Manage wait cursor for task - javafx

Question

I'm outside the UI and wish to display a wait cursor while stuff is
happening and using this basic pattern:
on UI - primaryStage.scene.cursor = Cursor.WAIT
try {
do stuff off UI...
} finally {
on UI - primaryStage.scene.cursor = Cursor.DEFAULT
}
While running I can start another process which completes quickly and the Cursor is restored before the first task completes.
I don't mind "waiting" while the first task completes, but I don't think this means doing the work on the UI thread?
Is there any built in solution for this pattern provided in javafx?
My tab contains 2 Combo Box. When I hit the 2nd Combo Box drop down, a WAIT cursor sometimes appears over the list even though the Cursor is currently DEFAULT state. If I move the mouse pointer outside/back on the list the cursor is correctly displayed as Default. Would this be a separate issue or somehow related?
VIEW
label 'From'
comboBox(items: bind(model.wcomboFromItemsProperty()), value: bind(model.wcomboFromProperty()), selectFromAction)
label 'To'
comboBox(items: bind(model.wcomboFromItemsProperty()), value: bind(model.wcomboToProperty()), selectToAction)
MODEL
#FXObservable ListElement wcomboFrom = new ListElement()
#FXObservable ListElement wcomboTo = new ListElement()
#FXObservable List wcomboFromItems = FXCollections.observableArrayList()
#FXObservable List wcomboToItems = FXCollections.observableArrayList()
final ObjectProperty<Cursor> CURSOR_DEFAULT = new SimpleObjectProperty<>(Cursor.DEFAULT)
final ObjectProperty<Cursor> CURSOR_WAIT = new SimpleObjectProperty<>(Cursor.WAIT)
CONTROLLER
//lifecycle
void onReadyStart(GriffonApplication application) {
loadWindowData()
}
// both combo boxes contain the same items
protected void loadWindowData() {
def list = [new ListElement(textValue: '')]
list.addAll dataService.getData().collect {
new ListElement(textValue: it.name, objectValue: it)
}
runInsideUIAsync {
model.wcomboFromItems.addAll(list)
model.wcomboToItems.addAll(list)
}
}
void selectFrom() {
performAction {
gcListFrom = getControlList(model.wcomboFrom.objectValue)
setTreeItems(model.wtreeGcFrom, gcListFrom, model.wcomboFrom)
setTreeItems(model.wtreeGcTo, gcListTo, model.wcomboTo)
}
}
void selectTo() {
performAction {
gcListTo = getControlList(model.wcomboTo.objectValue)
setTreeItems(model.wtreeGcTo, gcListTo, model.wcomboTo)
}
}
def performAction = {c ->
Task<Void> t = new Task() {
#Override protected Void call() {
println "Running closure " + isUIThread()
c.call()
}
}
runInsideUISync {
application.primaryStage.scene.cursorProperty().bind(Bindings.when(t.runningProperty())
.then(model.CURSOR_WAIT).otherwise(model.CURSOR_DEFAULT))
}
runOutsideUI(t)
}
OTHER
#EqualsAndHashCode(includes = 'textValue')
class ListElement implements Serializable {
String textValue = ""
Serializable objectValue // Serializable object from business model
#Override
String toString() {
textValue
}
}
The Griffon framework automatically invokes the onAction controller events outside the UI thread. GroovyFX contains some magic which adds an "onSelect" action bound to selectionModel.selectedItemProperty i.e.
class GroovyFXEnhancer {
static void enhanceClasses() {
...
ComboBox.metaClass {
cellFactory << { Closure closure -> delegate.setCellFactory(closure as Callback)}
onSelect << { Closure closure ->
delegate.selectionModel.selectedItemProperty().addListener(closure as ChangeListener);
}
...
}
}

Answer 1

Is there any built in solution for this pattern provided in javafx?
I would advice you to use the built in Task ;)
It has predefined methods to handle everything you need.
private Task<Void> backgroundTask = new Task() {
#Override
protected Void call() throws Exception {
// Something to do on background thread ;
return null;
}
};
It has a runningProperty(), which can bind to the cursorProperty() of the scene.
You can create two ObjectProperty<Cursor> containing Cursor.DEFAULT and CURSOR.WAIT.
final ObjectProperty<Cursor> CURSOR_DEFAULT = new SimpleObjectProperty<>(Cursor.DEFAULT);
final ObjectProperty<Cursor> CURSOR_WAIT = new SimpleObjectProperty<>(Cursor.WAIT);
Then you can bind them to the task :
scene.cursorProperty().bind(Bindings.when(backgroundTask.runningProperty())
.then(CURSOR_WAIT).otherwise(CURSOR_DEFAULT));
Would this be a separate issue or somehow related?
If your action on the ComboBox is somehow invoking the background thread, then it might be related, else it is difficult to comment.

Answer 2

You can also use the griffon-tasks-plugin http://griffon-plugins.github.io/griffon-tasks-plugin/
This plugin delivers and UI toolkit agnostik SwingWorker-like API for executing tasks in a background thread.