NAME

       Grid - displays a grid in a viewer and constrains points to lie on it

SYNOPSIS

       #include <Unidraw/grid.h>

DESCRIPTION

       The  Grid  object  performs  two  functions:  it  displays  a grid in a viewer, and it can
       constrain points to lie on the grid.  The base class draws the grid as a simple  array  of
       dots; subclasses can draw arbitrarily complex grids.

PUBLIC OPERATIONS

       Grid(float w, float h, float xincr, float yincr)
              The  constructor  parameters correspond to a width, a height, and independent units
              of graduation for the horizontal and vertical axes, all in pixels.  The  Grid  base
              class  employs  a special-purpose graphic to render itself, one that draws an array
              of dots based on the information supplied in this constructor.

       virtual Graphic* GetGraphic()
              Return the graphic used to render the grid.

       virtual void Constrain(Coord&, Coord&)
              Constrain the given coordinate pair to fall on the grid.  The pair  is  changed  to
              fall on the nearest grid point by default.

       virtual void Visiblity(boolean)
              Make the grid visible (specify true) or invisible (specify false).

       virtual boolean IsVisible()
              Return whether the grid is visible or not.

       virtual void SetSpacing(float xincr, float yincr)
              Reset the grid's units of graduation.

PROTECTED OPERATIONS

       Grid(Graphic*)
              The  protected  constructor  allows  subclasses to specify an arbitrary graphic for
              rendering the grid.  Subclasses that use this constructor must  also  redefine  the
              Constrain operation.

SEE ALSO

       Graphic(3U), Viewer(3U)