Whether the layer the reader is on has a list to offer.
True when o would open one
Builds the list for the layer the reader is on, in the order and filter they last chose on it. Does not open the dialog: the view model shows the list first, so the dialog has it to render the moment its scope opens.
The list, or null when the layer has none
Puts the reader in the object list's scope.
Leaves the object list's scope for whichever scope opened it -- the chart, or braille. Tested against OBJECT_LIST rather than "not TRACE" for the reason GoToExtremaService.returnToTraceScope gives: a dismissal that runs after the scope was restored must not push the list back.
Steps to the next or previous order the chart offers.
1 for the next, -1 for the previous
The list in the new order, or null when there is no other
Steps to the next or previous filter, passing through "all" between the last and the first.
1 for the next, -1 for the previous
The list under the new filter, or null when there is none
Takes the reader to an object once the dialog has closed.
The jump waits a turn, for the chart to have focus again: closing puts focus back on the chart in a timer of its own, and a jump announced before that would be talked over by the screen reader reading the chart it has just landed on. Timers of the same delay run in the order they were set, so this one runs after the refocus. From braille, the text field is focused before either.
The trace is read again when the jump runs, and must still be the layer the list was built from: live data can replace the chart under an open list, and a key that happens to exist in some other layer is not the object the reader chose. When it is gone, the reader is told so.
The key of the chosen object
Its name, to say when it is no longer there
The object list behind
o: every node, tile or region of a chart without axes, sorted and filtered the ways that chart offers, and the jump to the one the reader picks.Owns what the list is -- which objects, in what order, under which filter, and what each row says -- so the view model only shows it and keeps the selection. The objects come from the active trace, which alone knows what they are on its chart.