NAME

       Rubband - rubberbanding graphical objects

SYNOPSIS

       #include <InterViews/rubband.h>
       #include <InterViews/rubcurve.h>
       #include <InterViews/rubgroup.h>
       #include <InterViews/rubline.h>
       #include <InterViews/rubrect.h>
       #include <InterViews/rubverts.h>

DESCRIPTION

       Rubband  is  the  base  class  for  a  set of classes that provide graphical feedback to a user during an
       interactive operation such as sizing a rectangle.  A rubberband varies  in  appearance  as  its  tracking
       point changes.  A rubberband is not an interactor itself; interactors use rubberbands to provide animated
       effects.  Because rubberbands are not interactors, rubberband constructors must be passed the painter and
       canvas to use for drawing.

PUBLIC OPERATIONS

       RubberLine(
           Painter*, Canvas*, Coord fx, fy, mx, my, offx = 0, offy = 0
       )
              A rubber line stretches to follow the tracking point while its other endpoint stays tied down.

       RubberAxis(
           Painter*, Canvas*, Coord fx, fy, mx, my, offx = 0, offy = 0
       )
              A  rubber  axis stretches either horizontally or vertically to follow the tracking point while its
              other endpoint stays tied down.  One endpoint stays fixed while the other moves along  either  the
              horizontal or vertical axis, whichever is closer to the tracking point.

       SlidingLine(
           Painter*, Canvas*, Coord x0, y0, x1, y1, rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A  sliding  line  slides  around  without changing its length or angle as the tracking point moves
              around a reference point.

       RotatingLine(
           Painter*, Canvas*, Coord x0, y0, x1, y1, rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A rotating line rotates around (cx, cy) based on the angle between the  radius  from  (cx, cy)  to
              (rfx, rfy) and the radius from (cx, cy) to the tracking point.

       RubberRect(
           Painter*, Canvas*, Coord fx, fy, mx, my, offx = 0, offy = 0
       )
              A  rubber  rectangle  stretches  to  follow the tacking point while its opposite corner stays tied
              down.

       SlidingRect(
           Painter*, Canvas*, Coord x1, y1, x2, y2, rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A sliding rectangle slides around the screen without changing  its  side  or  orientation  as  the
              tracking point moves around a reference point.

       ScalingRect(
           Painter*, Canvas*, Coord x1, y1, x2, y2, cx, cy,
           Coord offx = 0, offy = 0
       )
              A scaling rectangle scales equally in both dimensions about (cx, cy) to keep one edge intersecting
              the tracking point.

       RotatingRect(
           Painter*, Canvas*, Coord x1, y1, x2, y2, cx, cy, rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A rotating rectangle rotates about (cx, cy) based on the radius from (cx, cy)  to  (rfx, rfy)  and
              the radius from (cx, cy) to the tracking point.

       StretchingRect(
           Painter*, Canvas*, Coord x1, y1, x2, y2, Side ts,
           Coord offx = 0, offy = 0
       )
              A  stretching  rectangle's  tracking side follows the tracking point while the opposite side stays
              fixed.  The side can be one of LeftSide, RightSide, BottomSide, or TopSide.

       RubberCircle(
           Painter*, Canvas*, Coord cx, cy, rx, ry, offx = 0, offy = 0
       )
              A rubber circle's radius varies with the magnitude of the tracking point's distance from (cx, cy).

       RubberEllipse(
           Painter*, Canvas*, Coord cx, cy, rx, ry, offx = 0, offy = 0
       )
              A rubber ellipse's horizontal and vertical radii vary with the magnitude of the  tracking  point's
              distance from (cx, cy).

       RubberSpline(
           Painter*, Canvas*, Coord x[], y[], int n, pt,
           Coord offx = 0, offy = 0
       )
       RubberClosedSpline(
           Painter*, Canvas*, Coord x[], y[], int n, pt,
           Coord offx = 0, offy = 0
       )
              A rubber spline is the section of a B-spline defined by n control points that changes shape as the
              control point indexed by pt is set to the tracking point.

       RubberHandles(
           Painter*, Canvas*, Coord x[], y[], int n, pt, size,
           Coord offx = 0, offy = 0
       )
              A rubber handles object is a set of filled squares centered about each point  in  the  list.   The
              point index by pt follows the tracking point.

       SlidingPointList(
           Painter*, Canvas*, Coord x[], y[], int n, pt, Coord rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A  sliding  point  list  slides  around the screen without changing its appearance as the tracking
              point moves around a reference point.

       SlidingLineList(
           Painter*, Canvas*, Coord x[], y[], int n, pt, Coord rfx, rfy,
           Coord offx = 0, offy = 0
       )
              A sliding line list slides around the screen without changing  the  appearance  of  its  connected
              lines as the tracking point moves around (rfx, rfy).

       ScalingLineList(
           Painer*, Canvas*, Coord x[], Coord y[], int n,
           Coord cx, cy, rfx, rfy, offx = 0, offy = 0
       )
              A  scaling  line  list  scales a list of lines about (cx, cy) to keep the line list's bounding box
              intersecting the tracking point.

       RotatingLineList(
           Painer*, Canvas*, Coord x[], Coord y[], int n,
           Coord cx, cy, rfx, rfy, offx = 0, offy = 0
       )
              A rotating line list rotates a list of lines about (cx, cy) based on the angle between the  radius
              from (cx, cy) to (rfx, rfy) and the radius from (cx, cy) to the tracking point.

       GrowingVertices(
           Painter*, Canvas*, Coord x[], y[], int n,
           int pt = -1, int handleSize = -1
       )
       GrowingMultiLine(
           Painter*, Canvas*, Coord x[], y[], int n,
           int pt = -1, int handleSize = -1
       )
       GrowingPolygon(
           Painter*, Canvas*, Coord x[], y[], int n,
           int pt = -1, int handleSize = -1
       )
       GrowingBSpline(
           Painter*, Canvas*, Coord x[], y[], int n,
           int pt = -1, int handleSize = -1
       )
       GrowingClosedBSpline(
           Painter*, Canvas*, Coord x[], y[], int n,
           int pt = -1, int handleSize = -1
       )
       virtual void AddVertex(Coord, Coord)
       virtual void RemoveVertex()
              GrowingVertices  is  an  abstract  rubberband  containing a list of vertices that grows or shrinks
              dynamically.  The pt parameter specifies the index of the vertex that  will  follow  the  tracking
              point;  a value of -1 specifies a vertex after the last one in the list.  The handleSize parameter
              specifies the size of the handle drawn at each vertex (as in RubberHandles above); a value  of  -1
              specifies that no handles be drawn.

              The AddVertex operation adds a new vertex at the tracking point to the list and makes the next (or
              last) vertex in the list follow the tracking  point.   RemoveVertex  removes  the  vertex  at  the
              tracking point and makes the previous (or first) vertex the new tracking point.  GrowingMultiLine,
              GrowingPolygon, GrowingBSpline, and GrowingClosedBSpline are GrowingVertices subclasses that  draw
              a multiline, polygon, B-spline, and closed B-spline, respectively.

       RubberGroup(Painter*, Canvas*)
       void Append(
           Rubberband*, Rubberband* = nil, Rubberband* = nil,
           Rubberband* = nil
       )
       void Remove(Rubberband*)
       void RemoveCur()
       void SetCurrent(Rubberband*)
       Rubberband* GetCurrent()
       Rubberband* First()
       Rubberband* Last()
       Rubberband* Next()
       Rubberband* Prev()
       boolean IsEmpty()
       boolean AtEnd()
              A  RubberGroup  composes  other  rubberbands,  providing  operations for including, excluding, and
              traversing its children. RubberGroups are useful for combining the behavior of several rubberbands
              into  one, eliminating the need to call Track on multiple rubberbands. The RubberGroup's SetCanvas
              and SetPainter operations set the children's canvas and painter as well as the RubberGroup's,  but
              the  children  do not otherwise inherit the group's canvas and painter.  The Track operation calls
              Track on each child with the same parameters.

       virtual void Draw()
       void Redraw()
       virtual void Erase()
              Explicitly draw, redraw, and erase the rubberband.  Multiple calls to Draw without an  intervening
              Erase  will  only  draw  the  rubberband  once.   Redraw forces the rubberband to be drawn.  Since
              rubberbands are drawn in XOR mode, Redraw will erase the rubberband every other time it is called.
              These  functions are used only on occasion, for example, when part of the screen is erased while a
              rubberband is visible.  The Track function is normally used to draw the rubberband in response  to
              mouse input.

       virtual void Track(Coord x, Coord y)
              Erase the rubberband and redraw it using the new tracking point.

       void GetOriginal(Coord& x1, Coord& y2, Coord& x2, Coord& y2)
       void GetCurrent(Coord& x1, Coord& y2, Coord& x2, Coord& y2)
              GetOriginal  obtains  the  original  points  specified for the rubberband.  GetCurrent obtains the
              current points based on the most recent call to Track.  The meaning of the points depends  on  the
              kind  of  rubberband.   For  lines,  the  points are the endpoints; for rectangles, the points are
              opposite corners; for curves, (x1, y1) is the center and x2 and y2 are the radii.

       virtual void SetPainter(Painter*)
       Painter* GetPainter()
              Explicitly set and get the painter used by the rubberband.  By default, rubberbands use a copy  of
              the  painter  passed  to  their  constructor.  The user can specify a particular painter to use by
              passing a nil painter to the constructor and later calling SetPainter.  N.B.: the  rubberband  may
              alter the painter specified via SetPainter.

       virtual void SetCanvas(Canvas*)
       Canvas* GetCanvas()
              Explicitly set and get the canvas used by the rubberband.

SEE ALSO

       Canvas(3I), Painter(3I)