#953810 /usr/bin/xmag: [xmag] Doesn't show the pixel RGB value any more.

Package:
x11-apps
Source:
x11-apps
Description:
X applications
Submitter:
boffi
Date:
2022-04-01 15:09:02 UTC
Severity:
important
#953810#5
Date:
2020-03-13 18:26:28 UTC
From:
To:
Dear Maintainer,

sometimes I use xmag to query the RGB value of a pixel on the screen
but now if I click in its window instead of a display of the RGB value
I see, in the terminal window from which I launched it, the error message

X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  91 (X_QueryColors)
  Value in failed request:  0xfff0fff0
  Serial number of failed request:  508
  Current serial number in output stream:  508

(the serial number varies over different attempts).

In this example, the sampled color is a very light green and probably the last
three bytes "f0 ff f0" of the out of range parameter are indeed the RGB values
under investigation.

Thank you, gb
#953810#10
Date:
2022-04-01 15:03:57 UTC
From:
To:
I'm having the same problem with xmag in Ubuntu.
In fact this is not limited to xmag.  Xfig (1:3.2.7b-2 in Ubuntu)
suffers from a similar issue: when adding a new color by using
"Lookup and Add", xfig may crash with an X_QueryColors badValue trap.

The problem seems to be related to the type of window you're trying
to query a pixel color of:
  - In "classic" X11 apps (xmag, fig2dev, even the icons in the
    GNOME taskbar), xmag and fig2dev can query colors fine,
  - In "modern" composed/anti-aliased apps (gnome-terminal, chromium),
    X_QueryColors fails.

I do not know if this is a bug in these applications, or in some
other layer (X libs, X server, compositor, ...).

Thanks!

Gr{oetje,eeting}s,

                        Geert