1 #define __SP_SPIRAL_C__
3 /** \file
4 * <sodipodi:spiral> implementation
5 */
6 /*
7 * Authors:
8 * Mitsuru Oka <oka326@parkcity.ne.jp>
9 * Lauris Kaplinski <lauris@kaplinski.com>
10 *
11 * Copyright (C) 1999-2002 Lauris Kaplinski
12 * Copyright (C) 2000-2001 Ximian, Inc.
13 *
14 * Released under GNU GPL, read the file 'COPYING' for more information
15 */
17 #include "config.h"
20 #include "svg/svg.h"
21 #include "attributes.h"
22 #include "display/bezier-utils.h"
23 #include "display/curve.h"
24 #include <glibmm/i18n.h>
25 #include "xml/repr.h"
26 #include "document.h"
28 #include "sp-spiral.h"
30 static void sp_spiral_class_init (SPSpiralClass *klass);
31 static void sp_spiral_init (SPSpiral *spiral);
33 static void sp_spiral_build (SPObject * object, SPDocument * document, Inkscape::XML::Node * repr);
34 static Inkscape::XML::Node *sp_spiral_write (SPObject *object, Inkscape::XML::Node *repr, guint flags);
35 static void sp_spiral_set (SPObject *object, unsigned int key, const gchar *value);
36 static void sp_spiral_update (SPObject *object, SPCtx *ctx, guint flags);
38 static gchar * sp_spiral_description (SPItem * item);
39 static void sp_spiral_snappoints(SPItem const *item, SnapPointsIter p);
41 static void sp_spiral_set_shape (SPShape *shape);
42 static void sp_spiral_update_patheffect (SPLPEItem *lpeitem, bool write);
44 static NR::Point sp_spiral_get_tangent (SPSpiral const *spiral, gdouble t);
46 static SPShapeClass *parent_class;
48 /**
49 * Register SPSpiral class and return its type number.
50 */
51 GType
52 sp_spiral_get_type (void)
53 {
54 static GType spiral_type = 0;
56 if (!spiral_type) {
57 GTypeInfo spiral_info = {
58 sizeof (SPSpiralClass),
59 NULL, /* base_init */
60 NULL, /* base_finalize */
61 (GClassInitFunc) sp_spiral_class_init,
62 NULL, /* class_finalize */
63 NULL, /* class_data */
64 sizeof (SPSpiral),
65 16, /* n_preallocs */
66 (GInstanceInitFunc) sp_spiral_init,
67 NULL, /* value_table */
68 };
69 spiral_type = g_type_register_static (SP_TYPE_SHAPE, "SPSpiral", &spiral_info, (GTypeFlags)0);
70 }
71 return spiral_type;
72 }
74 /**
75 * SPSpiral vtable initialization.
76 */
77 static void
78 sp_spiral_class_init (SPSpiralClass *klass)
79 {
80 GObjectClass * gobject_class;
81 SPObjectClass * sp_object_class;
82 SPItemClass * item_class;
83 SPLPEItemClass * lpe_item_class;
84 SPShapeClass *shape_class;
86 gobject_class = (GObjectClass *) klass;
87 sp_object_class = (SPObjectClass *) klass;
88 item_class = (SPItemClass *) klass;
89 lpe_item_class = (SPLPEItemClass *) klass;
90 shape_class = (SPShapeClass *) klass;
92 parent_class = (SPShapeClass *)g_type_class_ref (SP_TYPE_SHAPE);
94 sp_object_class->build = sp_spiral_build;
95 sp_object_class->write = sp_spiral_write;
96 sp_object_class->set = sp_spiral_set;
97 sp_object_class->update = sp_spiral_update;
99 item_class->description = sp_spiral_description;
100 item_class->snappoints = sp_spiral_snappoints;
102 lpe_item_class->update_patheffect = sp_spiral_update_patheffect;
104 shape_class->set_shape = sp_spiral_set_shape;
105 }
107 /**
108 * Callback for SPSpiral object initialization.
109 */
110 static void
111 sp_spiral_init (SPSpiral * spiral)
112 {
113 spiral->cx = 0.0;
114 spiral->cy = 0.0;
115 spiral->exp = 1.0;
116 spiral->revo = 3.0;
117 spiral->rad = 1.0;
118 spiral->arg = 0.0;
119 spiral->t0 = 0.0;
120 }
122 /**
123 * Virtual build: set spiral properties from corresponding repr.
124 */
125 static void
126 sp_spiral_build (SPObject * object, SPDocument * document, Inkscape::XML::Node * repr)
127 {
128 if (((SPObjectClass *) parent_class)->build)
129 ((SPObjectClass *) parent_class)->build (object, document, repr);
131 sp_object_read_attr (object, "sodipodi:cx");
132 sp_object_read_attr (object, "sodipodi:cy");
133 sp_object_read_attr (object, "sodipodi:expansion");
134 sp_object_read_attr (object, "sodipodi:revolution");
135 sp_object_read_attr (object, "sodipodi:radius");
136 sp_object_read_attr (object, "sodipodi:argument");
137 sp_object_read_attr (object, "sodipodi:t0");
138 }
140 /**
141 * Virtual write: write spiral attributes to corresponding repr.
142 */
143 static Inkscape::XML::Node *
144 sp_spiral_write (SPObject *object, Inkscape::XML::Node *repr, guint flags)
145 {
146 SPSpiral *spiral = SP_SPIRAL (object);
148 if ((flags & SP_OBJECT_WRITE_BUILD) && !repr) {
149 Inkscape::XML::Document *xml_doc = sp_document_repr_doc(SP_OBJECT_DOCUMENT(object));
150 repr = xml_doc->createElement("svg:path");
151 }
153 if (flags & SP_OBJECT_WRITE_EXT) {
154 /* Fixme: we may replace these attributes by
155 * sodipodi:spiral="cx cy exp revo rad arg t0"
156 */
157 repr->setAttribute("sodipodi:type", "spiral");
158 sp_repr_set_svg_double(repr, "sodipodi:cx", spiral->cx);
159 sp_repr_set_svg_double(repr, "sodipodi:cy", spiral->cy);
160 sp_repr_set_svg_double(repr, "sodipodi:expansion", spiral->exp);
161 sp_repr_set_svg_double(repr, "sodipodi:revolution", spiral->revo);
162 sp_repr_set_svg_double(repr, "sodipodi:radius", spiral->rad);
163 sp_repr_set_svg_double(repr, "sodipodi:argument", spiral->arg);
164 sp_repr_set_svg_double(repr, "sodipodi:t0", spiral->t0);
165 }
167 // make sure the curve is rebuilt with all up-to-date parameters
168 sp_spiral_set_shape ((SPShape *) spiral);
170 //Duplicate the path
171 SPCurve *curve = ((SPShape *) spiral)->curve;
172 //Nulls might be possible if this called iteratively
173 if ( !curve ) {
174 //g_warning("sp_spiral_write(): No path to copy\n");
175 return NULL;
176 }
177 NArtBpath const *bpath = SP_CURVE_BPATH(curve);
178 if ( !bpath ) {
179 //g_warning("sp_spiral_write(): No path to copy\n");
180 return NULL;
181 }
182 char *d = sp_svg_write_path ( bpath );
183 repr->setAttribute("d", d);
184 g_free (d);
186 if (((SPObjectClass *) (parent_class))->write)
187 ((SPObjectClass *) (parent_class))->write (object, repr, flags | SP_SHAPE_WRITE_PATH);
189 return repr;
190 }
192 /**
193 * Virtual set: change spiral object attribute.
194 */
195 static void
196 sp_spiral_set (SPObject *object, unsigned int key, const gchar *value)
197 {
198 SPSpiral *spiral;
199 SPShape *shape;
201 spiral = SP_SPIRAL (object);
202 shape = SP_SHAPE (object);
204 /// \todo fixme: we should really collect updates
205 switch (key) {
206 case SP_ATTR_SODIPODI_CX:
207 if (!sp_svg_length_read_computed_absolute (value, &spiral->cx)) {
208 spiral->cx = 0.0;
209 }
210 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
211 break;
212 case SP_ATTR_SODIPODI_CY:
213 if (!sp_svg_length_read_computed_absolute (value, &spiral->cy)) {
214 spiral->cy = 0.0;
215 }
216 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
217 break;
218 case SP_ATTR_SODIPODI_EXPANSION:
219 if (value) {
220 /** \todo
221 * FIXME: check that value looks like a (finite)
222 * number. Create a routine that uses strtod, and
223 * accepts a default value (if strtod finds an error).
224 * N.B. atof/sscanf/strtod consider "nan" and "inf"
225 * to be valid numbers.
226 */
227 spiral->exp = g_ascii_strtod (value, NULL);
228 spiral->exp = CLAMP (spiral->exp, 0.0, 1000.0);
229 } else {
230 spiral->exp = 1.0;
231 }
232 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
233 break;
234 case SP_ATTR_SODIPODI_REVOLUTION:
235 if (value) {
236 spiral->revo = g_ascii_strtod (value, NULL);
237 spiral->revo = CLAMP (spiral->revo, 0.05, 1024.0);
238 } else {
239 spiral->revo = 3.0;
240 }
241 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
242 break;
243 case SP_ATTR_SODIPODI_RADIUS:
244 if (!sp_svg_length_read_computed_absolute (value, &spiral->rad)) {
245 spiral->rad = MAX (spiral->rad, 0.001);
246 }
247 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
248 break;
249 case SP_ATTR_SODIPODI_ARGUMENT:
250 if (value) {
251 spiral->arg = g_ascii_strtod (value, NULL);
252 /** \todo
253 * FIXME: We still need some bounds on arg, for
254 * numerical reasons. E.g., we don't want inf or NaN,
255 * nor near-infinite numbers. I'm inclined to take
256 * modulo 2*pi. If so, then change the knot editors,
257 * which use atan2 - revo*2*pi, which typically
258 * results in very negative arg.
259 */
260 } else {
261 spiral->arg = 0.0;
262 }
263 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
264 break;
265 case SP_ATTR_SODIPODI_T0:
266 if (value) {
267 spiral->t0 = g_ascii_strtod (value, NULL);
268 spiral->t0 = CLAMP (spiral->t0, 0.0, 0.999);
269 /** \todo
270 * Have shared constants for the allowable bounds for
271 * attributes. There was a bug here where we used -1.0
272 * as the minimum (which leads to NaN via, e.g.,
273 * pow(-1.0, 0.5); see sp_spiral_get_xy for
274 * requirements.
275 */
276 } else {
277 spiral->t0 = 0.0;
278 }
279 object->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
280 break;
281 default:
282 if (((SPObjectClass *) parent_class)->set)
283 ((SPObjectClass *) parent_class)->set (object, key, value);
284 break;
285 }
286 }
288 /**
289 * Virtual update callback.
290 */
291 static void
292 sp_spiral_update (SPObject *object, SPCtx *ctx, guint flags)
293 {
294 if (flags & (SP_OBJECT_MODIFIED_FLAG | SP_OBJECT_STYLE_MODIFIED_FLAG | SP_OBJECT_VIEWPORT_MODIFIED_FLAG)) {
295 sp_shape_set_shape ((SPShape *) object);
296 }
298 if (((SPObjectClass *) parent_class)->update)
299 ((SPObjectClass *) parent_class)->update (object, ctx, flags);
300 }
302 static void
303 sp_spiral_update_patheffect(SPLPEItem *lpeitem, bool write)
304 {
305 SPShape *shape = (SPShape *) lpeitem;
306 sp_spiral_set_shape(shape);
308 if (write) {
309 Inkscape::XML::Node *repr = SP_OBJECT_REPR(shape);
310 if ( shape->curve != NULL ) {
311 NArtBpath *abp = shape->curve->first_bpath();
312 if (abp) {
313 gchar *str = sp_svg_write_path(abp);
314 repr->setAttribute("d", str);
315 g_free(str);
316 } else {
317 repr->setAttribute("d", "");
318 }
319 } else {
320 repr->setAttribute("d", NULL);
321 }
322 }
324 ((SPObject *)shape)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
325 }
327 /**
328 * Return textual description of spiral.
329 */
330 static gchar *
331 sp_spiral_description (SPItem * item)
332 {
333 // TRANSLATORS: since turn count isn't an integer, please adjust the
334 // string as needed to deal with an localized plural forms.
335 return g_strdup_printf (_("<b>Spiral</b> with %3f turns"), SP_SPIRAL(item)->revo);
336 }
339 /**
340 * Fit beziers together to spiral and draw it.
341 *
342 * \pre dstep \> 0.
343 * \pre is_unit_vector(*hat1).
344 * \post is_unit_vector(*hat2).
345 **/
346 static void
347 sp_spiral_fit_and_draw (SPSpiral const *spiral,
348 SPCurve *c,
349 double dstep,
350 NR::Point darray[],
351 NR::Point const &hat1,
352 NR::Point &hat2,
353 double *t)
354 {
355 #define BEZIER_SIZE 4
356 #define FITTING_MAX_BEZIERS 4
357 #define BEZIER_LENGTH (BEZIER_SIZE * FITTING_MAX_BEZIERS)
358 g_assert (dstep > 0);
359 g_assert (is_unit_vector (hat1));
361 NR::Point bezier[BEZIER_LENGTH];
362 double d;
363 int depth, i;
365 for (d = *t, i = 0; i <= SAMPLE_SIZE; d += dstep, i++) {
366 darray[i] = sp_spiral_get_xy(spiral, d);
368 /* Avoid useless adjacent dups. (Otherwise we can have all of darray filled with
369 the same value, which upsets chord_length_parameterize.) */
370 if ((i != 0)
371 && (darray[i] == darray[i - 1])
372 && (d < 1.0)) {
373 i--;
374 d += dstep;
375 /** We mustn't increase dstep for subsequent values of
376 * i: for large spiral.exp values, rate of growth
377 * increases very rapidly.
378 */
379 /** \todo
380 * Get the function itself to decide what value of d
381 * to use next: ensure that we move at least 0.25 *
382 * stroke width, for example. The derivative (as used
383 * for get_tangent before normalization) would be
384 * useful for estimating the appropriate d value. Or
385 * perhaps just start with a small dstep and scale by
386 * some small number until we move >= 0.25 *
387 * stroke_width. Must revert to the original dstep
388 * value for next iteration to avoid the problem
389 * mentioned above.
390 */
391 }
392 }
394 double const next_t = d - 2 * dstep;
395 /* == t + (SAMPLE_SIZE - 1) * dstep, in absence of dups. */
397 hat2 = -sp_spiral_get_tangent (spiral, next_t);
399 /** \todo
400 * We should use better algorithm to specify maximum error.
401 */
402 depth = sp_bezier_fit_cubic_full (bezier, NULL, darray, SAMPLE_SIZE,
403 hat1, hat2,
404 SPIRAL_TOLERANCE*SPIRAL_TOLERANCE,
405 FITTING_MAX_BEZIERS);
406 g_assert(depth * BEZIER_SIZE <= gint(G_N_ELEMENTS(bezier)));
407 #ifdef SPIRAL_DEBUG
408 if (*t == spiral->t0 || *t == 1.0)
409 g_print ("[%s] depth=%d, dstep=%g, t0=%g, t=%g, arg=%g\n",
410 debug_state, depth, dstep, spiral->t0, *t, spiral->arg);
411 #endif
412 if (depth != -1) {
413 for (i = 0; i < 4*depth; i += 4) {
414 c->curveto(bezier[i + 1],
415 bezier[i + 2],
416 bezier[i + 3]);
417 }
418 } else {
419 #ifdef SPIRAL_VERBOSE
420 g_print ("cant_fit_cubic: t=%g\n", *t);
421 #endif
422 for (i = 1; i < SAMPLE_SIZE; i++)
423 c->lineto(darray[i]);
424 }
425 *t = next_t;
426 g_assert (is_unit_vector (hat2));
427 }
429 static void
430 sp_spiral_set_shape (SPShape *shape)
431 {
432 NR::Point darray[SAMPLE_SIZE + 1];
433 double t;
435 SPSpiral *spiral = SP_SPIRAL(shape);
437 SP_OBJECT (spiral)->requestModified(SP_OBJECT_MODIFIED_FLAG);
439 SPCurve *c = new SPCurve ();
441 #ifdef SPIRAL_VERBOSE
442 g_print ("cx=%g, cy=%g, exp=%g, revo=%g, rad=%g, arg=%g, t0=%g\n",
443 spiral->cx,
444 spiral->cy,
445 spiral->exp,
446 spiral->revo,
447 spiral->rad,
448 spiral->arg,
449 spiral->t0);
450 #endif
452 /* Initial moveto. */
453 c->moveto(sp_spiral_get_xy(spiral, spiral->t0));
455 double const tstep = SAMPLE_STEP / spiral->revo;
456 double const dstep = tstep / (SAMPLE_SIZE - 1);
458 NR::Point hat1 = sp_spiral_get_tangent (spiral, spiral->t0);
459 NR::Point hat2;
460 for (t = spiral->t0; t < (1.0 - tstep);) {
461 sp_spiral_fit_and_draw (spiral, c, dstep, darray, hat1, hat2, &t);
463 hat1 = -hat2;
464 }
465 if ((1.0 - t) > SP_EPSILON)
466 sp_spiral_fit_and_draw (spiral, c, (1.0 - t)/(SAMPLE_SIZE - 1.0),
467 darray, hat1, hat2, &t);
469 sp_lpe_item_perform_path_effect(SP_LPE_ITEM (spiral), c);
470 sp_shape_set_curve_insync ((SPShape *) spiral, c, TRUE);
471 c->unref();
472 }
474 /**
475 * Set spiral properties and update display.
476 */
477 void
478 sp_spiral_position_set (SPSpiral *spiral,
479 gdouble cx,
480 gdouble cy,
481 gdouble exp,
482 gdouble revo,
483 gdouble rad,
484 gdouble arg,
485 gdouble t0)
486 {
487 g_return_if_fail (spiral != NULL);
488 g_return_if_fail (SP_IS_SPIRAL (spiral));
490 /** \todo
491 * Consider applying CLAMP or adding in-bounds assertions for
492 * some of these parameters.
493 */
494 spiral->cx = cx;
495 spiral->cy = cy;
496 spiral->exp = exp;
497 spiral->revo = revo;
498 spiral->rad = MAX (rad, 0.001);
499 spiral->arg = arg;
500 spiral->t0 = CLAMP(t0, 0.0, 0.999);
502 ((SPObject *)spiral)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
503 }
505 /**
506 * Virtual snappoints callback.
507 */
508 static void sp_spiral_snappoints(SPItem const *item, SnapPointsIter p)
509 {
510 if (((SPItemClass *) parent_class)->snappoints) {
511 ((SPItemClass *) parent_class)->snappoints (item, p);
512 }
513 }
515 /**
516 * Return one of the points on the spiral.
517 *
518 * \param t specifies how far along the spiral.
519 * \pre \a t in [0.0, 2.03]. (It doesn't make sense for t to be much more
520 * than 1.0, though some callers go slightly beyond 1.0 for curve-fitting
521 * purposes.)
522 */
523 NR::Point sp_spiral_get_xy (SPSpiral const *spiral, gdouble t)
524 {
525 g_assert (spiral != NULL);
526 g_assert (SP_IS_SPIRAL(spiral));
527 g_assert (spiral->exp >= 0.0);
528 /* Otherwise we get NaN for t==0. */
529 g_assert (spiral->exp <= 1000.0);
530 /* Anything much more results in infinities. Even allowing 1000 is somewhat overkill. */
531 g_assert (t >= 0.0);
532 /* Any callers passing -ve t will have a bug for non-integral values of exp. */
534 double const rad = spiral->rad * pow(t, (double) spiral->exp);
535 double const arg = 2.0 * M_PI * spiral->revo * t + spiral->arg;
537 return NR::Point(rad * cos (arg) + spiral->cx,
538 rad * sin (arg) + spiral->cy);
539 }
542 /**
543 * Returns the derivative of sp_spiral_get_xy with respect to t,
544 * scaled to a unit vector.
545 *
546 * \pre spiral != 0.
547 * \pre 0 \<= t.
548 * \pre p != NULL.
549 * \post is_unit_vector(*p).
550 */
551 static NR::Point
552 sp_spiral_get_tangent (SPSpiral const *spiral, gdouble t)
553 {
554 NR::Point ret(1.0, 0.0);
555 g_return_val_if_fail (( ( spiral != NULL )
556 && SP_IS_SPIRAL(spiral) ),
557 ret);
558 g_assert (t >= 0.0);
559 g_assert (spiral->exp >= 0.0);
560 /* See above for comments on these assertions. */
562 double const t_scaled = 2.0 * M_PI * spiral->revo * t;
563 double const arg = t_scaled + spiral->arg;
564 double const s = sin (arg);
565 double const c = cos (arg);
567 if (spiral->exp == 0.0) {
568 ret = NR::Point(-s, c);
569 } else if (t_scaled == 0.0) {
570 ret = NR::Point(c, s);
571 } else {
572 NR::Point unrotated(spiral->exp, t_scaled);
573 double const s_len = L2 (unrotated);
574 g_assert (s_len != 0);
575 /** \todo
576 * Check that this isn't being too hopeful of the hypot
577 * function. E.g. test with numbers around 2**-1070
578 * (denormalized numbers), preferably on a few different
579 * platforms. However, njh says that the usual implementation
580 * does handle both very big and very small numbers.
581 */
582 unrotated /= s_len;
584 /* ret = spiral->exp * (c, s) + t_scaled * (-s, c);
585 alternatively ret = (spiral->exp, t_scaled) * (( c, s),
586 (-s, c)).*/
587 ret = NR::Point(dot(unrotated, NR::Point(c, -s)),
588 dot(unrotated, NR::Point(s, c)));
589 /* ret should already be approximately normalized: the
590 matrix ((c, -s), (s, c)) is orthogonal (it just
591 rotates by arg), and unrotated has been normalized,
592 so ret is already of unit length other than numerical
593 error in the above matrix multiplication. */
595 /** \todo
596 * I haven't checked how important it is for ret to be very
597 * near unit length; we could get rid of the below.
598 */
600 ret.normalize();
601 /* Proof that ret length is non-zero: see above. (Should be near 1.) */
602 }
604 g_assert (is_unit_vector (ret));
605 return ret;
606 }
608 /**
609 * Compute rad and/or arg for point on spiral.
610 */
611 void
612 sp_spiral_get_polar (SPSpiral const *spiral, gdouble t, gdouble *rad, gdouble *arg)
613 {
614 g_return_if_fail (spiral != NULL);
615 g_return_if_fail (SP_IS_SPIRAL(spiral));
617 if (rad)
618 *rad = spiral->rad * pow(t, (double) spiral->exp);
619 if (arg)
620 *arg = 2.0 * M_PI * spiral->revo * t + spiral->arg;
621 }
623 /**
624 * Return true if spiral has properties that make it invalid.
625 */
626 bool
627 sp_spiral_is_invalid (SPSpiral const *spiral)
628 {
629 gdouble rad;
631 sp_spiral_get_polar (spiral, 0.0, &rad, NULL);
632 if (rad < 0.0 || rad > SP_HUGE) {
633 g_print ("rad(t=0)=%g\n", rad);
634 return TRUE;
635 }
636 sp_spiral_get_polar (spiral, 1.0, &rad, NULL);
637 if (rad < 0.0 || rad > SP_HUGE) {
638 g_print ("rad(t=1)=%g\n", rad);
639 return TRUE;
640 }
641 return FALSE;
642 }
644 /*
645 Local Variables:
646 mode:c++
647 c-file-style:"stroustrup"
648 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
649 indent-tabs-mode:nil
650 fill-column:99
651 End:
652 */
653 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :