210823 - Text underlining is broken when using non-xft build on XFree86 4.3.0

Status: RESOLVED WONTFIX

(Core Graveyard :: GFX: Gtk, defect)

Description

[Brian Ryner (not reading)]

If you run Mozilla on a system that uses XFree86 4.3.0 (e.g. RedHat 9), and
don't build with xft enabled, underlines will be missing from links.

The problem is that the sign of the UNDERLINE_POSITION property that X returns
has changed in this release (it used to be positive, now it's negative).  We
need to convert the value so that we always end up with a negative number.

Comment 1

[Brian Ryner (not reading)]

Attachment: patch

Convert the value to a signed long, then take the absolute value.

Comment 2

[Brendan Eich [:brendan]]

Asa, can you add this to the 1.4.1 candidate list?

/be

Comment 3

[mharris]

Date: 06 Mar 2003 13:48:50 +0100
From: Juliusz Chroboczek <[e-mail]>
To: [e-mail]
Cc: [e-mail], Roman Kagan <[e-mail]>
Content-Type: text/plain; charset=us-ascii
Subject: (patch seq: 5665) Re: [Fonts] [PATCH] restore the sign of
UNDERLINE_POSITION in FreeType rasterizer

RK> In FreeType font rasterizer the sign of the XLFD property
RK> UNDERLINE_POSITION has changed between 4.2.1 and 4.3.0.  Because of
RK> this, Type1 and TrueType fonts now have UNDERLINE_POSITION negative,
RK> which makes gtk1 builds of mozilla loose underlining.

Yep, this is right.  UNDERLINE_POSITION counts downwards, which is not
stated explicitly by the XLFD, but clearly implied by the formula in
3.2.30:

  UNDERLINE_POSITION = ROUND(maximum_descent / 2)

David, please apply and attribute to Roman Kagan.

                                        Juliusz

--- xc/lib/font/FreeType/ftfuncs.c~     2003-02-13 06:01:45.000000000 +0300
+++ xc/lib/font/FreeType/ftfuncs.c      2003-03-04 20:27:16.000000000 +0300
@@ -959,11 +959,11 @@
         int underlinePosition, underlineThickness;

         if(post) {
-            underlinePosition = TRANSFORM_FUNITS_Y(post->underlinePosition);
+            underlinePosition = TRANSFORM_FUNITS_Y(-post->underlinePosition);
             underlineThickness = TRANSFORM_FUNITS_Y(post->underlineThickness);
         } else {
             underlinePosition =
-                TRANSFORM_FUNITS_Y(t1info->underline_position);
+                TRANSFORM_FUNITS_Y(-t1info->underline_position);
             underlineThickness =
                 TRANSFORM_FUNITS_Y(t1info->underline_thickness);
         }

Comment 4

[Christopher Blizzard (:blizzard)]

Juliusz says that this is a bug in 4.3.0 that was fixed in later releases.  I'm
not sure where to go from here.

Comment 5

[Brian Ryner (not reading)]

Comment on attachment 126588 [details] [diff] [review]
patch

I think we should put in this workarond... I can't see how it would hurt
anything.

Comment 6

[Christopher Blizzard (:blizzard)]

Because we're changing the meaning of the underline element?

Comment 7

[Christopher Blizzard (:blizzard)]

Comment on attachment 126588 [details] [diff] [review]
patch

Clearing due to unresolved questions in the bug.

Comment 8

[Mats Palmgren (inactive)]

gfx/src/gtk/ has been removed on trunk.
This bug doesn't look like a branch candidate to me.

-> WONTFIX