Adjuster(3I)

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)

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