proportional panning

Alex Deucher alexdeucher at
Mon May 25 08:03:00 PDT 2009

On Sat, May 23, 2009 at 2:24 PM, David De La Harpe Golden
<david.delaharpe.golden at> wrote:
> Panning's made a welcome return...
> But it's "border-push" type panning. That means to scroll new sections
> of the display into view you "push" against the border. Back in the
> day, some amiga stuff instead used "proportional" panning to move the
> viewport about the screen. Why would you want this?  "Pushing" against
> a border means you need to push beyond where you want to click on to
> bring whatever it is fully on-screen, then move back.  With the
> proportional way, every viewport pointer position corresponds to a
> particular point on the panning area. It allows rapid scrolling about
> large panning areas, at cost of some precision.
> You can sortof-nearly get a vaguely similar effect by using something like
> xrandr --output DVI-I_1/analog --mode 800x600 --panning
> 1600x1200+0+0/1600x1200+0+0/400/300/400/300
> - but it's noticeably nonuniform.
> Anyway, it might be nice if one could say something like
> xrandr --panning blah --panning-mode proportional
> vs.
> xrandr --panning blah --panning-mode borderpush
> Just putting the idea out there, beyond "see the source code"  I
> don't presently know where to begin implementing it beyond rough
> description...

Take a look at hw/xfree86/modes/ in the xserver tree.  xf86Crtc.c and
xf86RandR12.c for the randr 1.3 implementation.


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