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sp-star.cpp

#define __SP_STAR_C__

/*
 * <sodipodi:star> implementation
 *
 * Authors:
 *   Mitsuru Oka <oka326@parkcity.ne.jp>
 *   Lauris Kaplinski <lauris@kaplinski.com>
 *
 * Copyright (C) 1999-2002 Lauris Kaplinski
 * Copyright (C) 2000-2001 Ximian, Inc.
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "config.h"

#include <math.h>
#include <string.h>
#include <stdlib.h>

#include "svg/svg.h"
#include "attributes.h"
#include "desktop.h"
#include "desktop-affine.h"
#include "dialogs/object-attributes.h"
#include "display/curve.h"
#include <glibmm/i18n.h>
#include "xml/repr.h"
#include "libnr/nr-point.h"
#include "libnr/nr-point-fns.h"
#include "libnr/nr-point-ops.h"
#include "libnr/nr-matrix-ops.h"
#include "libnr/nr-point-l.h"

#include "sp-star.h"

static void sp_star_class_init (SPStarClass *klass);
static void sp_star_init (SPStar *star);

static void sp_star_build (SPObject * object, SPDocument * document, SPRepr * repr);
static SPRepr *sp_star_write (SPObject *object, SPRepr *repr, guint flags);
static void sp_star_set (SPObject *object, unsigned int key, const gchar *value);
static void sp_star_update (SPObject *object, SPCtx *ctx, guint flags);

static gchar * sp_star_description (SPItem * item);
static void sp_star_snappoints(SPItem const *item, SnapPointsIter p);

static void sp_star_set_shape (SPShape *shape);

static SPShapeClass *parent_class;

GType
sp_star_get_type (void)
{
      static GType type = 0;

      if (!type) {
            GTypeInfo info = {
                  sizeof (SPStarClass),
                  NULL, NULL,
                  (GClassInitFunc) sp_star_class_init,
                  NULL, NULL,
                  sizeof (SPStar),
                  16,
                  (GInstanceInitFunc) sp_star_init,
                  NULL, /* value_table */
            };
            type = g_type_register_static (SP_TYPE_SHAPE, "SPStar", &info, (GTypeFlags)0);
      }
      return type;
}

static void
sp_star_class_init (SPStarClass *klass)
{
      GObjectClass * gobject_class;
      SPObjectClass * sp_object_class;
      SPItemClass * item_class;
      SPPathClass * path_class;
      SPShapeClass * shape_class;

      gobject_class = (GObjectClass *) klass;
      sp_object_class = (SPObjectClass *) klass;
      item_class = (SPItemClass *) klass;
      path_class = (SPPathClass *) klass;
      shape_class = (SPShapeClass *) klass;

      parent_class = (SPShapeClass *)g_type_class_ref (SP_TYPE_SHAPE);

      sp_object_class->build = sp_star_build;
      sp_object_class->write = sp_star_write;
      sp_object_class->set = sp_star_set;
      sp_object_class->update = sp_star_update;

      item_class->description = sp_star_description;
      item_class->snappoints = sp_star_snappoints;

      shape_class->set_shape = sp_star_set_shape;
}

static void
sp_star_init (SPStar * star)
{
      star->sides = 5;
      star->center = NR::Point(0, 0);
      star->r[0] = 1.0;
      star->r[1] = 0.001;
      star->arg[0] = star->arg[1] = 0.0;
      star->flatsided = 0;
      star->rounded = 0.0;
      star->randomized = 0.0;
}

static void
sp_star_build (SPObject * object, SPDocument * document, SPRepr * repr)
{
      if (((SPObjectClass *) parent_class)->build)
            ((SPObjectClass *) parent_class)->build (object, document, repr);

      sp_object_read_attr (object, "sodipodi:cx");
      sp_object_read_attr (object, "sodipodi:cy");
      sp_object_read_attr (object, "sodipodi:sides");
      sp_object_read_attr (object, "sodipodi:r1");
      sp_object_read_attr (object, "sodipodi:r2");
      sp_object_read_attr (object, "sodipodi:arg1");
      sp_object_read_attr (object, "sodipodi:arg2");
      sp_object_read_attr (object, "inkscape:flatsided");
      sp_object_read_attr (object, "inkscape:rounded");
      sp_object_read_attr (object, "inkscape:randomized");
}

static SPRepr *
sp_star_write (SPObject *object, SPRepr *repr, guint flags)
{
      SPStar *star = SP_STAR (object);

      if ((flags & SP_OBJECT_WRITE_BUILD) && !repr) {
            repr = sp_repr_new ("svg:path");
      }

      if (flags & SP_OBJECT_WRITE_EXT) {
            sp_repr_set_attr (repr, "sodipodi:type", "star");
            sp_repr_set_int (repr, "sodipodi:sides", star->sides);
            sp_repr_set_double (repr, "sodipodi:cx", star->center[NR::X]);
            sp_repr_set_double (repr, "sodipodi:cy", star->center[NR::Y]);
            sp_repr_set_double (repr, "sodipodi:r1", star->r[0]);
            sp_repr_set_double (repr, "sodipodi:r2", star->r[1]);
            sp_repr_set_double (repr, "sodipodi:arg1", star->arg[0]);
            sp_repr_set_double (repr, "sodipodi:arg2", star->arg[1]);
            sp_repr_set_boolean (repr, "inkscape:flatsided", star->flatsided);
            sp_repr_set_double (repr, "inkscape:rounded", star->rounded);
            sp_repr_set_double (repr, "inkscape:randomized", star->randomized);
      }

      sp_star_set_shape ((SPShape *) star);
      char *d = sp_svg_write_path (((SPShape *) star)->curve->bpath);
      sp_repr_set_attr (repr, "d", d);
      g_free (d);

      if (((SPObjectClass *) (parent_class))->write)
            ((SPObjectClass *) (parent_class))->write (object, repr, flags);

      return repr;
}

static void
sp_star_set (SPObject *object, unsigned int key, const gchar *value)
{
      SPSVGLengthUnit unit;

      SPStar *star = SP_STAR (object);

      /* fixme: we should really collect updates */
      switch (key) {
      case SP_ATTR_SODIPODI_SIDES:
            if (value) {
                  star->sides = atoi (value);
                  star->sides = CLAMP (star->sides, 3, 1024);
            } else {
                  star->sides = 5;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_SODIPODI_CX:
            if (!sp_svg_length_read_ldd (value, &unit, NULL, &star->center[NR::X]) ||
                (unit == SP_SVG_UNIT_EM) ||
                (unit == SP_SVG_UNIT_EX) ||
                (unit == SP_SVG_UNIT_PERCENT)) {
                  star->center[NR::X] = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_SODIPODI_CY:
            if (!sp_svg_length_read_ldd (value, &unit, NULL, &star->center[NR::Y]) ||
                (unit == SP_SVG_UNIT_EM) ||
                (unit == SP_SVG_UNIT_EX) ||
                (unit == SP_SVG_UNIT_PERCENT)) {
                  star->center[NR::Y] = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_SODIPODI_R1:
            if (!sp_svg_length_read_ldd (value, &unit, NULL, &star->r[0]) ||
                (unit == SP_SVG_UNIT_EM) ||
                (unit == SP_SVG_UNIT_EX) ||
                (unit == SP_SVG_UNIT_PERCENT)) {
                  star->r[0] = 1.0;
            }
            /* fixme: Need CLAMP (Lauris) */
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_SODIPODI_R2:
            if (!sp_svg_length_read_ldd (value, &unit, NULL, &star->r[1]) ||
                (unit == SP_SVG_UNIT_EM) ||
                (unit == SP_SVG_UNIT_EX) ||
                (unit == SP_SVG_UNIT_PERCENT)) {
                  star->r[1] = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            return;
      case SP_ATTR_SODIPODI_ARG1:
            if (value) {
                  star->arg[0] = g_ascii_strtod (value, NULL);
            } else {
                  star->arg[0] = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_SODIPODI_ARG2:
            if (value) {
                  star->arg[1] = g_ascii_strtod (value, NULL);
            } else {
                  star->arg[1] = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_INKSCAPE_FLATSIDED:
            if (value && !strcmp (value, "true"))
                  star->flatsided = true;
            else star->flatsided = false;
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_INKSCAPE_ROUNDED:
            if (value) {
                  star->rounded = g_ascii_strtod (value, NULL);
            } else {
                  star->rounded = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      case SP_ATTR_INKSCAPE_RANDOMIZED:
            if (value) {
                  star->randomized = g_ascii_strtod (value, NULL);
            } else {
                  star->randomized = 0.0;
            }
            object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
            break;
      default:
            if (((SPObjectClass *) parent_class)->set)
                  ((SPObjectClass *) parent_class)->set (object, key, value);
            break;
      }
}

static void
sp_star_update (SPObject *object, SPCtx *ctx, guint flags)
{
      if (flags & (SP_OBJECT_MODIFIED_FLAG | 
                 SP_OBJECT_STYLE_MODIFIED_FLAG | 
                 SP_OBJECT_VIEWPORT_MODIFIED_FLAG)) {
            sp_shape_set_shape ((SPShape *) object);
      }

      if (((SPObjectClass *) parent_class)->update)
            ((SPObjectClass *) parent_class)->update (object, ctx, flags);
}

static gchar *
sp_star_description (SPItem *item)
{
    SPStar *star = SP_STAR (item);

    // while there will never be less than 3 vertices, we still need to
    // make calls to ngettext because the pluralization may be different
    // for various numbers >=3.  The singular form is used as the index.
    if (star->flatsided == false )
      return g_strdup_printf (ngettext("<b>Star</b> with %d vertex",
                                 "<b>Star</b> with %d vertices",
                               star->sides), star->sides);
    else
        return g_strdup_printf (ngettext("<b>Polygon</b> with %d vertex",
                                 "<b>Polygon</b> with %d vertices",
                               star->sides), star->sides);
}

/**
Returns a unit-length vector at 90 degrees to the direction from o to n
 */
static NR::Point
rot90_rel (NR::Point o, NR::Point n)
{
      return ((1/NR::L2(n - o)) * NR::Point ((n - o)[NR::Y],  (o - n)[NR::X]));
}

/**
Returns a unique 32 bit int for a given point.
Obvious (but acceptable for my purposes) limits to uniqueness:
- returned value for x,y repeats for x+n*1024,y+n*1024
- returned value is unchanged when the point is moved by less than 1/1024 of px
*/
static guint32
point_unique_int (NR::Point o)
{
      return ((guint32) 
      65536 * 
            (((int) floor (o[NR::X] * 64)) % 1024 + ((int) floor (o[NR::X] * 1024)) % 64) 
      +
            (((int) floor (o[NR::Y] * 64)) % 1024 + ((int) floor (o[NR::Y] * 1024)) % 64)
      );
}

/**
Returns the next pseudorandom value using the Linear Congruential Generator algorithm (LCG)
with the parameters (m = 2^32, a = 69069, b = 1). These parameters give a full-period generator,
i.e. it is guaranteed to go through all integers < 2^32 (see http://random.mat.sbg.ac.at/~charly/server/server.html)
*/
static inline guint32
lcg_next(guint32 const prev)
{
      return (guint32) ( 69069 * prev + 1 );
}

/**
Returns a random number in the range [-0.5, 0.5) from the given seed, stepping the given number of steps from the seed.
*/
static double
rnd (guint32 const seed, unsigned steps) {
      guint32 lcg = seed;
      for (; steps > 0; steps --)
            lcg = lcg_next (lcg);

      return ( lcg / 4294967296. ) - 0.5;
}

static NR::Point
sp_star_get_curvepoint (SPStar *star, SPStarPoint point, gint index, bool previ)
{
      // the point whose neighboring curve handle we're calculating
      NR::Point o = sp_star_get_xy (star, point, index);

      // indices of previous and next points
      gint pi = (index > 0)? (index - 1) : (star->sides - 1);
      gint ni = (index < star->sides - 1)? (index + 1) : 0;

      // the other point type
      SPStarPoint other = (point == SP_STAR_POINT_KNOT2? SP_STAR_POINT_KNOT1 : SP_STAR_POINT_KNOT2);

      // the neighbors of o; depending on flatsided, they're either the same type (polygon) or the other type (star)
      NR::Point prev = (star->flatsided? sp_star_get_xy (star, point, pi) : sp_star_get_xy (star, other, point == SP_STAR_POINT_KNOT2? index : pi));
      NR::Point next = (star->flatsided? sp_star_get_xy (star, point, ni) : sp_star_get_xy (star, other, point == SP_STAR_POINT_KNOT1? index : ni));

      // prev-next midpoint
      NR::Point mid =  0.5 * (prev + next);

      // point to which we direct the bissector of the curve handles;
      // it's far enough outside the star on the perpendicular to prev-next through mid
      NR::Point biss =  mid + 100000 * rot90_rel (mid, next); 

      // lengths of vectors to prev and next
      gdouble prev_len = NR::L2 (prev - o);
      gdouble next_len = NR::L2 (next - o);

      // unit-length vector perpendicular to o-biss
      NR::Point rot = rot90_rel (o, biss);

      // multiply rot by star->rounded coefficient and the distance to the star point; flip for next
      NR::Point ret;
      if (previ) {
            ret = (star->rounded * prev_len) * rot;
      } else {
            ret = (star->rounded * next_len * -1) * rot;
      }

      if (star->randomized == 0) {
            // add the vector to o to get the final curvepoint
            return o + ret;
      } else {
            // the seed corresponding to the exact point
            guint32 seed = point_unique_int (o);

            // randomly rotate (by step 3 from the seed) and scale (by step 4) the vector
            ret = ret * NR::Matrix (NR::rotate (star->randomized * M_PI * rnd (seed, 3)));
            ret *= ( 1 + star->randomized * rnd (seed, 4));

            // the randomized corner point
            NR::Point o_randomized = sp_star_get_xy (star, point, index, true);

            return o_randomized + ret;
      }
}


#define NEXT false
#define PREV true

static void
sp_star_set_shape (SPShape *shape)
{
      SPStar *star = SP_STAR (shape);

      SPCurve *c = sp_curve_new ();
      
      gint sides = star->sides;
      bool not_rounded = (fabs (star->rounded) < 1e-4);

      // note that we pass randomized=true to sp_star_get_xy, because the curve must be randomized;
      // other places that call that function (e.g. the knotholder) need the exact point

      // draw 1st segment
      sp_curve_moveto (c, sp_star_get_xy (star, SP_STAR_POINT_KNOT1, 0, true));
      if (star->flatsided == false) {
            if (not_rounded) {
                  sp_curve_lineto (c, sp_star_get_xy (star, SP_STAR_POINT_KNOT2, 0, true));
            } else {
                  sp_curve_curveto (c, 
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, 0, NEXT),
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT2, 0, PREV),
                        sp_star_get_xy (star, SP_STAR_POINT_KNOT2, 0, true));
            }
      }

      // draw all middle segments
      for (gint i = 1; i < sides; i++) {
            if (not_rounded) {
                  sp_curve_lineto (c, sp_star_get_xy (star, SP_STAR_POINT_KNOT1, i, true));
            } else {
                  if (star->flatsided == false) {
                        sp_curve_curveto (c, 
                                    sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT2, i - 1, NEXT),
                                    sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, i, PREV),
                                    sp_star_get_xy (star, SP_STAR_POINT_KNOT1, i, true));
                  } else {
                        sp_curve_curveto (c, 
                                    sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, i - 1, NEXT),
                                    sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, i, PREV),
                                    sp_star_get_xy (star, SP_STAR_POINT_KNOT1, i, true));
                  }
            }
            if (star->flatsided == false) {

                  if (not_rounded) {
                       sp_curve_lineto (c, sp_star_get_xy (star, SP_STAR_POINT_KNOT2, i, true));
                  } else {
                        sp_curve_curveto (c,
                              sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, i, NEXT),
                              sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT2, i, PREV),
                              sp_star_get_xy (star, SP_STAR_POINT_KNOT2, i, true));
                  }
            }
      }
      
      // draw last segment
            if (not_rounded) {
                  sp_curve_lineto (c, sp_star_get_xy (star, SP_STAR_POINT_KNOT1, 0, true));
            } else {
                  if (star->flatsided == false) {
                  sp_curve_curveto (c, 
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT2, sides - 1, NEXT),
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, 0, PREV),
                        sp_star_get_xy (star, SP_STAR_POINT_KNOT1, 0, true));
                  } else {
                  sp_curve_curveto (c, 
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, sides - 1, NEXT),
                        sp_star_get_curvepoint (star, SP_STAR_POINT_KNOT1, 0, PREV),
                        sp_star_get_xy (star, SP_STAR_POINT_KNOT1, 0, true));
                  }
            }

      sp_curve_closepath (c);
      sp_shape_set_curve_insync (SP_SHAPE (star), c, TRUE);
      sp_curve_unref (c);
}

void
sp_star_position_set (SPStar *star, gint sides, NR::Point center, gdouble r1, gdouble r2, gdouble arg1, gdouble arg2, bool isflat, double rounded, double randomized)
{
      g_return_if_fail (star != NULL);
      g_return_if_fail (SP_IS_STAR (star));
      
      star->sides = CLAMP (sides, 3, 1024);
      star->center = center;
      star->r[0] = MAX (r1, 0.001);
      if (isflat == false) {
            star->r[1] = CLAMP (r2, 0.0, star->r[0]);
      } else {
            star->r[1] = CLAMP ( r1*cos(M_PI/sides) ,0.0, star->r[0] );
      }
      star->arg[0] = arg1;
      star->arg[1] = arg2;
      star->flatsided = isflat;
      star->rounded = rounded;
      star->randomized = randomized;
      SP_OBJECT(star)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
}

/* fixme: We should use all corners of star (Lauris) */

static void sp_star_snappoints(SPItem const *item, SnapPointsIter p)
{
      if (((SPItemClass *) parent_class)->snappoints) {
            ((SPItemClass *) parent_class)->snappoints (item, p);
      }
}

/**
 * sp_star_get_xy: Get X-Y value as item coordinate system
 * @star: star item
 * @point: point type to obtain X-Y value
 * @index: index of vertex
 * @p: pointer to store X-Y value
 * @randomized: false (default) if you want to get exact, not randomized point
 *
 * Initial item coordinate system is same as document coordinate system.
 */

NR::Point
sp_star_get_xy (SPStar *star, SPStarPoint point, gint index, bool randomized)
{
      gdouble darg = 2.0 * M_PI / (double) star->sides;

      double arg = star->arg[point];
      arg += index * darg;

      NR::Point xy = star->r[point] * NR::Point(cos(arg), sin(arg)) + star->center;

      if (!randomized || star->randomized == 0) {
            // return the exact point
            return xy;
      } else { // randomize the point
            // find out the seed, unique for this point so that randomization is the same so long as the original point is stationary
            guint32 seed = point_unique_int (xy);
            // the full range (corresponding to star->randomized == 1.0) is equal to the star's diameter
            double range = 2 * MAX (star->r[0], star->r[1]);
            // find out the random displacement; x is controlled by step 1 from the seed, y by the step 2
            NR::Point shift (star->randomized * range * rnd (seed, 1), star->randomized * range * rnd (seed, 2));
            // add the shift to the exact point
            return xy + shift;
      }
}


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