Re: [MacPerl] [ANN] Mac::Utils::ProgressBar

[online@mactech.com (Jeff at MacTech)]

In article <mac-perl.E0zeiOh-0001ew-00@post.mail.demon.net>,
ajf@afco.demon.co.uk (Alan Fry) wrote:

>When the 'goaway box' is clicked during a run, the window closes. but the
>script continues to run. It might be better if the script stopped I think.

Alternatively, it might be better to not have a go-away box at all, since
it could be a bit ambiguous--does it stop the process or just hide the
window? Stopping the process would be best, but forcing the user to use
the "Cancel" button for this would be unambiguous.

>I haven't got to the bottom of this, but suspect it is to do with knowing
>when it is safe to change the graphics port(s). You can say 'SetPort(here)'
>and then 'now draw this here', but MacOS gives no indication back (so far
>as I can see) when it has finished. Hence you don't know when it is safe to
>release the port.

I might be misunderstanding what you mean, but the "now draw this here"
method shouldn't return until the drawing is done. If the port switched at
the wrong time you could get a crash but you would likely see some visual
indication (junk being drawn in another window) as well.

>Incidentally (in the PS to Eric's leter) what is meant by 'indeterminate
>state' and why is that wanted?

I think this is the "barber pole" progress bar, for those times when you
feel like you should have a progress bar but don't have a way to measure
the progress. One concrete example is an ftp client. Most of the time, it
is straightforward to indicate download progress, but some ftp servers (I
am told) won't in a straightforward manner tell you the size of a file, so
if you are downloading it you can't produce the usual progress bar. But,
since the user expects to see a progress bar, they would be confused by
its absence in these rare cases.

The other common use for the "barber pole" is in situations like BBEdit's
multi-file search operation, where the indeterminate bar is displayed
during the "preparation" stage where BBEdit is counting the number of
files it is about to search. Then, when it is doing the actual searching,
it becomes a "normal" progress bar.
-- 
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Jeff Clites                Online Editor           http://www.MacTech.com/
online@MacTech.com         MacTech Magazine
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