Markers should use core.Item

[alatdneg]

Hi, I'm having issues with markers, I'm implementing a treeview representation of the otio structure, which is going well but Markers are a pain as they are not parented, which is odd, as they are useless out of context, they always need a parent for calculating their position in the timeline.

So would it make sense for then to work the same way as every other structure in otio, i.e. using core.Item, this also means that their clip/timeline position can be resolved through a function call, instead of guesswork (took ages to work out how they work).

cheers

[ssteinbach]

Markers have definitely been loose in their definition, and the time hierarchy stuff (like range_in_parent) is definitely newer (and still IP! see #232 ). core.Item directly is probably not a good fit for Marker, since items have a marker and effects list. Is the parent() pointer and range_in_parent() stuff what you're looking for?

I think we could also explicitly define what space marked_range (or whatever it becomes is in). Right now it could be in the world coordinates or the local coordinates, we have implicitly specified it by convention in the viewer and the adapters, but not explcitly. We're also clearly missing a documentation page on how the markers work.