randr: "reverse panning"

Matthias Hopf mhopf at suse.de
Mon Apr 26 08:33:34 PDT 2010

On Feb 25, 10 01:36:53 +0200, Andriy Gapon wrote:
> Sorry for not following the latest RandR developments, but let me ask.
> Does RandR support setting a monitor mode to NxM resolution (e.g. its native
> resolution) while setting its 'effective pixel resolution' (a term just invented
> by me) to PxR where P <= N and/or R <= M?
> In other words, can I have a monitor set to its native resolution while using
> only a portion of its pixels as if it had some other, smaller resolution.

If you choose a resolution for a monitor, then by *definition* the
scanout area has to be scanned out. Which means, you cannot allocate
less pixels than are actually shown.

You might have a chance, though, to create a modeline manually, that
uses the timings for the native mode, but is only active for a smaller
number of pixels. Whether this works with your monitor is doubtful, but
it might be worth a try.

Most graphics cards can be programmed to scan out a larger area, but
only access the framebuffer for a smaller subset - which would be
exactly what you want. AFAIR there is no API to provide that information
to the driver, or for the driver to provide information about this
ability to the server.

What you probably *really* want is working shatter support. Which is
still in the flux.


Matthias Hopf <mhopf at suse.de>      __        __   __
Maxfeldstr. 5 / 90409 Nuernberg   (_   | |  (_   |__          mat at mshopf.de
Phone +49-911-74053-715           __)  |_|  __)  |__  R & D   www.mshopf.de

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