GWT DataGrid: use of CheckboxCell-selection and standard line mode selection at the same time - gwt

Question

I'm using a GWT DataGrid with a MultiSelectionModel.
The selections of the items of the grid should be achieved by
a) a CheckboxColumn with a CheckboxCell
and additionally at the same time by
b) the standard line mode selection-model (by clicking on the rest of the line).
With the CheckboxColumn the user should be enabled to multi-select different entries. But when clicking somewhere else on the datagrid-lines, a single-line-selection-policy should be done, that means, if a multiple-selection was done before using the checkboxes, this selection should be resetted and only the the clicked line should be selected afterwards.
This is what I have. Does anyone know how to enable CheckBox-Mode and line-selection-mode at the same time?
public class JobDataGrid extends DataGrid<Job>
{
private MultiSelectionModel<Job> selectionModel;
private Column<Job, Boolean> checkboxColumn;
private TextColumn<Job> idColumn;
private TextColumn<Job> titleColumn;
private TextColumn<Job> timestampColumn;
private TexTColumn<Job> ...
public JobDataGrid ()
{
super ();
checkboxColumn = new Column<Job, Boolean> (new CheckboxCell (true, false)) {
#Override
public Boolean getValue (Job job)
{
// Get the value from the selection model.
return selectionModel.isSelected (job);
}
};
checkboxColumn.setFieldUpdater (new FieldUpdater<Job, Boolean> () {
public void update (int index, Job job, Boolean value)
{
// Called when the user clicks on a checkbox.
selectionModel.setSelected (job, value);
}
});
// [...]
// [...]
// [...]
selectionModel = new MultiSelectionModel<Job> ();
setSelectionModel (selectionModel);
// setKeyboardSelectionPolicy (KeyboardSelectionPolicy.DISABLED);
// [...]
// [...]
// [...]
}
}
I've tried out all 4 variants
new CheckboxCell (false, false);
new CheckboxCell (true, false);
new CheckboxCell (false, true);
new CheckboxCell (true, true);
but none of them showed up what I need. And I've also played with
setSelectionModel (selectionModel, DefaultSelectionEventManager.<Job> createCheckboxManager ());
Maybe
createCustomManager(DefaultSelectionEventManager.EventTranslator<T> translator)
would help?
Thanx
Thomas

Answer 1

You can create your own "checkbox manager" and do what you want there.
table.setSelectionModel(selectModel, DefaultSelectionEventManager.<DocumentListItemDTO> createCustomManager(
new DefaultSelectionEventManager.CheckboxEventTranslator<DocumentListItemDTO>() {
#Override
public SelectAction translateSelectionEvent(CellPreviewEvent<DocumentListItemDTO> event) {
SelectAction action = super.translateSelectionEvent(event);
if (action.equals(SelectAction.IGNORE)) {
if (!event.getNativeEvent().getCtrlKey() && !event.getNativeEvent().getShiftKey())
selectionModel.clear();
return SelectAction.TOGGLE;
}
return action;
}
}));

Answer 2

Lista's answer showed up the right direction!
In order to show the usage of DefaultSelectionEventManager.CheckboxEventTranslator for which on the web only hardly can be found examples, here is a fully functional solution as requested:
setSelectionModel (selectionModel, DefaultSelectionEventManager.<Job> createCustomManager (
new DefaultSelectionEventManager.CheckboxEventTranslator<Job> () {
#Override
public SelectAction translateSelectionEvent (CellPreviewEvent<Job> event)
{
NativeEvent nativeEvent = event.getNativeEvent ();
// Determine if we clicked on a checkbox.
Element target = nativeEvent.getEventTarget ().cast ();
if ("input".equals (target.getTagName ().toLowerCase (Locale.ROOT)))
{
final InputElement input = target.cast ();
if ("checkbox".equals (input.getType ().toLowerCase (Locale.ROOT)))
{
// Synchronize the checkbox with the current selection state.
input.setChecked (event.getDisplay ().getSelectionModel ().isSelected (
event.getValue ()));
return SelectAction.TOGGLE;
}
}
else
{
if (BrowserEvents.CLICK.equals (nativeEvent.getType ()))
{
selectionModel.clear ();
return SelectAction.SELECT;
}
}
return SelectAction.IGNORE;
}
}));