Subject: Re: [linux-audio-dev] multitrack and editor separate?
From: Richard Guenther (rguenth_AT_tat.physik.uni-tuebingen.de)
Date: Wed Oct 31 2001 - 11:21:14 EET
On Tue, 30 Oct 2001, Paul Davis wrote:
> >If they are, this undo splitting should be available on every editor
> >already (at least for GLAME). But thinking of it - if you want to have
> >a "undo last operation done on the range the mouse/marker is at"
> >operation, it should be a matter of minutes to implement this in GLAME,
> >too (the information is all there).
>
> *that's* impressive.
>
> what kinds of data structures are you using to maintain the edit
> history?
Whoops, seems I was wrong (too long break from the code), we dont
track the region information yet, but its very easy to include (I'll
try that). Basically for each track we have a stack of states where
we pop/push undo/redo information - to have region undo working I'd
need to extend that push/pop operation to specify that region. Thinking
about it, for the simplest implementation a insert/cut operation would
block region undo, as a insert/cut operation doesnt fit a "operation
on a region" description very well.
> what happens to the edit history when you carry out a
> "localized" undo like that?
The edit history would stay intact (always assuming there are no
"conflicting" edit operations later on, in which case the region
based undo would choose the last operation anyway), i.e. you would
get the following (stack like, top is most recent), from
op n
op n-1
op n-2
...
to (if you undo on a region that happens to have op n-1 on top)
op n-1 redo information
op n
op n-2
> is GLAME region based? i can't recall ...
Well, that depends on the exact definition of region based, but
the backend where the data is stored has a linear representation
of the data where you can exchange/cut/insert regions on a copy
on write basis.
I'll try to hack up the region based undo and see, if I encounter
problems.
Richard.
-- Richard Guenther <richard.guenther_AT_uni-tuebingen.de> WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/ The GLAME Project: http://www.glame.de/
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