package ui import ( "errors" "sync" "git.kirsle.net/go/render" "git.kirsle.net/go/render/event" ) // Event is a named event that the supervisor will send. type Event int // Events. const ( NullEvent Event = iota MouseOver MouseOut MouseDown MouseUp Click KeyDown KeyUp KeyPress Drop ) // Supervisor keeps track of widgets of interest to notify them about // interaction events such as mouse hovers and clicks in their general // vicinity. type Supervisor struct { lock sync.RWMutex serial int // ID number of each widget added in order widgets map[int]WidgetSlot // map of widget ID to WidgetSlot hovering map[int]interface{} // map of widgets under the cursor clicked map[int]interface{} // map of widgets being clicked dd *DragDrop } // WidgetSlot holds a widget with a unique ID number in a sorted list. type WidgetSlot struct { id int widget Widget } // NewSupervisor creates a supervisor. func NewSupervisor() *Supervisor { return &Supervisor{ widgets: map[int]WidgetSlot{}, hovering: map[int]interface{}{}, clicked: map[int]interface{}{}, dd: NewDragDrop(), } } // DragStart sets the drag state. func (s *Supervisor) DragStart() { s.dd.Start() } // DragStop stops the drag state. func (s *Supervisor) DragStop() { s.dd.Stop() } // IsDragging returns whether the drag state is enabled. func (s *Supervisor) IsDragging() bool { return s.dd.IsDragging() } // Error messages that may be returned by Supervisor.Loop() var ( // The caller should STOP forwarding any mouse or keyboard events to any // other handles for the remainder of this tick. ErrStopPropagation = errors.New("stop all event propagation") ) // Loop to check events and pass them to managed widgets. // // Useful errors returned by this may be: // - ErrStopPropagation func (s *Supervisor) Loop(ev *event.State) error { var ( XY = render.Point{ X: int32(ev.CursorX), Y: int32(ev.CursorY), } ) // See if we are hovering over any widgets. hovering, outside := s.Hovering(XY) // If we are dragging something around, do not trigger any mouse events // to other widgets but DO notify any widget we dropped on top of! if s.dd.IsDragging() { if !ev.Button1 && !ev.Button3 { // The mouse has been released. TODO: make mouse button important? for _, child := range hovering { child.widget.Event(Drop, XY) } s.DragStop() } return ErrStopPropagation } for _, child := range hovering { var ( id = child.id w = child.widget ) if w.Hidden() { // TODO: somehow the Supervisor wasn't triggering hidden widgets // anyway, but I don't know why. Adding this check for safety. continue } // Cursor has intersected the widget. if _, ok := s.hovering[id]; !ok { w.Event(MouseOver, XY) s.hovering[id] = nil } _, isClicked := s.clicked[id] if ev.Button1 { if !isClicked { w.Event(MouseDown, XY) s.clicked[id] = nil } } else if isClicked { w.Event(MouseUp, XY) w.Event(Click, XY) delete(s.clicked, id) } } for _, child := range outside { var ( id = child.id w = child.widget ) // Cursor is not intersecting the widget. if _, ok := s.hovering[id]; ok { w.Event(MouseOut, XY) delete(s.hovering, id) } if _, ok := s.clicked[id]; ok { w.Event(MouseUp, XY) delete(s.clicked, id) } } return nil } // Hovering returns all of the widgets managed by Supervisor that are under // the mouse cursor. Returns the set of widgets below the cursor and the set // of widgets not below the cursor. func (s *Supervisor) Hovering(cursor render.Point) (hovering, outside []WidgetSlot) { var XY = cursor // for shorthand hovering = []WidgetSlot{} outside = []WidgetSlot{} // Check all the widgets under our care. for child := range s.Widgets() { var ( w = child.widget P = w.Point() S = w.Size() P2 = render.Point{ X: P.X + S.W, Y: P.Y + S.H, } ) if XY.X >= P.X && XY.X < P2.X && XY.Y >= P.Y && XY.Y < P2.Y { // Cursor intersects the widget. hovering = append(hovering, child) } else { outside = append(outside, child) } } return hovering, outside } // Widgets returns a channel of widgets managed by the supervisor in the order // they were added. func (s *Supervisor) Widgets() <-chan WidgetSlot { pipe := make(chan WidgetSlot) go func() { for i := 0; i < s.serial; i++ { if w, ok := s.widgets[i]; ok { pipe <- w } } close(pipe) }() return pipe } // Present all widgets managed by the supervisor. func (s *Supervisor) Present(e render.Engine) { s.lock.RLock() defer s.lock.RUnlock() for child := range s.Widgets() { var w = child.widget w.Present(e, w.Point()) } } // Add a widget to be supervised. func (s *Supervisor) Add(w Widget) { s.lock.Lock() s.widgets[s.serial] = WidgetSlot{ id: s.serial, widget: w, } s.serial++ s.lock.Unlock() }