Fire selection change events when selection changes indirectly
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Key: PIVOT-548
URL: https://issues.apache.org/jira/browse/PIVOT-548
Project: Pivot
Issue Type: Improvement
Components: wtk
Reporter: Greg Brown
Assignee: Greg Brown
Fix For: 2.0
Currently, selection change events are fired only when an explicit call has
been made that affects the selection. For example, in ListView, calling either
setSelectedRanges() or clearSelection() will fire this event. However, an
operation that indirectly changes the selection state (such as adding or
removing an item from the ListView's model data) does not trigger an event.
This was originally done by design - selectedRangesChanged() includes the
previous selection as an argument, and we didn't want to have to manually
re-construct that every time the selection changed as a side effect of a model
change:
public void selectedRangesChanged(ListView listView, Sequence<Span>
previousSelectedRanges);
However, in practice, working within this model can be challenging. More than
once I have registered a selection change listener expecting to receive
notification of all selection changes, forgetting that it is not designed that
way. I'm guessing that other developers may be confused by this as well.
So, I am proposing that components that maintain a selection state also fire
selection change events when the selection changes indirectly. In this case, a
null value would be passed for the previous selection. This will save the
effort of re-constructing the previous selection info and will give the
listener additional information about the nature of the change (i.e. null ==
indirect state change).
This change should also be propagated to TextInput, which has a similar issue
with character change events. Currently, TextInput fires character change
events via TextInputCharacterListener and text change events via
TextInputTextListener. The textChanged() event does not pass the previous text
value, which is inconsistent with other change events. textChanged() should be
incorporated into TextInputCharacterListener and should pass the previous text
value when it is changed via an explicit call to setText(); otherwise, it
should pass null.
The updated version of TextArea should probably follow the same approach.
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