roassal-experiments_drag-and-drop.st

v := RTView new.
"o := TRAnnouncingOverseer new.
v canvas eventOverseer: o.
o announcer inspect."

droppable := RTBox new
	size: 300;
	borderColor: Color black;
	elementOn: 'drop here'.

draggable := RTEllipse new
	size: 60;
	borderColor: Color black;
	elementOn: 'drag me'.

v add: droppable; add: draggable.

draggable translateBy: -400 @ -200.
draggable @ RTDraggable.

droppable @ (RTLabeled new center color: Color black).
draggable @ (RTLabeled new center color: Color black).

entered := false.

draggable when: TRMouseDragging do: [ :evt |
	entered
		ifTrue: [
			(droppable encompassingRectangle containsPoint: draggable position) ifFalse: [
				entered := false.
				droppable shape color: Color veryVeryLightGray.
				droppable update; signalUpdate.
			]
		]
		ifFalse: [
			(droppable encompassingRectangle containsPoint: draggable position) ifTrue: [
				entered := true.
				droppable shape color: Color yellow.
				droppable update; signalUpdate.
			]
		]
].


v