NAME

       Adjuster - button-like interactors for incremental scrolling and zooming

SYNOPSIS

       #include <InterViews/adjuster.h>

DESCRIPTION

       Adjuster  objects  manipulate a perspective using a pushbutton-like interface.  Adjusters also provide an
       auto-repeat capability.  Depressing and holding down any mouse button on an adjuster for a specified time
       causes it to repeatedly perform its operation.  The auto-repeat terminates when the button is released.

       Predefined subclasses of Adjuster include Zoomer and Mover.  Zoomers adjust  the  perspective's  curwidth
       and  curheight  members  to  suggest magnification.  The user clicks on a zoomer to magnify or reduce the
       contents of the interactor through its perspective.  The Enlarger zoomer subclass halves the  perspective
       values  while  the Reducer class doubles them.  Movers provide an incremental movement of the perspective
       in one of four directions; left, right, down, or up.  The user clicks on a mover to move the perspective.

PUBLIC OPERATIONS

       Adjuster(Interactor*, int = NO_AUTOREPEAT)
              Adjuster constructors take a pointer to the interactor whose perspective will be  adjusted  and  a
              delay (in tenths of a second) after which auto-repeat will begin once the adjuster is ``pressed''.

       virtual void Highlight()
       virtual void UnHighlight()
              These  functions  define  how  the  adjuster  draws  itself  when  it is pressed.  The adjuster is
              highlighted when it is pressed with  any  mouse  button  and  unhighlighted  when  the  button  is
              released.  The default is to invert the adjuster when highlighted.

PROTECTED OPERATIONS

       virtual void AdjustView(Event&)
              This  function  defines how the adjuster adjusts the interactor's perspective.  It is called after
              the adjuster is pressed and released, or repeatedly during auto-repeat.   Derived  classes  should
              redefine this function to implement the desired behavior.

DERIVED CLASSES

       Enlarger(Interactor*)
       Reducer(Interactor*)
              Enlargers  and  reducers adjust an interactor's perspective to enlarge and reduce the visible area
              by factors of one half and two, respectively.  This suggests to an interactor to enlarge or reduce
              its contents.  Auto-repeat is disabled on these adjusters.

       LeftMover(Interactor*, int delay = NO_AUTOREPEAT)
       RightMover(Interactor*, int delay = NO_AUTOREPEAT)
       DownMover(Interactor*, int delay = NO_AUTOREPEAT)
       UpMover(Interactor*, int delay = NO_AUTOREPEAT)
              These subclasses of Mover adjust the current origin of the interactor's perspective by  an  amount
              in  the  corresponding direction.  If the shift key is down while the mover is pressed, the amount
              corresponds to the perspective's lx or ly member variables; otherwise, the sx  or  sy  values  are
              used.

SEE ALSO

       Interactor(3I), Perspective(3I)

InterViews                                       15 January 1988                                    Adjuster(3I)