- Direct Known Subclasses:
Rendering of an item in a
WAbstractItemView is delegated to an implementation of this
delegate class. The default implementation used by JWt's item views is
WItemDelegate. To provide specialized rendering support, you can reimplement this class (or
As a delegate is used for rendering multiple items, the class should not keep state about one specific item.
A delegate may provide editing support by instantiating an editor when
called with the
ViewItemRenderFlag.Editing flag. In that case, you will also need to
setEditState() to support virtual scrolling and
setModelData() to save the edited value to the model. For an example, see the
Nested Class Summary
Method SummaryModifier and TypeMethodDescriptionSignal which indicates that an editor needs to be closed.Returns the current edit state.
voidSets the editor data from the editor state.
voidSaves the edited data to the model.
final WWidgetCreates or updates a widget that renders an item.
abstract WWidgetCreates or updates a widget that renders an item.
voidUpdates the model index of a widget.Returns whether the edited value is valid.
Methods inherited from class eu.webtoolkit.jwt.WObject
getId, getObjectName, remove, setFormData, setObjectName, tr
updatepublic abstract WWidget update
(WWidget widget, WModelIndex index, EnumSet<ViewItemRenderFlag> flags)Creates or updates a widget that renders an item.
The item is specified by its model
index, which also indicates the model. If an existing widget already renders the item, but needs to be updated, it is passed as the
null, a new widget needs to be created and returned.
If you want to replace the
widgetwith a new one, return the new widget. The old
widgetwill be removed. Return
nullif you do not want to replace the
You can remove the
widgetfrom its parent for reuse with
The returned widget should be a widget that responds properly to be given a height, width and style class. In practice, that means it cannot have a border or margin, and thus cannot be a
WFormWidgetsince those widgets typically have built-in borders and margins. If you want to return a form widget (for editing the item), you should wrap it in a container widget.
flagsparameter indicates options for rendering the item.
updatepublic final WWidget update
(WWidget widget, WModelIndex index, ViewItemRenderFlag flag, ViewItemRenderFlag... flags)Creates or updates a widget that renders an item.
updateModelIndexUpdates the model index of a widget.
This method is invoked by the view when due to row/column insertions or removals, the index has shifted.
You should reimplement this method only if you are storing the model index in the
widget, to update the stored model index.
The default implementation does nothing.
getEditStateReturns the current edit state.
Because a View may support virtual scrolling in combination with editing, it may happen that the view decides to delete the editor widget while the user is editing. To allow to reconstruct the editor in its original state, the View will therefore ask for the editor to serialize its state in a boost::any.
The default implementation assumes a read-only delegate, and returns a boost::any().
setEditStateSets the editor data from the editor state.
When the View scrolls back into view an item that was being edited, he will use
setEditState()to allow the editor to restore its current editor state.
The default implementation assumes a read-only delegate and does nothing.
validateReturns whether the edited value is valid.
The default implementation does nothing and returns Valid.
- See Also:
setModelDataSaves the edited data to the model.
The View will use this method to save the edited value to the model. The
editStateis first fetched from the editor using
The default implementation assumes a read-only delegate does nothing.
closeEditorSignal which indicates that an editor needs to be closed.
The delegate should emit this signal when it decides for itself that it should be closed (e.g. because the user confirmed the edited value or cancelled the editing). The View will then rerender the item if needed.
The second boolean argument passed to the signal is a flag which indicates whether the editor feels that the value should be saved or cancelled.