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)