1 /*
2  * Copyright © 2011,2012  Google, Inc.
3  * Copyright © 2018  Ebrahim Byagowi
4  *
5  *  This is part of HarfBuzz, a text shaping library.
6  *
7  * Permission is hereby granted, without written agreement and without
8  * license or royalty fees, to use, copy, modify, and distribute this
9  * software and its documentation for any purpose, provided that the
10  * above copyright notice and the following two paragraphs appear in
11  * all copies of this software.
12  *
13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
17  * DAMAGE.
18  *
19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
24  *
25  * Google Author(s): Behdad Esfahbod
26  */
27 
28 #ifndef HB_OT_OS2_TABLE_HH
29 #define HB_OT_OS2_TABLE_HH
30 
31 #include "hb-open-type.hh"
32 #include "hb-ot-os2-unicode-ranges.hh"
33 
34 #include "hb-set.hh"
35 
36 /*
37  * OS/2 and Windows Metrics
38  * https://docs.microsoft.com/en-us/typography/opentype/spec/os2
39  */
40 #define HB_OT_TAG_OS2 HB_TAG('O','S','/','2')
41 
42 
43 namespace OT {
44 
45 struct OS2V1Tail
46 {
sanitizeOT::OS2V1Tail47   bool sanitize (hb_sanitize_context_t *c) const
48   {
49     TRACE_SANITIZE (this);
50     return_trace (c->check_struct (this));
51   }
52 
53   public:
54   HBUINT32	ulCodePageRange1;
55   HBUINT32	ulCodePageRange2;
56   public:
57   DEFINE_SIZE_STATIC (8);
58 };
59 
60 struct OS2V2Tail
61 {
has_dataOT::OS2V2Tail62   bool has_data () const { return sxHeight || sCapHeight; }
63 
operator ->OT::OS2V2Tail64   const OS2V2Tail * operator -> () const { return this; }
65 
sanitizeOT::OS2V2Tail66   bool sanitize (hb_sanitize_context_t *c) const
67   {
68     TRACE_SANITIZE (this);
69     return_trace (c->check_struct (this));
70   }
71 
72   public:
73   HBINT16	sxHeight;
74   HBINT16	sCapHeight;
75   HBUINT16	usDefaultChar;
76   HBUINT16	usBreakChar;
77   HBUINT16	usMaxContext;
78   public:
79   DEFINE_SIZE_STATIC (10);
80 };
81 
82 struct OS2V5Tail
83 {
get_optical_sizeOT::OS2V5Tail84   inline bool get_optical_size (unsigned int *lower, unsigned int *upper) const
85   {
86     unsigned int lower_optical_size = usLowerOpticalPointSize;
87     unsigned int upper_optical_size = usUpperOpticalPointSize;
88 
89     /* Per https://docs.microsoft.com/en-us/typography/opentype/spec/os2#lps */
90     if (lower_optical_size < upper_optical_size &&
91 	lower_optical_size >= 1 && lower_optical_size <= 0xFFFE &&
92 	upper_optical_size >= 2 && upper_optical_size <= 0xFFFF)
93     {
94       *lower = lower_optical_size;
95       *upper = upper_optical_size;
96       return true;
97     }
98     return false;
99   }
100 
sanitizeOT::OS2V5Tail101   bool sanitize (hb_sanitize_context_t *c) const
102   {
103     TRACE_SANITIZE (this);
104     return_trace (c->check_struct (this));
105   }
106 
107   public:
108   HBUINT16	usLowerOpticalPointSize;
109   HBUINT16	usUpperOpticalPointSize;
110   public:
111   DEFINE_SIZE_STATIC (4);
112 };
113 
114 struct OS2
115 {
116   static constexpr hb_tag_t tableTag = HB_OT_TAG_OS2;
117 
has_dataOT::OS2118   bool has_data () const { return usWeightClass || usWidthClass || usFirstCharIndex || usLastCharIndex; }
119 
v1OT::OS2120   const OS2V1Tail &v1 () const { return version >= 1 ? v1X : Null (OS2V1Tail); }
v2OT::OS2121   const OS2V2Tail &v2 () const { return version >= 2 ? v2X : Null (OS2V2Tail); }
v5OT::OS2122   const OS2V5Tail &v5 () const { return version >= 5 ? v5X : Null (OS2V5Tail); }
123 
124   enum selection_flag_t {
125     ITALIC		= 1u<<0,
126     UNDERSCORE		= 1u<<1,
127     NEGATIVE		= 1u<<2,
128     OUTLINED		= 1u<<3,
129     STRIKEOUT		= 1u<<4,
130     BOLD		= 1u<<5,
131     REGULAR		= 1u<<6,
132     USE_TYPO_METRICS	= 1u<<7,
133     WWS			= 1u<<8,
134     OBLIQUE		= 1u<<9
135   };
136 
is_italicOT::OS2137   bool        is_italic () const { return fsSelection & ITALIC; }
is_obliqueOT::OS2138   bool       is_oblique () const { return fsSelection & OBLIQUE; }
use_typo_metricsOT::OS2139   bool use_typo_metrics () const { return fsSelection & USE_TYPO_METRICS; }
140 
141   enum width_class_t {
142     FWIDTH_ULTRA_CONDENSED	= 1, /* 50% */
143     FWIDTH_EXTRA_CONDENSED	= 2, /* 62.5% */
144     FWIDTH_CONDENSED		= 3, /* 75% */
145     FWIDTH_SEMI_CONDENSED	= 4, /* 87.5% */
146     FWIDTH_NORMAL		= 5, /* 100% */
147     FWIDTH_SEMI_EXPANDED	= 6, /* 112.5% */
148     FWIDTH_EXPANDED		= 7, /* 125% */
149     FWIDTH_EXTRA_EXPANDED	= 8, /* 150% */
150     FWIDTH_ULTRA_EXPANDED	= 9  /* 200% */
151   };
152 
get_widthOT::OS2153   float get_width () const
154   {
155     switch (usWidthClass) {
156     case FWIDTH_ULTRA_CONDENSED:return 50.f;
157     case FWIDTH_EXTRA_CONDENSED:return 62.5f;
158     case FWIDTH_CONDENSED:	return 75.f;
159     case FWIDTH_SEMI_CONDENSED:	return 87.5f;
160     default:
161     case FWIDTH_NORMAL:		return 100.f;
162     case FWIDTH_SEMI_EXPANDED:	return 112.5f;
163     case FWIDTH_EXPANDED:	return 125.f;
164     case FWIDTH_EXTRA_EXPANDED:	return 150.f;
165     case FWIDTH_ULTRA_EXPANDED:	return 200.f;
166     }
167   }
168 
subsetOT::OS2169   bool subset (hb_subset_context_t *c) const
170   {
171     TRACE_SUBSET (this);
172     OS2 *os2_prime = c->serializer->embed (this);
173     if (unlikely (!os2_prime)) return_trace (false);
174     if (c->plan->flags & HB_SUBSET_FLAGS_NO_PRUNE_UNICODE_RANGES)
175       return_trace (true);
176 
177     /* when --gids option is not used, no need to do collect_mapping that is
178        * iterating all codepoints in each subtable, which is not efficient */
179     uint16_t min_cp, max_cp;
180     find_min_and_max_codepoint (c->plan->unicodes, &min_cp, &max_cp);
181     os2_prime->usFirstCharIndex = min_cp;
182     os2_prime->usLastCharIndex = max_cp;
183 
184     _update_unicode_ranges (c->plan->unicodes, os2_prime->ulUnicodeRange);
185 
186     return_trace (true);
187   }
188 
_update_unicode_rangesOT::OS2189   void _update_unicode_ranges (const hb_set_t *codepoints,
190 			       HBUINT32 ulUnicodeRange[4]) const
191   {
192     HBUINT32	newBits[4];
193     for (unsigned int i = 0; i < 4; i++)
194       newBits[i] = 0;
195 
196     hb_codepoint_t cp = HB_SET_VALUE_INVALID;
197     while (codepoints->next (&cp)) {
198       unsigned int bit = _hb_ot_os2_get_unicode_range_bit (cp);
199       if (bit < 128)
200       {
201 	unsigned int block = bit / 32;
202 	unsigned int bit_in_block = bit % 32;
203 	unsigned int mask = 1 << bit_in_block;
204 	newBits[block] = newBits[block] | mask;
205       }
206       if (cp >= 0x10000 && cp <= 0x110000)
207       {
208 	/* the spec says that bit 57 ("Non Plane 0") implies that there's
209 	   at least one codepoint beyond the BMP; so I also include all
210 	   the non-BMP codepoints here */
211 	newBits[1] = newBits[1] | (1 << 25);
212       }
213     }
214 
215     for (unsigned int i = 0; i < 4; i++)
216       ulUnicodeRange[i] = ulUnicodeRange[i] & newBits[i]; // set bits only if set in the original
217   }
218 
find_min_and_max_codepointOT::OS2219   static void find_min_and_max_codepoint (const hb_set_t *codepoints,
220 					  uint16_t *min_cp, /* OUT */
221 					  uint16_t *max_cp  /* OUT */)
222   {
223     *min_cp = hb_min (0xFFFFu, codepoints->get_min ());
224     *max_cp = hb_min (0xFFFFu, codepoints->get_max ());
225   }
226 
227   /* https://github.com/Microsoft/Font-Validator/blob/520aaae/OTFontFileVal/val_OS2.cs#L644-L681 */
228   enum font_page_t
229   {
230     FONT_PAGE_HEBREW		= 0xB100, /* Hebrew Windows 3.1 font page */
231     FONT_PAGE_SIMP_ARABIC	= 0xB200, /* Simplified Arabic Windows 3.1 font page */
232     FONT_PAGE_TRAD_ARABIC	= 0xB300, /* Traditional Arabic Windows 3.1 font page */
233     FONT_PAGE_OEM_ARABIC	= 0xB400, /* OEM Arabic Windows 3.1 font page */
234     FONT_PAGE_SIMP_FARSI	= 0xBA00, /* Simplified Farsi Windows 3.1 font page */
235     FONT_PAGE_TRAD_FARSI	= 0xBB00, /* Traditional Farsi Windows 3.1 font page */
236     FONT_PAGE_THAI		= 0xDE00  /* Thai Windows 3.1 font page */
237   };
get_font_pageOT::OS2238   font_page_t get_font_page () const
239   { return (font_page_t) (version == 0 ? fsSelection & 0xFF00 : 0); }
240 
get_sizeOT::OS2241   unsigned get_size () const
242   {
243     unsigned result = min_size;
244     if (version >= 1) result += v1X.get_size ();
245     if (version >= 2) result += v2X.get_size ();
246     if (version >= 5) result += v5X.get_size ();
247     return result;
248   }
249 
sanitizeOT::OS2250   bool sanitize (hb_sanitize_context_t *c) const
251   {
252     TRACE_SANITIZE (this);
253     if (unlikely (!c->check_struct (this))) return_trace (false);
254     if (unlikely (version >= 1 && !v1X.sanitize (c))) return_trace (false);
255     if (unlikely (version >= 2 && !v2X.sanitize (c))) return_trace (false);
256     if (unlikely (version >= 5 && !v5X.sanitize (c))) return_trace (false);
257     return_trace (true);
258   }
259 
260   public:
261   HBUINT16	version;
262   HBINT16	xAvgCharWidth;
263   HBUINT16	usWeightClass;
264   HBUINT16	usWidthClass;
265   HBUINT16	fsType;
266   HBINT16	ySubscriptXSize;
267   HBINT16	ySubscriptYSize;
268   HBINT16	ySubscriptXOffset;
269   HBINT16	ySubscriptYOffset;
270   HBINT16	ySuperscriptXSize;
271   HBINT16	ySuperscriptYSize;
272   HBINT16	ySuperscriptXOffset;
273   HBINT16	ySuperscriptYOffset;
274   HBINT16	yStrikeoutSize;
275   HBINT16	yStrikeoutPosition;
276   HBINT16	sFamilyClass;
277   HBUINT8	panose[10];
278   HBUINT32	ulUnicodeRange[4];
279   Tag		achVendID;
280   HBUINT16	fsSelection;
281   HBUINT16	usFirstCharIndex;
282   HBUINT16	usLastCharIndex;
283   HBINT16	sTypoAscender;
284   HBINT16	sTypoDescender;
285   HBINT16	sTypoLineGap;
286   HBUINT16	usWinAscent;
287   HBUINT16	usWinDescent;
288   OS2V1Tail	v1X;
289   OS2V2Tail	v2X;
290   OS2V5Tail	v5X;
291   public:
292   DEFINE_SIZE_MIN (78);
293 };
294 
295 } /* namespace OT */
296 
297 
298 #endif /* HB_OT_OS2_TABLE_HH */
299