Jtdylktuy

Whenever I configure xterm to use core X11 fonts:

*.vt100.renderFont:             False

*.vt100.locale:                 False

*.vt100.font:                   -monotype-courier new-medium-r-normal--*-120-*-*-m-*-koi8-r

it renders double-sized characters properly:

But when I configure it to use client-side fonts:

*.vt100.renderFont:             True

*.vt100.faceName:               Courier New:antialias=false

*.vt100.faceSize:               12

*.vt100.utf8:                   1

*.vt100.utf8Fonts:              True

*.vt100.utf8Title:              True

it fails to render double-sized characters, which can be confirmed via the vttest utility:

Both PuTTY (on Windows) and konsole do use client-side fonts and still render the double-sized text properly.

Have I mis-configured my xterm, or is this a known issue?

It's a known limitation. The manual page says (note the omission of TrueType fonts from the discussion):

           Although xterm attempts to derive a bold font for other

           font selections, the font server may not cooperate.  Since

           X11R6, bitmap fonts have been scaled.  The font server claims

           to provide the bold font that xterm requests, but the

           result is not always readable.  XFree86 introduced a feature

           which can be used to suppress the scaling.  In the X server's

           configuration file (e.g., “/etc/X11/XFree86” or

           “/etc/X11/xorg.conf”), you can add “:unscaled” to the end of

           the directory specification for the “misc” fonts, which

           comprise the fixed-pitch fonts that are used by xterm.  For

           example



               FontPath                 "/usr/lib/X11/fonts/misc/"



           would become



               FontPath                 "/usr/lib/X11/fonts/misc/:unscaled"



           Depending on your configuration, the font server may have its

           own configuration file.  The same “:unscaled” can be added to

           its configuration file at the end of the directory

           specification for “misc”.



           The bitmap scaling feature is also used by xterm to

           implement VT102 double-width and double-height characters.

Handling double-width/double-height characters using TrueType fonts could be implemented differently, by drawing/clipping one character at a time with a font that's been double-sized. Of course, with fontconfig's metrics (which often ignore the nominal bounding box), there would be no guarantee that the result would look nice.

For what it's worth, PuTTY and konsole have their own problems with this test:

PuTTY doesn't handle the line-drawing part of the test, and Konsole's typically coming up with some odd window sizes. Also, if you look closely, there are minor discrepancies in the alignment of the single- and double-width text (ymmv).