172162 - Scrolling garbles on-screen fonts

Status: NEW

(Core :: Web Painting, defect)

Description

[Gary Lawrence Murphy]

I will attach a screenshot, but what happens is the line of text at the bottom
of the window, when the window is scrolled up, gets munged illegibly.

Comment 1

[Gary Lawrence Murphy]

Attachment: screen shot showing the munged fonts mid-window.

note: this is on a Gnome2 Linux Mandrake 9.0 system running the Sawfish window
manager.

Comment 2

[richard]

Tried to verify this, but works for me with Mozilla 1.2b build 2002101612 on
Mandrake Linux 9.0 with Gnome 2

Comment 3

[Gary Lawrence Murphy]

Attachment: garbled fonts in Mozilla 1.2b build 2002101612

It's better, but still there.  I can duplicate the effect by lining any line of
text along the bottom of the window such that the edge of the pane cuts the
text in the middle (like at strikeout height) and then quicky moving the
scrollbar to move that bottom line up.

Now here's a clue: with this build, it only happens with the sans-serif font 
adobe-helvetica-iso8859-1 or B7H luxi-sans ... at least I believe this is what
I see on http://www.teledyn.com/mt/ ... I am unable to duplicate the bug with
the fonts used in the bugzilla bug-entry page.

Comment 4

[taintedwheat]

Attachment: Another example

This is not nearly as drastic.	Here, it looks like a few pixels are chopped
from the letters, and the letters are pushed back together.  This happens after
scrolling, when a line of text is partially on- and partially off-screen.

Comment 5

[Felix Enning]

Hi.
Screenshots looks quite familiar for me. I have the same problem with SuSE 8,
XFree 4.2.0 and Icewm. For me, the problem gets worse when using Freetype-Fonts.
But it also exist with "normal" X Fonts.

Felix

Comment 6

[daniel_bruns]

Same problem here, using Solaris, XFree3, Moz1.2.1, fvwm2. Lines from fonts are
chopped, happens very often when using true type fonts with small font sizes,
but also happens with other/bigger fonts. Characters get redrawn correctly when
I mark the text with the mouse.

Comment 7

[Tom Mraz]

Probably DUP of bug 171282

Comment 8

[Daniel Wang]

reporter (Gary Lawrence Murphy), is this dupe of bug 87738?

Comment 9

[Gary Lawrence Murphy]

from what I can understand of bug 87738 in it's own comment thread, no, I don't
think this is the same bug; this one was caused only by scrolling (although I
didn't try highlighting the text to see if that fixes it)

I have upgraded to Mandrake 9.1 using the XFree86 4.3.0 binary for the i810
Intel graphics and Mozilla 1.3, and this current bug (172162), if it does still
exist, is not so easy to reproduce.  In general, I find this release of Mandrake
much improved in the font department and my guess is that this bug was really a
bug in the XFree86 that something specific about the way Mozilla 1.2 wrote these
fonts tripped on this display bug.  That's just a guess.

Comment 10

[David Campbell]

Attachment: Win illustration #1

Comment 11

[David Campbell]

Attachment: Win illustration #2

Comment 12

[David Campbell]

Attachment: Win illustration #3

Comment 13

[David Campbell]

I'm getting similar but slightly different behaviour with Windows 2000.

I've attached some examples...

Comment 14

[pbclarke]

I am seeing this with Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4b)
Gecko/20030516 Mozilla Firebird/0.6

Running RH9.0.

am creating an attachment

Comment 15

[pbclarke]

Attachment: Grabled font in "Step One" section

Comment 16

[John W. O'Brien]

Attachment: Screenshot of mis-rendered fonts on Win2k, Moz 1.4

Bug confirmed on Windows 2000 using latest video drivers (NVIDIA v4.4.0.3 for a
Quadro2 Pro) and SP4.

I've have not seen the font corruption occur upon initial drawing of a page,
only after scrolling. If the garbled text is highlighted with the mouse or with
a Ctrl-A then it is redrawn correctly.

I'll add more info if I find anything else.

Comment 17

[daniel_bruns]

The characters get also redrawn correctly when I mark the location bar with CTRL+l. 

The problem completely disappeared when I set the display resolution from
"System Setting" to "96dpi" and restart.

Comment 18

[Jacob]

This bug is the same as bug 94734 
http://bugzilla.mozilla.org/show_bug.cgi?id=94739

Comment 19

[Jacob]

This bug is the same as bug 94739
http://bugzilla.mozilla.org/show_bug.cgi?id=94739

Comment 20

[Christian Hamacher]

Seems like the dupes are starting to pile up for this:

bug 217313 and bug 217825 might also be duplicates

Comment 21

[Asa Dotzler [:asa]]

->Layout.

Comment 22

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

.

Comment 23

[Wout.Mertens]

See bug #94739, comment 42 for a reliable test case
(http://bugzilla.mozilla.org/show_bug.cgi?id=94739#c42)

Comment 24

[Patrick]

I am seing this too with FireFox 1.0 (Linux/Suse9.1/KDE3.3.1).

In an attempt to put things together, I am listing here bug reports that seem
related to me. Sorry for not doing more analysis (and reading all the comments
of all bugs listed here) or for the bugspam but I really think this linking
might be useful. Please note that this bug is listed too (as I put the same in
different bugs).

bug 172162 Linux
bug 174977 All (was Solaris)
bug 199840 Linux
bug 211704 Linux
bug 215759 Linux
bug 217336 Linux
bug 217825 All (was Linux)
bug 228808 MacOS X
bug 248799 Linux

I built this list by searching for scroll and font in the comments from newest
to oldest going up to the first one of this list (feel free to search further)
and I might have missed some.

I put the OS as it seems there is a link between them: is it due to the usage of
a common deployed library, a bug in an OS' library, ...?

Comment 25

[klonos]

This is a very old bug and I am trying to repro/confirm, but there are no steps. Any url that displays the issue??