Replace the key.Filter.Target field with a Focus field that matches only
of the specified tag has focus. This has the advantage of simpler event
delivery and for lower latency in delivering key events to new handlers.
For example, consider a UI where a button is activated by a key press,
which is turn displays a dialog with another button activated by the
same key. This change allows two button press(+releases) in the same frame
to arrive at the intended targets: one key press(+release) for each
button.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Until now, every event has had a particular target. We're about to simplify
key event delivery to match the first matching filter, so there is no
longer a global meaning to the tag argument to Source.Event.
Add fields to filters to specify their target tags.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Processing one event at a time allows a widget to execute commands after
the event that triggered it, instead of after all matching events.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Change the semantics of commands to execute immediately. In cases where
execution of a command introduces a inconsistency, freeze event routing
and defer the command as well as queued events to the next frame.
Rename Source.Queue to Source.Execute to better fit the new command
semantics.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
This change defers event routing from the time the event is queued until
the time Events is called. This allows a future change to execute
commands immediately and to react to event order changes during a frame.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Instead of having to supply the predicates for event filtering at the
time of layout, the new Filter type allows widgets to filter at the time
of calling Source.Events. There is then only the need for a single input
op type, in package event.
Filters most importantly allow the use of one tag for several event types,
and we can define that a widget w has &w as its primary tag, by convention.
This allows the replacement of per-widget Focus methods with direct uses
of FocusCmd{&w}, and the later addition of Source.Focused(&w) queries.
Note that the TestCursor test needed restructuring to avoid its use of
InputOps.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur