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 {
  47   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 {
  62   bool sanitize (hb_sanitize_context_t *c) const
  63   {
  64     TRACE_SANITIZE (this);
  65     return_trace (c->check_struct (this));
  66   }
  67 
  68   public:
  69   HBINT16       sxHeight;
  70   HBINT16       sCapHeight;
  71   HBUINT16      usDefaultChar;
  72   HBUINT16      usBreakChar;
  73   HBUINT16      usMaxContext;
  74   public:
  75   DEFINE_SIZE_STATIC (10);
  76 };
  77 
  78 struct OS2V5Tail
  79 {
  80   bool sanitize (hb_sanitize_context_t *c) const
  81   {
  82     TRACE_SANITIZE (this);
  83     return_trace (c->check_struct (this));
  84   }
  85 
  86   public:
  87   HBUINT16      usLowerOpticalPointSize;
  88   HBUINT16      usUpperOpticalPointSize;
  89   public:
  90   DEFINE_SIZE_STATIC (4);
  91 };
  92 
  93 struct OS2
  94 {
  95   static constexpr hb_tag_t tableTag = HB_OT_TAG_OS2;
  96 
  97   bool has_data () const { return this != &Null (OS2); }
  98 
  99   const OS2V1Tail &v1 () const { return version >= 1 ? v1X : Null (OS2V1Tail); }
 100   const OS2V2Tail &v2 () const { return version >= 2 ? v2X : Null (OS2V2Tail); }
 101   const OS2V5Tail &v5 () const { return version >= 5 ? v5X : Null (OS2V5Tail); }
 102 
 103   enum selection_flag_t {
 104     ITALIC              = 1u<<0,
 105     UNDERSCORE          = 1u<<1,
 106     NEGATIVE            = 1u<<2,
 107     OUTLINED            = 1u<<3,
 108     STRIKEOUT           = 1u<<4,
 109     BOLD                = 1u<<5,
 110     REGULAR             = 1u<<6,
 111     USE_TYPO_METRICS    = 1u<<7,
 112     WWS                 = 1u<<8,
 113     OBLIQUE             = 1u<<9
 114   };
 115 
 116   bool is_italic () const       { return fsSelection & ITALIC; }
 117   bool is_oblique () const      { return fsSelection & OBLIQUE; }
 118   bool is_typo_metrics () const { return fsSelection & USE_TYPO_METRICS; }
 119 
 120   enum width_class_t {
 121     FWIDTH_ULTRA_CONDENSED      = 1, /* 50% */
 122     FWIDTH_EXTRA_CONDENSED      = 2, /* 62.5% */
 123     FWIDTH_CONDENSED            = 3, /* 75% */
 124     FWIDTH_SEMI_CONDENSED       = 4, /* 87.5% */
 125     FWIDTH_NORMAL               = 5, /* 100% */
 126     FWIDTH_SEMI_EXPANDED        = 6, /* 112.5% */
 127     FWIDTH_EXPANDED             = 7, /* 125% */
 128     FWIDTH_EXTRA_EXPANDED       = 8, /* 150% */
 129     FWIDTH_ULTRA_EXPANDED       = 9  /* 200% */
 130   };
 131 
 132   float get_width () const
 133   {
 134     switch (usWidthClass) {
 135     case FWIDTH_ULTRA_CONDENSED:return 50.f;
 136     case FWIDTH_EXTRA_CONDENSED:return 62.5f;
 137     case FWIDTH_CONDENSED:      return 75.f;
 138     case FWIDTH_SEMI_CONDENSED: return 87.5f;
 139     default:
 140     case FWIDTH_NORMAL:         return 100.f;
 141     case FWIDTH_SEMI_EXPANDED:  return 112.5f;
 142     case FWIDTH_EXPANDED:       return 125.f;
 143     case FWIDTH_EXTRA_EXPANDED: return 150.f;
 144     case FWIDTH_ULTRA_EXPANDED: return 200.f;
 145     }
 146   }
 147 
 148   bool subset (hb_subset_plan_t *plan) const
 149   {
 150     hb_blob_t *os2_blob = hb_sanitize_context_t ().reference_table<OS2> (plan->source);
 151     hb_blob_t *os2_prime_blob = hb_blob_create_sub_blob (os2_blob, 0, -1);
 152     // TODO(grieger): move to hb_blob_copy_writable_or_fail
 153     hb_blob_destroy (os2_blob);
 154 
 155     OS2 *os2_prime = (OS2 *) hb_blob_get_data_writable (os2_prime_blob, nullptr);
 156     if (unlikely (!os2_prime)) {
 157       hb_blob_destroy (os2_prime_blob);
 158       return false;
 159     }
 160 
 161     uint16_t min_cp, max_cp;
 162     find_min_and_max_codepoint (plan->unicodes, &min_cp, &max_cp);
 163     os2_prime->usFirstCharIndex.set (min_cp);
 164     os2_prime->usLastCharIndex.set (max_cp);
 165 
 166     _update_unicode_ranges (plan->unicodes, os2_prime->ulUnicodeRange);
 167     bool result = plan->add_table (HB_OT_TAG_OS2, os2_prime_blob);
 168 
 169     hb_blob_destroy (os2_prime_blob);
 170     return result;
 171   }
 172 
 173   void _update_unicode_ranges (const hb_set_t *codepoints,
 174                                HBUINT32 ulUnicodeRange[4]) const
 175   {
 176     for (unsigned int i = 0; i < 4; i++)
 177       ulUnicodeRange[i].set (0);
 178 
 179     hb_codepoint_t cp = HB_SET_VALUE_INVALID;
 180     while (codepoints->next (&cp)) {
 181       unsigned int bit = _hb_ot_os2_get_unicode_range_bit (cp);
 182       if (bit < 128)
 183       {
 184         unsigned int block = bit / 32;
 185         unsigned int bit_in_block = bit % 32;
 186         unsigned int mask = 1 << bit_in_block;
 187         ulUnicodeRange[block].set (ulUnicodeRange[block] | mask);
 188       }
 189       if (cp >= 0x10000 && cp <= 0x110000)
 190       {
 191         /* the spec says that bit 57 ("Non Plane 0") implies that there's
 192            at least one codepoint beyond the BMP; so I also include all
 193            the non-BMP codepoints here */
 194         ulUnicodeRange[1].set (ulUnicodeRange[1] | (1 << 25));
 195       }
 196     }
 197   }
 198 
 199   static void find_min_and_max_codepoint (const hb_set_t *codepoints,
 200                                                  uint16_t *min_cp, /* OUT */
 201                                                  uint16_t *max_cp  /* OUT */)
 202   {
 203     *min_cp = codepoints->get_min ();
 204     *max_cp = codepoints->get_max ();
 205   }
 206 
 207   enum font_page_t {
 208     HEBREW_FONT_PAGE            = 0xB100, // Hebrew Windows 3.1 font page
 209     SIMP_ARABIC_FONT_PAGE       = 0xB200, // Simplified Arabic Windows 3.1 font page
 210     TRAD_ARABIC_FONT_PAGE       = 0xB300, // Traditional Arabic Windows 3.1 font page
 211     OEM_ARABIC_FONT_PAGE        = 0xB400, // OEM Arabic Windows 3.1 font page
 212     SIMP_FARSI_FONT_PAGE        = 0xBA00, // Simplified Farsi Windows 3.1 font page
 213     TRAD_FARSI_FONT_PAGE        = 0xBB00, // Traditional Farsi Windows 3.1 font page
 214     THAI_FONT_PAGE              = 0xDE00  // Thai Windows 3.1 font page
 215   };
 216 
 217   // https://github.com/Microsoft/Font-Validator/blob/520aaae/OTFontFileVal/val_OS2.cs#L644-L681
 218   font_page_t get_font_page () const
 219   { return (font_page_t) (version == 0 ? fsSelection & 0xFF00 : 0); }
 220 
 221   bool sanitize (hb_sanitize_context_t *c) const
 222   {
 223     TRACE_SANITIZE (this);
 224     if (unlikely (!c->check_struct (this))) return_trace (false);
 225     if (unlikely (version >= 1 && !v1X.sanitize (c))) return_trace (false);
 226     if (unlikely (version >= 2 && !v2X.sanitize (c))) return_trace (false);
 227     if (unlikely (version >= 5 && !v5X.sanitize (c))) return_trace (false);
 228     return_trace (true);
 229   }
 230 
 231   public:
 232   HBUINT16      version;
 233   HBINT16       xAvgCharWidth;
 234   HBUINT16      usWeightClass;
 235   HBUINT16      usWidthClass;
 236   HBUINT16      fsType;
 237   HBINT16       ySubscriptXSize;
 238   HBINT16       ySubscriptYSize;
 239   HBINT16       ySubscriptXOffset;
 240   HBINT16       ySubscriptYOffset;
 241   HBINT16       ySuperscriptXSize;
 242   HBINT16       ySuperscriptYSize;
 243   HBINT16       ySuperscriptXOffset;
 244   HBINT16       ySuperscriptYOffset;
 245   HBINT16       yStrikeoutSize;
 246   HBINT16       yStrikeoutPosition;
 247   HBINT16       sFamilyClass;
 248   HBUINT8       panose[10];
 249   HBUINT32      ulUnicodeRange[4];
 250   Tag           achVendID;
 251   HBUINT16      fsSelection;
 252   HBUINT16      usFirstCharIndex;
 253   HBUINT16      usLastCharIndex;
 254   HBINT16       sTypoAscender;
 255   HBINT16       sTypoDescender;
 256   HBINT16       sTypoLineGap;
 257   HBUINT16      usWinAscent;
 258   HBUINT16      usWinDescent;
 259   OS2V1Tail     v1X;
 260   OS2V2Tail     v2X;
 261   OS2V5Tail     v5X;
 262   public:
 263   DEFINE_SIZE_MIN (78);
 264 };
 265 
 266 } /* namespace OT */
 267 
 268 
 269 #endif /* HB_OT_OS2_TABLE_HH */