[ddccontrol-devel] Automatic rotation: Proof of Concept

[Daniel E. <dan...@go...>]

Hello,

first, let me thank you for this great piece of software.  I own a
Samsung SyncMaster 970p and thus would not be able to change the monitor
setup at all without a tool like ddccontrol.

Addicted to technical gimmicks as I am, I obviously also wanted to make
use of the pivot functionality of my flat panel.  But even with a simple
graphical tool like gnome-randr-applet, having to change the rotation
setting of the X screen manually each time is highly annoying.  (Just
try using your mouse with the panel already rotated...  Go figure.)

Well, the result of the hacking frenzy that followed is attached to this
mail.  Simply by diff'ing the output of two ddccontrol runs, I found the
control I need to listen for.  I then put together a tiny C program that
uses libddccontrol to poll the monitor every second, and XRandR to set
the screen rotation whenever the panel rotation changed.  This is just a
proof of concept for now as you have to start the tool manually and keep
it running all the time.  Nonetheless it works quite well on my system.

I'd be glad if interested people could pick up this piece and have some
fun with it, and share the results on this list.  Simple build and usage
instructions are to be found at the top of the source file.  Thank you!

However, for a proper solution, a couple of questions need to be
considered first:

1) Is the control index 0xF8 standardized in any way?  If not, it might
be necessary to add an entry to ddccontrol's monitor database.

2) Is there a better way than polling?  I already tried to keep the
overhead at a minimum by reducing the work that is done periodically.
The bash script I initially wrote called ddccontrol every second, which
caused simply unacceptable overhead for something running in the
background.  With the current code there are no CPU usage spikes
noticeable anymore; but nonetheless, it'd be cool if the polling could
be avoided altogether.

3) The big question:  Where to put this?  System service, X itself, gdm,
addition to gnome-randr-applet, ddccontrol applet, whatever?  The goal
should be to make this as most "out of the box" as possible.  Of course
this requires to first get ddccontrol itself into distros :)

4) Minor one:  I think libddccontrol should install a .pc file for use
with pkg-config, in order to ease the burden of linking to it.

5) Do you like the idea?  :-)

I probably forgot one issue or another, but that's enough for now
anyway.  I'll be glad to hear your opinions/suggestions/flames.

Have fun!
--Daniel