XForms: Best way to ...

Rob Fletcher (rpf1@york.ac.uk)
Fri, 29 Aug 1997 14:46:42 +0100 (BST)

To subscribers of the xforms list from Rob Fletcher <rpf1@york.ac.uk> :


I have an interactive app using live video input. Bascially I need the
video running grabbing frames and displaying via a gl canvas but also
need to wiggle buttons and sliders around which alter stuff in the video

I am trying to work out the best way to "interrupt" the video input
when I use other parts of the interface.

My view is to run the video in the idle_callback. However, when I
touch the other interface objects, how can I be sure the video code
in the idle_callback has completed.

I suspect this is basically a question for TC as I need to know at
what state the running code in a idle_callback is left when interrupted
by another XFORMS event. Is it a true interrupt, or does it wait for
completion of the code in the idle_callback before switching to the
activated callback for the object? TC?

If it undetermined, how can I make sure the switch to the other
interface object callback only happens at the end of a video frame
(given a user will of course not be able to "insert" their actions
between video frames reliably ... joking....)

I was also thinking of setting and clearing a flag at start end of video
grab code, and then using this flag in a check_forms loop, but I am still
wary of having the video code running "on its own" in the idle_callback

Regards, Rob

| Dr R P Fletcher (Rob) | Email R.Fletcher@york.ac.uk |
| Graphics Coordinator | Phone +44 1904 433816 (ddi) |
| Computing Service | Frontdesk +44 1904 433800 (ddi) |
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