| [GEF5 MVC] Change focus/selection by TAB [message #1820869] |
Thu, 30 January 2020 20:54  |
 Frank Benoit
Messages: 179
Registered: July 2009 |
Senior Member |
|
|
Hi,
I try to get an example working, changing the focus and selection of next node (content part) via Tab.
I see in the MindMap example that it is not implemented as TAB leads to this exception:
java.lang.NullPointerException
at org.eclipse.gef.mvc.fx.gestures.DefaultHandlerResolver.resolve(DefaultHandlerResolver.java:65)
In my trial, I have a viewer with 3 parts, with selection feedback.
To make focus change by TAB work, i need to configure for my content part adapters FocusTraversalPolicy+FocusBehavior+TraverseFocusOnTypeHandler
Doing this, having one part selected by click, then TAB, the selection feedback is not changing. However, via debugger i see the focus is changing.
To solve, i can listen on the focusProperty and set the part in the selection model.
visual.focusedProperty().addListener((obsv, ov, nv) -> {
SelectionModel sm = getViewer().getAdapter(SelectionModel.class);
if( !ov && nv ) {
sm.setSelection(this);
System.out.println("focused " + visual);
}
if( ov && !nv ) {
sm.removeFromSelection(this);
System.out.println("unfocused " + visual);
}
});
Is there an existing mechanism that implements this?
When I TAB through, after last part, it selects the viewer. TAB again does not start with the first part.
Cyclic tabbing is supported with existing logic?
And finally
Backwards tabbing seems not be supported, so I need to implement my own version of TraverseFocusOnTypeHandler?
Frank
|
|
|
|
|
|
| Re: [GEF5 MVC] Change focus/selection by TAB [message #1822409 is a reply to message #1820934] |
Thu, 05 March 2020 18:30  |
|
Hi Frank,
apart from the tab traversal problems in the MVC logo example, this is how it should work:
There is a distinction between focus and selection, i.e. focus traversal does not necessarily be visible (e.g. if there is no focus feedback) and it is independent from selection.
FocusTraversalPolicy implements the focus traversal algorithm. The resulting focus change is executed via ChangeFocusOperation.
FocusModel stores the currently focused part.
SelectionModel stores the currently selected parts.
Feedback and Handles are generated for focus and selection via FocusBehavior, SelectionBehavior, and the corresponding factories and providers.
1) Changing selection when changing focus.
You should perform (model) changes via operations, so that they will be undoable. In this case, you want to change the actions taken when traversing focus. Therefore, the ideal entry point would be the FocusTraversalPolicy:
- SelectionFocusTraversalPolicy extends FocusTraversalPolicy
-- ensure that focus traversal will also change the selection (override createOperation(), getFocusChangeOperation(), traverse(), add getSelectionChangeOperation()).
- Exchange the binding in your module.
2) Cyclic tabbing should work. However, the "nothing is focused" (focus=null) case is part of the cycle. For details, take a look at FocusTraversalPolicy#traverse() etc.
3) Due to the SHIFT-bug, I believe you need to fix backwards tabbing by implementing your own (maybe subclassed) handler. The policy does provide means to traverse backwards.
I hope this makes sense. The tab traversal code is definitely not challenged enough.
Best regards,
Matthias
|
|
|
Powered by
FUDForum. Page generated in 0.02061 seconds
] 
Search
Help
Register
Login
Home
