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1 /*
2  * Copyright © 2018 Adobe Inc.
3  *
4  *  This is part of HarfBuzz, a text shaping library.
5  *
6  * Permission is hereby granted, without written agreement and without
7  * license or royalty fees, to use, copy, modify, and distribute this
8  * software and its documentation for any purpose, provided that the
9  * above copyright notice and the following two paragraphs appear in
10  * all copies of this software.
11  *
12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16  * DAMAGE.
17  *
18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23  *
24  * Adobe Author(s): Michiharu Ariza
25  */
26 
27 #include "hb-ot-cff-common.hh"
28 #include "hb-ot-cff2-table.hh"
29 #include "hb-subset-cff-common.hh"
30 
31 /* Disable FDSelect format 0 for compatibility with fonttools which doesn't seem choose it.
32  * Rarely any/much smaller than format 3 anyway. */
33 #define CFF_SERIALIZE_FDSELECT_0  0
34 
35 using namespace CFF;
36 
37 /**
38  * hb_plan_subset_cff_fdselect
39  * Determine an optimal FDSelect format according to a provided plan.
40  *
41  * Return value: FDSelect format, size, and ranges for the most compact subset FDSelect
42  * along with a font index remapping table
43  **/
44 
45 bool
hb_plan_subset_cff_fdselect(const hb_vector_t<hb_codepoint_t> & glyphs,unsigned int fdCount,const FDSelect & src,unsigned int & subset_fd_count,unsigned int & subset_fdselect_size,unsigned int & subset_fdselect_format,hb_vector_t<code_pair> & fdselect_ranges,Remap & fdmap)46 hb_plan_subset_cff_fdselect (const hb_vector_t<hb_codepoint_t> &glyphs,
47 			    unsigned int fdCount,
48 			    const FDSelect &src, /* IN */
49 			    unsigned int &subset_fd_count /* OUT */,
50 			    unsigned int &subset_fdselect_size /* OUT */,
51 			    unsigned int &subset_fdselect_format /* OUT */,
52 			    hb_vector_t<code_pair> &fdselect_ranges /* OUT */,
53 			    Remap &fdmap /* OUT */)
54 {
55   subset_fd_count = 0;
56   subset_fdselect_size = 0;
57   subset_fdselect_format = 0;
58   unsigned int  num_ranges = 0;
59 
60   unsigned int subset_num_glyphs = glyphs.len;
61   if (subset_num_glyphs == 0)
62     return true;
63 
64   {
65     /* use hb_set to determine the subset of font dicts */
66     hb_set_t  *set = hb_set_create ();
67     if (set == &Null (hb_set_t))
68       return false;
69     hb_codepoint_t  prev_fd = CFF_UNDEF_CODE;
70     for (hb_codepoint_t i = 0; i < subset_num_glyphs; i++)
71     {
72       hb_codepoint_t  fd = src.get_fd (glyphs[i]);
73       set->add (fd);
74 
75       if (fd != prev_fd)
76       {
77 	num_ranges++;
78 	prev_fd = fd;
79 	code_pair pair = { fd, i };
80 	fdselect_ranges.push (pair);
81       }
82     }
83 
84     subset_fd_count = set->get_population ();
85     if (subset_fd_count == fdCount)
86     {
87       /* all font dicts belong to the subset. no need to subset FDSelect & FDArray */
88       fdmap.identity (fdCount);
89       hb_set_destroy (set);
90     }
91     else
92     {
93       /* create a fdmap */
94       if (!fdmap.reset (fdCount))
95       {
96 	hb_set_destroy (set);
97 	return false;
98       }
99 
100       hb_codepoint_t  fd = CFF_UNDEF_CODE;
101       while (set->next (&fd))
102 	fdmap.add (fd);
103       hb_set_destroy (set);
104       if (unlikely (fdmap.get_count () != subset_fd_count))
105       	return false;
106     }
107 
108     /* update each font dict index stored as "code" in fdselect_ranges */
109     for (unsigned int i = 0; i < fdselect_ranges.len; i++)
110       fdselect_ranges[i].code = fdmap[fdselect_ranges[i].code];
111   }
112 
113   /* determine which FDSelect format is most compact */
114   if (subset_fd_count > 0xFF)
115   {
116     if (unlikely (src.format != 4))
117       return false;
118     subset_fdselect_format = 4;
119     subset_fdselect_size = FDSelect::min_size + FDSelect4::min_size + FDSelect4_Range::static_size * num_ranges + HBUINT32::static_size;
120   }
121   else
122   {
123 #if CFF_SERIALIZE_FDSELECT_0
124     unsigned int format0_size = FDSelect::min_size + FDSelect0::min_size + HBUINT8::static_size * subset_num_glyphs;
125 #endif
126     unsigned int format3_size = FDSelect::min_size + FDSelect3::min_size + FDSelect3_Range::static_size * num_ranges + HBUINT16::static_size;
127 
128 #if CFF_SERIALIZE_FDSELECT_0
129     if (format0_size <= format3_size)
130     {
131       // subset_fdselect_format = 0;
132       subset_fdselect_size = format0_size;
133     }
134     else
135 #endif
136     {
137       subset_fdselect_format = 3;
138       subset_fdselect_size = format3_size;
139     }
140   }
141 
142   return true;
143 }
144 
145 template <typename FDSELECT3_4>
146 static inline bool
serialize_fdselect_3_4(hb_serialize_context_t * c,const unsigned int num_glyphs,const FDSelect & src,unsigned int size,const hb_vector_t<code_pair> & fdselect_ranges)147 serialize_fdselect_3_4 (hb_serialize_context_t *c,
148 			  const unsigned int num_glyphs,
149 			  const FDSelect &src,
150 			  unsigned int size,
151 			  const hb_vector_t<code_pair> &fdselect_ranges)
152 {
153   TRACE_SERIALIZE (this);
154   FDSELECT3_4 *p = c->allocate_size<FDSELECT3_4> (size);
155   if (unlikely (p == nullptr)) return_trace (false);
156   p->nRanges.set (fdselect_ranges.len);
157   for (unsigned int i = 0; i < fdselect_ranges.len; i++)
158   {
159     p->ranges[i].first.set (fdselect_ranges[i].glyph);
160     p->ranges[i].fd.set (fdselect_ranges[i].code);
161   }
162   p->sentinel().set (num_glyphs);
163   return_trace (true);
164 }
165 
166 /**
167  * hb_serialize_cff_fdselect
168  * Serialize a subset FDSelect format planned above.
169  **/
170 bool
hb_serialize_cff_fdselect(hb_serialize_context_t * c,const unsigned int num_glyphs,const FDSelect & src,unsigned int fd_count,unsigned int fdselect_format,unsigned int size,const hb_vector_t<code_pair> & fdselect_ranges)171 hb_serialize_cff_fdselect (hb_serialize_context_t *c,
172 			  const unsigned int num_glyphs,
173 			  const FDSelect &src,
174 			  unsigned int fd_count,
175 			  unsigned int fdselect_format,
176 			  unsigned int size,
177 			  const hb_vector_t<code_pair> &fdselect_ranges)
178 {
179   TRACE_SERIALIZE (this);
180   FDSelect  *p = c->allocate_min<FDSelect> ();
181   if (unlikely (p == nullptr)) return_trace (false);
182   p->format.set (fdselect_format);
183   size -= FDSelect::min_size;
184 
185   switch (fdselect_format)
186   {
187 #if CFF_SERIALIZE_FDSELECT_0
188     case 0:
189     {
190       FDSelect0 *p = c->allocate_size<FDSelect0> (size);
191       if (unlikely (p == nullptr)) return_trace (false);
192       unsigned int range_index = 0;
193       unsigned int  fd = fdselect_ranges[range_index++].code;
194       for (unsigned int i = 0; i < num_glyphs; i++)
195       {
196 	if ((range_index < fdselect_ranges.len) &&
197 	    (i >= fdselect_ranges[range_index].glyph))
198 	{
199 	  fd = fdselect_ranges[range_index++].code;
200 	}
201 	p->fds[i].set (fd);
202       }
203       break;
204     }
205 #endif /* CFF_SERIALIZE_FDSELECT_0 */
206 
207     case 3:
208       return serialize_fdselect_3_4<FDSelect3> (c,
209 						num_glyphs,
210 						src,
211 						size,
212 						fdselect_ranges);
213 
214     case 4:
215       return serialize_fdselect_3_4<FDSelect4> (c,
216 						num_glyphs,
217 						src,
218 						size,
219 						fdselect_ranges);
220 
221     default:
222       assert(false);
223   }
224 
225   return_trace (true);
226 }
227