Scene(3I)

NAME

   Scene, MonoScene - composite interactors

SYNOPSIS

   #include <InterViews/scene.h>

DESCRIPTION

   Scene  is  the base class for all interactors that are defined in terms
   of one or more instances of other interactors.  MonoScene is a subclass
   for  scenes  that  contain  a  single instance.  A monoscene's shape is
   copied from its component and the component's canvas is given the  same
   size and location as the monoscene's canvas.

   When   a   scene  is  deleted,  it  should  delete  all  its  component
   interactors.  A monoscene deletes  its  existing  component  if  a  new
   component is inserted.

PUBLIC OPERATIONS

   void Insert(Interactor*)
   void Insert(Interactor*, Coord x, Coord y, Alignment = BottomLeft)
   virtual Interactor* Wrap(Interactor*)
   virtual void DoInsert(Interactor*, boolean, Coord& x, Coord& y, Shape*)
          Add  an interactor to the scene, optionally aligned with respect
          to a specific position relative to the lower-left corner of  the
          scene.   Valid alignment types are TopLeft, TopCenter, TopRight,
          CenterLeft,  Center,  CenterRight,   BottomLeft,   BottomCenter,
          BottomRight,   Left,   Right,   Top,  Bottom,  HorizCenter,  and
          VertCenter.  The scene uses the interactor's desired  shape,  if
          it  has  non-zero width, to size the interactor.  The base scene
          class  always  calls  Wrap  and  DoInsert  from   Insert;   thus
          subclasses  only  implement  DoInsert  (and Wrap if they want to
          wrap additional interactors around the inserted interactor)  and
          users only call Insert.  In the case of a monoscene, the current
          interior interactor, if not nil, is deleted and replaced by  the
          given  interactor.   If  an  interactor is inserted into a scene
          that is already mapped, the interactor and its descendants  will
          be configured before DoInsert is called.

   void Propagate(boolean)
   void Change(Interactor*)
   virtual void DoChange(Interactor*, Shape*)
          Change  notifies a scene that a given interactor has changed its
          desired shape.  If the propagate flag associated with the  scene
          is  true, Change will call DoChange and then Change(this) on the
          scene's parent.  If the propagate flag is false, Resize will  be
          called  instead.   The propagate flag is true by default and can
          be set with the Propagate operation.

   void Move(Interactor*, Coord x, Coord y, Alignment = BottomLeft)
   virtual void DoMove(Interactor*, Coord& x, Coord& y)
          Request that an interactor be moved  to  the  given  coordinates
          using  the  given  alignment.   As with Insert and Change, users
          call Move and subclasses implement DoMove.

   void Remove(Interactor*)
   virtual void DoRemove(Interactor*)
          Remove an interactor  from  a  scene.   Users  call  Remove  and
          subclasses implement DoRemove.

   void Lower(Interactor*)
   virtual void DoLower(Interactor*)
          Put  the  interactor's  canvas  below  all  others in the scene,
          potentially obscuring  it.   Users  call  Lower  and  subclasses
          implement DoLower.

   void Raise(Interactor*)
   virtual void DoRaise(Interactor*)
          Put  the  interactor's  canvas  above  all  others in the scene,
          making it  fully  visible.   Users  call  Raise  and  subclasses
          implement DoRaise.

PROTECTED OPERATIONS

   Scene()
   MonoScene()
          Construct  a  new scene or monoscene.  Scenes and monoscenes are
          abstract classes; thus, the constructors should only  be  called
          implicitly by subclass constructors.

   void Place(Interactor*, Coord x1, Coord y1, Coord x2, Coord y2, boolean
   = true)
          Assign an interactor's canvas  to  be  a  given  region  of  the
          scene's  canvas.   Unless the optional sixth parameter is false,
          the interactor will be mapped.  If  the  interactor  is  already
          assigned  the  given position and size, then this operation will
          have no effect.  This optimization means that a scene can  place
          all  of its elements in response to a Change and be assured that
          only those elements that have really changed will be redrawn.

   void Map(Interactor*, boolean = true)
          Make the interactor visible on the display if and when the scene
          is  visible.  Unless the optional second parameter is false, the
          interactor will be raised to the top of the scene.

   void Unmap(Interactor*)
          Make the interactor not be visible on the display  if  and  when
          the scene is visible.

   void UserPlace(Interactor*, int w, int h)
          Let  the  user  interact  with the window manager to specify the
          size and location of  the  interactor's  canvas,  whose  default
          width and height must also be supplied by the program.

SEE ALSO

   Canvas(3I), Interactor(3I), Shape(3I)

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