LCD, pan, randr1.2, and pan-to-downscale

Carsten Haitzler (The Rasterman) raster at
Sun Apr 15 19:26:15 PDT 2007

On Sun, 15 Apr 2007 10:04:28 -0700 Eric Anholt <eric at> babbled:

> On Sun, 2007-04-15 at 18:09 +0800, Austin Yuan wrote:
> > Hi!
> > 
> > I know if configuring a screen size larger than the physical size of a
> > LCD, pan will occur, and users need to scroll to view the far edges of
> > the desktop.
> > 
> > Pan-to-downscale here means when the screen size is bigger than LCD
> > size, downscale screen content in order to fit its whole content into
> > the viewable area. Pan-to-downscale is useful for those small LCD with
> > lower resolution (such as 800x480) on small devices,so that user can
> > view more content larger than LCD size without scrolling.
> > 
> > Pan-to-downscale currently needs to do some ugly hacking in the video
> > driver to achieve it. I saw randr1.2 has many significantly changes
> > compared with version 1.1, and there are some discussion about
> > pan-and-scan. I am curious whether randr1.2 has addressed this
> > pan-to-downscale feature, and will it support it in future?
> I think most people would agree that that should really be a compositing
> manager feature.
> I'm personally pretty convinced that even basic pan-and-scan ought to be
> a compositing manager feature, as if I was to ever use pan-and-scan (not
> that I do), it seems like I'd surely want a more interesting policy for
> when and where to move the crtc in the framebuffer than what that the
> server used to have.

agreed - scrolling, zooming etc. should be left to the wm/compositor to
implement as needed per application window, or within toolkits to have
scrollable regions of a window. the xserver itself should get out of the
business of determining policy on this.

> -- 
> Eric Anholt                             anholt at
> eric at                         eric.anholt at

------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at
Tokyo, Japan (東京 日本)

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