gnome terminal does not display all unicode correctly

Asked by Robert Bernecky on 2011-07-21

I am having a problem with character display in Gnome Terminal 2.32.0
under Ubuntu 10.10:

The APL "diamond" character displays as a slightly raised dot, instead of
a diamond: ⋄⋄ (which does display properly as I type this
with ALT-tilde).

This unicode character is U+22C4, according to the
Applications/ Accessories/Character Map app.

If I copy/paste that character into an xterm, it displays correctly.
If I paste it back into the Gnome Terminal, it does NOT display
correctly. The same behavior occurs if I enter the character
through the keyboard.

I have Gnome Terminal configured to use the "system fixed-width font".
If I change that font to use APL385.ttf, it DOES display the diamond
correctly. However, that changes the entire font on all Terminals
to the APL font, which is not acceptable to me, for several reasons.

Oddly enough, it looks to me that all of the other APL characters
(or all that I can see, anyway...) display properly in Gnome Terminal.

This stuff all worked properly a few releases of Ubuntu ago,
but I do not know exactly when things started failing.

Any suggestions as to:

 - what is going on
 - why it only affects one (or a few) characters
 and
 - how I can make Gnome Terminal behave properly here

are welcome.

Thanks!

Question information

Language:
English Edit question
Status:
Open
For:
Ubuntu gnome-terminal Edit question
Assignee:
No assignee Edit question
Last query:
2011-07-22
Last reply:
2011-07-22

This happens for me as well, using monospace font (which is default) in LXTerminal (in Lubuntu 11.04 amd64). The raised dot seems vaguely diamond-shaped if I put my eye right up to the screen, so perhaps the problem is that the diamond is so tiny as to have no center. It seems like this should probably be reported as a bug (https://help.ubuntu.com/community/ReportingBugs), but I agree with your sentiment that it would be good to know exactly what is going on here first, if possible. If no one can say (I've left this question open in case someone knows and can tell us), then it should be sufficient to file a bug against gnome-terminal (invoke ubuntu-bug with the PID of the running gnome-terminal process, which will make sense after you read ReportingBugs), attach a screenshot of the problem in the original bug report, and describe the problem in as much detail as possible. Before reporting this or any bug in Ubuntu, please read https://help.ubuntu.com/community/ReportingBugs carefully.

Robert Bernecky (bernecky) said : #2

Thank you.

I think your analysis -- that the diamond IS being displayed, but is so tiny as to be not recognizable,
is correct. I'll file a bug report on this.

Robert Bernecky (bernecky) said : #3

I set my System/Preferences/Appearance/Fonts "fixed-width font" to Monospace/40pt, and was
able to see that the other characters scale correctly, but the diamond, for some reason, does not scale properly.
It DOES, however, display clearly as a diamond, confirming your analysis.

In what way does it not scale correctly?

Robert Bernecky (bernecky) said : #5

https://bugs.launchpad.net/ubuntu/+source/gnome-terminal/+bug/814796

Bug report filed:

https://bugs.launchpad.net/ubuntu/+source/gnome-terminal/+bug/814796

Re your last question: The diamond character SHOULD be, roughly, the
same height as most upper-case letters.

I think this screen shot in the launchpad bug entry demonstrates the problem:

Screen shot of xterm and gnome-terminal w/same text (70.8 KiB, image/png)

Is it displayed at the correct height for some font sizes, but not others? If so, you have not shown how that is the case. If not, then the problem isn't that it doesn't *scale* correctly.

Also, should the character have the same vertical extent (distance between the top and bottom pixels in the rendered symbol) as most upper-case characters? If so, then xterm is also displaying it incorrectly, and so is LibreOffice (in Times New Roman). Or is it simply that the top of the diamond character is supposed to be as high as the top of most upper-case letters?

Robert Bernecky (bernecky) said : #7

Hi. I've added an Open Office screenshot to bug #814796 that I think shows up the problem.
That should clarify matters.

As to your question about character height: it looks to me that the diamond
is "properly" a bit higher than most upper-case letters. E.g, the T in Times New Roman.

Can you help with this problem?

Provide an answer of your own, or ask Robert Bernecky for more information if necessary.

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