, it only displays squares with the freetype backend, and empty text with the pango backend... :(

(This was tested with revision 31667)

[Mike Hommey]

Interestingly, with LANG=ja_JP.UTF-8 and pango backend, ASCII text is displayed as garbage.

[Marco Barisione]

I reproduced the bug with the pango back-end and it's not a WebKit bug, see http://bugzilla.gnome.org/show_bug.cgi?id=528272

[Mike Hommey]

(In reply to comment #2)
> I reproduced the bug with the pango back-end and it's not a WebKit bug, see
> http://bugzilla.gnome.org/show_bug.cgi?id=528272

That doesn't explain the text garbling for ASCII depending on locale...

[Marco Barisione]

(In reply to comment #3)
> (In reply to comment #2)
> > I reproduced the bug with the pango back-end and it's not a WebKit bug, see
> > http://bugzilla.gnome.org/show_bug.cgi?id=528272
> 
> That doesn't explain the text garbling for ASCII depending on locale...

I can reproduce it only with the japanese locale, not with other non-european ones.

If a font is specified using CSS everything is ok, if not you get an ugly font and wrong chars using tha pango back-end. I also tested the freetype (with debian's webkit not a revision from svn) and you get ugly fonts but the right characters.

[Marco Barisione]

Created attachment 20579 [details]
No font is set -> junk and ugly font

[Marco Barisione]

Created attachment 20580 [details]
Font set -> ok

[Marco Barisione]

Created attachment 20581 [details]
Screenshot of GtkLauncher with the wrong rendered page

To reproduce it use:
LANG=ja_JP.UTF-8 ./Programs/GtkLauncher https://bugs.webkit.org/attachment.cgi?id=20579

[Marco Barisione]

I found where the problem is but I don't know if it's a bug in pango or in our function pango_font_get_glyph() defined in WebCore/platform/graphics/gtk/GlyphPageTreeNodePango.cpp.

I opened a bug in the pango bugzilla, let's see what they think: http://bugzilla.gnome.org/show_bug.cgi?id=528550

[Marco Barisione]

Created attachment 20629 [details]
Pass the right font to pango_shape

I didn't notice we were not passing the font to pango, so pango was returning the glyph index for another font.

[Mike Hommey]

Shouldn't the changelog be changed to not include the whole bug report summary, which leads to think both freetype and pango are being fixed ? BTW, shall I clone this bug and retitle both for each individual issue ?

[Alp Toker]

Comment on attachment 20629 [details]
Pass the right font to pango_shape

r=me

[Alp Toker]

Mike: I retitled this bug to make it Pango-specific.

Could you triage the current Chinese/Japanese bugs? I asked aroben to sort out bug tracker permissions for you.

Thanks!

[Alp Toker]

Landed in r32010.