hpoj reference: xojpanel
xojpanel is a graphical application that continuously displays
the contents of the LCD (liquid crystal display) on the device's front
panel, for devices which support readback of this information.
See the xojpanel column on the hpoj
Supported devices page
for the most up-to-date information about which models support this feature.
The syntax of xojpanel is as follows:
xojpanel [devname] [options...] &
- devname is the optional PTAL
- options... is zero or more of:
- -caption "text" -- Text to be displayed in titlebar
- -notrans -- Disables translation of nonprintable characters
- -hidedevname -- Hides device name from titlebar
- & -- Runs xojpanel in the background
xojpanel should work with most recent 1.x, 2.x, and 3.x versions of
the QT library from Trolltech. If you
don't have QT installed on your system, then the hpoj ./configure
script should disable compilation of xojpanel.
xojpanel refuses to start, or exits if it has already started,
upon any of the following conditions:
xojpanel mimics the look of a typical LCD with the font and
foreground/background colors. It currently has two lines and is 20
characters wide. If the text on either line is too long, then it scrolls
the text from right to left.
- The device doesn't support LCD readback (returns an error on the
"display" PML objects).
- The device is disconnected or powered off.
- The low-level I/O daemon for locally-connected devices
(ptal-mlcd) isn't running, presumably
because "ptal-init start" has not been
- There is some other problem communicating with the device.
Advanced users may wish to hack the xojpanel source code to
customize various compile-time options, such as font, colors, scroll
speeds, poll rates, etc. See the xojpanel.cpp and xojpanel.h
files in the hpoj source package's apps/xojpanel directory for
Some models have a color LCD for previewing and adjusting photos before
printing. It is not possible for xojpanel to retrieve graphical
information from such displays.
Several models have quirks related to xojpanel and
"ptal-hp display" that are worth
Andreas Fester originally wrote xojpanel, but Joe Piolunek wrote
most of the code that is in the current version of xojpanel.
- Many models, such as the OfficeJet G series and later models,
occasionally display non-standard characters, such as a filled-triangle
right arrow (0x81) and a filled circle (0x83). By default, xojpanel
translates non-standard characters to reasonable printable equivalents if
possible or spaces otherwise. The -notrans command-line option
disables this behavior.
- The LaserJet 3200 series incorrectly formats the information it
returns when there are leading or trailing spaces on either line.
For example (dots indicate spaces for clarity):
on the device is correctly returned to the PC, but
...FAX JOB STATUS...
on the device is incorrectly returned to the PC as
MAIN MENUFAX JOB STA
It is not feasible to fix or work around this problem in software.
- The LaserJet 1220, which doesn't even have a physical LCD,
displays the string "DOCUMENT LOADED" most of the time, even
when no document is loaded, due to the way its scanner subsystem works.
- Some models answer queries of the "display" PML objects but return
an empty string.