Stealing key presses

pigeonhill

488

Stealing key presses

« on: 24 / January / 2020, 02:18:12 »

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@reyalp

Hope you can help with my CHDK insight...again

Over in Magic Lantern land I make use of the event handler, especially the key/button events.

This allows my Lua script to call my function to handle the key press, and critically, decide not to allow that key press to propagate through to the Canon side, ie I can decide to hyjack it.

I’ve looked in the basic CHDK scripting area, but, at the moment, I can’t seem to spot an equivalent functionality.

As I say, any insight would be gratefully received.

Cheers

Garry

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waterwingz

11953

Re: Stealing key presses

« Reply #1 on: 24 / January / 2020, 10:23:09 »

When CHDK is in <ALT> mode all key presses are blocked from reaching the Canon firmware. CHDK scripts run in <ALT> mode. You use the various script keyboard function to poll the buttons and take action as required. If you want to have the Canon firmware react to a button press, you have to explicitly detect it in your code and call the press( ) or click( ) function for the key needed.

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Ported : A1200 SD940 G10 Powershot N G16

pigeonhill

488

Re: Stealing key presses

« Reply #2 on: 24 / January / 2020, 10:26:48 »

@waterwingz

Sorry, should have been clearer.
My script runs outside of Alt mode, ie always on in the background.
Are you saying I can only manage key events when in Alt mode?
Cheers
Garry

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waterwingz

11953

Re: Stealing key presses

« Reply #3 on: 24 / January / 2020, 10:44:40 »

Quote from: pigeonhill on 24 / January / 2020, 10:26:48

My script runs outside of Alt mode, ie always on in the background. Are you saying I can only manage key events when in Alt mode?

I'll remind you here that running scripts outside of <ALT> mode is in "undefined" or "indeterminate" untested territory.

That being said, you are going to have a tough time managing any keyboard interactions in that mode. CHDK was not designed to do that so you are essentially in a race condition with the Canon firmware to detect and clear key presses. I do not know if fake key presses will work reliably either.

While I can conceive of ways to add script controlled functionality to support managing key events outside of <ALT>, I have no idea what side effects and glitches that might create. Probably a dark black hole we don't want tio enter?

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Ported : A1200 SD940 G10 Powershot N G16

pigeonhill

488

Re: Stealing key presses

« Reply #4 on: 24 / January / 2020, 11:01:33 »

@waterwingz

Understood, sound advice and I won’t go there

BTW my G5X just arrived

Looking forward to testing CHDK out on it, even if the 5X version is at alpha.

Cheers

Garry

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