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Groups > comp.sys.acorn.programmer > #1628

Re: Clipboard

From Martin Wuerthner <spamtrap@mw-software.com>
Newsgroups comp.sys.acorn.programmer
Subject Re: Clipboard
Date 2012-04-14 16:18 +0200
Organization MW Software
Message-ID <e538528052.martin@bach.planiverse.com> (permalink)
References (2 earlier) <gemini.m2eu7v001sqn5031g.spamhater@keepyourfilthyspamtoyourself.co.uk> <mpro.m2fsns04q0yxs02ba.news@stevefryatt.org.uk> <gemini.m2fur300tzko1031g.spamhater@keepyourfilthyspamtoyourself.co.uk> <d5acfb7f52.martin@bach.planiverse.com> <gemini.m2gmxv0004eox02ds.spamhater@keepyourfilthyspamtoyourself.co.uk>

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In message <gemini.m2gmxv0004eox02ds.spamhater@keepyourfilthyspamtoyou 
rself.co.uk>
          Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> 
wrote:

> Martin Wuerthner <spamtrap@mw-software.com> wrote:

>> In message <gemini.m2fur300tzko1031g.spamhater@keepyourfilthyspamtoyou
>> rself.co.uk>
>>           Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk>
>> wrote:
>> 
>>> Steve Fryatt <news@stevefryatt.org.uk> wrote:
>> 
>>>> So, are you saying that the problem is that Windows can't be made to
>>>> *ask* Uniclip for the current contents whenever a paste is required?
>> 
>>> Yes it can ask UniClip to get the current contents of the RO
>>> clipboard, but it has no way of knowing whether that clip is older or
>>> newer than whatever clip is on the Windows clipboard.
>> 
>> It does know, and that is what Steve tried to point out in his reply.

>> [..snip..]

>> Great, so at that moment, UniClip *claims* A's clipboard, so that
>> removes precisely the problem you describe in your next paragraph:

> We're talking at cross-purposes, Martin. I was responding to Steve's
> original question, which was why UniClip needed to claim the clipboard, and
> explaining what the situation would be if it didn't do so.

No, not at all. I am referring to exactly the same issue. The crucial 
point is that only the *local* claim of the clipboard is disputed 
(i.e, the claim on the machine where the COPY happened). See below.

Steve's proposal is viable, but it would work very differently from 
the existing UniClip approach, so that might not be feasible in 
commercial terms.

The priority should be to fix the current issues, and as we have 
established that can be done without changing the existing approach 
too much. UniClip can still continue claiming the local clipboard as 
long as it makes sure that the native data is still present on the 
local clipboard in addition to the text data. That change would solve 
almost all issues.

It can be done in a much better way though, which would not only solve 
the existing RISC OS clipboard problems, but would also have massively 
improved performance (in particular with a view to extending the 
system to other data types, most notably bitmaps, which can huge):

The problem with the current approach is that UniClip claims the local 
clipboard on the machine where the most recent copy happened, i.e., 
the machine that owns the current clipboard. The question was why that 
is necessary because that local claim (in its current form) is 
harmful. In the alternative approach that Steve proposed the local 
claim would be avoided, but UniClip would still claim the clipboard on 
all *other* machines. These other claims are not harmful and they are 
required to make the mechanism work.

You can make the Windows clipboard work in exactly the same way as the 
RISC OS clipboard, i.e., the data is pulled from the owning 
application at the moment a paste happens, so there is no need to push 
the data to all the other machines in advance. When a copy happens on 
a machine, it is enough for the local UniClip to remember that it is 
the holder of the universal clipboard and to send messages around that 
make the other UniClip instances claim the clipboard on all the 
*other* machines. When a paste happens the data is pulled from the 
clipboard owner. If the paste happned on the machine that owns the 
universal clipboard the owner is the original application that claimed 
the clipboard, not UniClip, so the existing RISC OS protocol works 
perfectly. If a paste happens on one of the other machines, UniClip is 
the owner and it pulls the data via the network from the UniClip 
instance on the machine that owns the universal clipboard.

Apart from fixing all RISC OS clipboard issues, that approach would 
have another huge benefit: It would save lots of memory and processing 
time because no data would ever be transferred unless it is actually 
needed for a paste operation. At the moment, any copy operation 
anywhere in the network prompts UniClip to retrieve and transfer the 
data to all other machines in the network, which is very wasteful 
because most of the transferred data will never be needed.

-- 
Martin
---------------------------------------------------------------------
Martin Wuerthner         MW Software      http://www.mw-software.com/
        RISC OS Software for Design, Printing and Publishing
---------------------------------------------------------------------

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Thread

Clipboard Alan Wrigley <alan@alanwrigley.com> - 2012-04-12 23:01 +0100
  Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-12 23:32 +0100
    Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 09:50 +0100
      Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-13 22:11 +0100
  Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-12 23:46 +0100
    Re: Clipboard Fred Graute <fjgraute@casema.nl> - 2012-04-13 02:19 +0200
      Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 10:16 +0100
    Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 10:15 +0100
      Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 10:30 +0100
        Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-13 13:35 +0100
          Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 14:26 +0100
            Re: Clipboard Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-04-13 16:42 +0100
              Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 17:04 +0100
            Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-13 21:43 +0100
              Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 23:21 +0100
      Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-13 13:41 +0100
        Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 14:29 +0100
          Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-13 21:52 +0100
        Re: Clipboard Martin Wuerthner <spamtrap@mw-software.com> - 2012-04-13 16:13 +0200
  Re: Clipboard Fred Graute <fjgraute@casema.nl> - 2012-04-13 02:19 +0200
    Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 09:57 +0100
      Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-13 22:21 +0100
        Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-13 23:06 +0100
          Re: Clipboard Martin Wuerthner <spamtrap@mw-software.com> - 2012-04-14 00:33 +0200
            Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 09:15 +0100
              Re: Clipboard Martin Wuerthner <spamtrap@mw-software.com> - 2012-04-14 16:18 +0200
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 17:02 +0100
                Re: Clipboard Fred Graute <fjgraute@casema.nl> - 2012-04-15 02:12 +0200
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-15 11:46 +0100
                Re: Clipboard "John Williams (News)" <UCEbin@tiscali.co.uk> - 2012-04-15 13:09 +0200
                Re: Clipboard Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-04-14 21:08 +0100
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 21:22 +0100
          Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-13 23:54 +0100
            Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 09:17 +0100
              Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-14 10:48 +0100
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 11:07 +0100
                Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-14 11:31 +0100
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 12:14 +0100
                Re: Clipboard Alan Wrigley <spamhater@keepyourfilthyspamtoyourself.co.uk> - 2012-04-14 12:53 +0100
                Re: Clipboard Steve Fryatt <news@stevefryatt.org.uk> - 2012-04-14 14:30 +0100
  Re: Clipboard Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-04-17 18:46 +0100
  Re: Clipboard Rick Murray <heyrickmail-usenet@yahoo.co.uk> - 2012-04-20 05:52 +0200
    Re: Clipboard Matthew Phillips <spam2011m@yahoo.co.uk> - 2012-04-20 23:15 +0100
    Re: Clipboard Vince M Hudd <vinceh@softrock.co.uk> - 2012-04-21 11:01 +0100

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