Re: experiments with clipboards and clipboard managers

[John Darrington]

On Mon, Oct 15, 2012 at 08:52:03PM -0700, Ben Pfaff wrote:
     I did a little bit of research tonight after thinking about our
     IRC conversation about when it takes a long time to compose
     selection data for a clipboard response.  I modified the function
     that responds to a clipboard request to printf a message, and
     then tried a few clipboard copies with two different clipboard
     managers running (Parcellite and Diodon) and with no clipboard
     manager running.
     
     Parcellite's behavior surprised me.  Twice a second, it requests
     a new copy of the primary selection from whatever app owns it.
     If an app has a big selection, it essentially DOSes the machine.
     
     Diodon seems a little better.  It appeared to request the
     selection three times (three formats? didn't check) and then
     stops.
     
     Without a clipboard manager, there's no problem.

None of the above surprises me.  Clipboard "managers" cause problems 
as you have discovered.
     
     Gnumeric doesn't handle large copy/cut/paste particularly well
     either.  It's easy to induce long pauses (seconds, maybe tens of
     seconds?) with a few hundred thousand cells.

Does this happen going in both directions, or only in one?  And is 
the bottleneck in the Gnumeric side or the Psppire side?

At the end of the day, I would never encourage anyone to make large
cut and pastes.  Not only because of the performance issue, but also
because it is so easy to inadvertently and unwittingly select the 
wrong cells - leading to data getting dropped or duplicated without
anyone realising it.

The clipboards (both PRIMARY and CLIPBOARD)  are IMO a convenience
feature designed to be used for quick transfer of small amounts of
data between applications.  The clipboards need to be able to 
generate text and html so that they can be pasted to spreadsheets
and to text editors.  The code in master does this quite well I 
think, so can probably be reused for the psppsheet branch.

J'

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