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<d1b2>
<Attie> is it typical/expected for t=0 to be the trigger point, or the first sample in memory?
<_whitenotifier-f>
[scopehal-apps] attie opened issue #283: Pin and Label in Waveform History - https://git.io/JkuVR
<azonenberg>
attie: T=0 is the first sample in memory by convention
<azonenberg>
The trigger point is at an arbitrary offset after that
<azonenberg>
it can even be outside the waveform if you have a big enough post-trigger delay etc
<azonenberg>
attie: Re #283, the technically simplest solution is to associate a boolean pin value with a waveform that prevents it from being purged when we're clearing out old waveforms
<azonenberg>
The timestamp is used as a key to index waveforms in history and needs to be kept, but i'm fine with adding a means of tagging waveforms with a string ID too
<azonenberg>
it should be as simple as adding two new columns to HistoryColumns in the HistoryWindow class
<azonenberg>
then adding the necessary UI logic to populate and edit them
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<d1b2>
<Attie> azonenberg: re t=0, interesting, thanks... I've always considered the trigger to be t=0, but I can see why that might be awkward / not ideal
<d1b2>
<Attie> this introduces the behaviour that altering the horizontal position on the scope will alter the position of the waveform in glscopeclient
<d1b2>
<Attie> not unacceptable, but certainly unexpected (by me)
<d1b2>
<Attie> re #283, that sounds pretty identical to what i was thinking... i might try to dig into it if I get some spare time...
<d1b2>
<Attie> okay, wow... looks like discord will edit previous messages if i start a new one with 's/.../...'
<d1b2>
<Attie> not sure what IRC will see, so >> s/might/will/ ... so don't prioritise it unless it's super easy / you or others want it too try to dig into it if I get some spare time
<azonenberg>
The irc bridge doesnt display the s/ or the correction
<azonenberg>
so it goes unnoticed
<azonenberg>
And with my lecroy scopes at least, the default view when not zoomed is for the entire memory to fill the screen, regardless of timebase config
<azonenberg>
moving the trigger offset then shifts the waveform
<azonenberg>
They define time zero to be the midpoint of the screen
<azonenberg>
and reference the trigger to before/after that
<azonenberg>
for the LA-type applications i'm targeting glscopeclient at, that's pretty illogical so i used the start of the acquisition as the zero point
<azonenberg>
Since the glscopeclient display is decoupled from the scope timebase
<azonenberg>
i.e. zooming or panning a view in glscopeclient wont change the acquired data
<azonenberg>
and ok let me rephrase how lecroy does stuff... they reference time zero to the trigger, but the trigger offset is measured wrt center of the screen
<d1b2>
<Attie> "so it goes unnoticed" - good to know
<d1b2>
<Attie> yeah, lecroy sounds similar to (my) agilent, in that i can put the "t=0" at "near left"/"center"/"near right", and the trigger will center on that point by default, with an optional offset / horizontal position
<d1b2>
<Attie> either way, all the cursors are based on t=0 being the trigger
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<azonenberg>
Yeah, i went with 0 as start of capture because that is really the time reference for everything that works on arrays of samples
<azonenberg>
In general i'm trying to break with the idea of a DSO pretending to be an analog scope
<azonenberg>
It's not
<azonenberg>
there's no grid divisions, voltage/time scale are expressed in terms of units rather than divisions
<d1b2>
<Darius> it can be helpful to the meatbag using to to be able to view the time relative to a variety of things..
<d1b2>
<Darius> beginning of capture, time of trigger, some cursor position etc.