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source: trunk/third/librsvg/rsvg-styles.c @ 18805

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Revision 18805, 21.9 KB checked in by ghudson, 21 years ago (diff)
This commit was generated by cvs2svn to compensate for changes in r18804, which included commits to RCS files with non-trunk default branches.

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1	/* vim: set sw=4: -- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -- */
2	/*
3	rsvg-styles.c: Handle SVG styles
4
5	Copyright (C) 2000 Eazel, Inc.
6	Copyright (C) 2002 Dom Lachowicz <cinamod@hotmail.com>
7
8	This program is free software; you can redistribute it and/or
9	modify it under the terms of the GNU Library General Public License as
10	published by the Free Software Foundation; either version 2 of the
11	License, or (at your option) any later version.
12
13	This program is distributed in the hope that it will be useful,
14	but WITHOUT ANY WARRANTY; without even the implied warranty of
15	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16	Library General Public License for more details.
17
18	You should have received a copy of the GNU Library General Public
19	License along with this program; if not, write to the
20	Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21	Boston, MA 02111-1307, USA.
22
23	Author: Raph Levien <raph@artofcode.com>
24	*/
25	#include <string.h>
26
27	#include "rsvg.h"
28	#include "rsvg-css.h"
29	#include "rsvg-styles.h"
30	#include "rsvg-private.h"
31
32	#include <libart_lgpl/art_rgba.h>
33	#include <libart_lgpl/art_affine.h>
34
35	/* Our default font */
36	#define DEFAULT_FONT "Times Roman"
37
38	gdouble
39	rsvg_viewport_percentage (gdouble width, gdouble height)
40	{
41	return ((width * width) + (height * height)) / M_SQRT2;
42	}
43
44	void
45	rsvg_state_init (RsvgState *state)
46	{
47	memset (state, 0, sizeof (*state));
48
49	art_affine_identity (state->affine);
50
51	state->opacity = 0xff;
52	state->fill = rsvg_paint_server_parse (NULL, "#000");
53	state->fill_opacity = 0xff;
54	state->stroke_opacity = 0xff;
55	state->stroke_width = 1;
56	state->miter_limit = 4;
57	state->cap = ART_PATH_STROKE_CAP_BUTT;
58	state->join = ART_PATH_STROKE_JOIN_MITER;
59	state->stop_opacity = 0xff;
60
61	state->font_family = g_strdup (DEFAULT_FONT);
62	state->font_size = 12.0;
63	state->font_style = PANGO_STYLE_NORMAL;
64	state->font_variant = PANGO_VARIANT_NORMAL;
65	state->font_weight = PANGO_WEIGHT_NORMAL;
66	state->font_stretch = PANGO_STRETCH_NORMAL;
67
68	state->visible = TRUE;
69	}
70
71	void
72	rsvg_state_clone (RsvgState dst, const RsvgState src)
73	{
74	gint i;
75
76	dst = src;
77	dst->font_family = g_strdup (src->font_family);
78	rsvg_paint_server_ref (dst->fill);
79	rsvg_paint_server_ref (dst->stroke);
80	dst->save_pixbuf = NULL;
81
82	if (src->dash.n_dash > 0)
83	{
84	dst->dash.dash = g_new (gdouble, src->dash.n_dash);
85	for (i = 0; i < src->dash.n_dash; i++)
86	dst->dash.dash[i] = src->dash.dash[i];
87	}
88	}
89
90	void
91	rsvg_state_finalize (RsvgState *state)
92	{
93	g_free (state->font_family);
94	rsvg_paint_server_unref (state->fill);
95	rsvg_paint_server_unref (state->stroke);
96
97	if (state->dash.n_dash != 0)
98	g_free (state->dash.dash);
99	}
100
101	/* Parse a CSS2 style argument, setting the SVG context attributes. */
102	static void
103	rsvg_parse_style_arg (RsvgHandle ctx, RsvgState state, const char *str)
104	{
105	RsvgState * parent_state = state; /* TODO: temporary hack */
106	int arg_off;
107
108	arg_off = rsvg_css_param_arg_offset (str);
109	if (rsvg_css_param_match (str, "opacity"))
110	{
111	state->opacity = rsvg_css_parse_opacity (str + arg_off);
112	}
113	else if (rsvg_css_param_match (str, "display"))
114	{
115	if (!strcmp (str + arg_off, "none"))
116	state->visible = FALSE;
117	else if (strcmp (str + arg_off, "inherit") != 0)
118	state->visible = TRUE;
119	/* else inherit */
120	}
121	else if (rsvg_css_param_match (str, "visibility"))
122	{
123	if (!strcmp (str + arg_off, "visable"))
124	state->visible = TRUE;
125	else if (strcmp (str + arg_off, "inherit") != 0)
126	state->visible = FALSE; /* collapse or hidden */
127	/* else inherit */
128	}
129	else if (rsvg_css_param_match (str, "fill"))
130	{
131	rsvg_paint_server_unref (state->fill);
132	state->fill = rsvg_paint_server_parse (ctx->defs, str + arg_off);
133	}
134	else if (rsvg_css_param_match (str, "fill-opacity"))
135	{
136	state->fill_opacity = rsvg_css_parse_opacity (str + arg_off);
137	}
138	else if (rsvg_css_param_match (str, "stroke"))
139	{
140	rsvg_paint_server_unref (state->stroke);
141	state->stroke = rsvg_paint_server_parse (ctx->defs, str + arg_off);
142	}
143	else if (rsvg_css_param_match (str, "stroke-width"))
144	{
145	state->stroke_width = rsvg_css_parse_normalized_length (str + arg_off, ctx->dpi,
146	(gdouble)ctx->height, state->font_size);
147	}
148	else if (rsvg_css_param_match (str, "stroke-linecap"))
149	{
150	if (!strcmp (str + arg_off, "butt"))
151	state->cap = ART_PATH_STROKE_CAP_BUTT;
152	else if (!strcmp (str + arg_off, "round"))
153	state->cap = ART_PATH_STROKE_CAP_ROUND;
154	else if (!strcmp (str + arg_off, "square"))
155	state->cap = ART_PATH_STROKE_CAP_SQUARE;
156	else
157	g_warning ("unknown line cap style %s", str + arg_off);
158	}
159	else if (rsvg_css_param_match (str, "stroke-opacity"))
160	{
161	state->stroke_opacity = rsvg_css_parse_opacity (str + arg_off);
162	}
163	else if (rsvg_css_param_match (str, "stroke-linejoin"))
164	{
165	if (!strcmp (str + arg_off, "miter"))
166	state->join = ART_PATH_STROKE_JOIN_MITER;
167	else if (!strcmp (str + arg_off, "round"))
168	state->join = ART_PATH_STROKE_JOIN_ROUND;
169	else if (!strcmp (str + arg_off, "bevel"))
170	state->join = ART_PATH_STROKE_JOIN_BEVEL;
171	else
172	g_warning ("unknown line join style %s", str + arg_off);
173	}
174	else if (rsvg_css_param_match (str, "font-size"))
175	{
176	state->font_size = rsvg_css_parse_normalized_length (str + arg_off, ctx->dpi,
177	(gdouble)ctx->height, state->font_size);
178	}
179	else if (rsvg_css_param_match (str, "font-family"))
180	{
181	char * save = g_strdup (rsvg_css_parse_font_family (str + arg_off, parent_state->font_family));
182	g_free (state->font_family);
183	state->font_family = save;
184	}
185	else if (rsvg_css_param_match (str, "font-style"))
186	{
187	state->font_style = rsvg_css_parse_font_style (str + arg_off, parent_state->font_style);
188	}
189	else if (rsvg_css_param_match (str, "font-variant"))
190	{
191	state->font_variant = rsvg_css_parse_font_variant (str + arg_off, parent_state->font_variant);
192	}
193	else if (rsvg_css_param_match (str, "font-weight"))
194	{
195	state->font_weight = rsvg_css_parse_font_weight (str + arg_off, parent_state->font_weight);
196	}
197	else if (rsvg_css_param_match (str, "font-stretch"))
198	{
199	state->font_stretch = rsvg_css_parse_font_stretch (str + arg_off, parent_state->font_stretch);
200	}
201	else if (rsvg_css_param_match (str, "text-decoration"))
202	{
203	if (!strcmp (str, "inherit"))
204	state->font_decor = parent_state->font_decor;
205	else
206	{
207	if (strstr (str, "underline"))
208	state->font_decor \|= TEXT_UNDERLINE;
209	if (strstr (str, "overline"))
210	state->font_decor \|= TEXT_OVERLINE;
211	if (strstr (str, "strike") \|\| strstr (str, "line-through")) /* strike though or line-through */
212	state->font_decor \|= TEXT_STRIKE;
213	}
214	}
215	else if (rsvg_css_param_match (str, "stop-color"))
216	{
217	state->stop_color = rsvg_css_parse_color (str + arg_off);
218	}
219	else if (rsvg_css_param_match (str, "stop-opacity"))
220	{
221	state->stop_opacity = rsvg_css_parse_opacity (str + arg_off);
222	}
223	else if (rsvg_css_param_match (str, "stroke-miterlimit"))
224	{
225	state->miter_limit = g_ascii_strtod (str + arg_off, NULL);
226	}
227	else if (rsvg_css_param_match (str, "stroke-dashoffset"))
228	{
229	state->dash.offset = rsvg_css_parse_normalized_length (str + arg_off, ctx->dpi,
230	rsvg_viewport_percentage((gdouble)ctx->width, (gdouble)ctx->height), state->font_size);
231	if (state->dash.offset < 0.)
232	state->dash.offset = 0.;
233	}
234	else if (rsvg_css_param_match (str, "stroke-dasharray"))
235	{
236	if(!strcmp(str + arg_off, "none"))
237	{
238	if (state->dash.n_dash != 0)
239	{
240	/* free any cloned dash data */
241	g_free (state->dash.dash);
242	state->dash.n_dash = 0;
243	}
244	}
245	else
246	{
247	gchar ** dashes = g_strsplit (str + arg_off, ",", -1);
248	if (NULL != dashes)
249	{
250	gint n_dashes, i;
251	gboolean is_even = FALSE ;
252
253	/* count the #dashes */
254	for (n_dashes = 0; dashes[n_dashes] != NULL; n_dashes++)
255	;
256
257	is_even = (n_dashes % 2 == 0);
258	state->dash.n_dash = (is_even ? n_dashes : n_dashes * 2);
259	state->dash.dash = g_new (double, state->dash.n_dash);
260
261	/* TODO: handle negative value == error case */
262
263	/* the even and base case */
264	for (i = 0; i < n_dashes; i++)
265	state->dash.dash[i] = g_ascii_strtod (dashes[i], NULL);
266
267	/* if an odd number of dashes is found, it gets repeated */
268	if (!is_even)
269	for (; i < state->dash.n_dash; i++)
270	state->dash.dash[i] = g_ascii_strtod (dashes[i - n_dashes], NULL);
271
272	g_strfreev (dashes) ;
273	}
274	}
275	}
276	}
277
278	/* tell whether @str is a supported style argument
279	whenever something gets added to parse_arg, please
280	remember to add it here too
281	*/
282	gboolean
283	rsvg_is_style_arg(const char *str)
284	{
285	static GHashTable *styles = NULL;
286	if (!styles)
287	{
288	styles = g_hash_table_new (g_str_hash, g_str_equal);
289
290	g_hash_table_insert (styles, "display", GINT_TO_POINTER (TRUE));
291	g_hash_table_insert (styles, "fill", GINT_TO_POINTER (TRUE));
292	g_hash_table_insert (styles, "fill-opacity", GINT_TO_POINTER (TRUE));
293	g_hash_table_insert (styles, "font-family", GINT_TO_POINTER (TRUE));
294	g_hash_table_insert (styles, "font-size", GINT_TO_POINTER (TRUE));
295	g_hash_table_insert (styles, "font-stretch", GINT_TO_POINTER (TRUE));
296	g_hash_table_insert (styles, "font-style", GINT_TO_POINTER (TRUE));
297	g_hash_table_insert (styles, "font-variant", GINT_TO_POINTER (TRUE));
298	g_hash_table_insert (styles, "font-weight", GINT_TO_POINTER (TRUE));
299	g_hash_table_insert (styles, "opacity", GINT_TO_POINTER (TRUE));
300	g_hash_table_insert (styles, "stop-color", GINT_TO_POINTER (TRUE));
301	g_hash_table_insert (styles, "stop-opacity", GINT_TO_POINTER (TRUE));
302	g_hash_table_insert (styles, "stroke", GINT_TO_POINTER (TRUE));
303	g_hash_table_insert (styles, "stroke-dasharray", GINT_TO_POINTER (TRUE));
304	g_hash_table_insert (styles, "stroke-dashoffset", GINT_TO_POINTER (TRUE));
305	g_hash_table_insert (styles, "stroke-linecap", GINT_TO_POINTER (TRUE));
306	g_hash_table_insert (styles, "stroke-linejoin", GINT_TO_POINTER (TRUE));
307	g_hash_table_insert (styles, "stroke-miterlimit", GINT_TO_POINTER (TRUE));
308	g_hash_table_insert (styles, "stroke-opacity", GINT_TO_POINTER (TRUE));
309	g_hash_table_insert (styles, "stroke-width", GINT_TO_POINTER (TRUE));
310	g_hash_table_insert (styles, "text-decoration", GINT_TO_POINTER (TRUE));
311	g_hash_table_insert (styles, "visibility", GINT_TO_POINTER (TRUE));
312	}
313
314	/* this will default to 0 (FALSE) on a failed lookup */
315	return GPOINTER_TO_INT (g_hash_table_lookup (styles, str));
316	}
317
318	/* take a pair of the form (fill="#ff00ff") and parse it as a style */
319	void
320	rsvg_parse_style_pair (RsvgHandle ctx, RsvgState state,
321	const char key, const char val)
322	{
323	gchar * str = g_strdup_printf ("%s:%s", key, val);
324	rsvg_parse_style_arg (ctx, state, str);
325	g_free (str);
326	}
327
328	/* Split a CSS2 style into individual style arguments, setting attributes
329	in the SVG context.
330
331	It's known that this is _way_ out of spec. A more complete CSS2
332	implementation will happen later.
333	*/
334	void
335	rsvg_parse_style (RsvgHandle ctx, RsvgState state, const char *str)
336	{
337	int start, end;
338	char *arg;
339
340	start = 0;
341	while (str[start] != '\0')
342	{
343	for (end = start; str[end] != '\0' && str[end] != ';'; end++);
344	arg = g_new (char, 1 + end - start);
345	memcpy (arg, str + start, end - start);
346	arg[end - start] = '\0';
347	rsvg_parse_style_arg (ctx, state, arg);
348	g_free (arg);
349	start = end;
350	if (str[start] == ';') start++;
351	while (str[start] == ' ') start++;
352	}
353	}
354
355	/*
356	* Extremely poor man's CSS parser. Not robust. Not compliant.
357	* Should work well enough for our needs ;-)
358	* See also: http://www.w3.org/TR/REC-CSS2/syndata.html
359	* I should use that sometime in order to make a complaint parser
360	*/
361	void
362	rsvg_parse_cssbuffer (RsvgHandle ctx, const char buff, size_t buflen)
363	{
364	size_t loc = 0;
365
366	while (loc < buflen)
367	{
368	GString * style_name = g_string_new (NULL);
369	GString * style_props = g_string_new (NULL);
370	const char * existing = NULL;
371
372	/* advance to the style's name */
373	while (loc < buflen && g_ascii_isspace (buff[loc]))
374	loc++;
375
376	while (loc < buflen && !g_ascii_isspace (buff[loc]))
377	g_string_append_c (style_name, buff[loc++]);
378
379	/* advance to the first { that defines the style's properties */
380	while (loc < buflen && buff[loc++] != '{' )
381	;
382
383	while (loc < buflen && g_ascii_isspace (buff[loc]))
384	loc++;
385
386	while (loc < buflen && buff[loc] != '}')
387	{
388	/* suck in and append our property */
389	while (loc < buflen && buff[loc] != ';' && buff[loc] != '}' )
390	g_string_append_c (style_props, buff[loc++]);
391
392	if (loc == buflen \|\| buff[loc] == '}')
393	break;
394	else
395	{
396	g_string_append_c (style_props, ';');
397
398	/* advance to the next property */
399	loc++;
400	while (loc < buflen && g_ascii_isspace (buff[loc]))
401	loc++;
402	}
403	}
404
405	/* push name/style pair into HT */
406	existing = (const char *)g_hash_table_lookup (ctx->css_props, style_name->str);
407	if (existing != NULL)
408	g_string_append_len (style_props, existing, strlen (existing));
409
410	/* will destroy the existing key and value for us */
411	g_hash_table_insert (ctx->css_props, style_name->str, style_props->str);
412
413	g_string_free (style_name, FALSE);
414	g_string_free (style_props, FALSE);
415
416	loc++;
417	while (loc < buflen && g_ascii_isspace (buff[loc]))
418	loc++;
419	}
420	}
421
422	/* Parse an SVG transform string into an affine matrix. Reference: SVG
423	working draft dated 1999-07-06, section 8.5. Return TRUE on
424	success. */
425	gboolean
426	rsvg_parse_transform (double dst[6], const char *src)
427	{
428	int idx;
429	char keyword[32];
430	double args[6];
431	int n_args;
432	guint key_len;
433	double tmp_affine[6];
434
435	art_affine_identity (dst);
436
437	idx = 0;
438	while (src[idx])
439	{
440	/* skip initial whitespace */
441	while (g_ascii_isspace (src[idx]))
442	idx++;
443
444	/* parse keyword */
445	for (key_len = 0; key_len < sizeof (keyword); key_len++)
446	{
447	char c;
448
449	c = src[idx];
450	if (g_ascii_isalpha (c) \|\| c == '-')
451	keyword[key_len] = src[idx++];
452	else
453	break;
454	}
455	if (key_len >= sizeof (keyword))
456	return FALSE;
457	keyword[key_len] = '\0';
458
459	/* skip whitespace */
460	while (g_ascii_isspace (src[idx]))
461	idx++;
462
463	if (src[idx] != '(')
464	return FALSE;
465	idx++;
466
467	for (n_args = 0; ; n_args++)
468	{
469	char c;
470	char *end_ptr;
471
472	/* skip whitespace */
473	while (g_ascii_isspace (src[idx]))
474	idx++;
475	c = src[idx];
476	if (g_ascii_isdigit (c) \|\| c == '+' \|\| c == '-' \|\| c == '.')
477	{
478	if (n_args == sizeof(args) / sizeof(args[0]))
479	return FALSE; /* too many args */
480	args[n_args] = g_ascii_strtod (src + idx, &end_ptr);
481	idx = end_ptr - src;
482
483	while (g_ascii_isspace (src[idx]))
484	idx++;
485
486	/* skip optional comma */
487	if (src[idx] == ',')
488	idx++;
489	}
490	else if (c == ')')
491	break;
492	else
493	return FALSE;
494	}
495	idx++;
496
497	/* ok, have parsed keyword and args, now modify the transform */
498	if (!strcmp (keyword, "matrix"))
499	{
500	if (n_args != 6)
501	return FALSE;
502	art_affine_multiply (dst, args, dst);
503	}
504	else if (!strcmp (keyword, "translate"))
505	{
506	if (n_args == 1)
507	args[1] = 0;
508	else if (n_args != 2)
509	return FALSE;
510	art_affine_translate (tmp_affine, args[0], args[1]);
511	art_affine_multiply (dst, tmp_affine, dst);
512	}
513	else if (!strcmp (keyword, "scale"))
514	{
515	if (n_args == 1)
516	args[1] = args[0];
517	else if (n_args != 2)
518	return FALSE;
519	art_affine_scale (tmp_affine, args[0], args[1]);
520	art_affine_multiply (dst, tmp_affine, dst);
521	}
522	else if (!strcmp (keyword, "rotate"))
523	{
524	if (n_args != 1)
525	return FALSE;
526	art_affine_rotate (tmp_affine, args[0]);
527	art_affine_multiply (dst, tmp_affine, dst);
528	}
529	else if (!strcmp (keyword, "skewX"))
530	{
531	if (n_args != 1)
532	return FALSE;
533	art_affine_shear (tmp_affine, args[0]);
534	art_affine_multiply (dst, tmp_affine, dst);
535	}
536	else if (!strcmp (keyword, "skewY"))
537	{
538	if (n_args != 1)
539	return FALSE;
540	art_affine_shear (tmp_affine, args[0]);
541	/* transpose the affine, given that we know [1] is zero */
542	tmp_affine[1] = tmp_affine[2];
543	tmp_affine[2] = 0;
544	art_affine_multiply (dst, tmp_affine, dst);
545	}
546	else
547	return FALSE; /* unknown keyword */
548	}
549	return TRUE;
550	}
551
552	/**
553	* rsvg_parse_transform_attr: Parse transform attribute and apply to state.
554	* @ctx: Rsvg context.
555	* @state: State in which to apply the transform.
556	* @str: String containing transform.
557	*
558	* Parses the transform attribute in @str and applies it to @state.
559	**/
560	static void
561	rsvg_parse_transform_attr (RsvgHandle ctx, RsvgState state, const char *str)
562	{
563	double affine[6];
564
565	if (rsvg_parse_transform (affine, str))
566	{
567	art_affine_multiply (state->affine, affine, state->affine);
568	}
569	else
570	{
571	/* parse error for transform attribute. todo: report */
572	}
573	}
574
575	static gboolean
576	rsvg_lookup_apply_css_style (RsvgHandle ctx, const char target)
577	{
578	const char * value = (const char *)g_hash_table_lookup (ctx->css_props, target);
579
580	if (value != NULL)
581	{
582	rsvg_parse_style (ctx, &ctx->state[ctx->n_state - 1],
583	value);
584	return TRUE;
585	}
586	return FALSE;
587	}
588
589	/**
590	* rsvg_parse_style_attrs: Parse style attribute.
591	* @ctx: Rsvg context.
592	* @tag: The SVG tag we're processing (eg: circle, ellipse), optionally %NULL
593	* @klazz: The space delimited class list, optionally %NULL
594	* @atts: Attributes in SAX style.
595	*
596	* Parses style and transform attributes and modifies state at top of
597	* stack.
598	**/
599	void
600	rsvg_parse_style_attrs (RsvgHandle *ctx,
601	const char * tag,
602	const char * klazz,
603	const char * id,
604	const xmlChar **atts)
605	{
606	int i = 0, j = 0;
607	char * target = NULL;
608	gboolean found = FALSE;
609	GString * klazz_list = NULL;
610
611	/* handle the all-encompassing "star" entry first, ignoring found-ness */
612	rsvg_lookup_apply_css_style (ctx, "*");
613
614	if (id != NULL)
615	{
616	target = g_strdup_printf ("#%s", id);
617	rsvg_lookup_apply_css_style (ctx, target);
618	g_free (target);
619	}
620
621	/* todo: see if klazz or tag should accumulate onto tag.klazz */
622
623	if (tag != NULL && klazz != NULL)
624	{
625	target = g_strdup_printf ("%s.%s", tag, klazz);
626	found = rsvg_lookup_apply_css_style (ctx, target);
627	g_free (target);
628	}
629
630	if (found == FALSE)
631	{
632	if (tag != NULL)
633	rsvg_lookup_apply_css_style (ctx, tag);
634
635	if (klazz != NULL)
636	{
637	i = strlen (klazz);
638	while (j < i)
639	{
640	klazz_list = g_string_new (".");
641
642	while (j < i && g_ascii_isspace(klazz[j]))
643	j++;
644
645	while (j < i && !g_ascii_isspace(klazz[j]))
646	g_string_append_c (klazz_list, klazz[j++]);
647
648	rsvg_lookup_apply_css_style (ctx, klazz_list->str);
649	g_string_free (klazz_list, TRUE);
650	}
651	}
652	}
653
654	if (atts != NULL)
655	{
656	for (i = 0; atts[i] != NULL; i += 2)
657	{
658	if (!strcmp ((char *)atts[i], "style"))
659	rsvg_parse_style (ctx, &ctx->state[ctx->n_state - 1],
660	(char *)atts[i + 1]);
661	else if (!strcmp ((char *)atts[i], "transform"))
662	rsvg_parse_transform_attr (ctx, &ctx->state[ctx->n_state - 1],
663	(char *)atts[i + 1]);
664	else if (rsvg_is_style_arg ((char *)atts[i]))
665	rsvg_parse_style_pair (ctx, &ctx->state[ctx->n_state - 1],
666	(char )atts[i], (char )atts[i + 1]);
667	}
668	}
669	}
670
671	static void
672	rsvg_pixmap_destroy (guchar *pixels, gpointer data)
673	{
674	g_free (pixels);
675	}
676
677	/**
678	* rsvg_push_opacity_group: Begin a new transparency group.
679	* @ctx: Context in which to push.
680	*
681	* Pushes a new transparency group onto the stack. The top of the stack
682	* is stored in the context, while the "saved" value is in the state
683	* stack.
684	**/
685	void
686	rsvg_push_opacity_group (RsvgHandle *ctx)
687	{
688	RsvgState *state;
689	GdkPixbuf *pixbuf;
690	art_u8 *pixels;
691	int width, height, rowstride;
692
693	state = &ctx->state[ctx->n_state - 1];
694	pixbuf = ctx->pixbuf;
695
696	state->save_pixbuf = pixbuf;
697
698	if (pixbuf == NULL)
699	{
700	/* FIXME: What warning/GError here? */
701	return;
702	}
703
704	if (!gdk_pixbuf_get_has_alpha (pixbuf))
705	{
706	g_warning ("push/pop transparency group on non-alpha buffer nyi");
707	return;
708	}
709
710	width = gdk_pixbuf_get_width (pixbuf);
711	height = gdk_pixbuf_get_height (pixbuf);
712	rowstride = gdk_pixbuf_get_rowstride (pixbuf);
713	pixels = g_new (art_u8, rowstride * height);
714	memset (pixels, 0, rowstride * height);
715
716	pixbuf = gdk_pixbuf_new_from_data (pixels,
717	GDK_COLORSPACE_RGB,
718	TRUE,
719	gdk_pixbuf_get_bits_per_sample (pixbuf),
720	width,
721	height,
722	rowstride,
723	rsvg_pixmap_destroy,
724	NULL);
725	ctx->pixbuf = pixbuf;
726	}
727
728	/**
729	* rsvg_pop_opacity_group: End a transparency group.
730	* @ctx: Context in which to push.
731	* @opacity: Opacity for blending (0..255).
732	*
733	* Pops a new transparency group from the stack, recompositing with the
734	* next on stack.
735	**/
736	void
737	rsvg_pop_opacity_group (RsvgHandle *ctx, int opacity)
738	{
739	RsvgState *state = &ctx->state[ctx->n_state - 1];
740	GdkPixbuf tos, nos;
741	art_u8 tos_pixels, nos_pixels;
742	int width;
743	int height;
744	int rowstride;
745	int x, y;
746	int tmp;
747
748	tos = ctx->pixbuf;
749	nos = state->save_pixbuf;
750
751	if (tos == NULL \|\| nos == NULL)
752	{
753	/* FIXME: What warning/GError here? */
754	return;
755	}
756
757	if (!gdk_pixbuf_get_has_alpha (nos))
758	{
759	g_warning ("push/pop transparency group on non-alpha buffer nyi");
760	return;
761	}
762
763	width = gdk_pixbuf_get_width (tos);
764	height = gdk_pixbuf_get_height (tos);
765	rowstride = gdk_pixbuf_get_rowstride (tos);
766
767	tos_pixels = gdk_pixbuf_get_pixels (tos);
768	nos_pixels = gdk_pixbuf_get_pixels (nos);
769
770	for (y = 0; y < height; y++)
771	{
772	for (x = 0; x < width; x++)
773	{
774	art_u8 r, g, b, a;
775	a = tos_pixels[4 * x + 3];
776	if (a)
777	{
778	r = tos_pixels[4 * x];
779	g = tos_pixels[4 * x + 1];
780	b = tos_pixels[4 * x + 2];
781	tmp = a * opacity + 0x80;
782	a = (tmp + (tmp >> 8)) >> 8;
783	art_rgba_run_alpha (nos_pixels + 4 * x, r, g, b, a, 1);
784	}
785	}
786	tos_pixels += rowstride;
787	nos_pixels += rowstride;
788	}
789
790	g_object_unref (tos);
791	ctx->pixbuf = nos;
792	}

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