Adding event locks to Ember

dev_view.coffee

# example view implements a simple dragging for mouse events.
Wall.DevView = Ember.View.extend

  mouseDown: (ev) ->
    ev.dispatcher.lock @, 'mouseMove', 'mouseUp'
    @_mouseDown = @$().offset()
    @_mouseDown.pageX = ev.pageX
    @_mouseDown.pageY = ev.pageY
    @_mouseDown.dispatcher = ev.dispatcher
    console.log 'mouseDown'

  mouseMove: (ev) ->
    return unless @_mouseDown
    left = @_mouseDown.left + ev.pageX - @_mouseDown.pageX
    top  = @_mouseDown.top + ev.pageY - @_mouseDown.pageY
    @$().offset { left: left, top: top }
    console.log 'mouseMove'

  mouseUp: (ev) ->
    return unless @_mouseDown
    @_mouseDown.dispatcher.unlock 'mouseMove', 'mouseUp'
    left = @_mouseDown.left + ev.pageX - @_mouseDown.pageX
    top  = @_mouseDown.top + ev.pageY - @_mouseDown.pageY
    @$().offset { left: left, top: top }
    @_mouseDown = null
    console.log 'mouseUp'

event_dispatcher_monkey_patch.coffee

# add ability to lock focus on a view for specific events.
# Call before you create your application instance.
Ember.EventDispatcher.reopen
  _bubbleEvent: (view, evt, eventName) ->
    view = @_locks[eventName] if @_locks?[eventName]
    evt.dispatcher = @
    @_super view, evt, eventName
    
  lock: (view, eventNames...) ->
    @_locks = {} if not @_locks
    eventNames.forEach (eventName) => @_locks[eventName] = view
    
  unlock: (eventNames...) ->
    return if not @_locks
    eventNames.forEach (eventName) => delete @_locks[eventName]

gistfile1.txt

Ember just sends events to whatever view your mouse or finger happens to be under. This causes really annoying breakage when trying to drag views around on the screen. This monkey patch adds the ability for an EventDispatcher to 'lock' delivery of some events to a particular view, so you can solve this.