Class: EventListener

• Inheritance
• Description
• Related information
• Instance protocol
  • event handling
  • events-window creation
  • listen

Inheritance:

   Object
   |
   +--EventListener
      |
      +--ActiveHelp

Package:

stx:libview2

Category:

Interface-Support-UI

Version:

rev: 1.27 date: 2009/06/01 08:43:48

user: cg

file: EventListener.st directory: libview2

module: stx stc-classLibrary: libview2

Author:

Claus Gittinger

Description:

abstract class for event listeners. EventListeners can be used to intercept
incoming events (keyboard & mouse) directly from a sensor, or even
for a complete display device.
A concrete application is the bubble help, which tracks entering/leaving
views, and pops up some help message. 
See concrete code in ActiveHelp.

For each intercepted event, a corresponding method is called for in instances
of myself - these MUST return true, if the event is to be ignored (i.e.
assumed to be processed and consumed by the reader, 
and MUST return false, if the normal event procedure should be performed. 
Since this is an abstract class,
all of my intercept methods return false. 
They are meant to be redefined in concrete subclasses.

Related information:

    WindowSensor
    WindowEvent
    WindowGroup

Instance protocol:

 buttonMotion: buttonAndModifierState x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 buttonMultiPress: button x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 buttonPress: button x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 buttonRelease: button x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 focusInView: aView

not handled here - should be redefined in a concrete subclass

 focusOutView: aView

not handled here - should be redefined in a concrete subclass

 hasKeyboardFocus: aBoolean view: aView

not handled here - should be redefined in a concrete subclass

 keyPress: key x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 keyRelease: key x: x y: y view: aView

not handled here - should be redefined in a concrete subclass

 mouseWheelMotion: state x: x y: y amount: amount deltaTime: dTime view: aView

not handled here - can be redefined in a concrete subclass

 pointerEnter: state x: x y: y view: view

not handled here - should be redefined in a concrete subclass

 pointerLeave: state view: view

not handled here - should be redefined in a concrete subclass

 postCreateView: aView

 preCreateView: aView

 preCreateView: aView origin: org

invoked right before a view is about to be physically created.
May return a new origin.

 listen

install myself as listener

 processEvent: ev

process an event; if true is returned, the event is considered to be
'eaten' by the listener, and not passed to the view.
If false is returned, the event is processed as usual.
Here, the event is dispatched into one of the button*/key* etc. methods

 unlisten

uninstall myself as listener