1 /*
   2  * Copyright © 2017  Google, 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  * Google Author(s): Behdad Esfahbod
  25  */
  26 
  27 #ifndef HB_OT_VAR_FVAR_TABLE_HH
  28 #define HB_OT_VAR_FVAR_TABLE_HH
  29 
  30 #include "hb-open-type.hh"
  31 
  32 /*
  33  * fvar -- Font Variations
  34  * https://docs.microsoft.com/en-us/typography/opentype/spec/fvar
  35  */
  36 
  37 #define HB_OT_TAG_fvar HB_TAG('f','v','a','r')
  38 
  39 
  40 namespace OT {
  41 
  42 
  43 struct InstanceRecord
  44 {
  45   friend struct fvar;
  46 
  47   hb_array_t<const Fixed> get_coordinates (unsigned int axis_count) const
  48   { return coordinatesZ.as_array (axis_count); }
  49 
  50   bool sanitize (hb_sanitize_context_t *c, unsigned int axis_count) const
  51   {
  52     TRACE_SANITIZE (this);
  53     return_trace (c->check_struct (this) &&
  54                   c->check_array (coordinatesZ.arrayZ, axis_count));
  55   }
  56 
  57   protected:
  58   NameID        subfamilyNameID;/* The name ID for entries in the 'name' table
  59                                  * that provide subfamily names for this instance. */
  60   HBUINT16      flags;          /* Reserved for future use — set to 0. */
  61   UnsizedArrayOf<Fixed>
  62                 coordinatesZ;   /* The coordinates array for this instance. */
  63   //NameID      postScriptNameIDX;/*Optional. The name ID for entries in the 'name'
  64   //                              * table that provide PostScript names for this
  65   //                              * instance. */
  66 
  67   public:
  68   DEFINE_SIZE_UNBOUNDED (4);
  69 };
  70 
  71 struct AxisRecord
  72 {
  73   enum
  74   {
  75     AXIS_FLAG_HIDDEN    = 0x0001,
  76   };
  77 
  78   bool sanitize (hb_sanitize_context_t *c) const
  79   {
  80     TRACE_SANITIZE (this);
  81     return_trace (c->check_struct (this));
  82   }
  83 
  84   public:
  85   Tag           axisTag;        /* Tag identifying the design variation for the axis. */
  86   Fixed         minValue;       /* The minimum coordinate value for the axis. */
  87   Fixed         defaultValue;   /* The default coordinate value for the axis. */
  88   Fixed         maxValue;       /* The maximum coordinate value for the axis. */
  89   HBUINT16      flags;          /* Axis flags. */
  90   NameID        axisNameID;     /* The name ID for entries in the 'name' table that
  91                                  * provide a display name for this axis. */
  92 
  93   public:
  94   DEFINE_SIZE_STATIC (20);
  95 };
  96 
  97 struct fvar
  98 {
  99   static constexpr hb_tag_t tableTag = HB_OT_TAG_fvar;
 100 
 101   bool has_data () const { return version.to_int (); }
 102 
 103   bool sanitize (hb_sanitize_context_t *c) const
 104   {
 105     TRACE_SANITIZE (this);
 106     return_trace (version.sanitize (c) &&
 107                   likely (version.major == 1) &&
 108                   c->check_struct (this) &&
 109                   axisSize == 20 && /* Assumed in our code. */
 110                   instanceSize >= axisCount * 4 + 4 &&
 111                   get_axes ().sanitize (c) &&
 112                   c->check_range (get_instance (0), instanceCount, instanceSize));
 113   }
 114 
 115   unsigned int get_axis_count () const { return axisCount; }
 116 
 117   void get_axis_deprecated (unsigned int axis_index,
 118                                    hb_ot_var_axis_t *info) const
 119   {
 120     const AxisRecord &axis = get_axes ()[axis_index];
 121     info->tag = axis.axisTag;
 122     info->name_id =  axis.axisNameID;
 123     info->default_value = axis.defaultValue / 65536.;
 124     /* Ensure order, to simplify client math. */
 125     info->min_value = MIN<float> (info->default_value, axis.minValue / 65536.);
 126     info->max_value = MAX<float> (info->default_value, axis.maxValue / 65536.);
 127   }
 128 
 129   void get_axis_info (unsigned int axis_index,
 130                       hb_ot_var_axis_info_t *info) const
 131   {
 132     const AxisRecord &axis = get_axes ()[axis_index];
 133     info->axis_index = axis_index;
 134     info->tag = axis.axisTag;
 135     info->name_id =  axis.axisNameID;
 136     info->flags = (hb_ot_var_axis_flags_t) (unsigned int) axis.flags;
 137     info->default_value = axis.defaultValue / 65536.;
 138     /* Ensure order, to simplify client math. */
 139     info->min_value = MIN<float> (info->default_value, axis.minValue / 65536.);
 140     info->max_value = MAX<float> (info->default_value, axis.maxValue / 65536.);
 141     info->reserved = 0;
 142   }
 143 
 144   unsigned int get_axes_deprecated (unsigned int      start_offset,
 145                                     unsigned int     *axes_count /* IN/OUT */,
 146                                     hb_ot_var_axis_t *axes_array /* OUT */) const
 147   {
 148     if (axes_count)
 149     {
 150       /* TODO Rewrite as hb_array_t<>::sub-array() */
 151       unsigned int count = axisCount;
 152       start_offset = MIN (start_offset, count);
 153 
 154       count -= start_offset;
 155       axes_array += start_offset;
 156 
 157       count = MIN (count, *axes_count);
 158       *axes_count = count;
 159 
 160       for (unsigned int i = 0; i < count; i++)
 161         get_axis_deprecated (start_offset + i, axes_array + i);
 162     }
 163     return axisCount;
 164   }
 165 
 166   unsigned int get_axis_infos (unsigned int           start_offset,
 167                                unsigned int          *axes_count /* IN/OUT */,
 168                                hb_ot_var_axis_info_t *axes_array /* OUT */) const
 169   {
 170     if (axes_count)
 171     {
 172       /* TODO Rewrite as hb_array_t<>::sub-array() */
 173       unsigned int count = axisCount;
 174       start_offset = MIN (start_offset, count);
 175 
 176       count -= start_offset;
 177       axes_array += start_offset;
 178 
 179       count = MIN (count, *axes_count);
 180       *axes_count = count;
 181 
 182       for (unsigned int i = 0; i < count; i++)
 183         get_axis_info (start_offset + i, axes_array + i);
 184     }
 185     return axisCount;
 186   }
 187 
 188   bool find_axis_deprecated (hb_tag_t tag,
 189                              unsigned int *axis_index,
 190                              hb_ot_var_axis_t *info) const
 191   {
 192     const AxisRecord *axes = get_axes ();
 193     unsigned int count = get_axis_count ();
 194     for (unsigned int i = 0; i < count; i++)
 195       if (axes[i].axisTag == tag)
 196       {
 197         if (axis_index)
 198           *axis_index = i;
 199         get_axis_deprecated (i, info);
 200         return true;
 201       }
 202     if (axis_index)
 203       *axis_index = HB_OT_VAR_NO_AXIS_INDEX;
 204     return false;
 205   }
 206 
 207   bool find_axis_info (hb_tag_t tag,
 208                        hb_ot_var_axis_info_t *info) const
 209   {
 210     const AxisRecord *axes = get_axes ();
 211     unsigned int count = get_axis_count ();
 212     for (unsigned int i = 0; i < count; i++)
 213       if (axes[i].axisTag == tag)
 214       {
 215         get_axis_info (i, info);
 216         return true;
 217       }
 218     return false;
 219   }
 220 
 221   int normalize_axis_value (unsigned int axis_index, float v) const
 222   {
 223     hb_ot_var_axis_info_t axis;
 224     get_axis_info (axis_index, &axis);
 225 
 226     v = MAX (MIN (v, axis.max_value), axis.min_value); /* Clamp. */
 227 
 228     if (v == axis.default_value)
 229       return 0;
 230     else if (v < axis.default_value)
 231       v = (v - axis.default_value) / (axis.default_value - axis.min_value);
 232     else
 233       v = (v - axis.default_value) / (axis.max_value - axis.default_value);
 234     return (int) (v * 16384.f + (v >= 0.f ? .5f : -.5f));
 235   }
 236 
 237   unsigned int get_instance_count () const { return instanceCount; }
 238 
 239   hb_ot_name_id_t get_instance_subfamily_name_id (unsigned int instance_index) const
 240   {
 241     const InstanceRecord *instance = get_instance (instance_index);
 242     if (unlikely (!instance)) return HB_OT_NAME_ID_INVALID;
 243     return instance->subfamilyNameID;
 244   }
 245 
 246   hb_ot_name_id_t get_instance_postscript_name_id (unsigned int instance_index) const
 247   {
 248     const InstanceRecord *instance = get_instance (instance_index);
 249     if (unlikely (!instance)) return HB_OT_NAME_ID_INVALID;
 250     if (instanceSize >= axisCount * 4 + 6)
 251       return StructAfter<NameID> (instance->get_coordinates (axisCount));
 252     return HB_OT_NAME_ID_INVALID;
 253   }
 254 
 255   unsigned int get_instance_coords (unsigned int  instance_index,
 256                                            unsigned int *coords_length, /* IN/OUT */
 257                                            float        *coords         /* OUT */) const
 258   {
 259     const InstanceRecord *instance = get_instance (instance_index);
 260     if (unlikely (!instance))
 261     {
 262       if (coords_length)
 263         *coords_length = 0;
 264       return 0;
 265     }
 266 
 267     if (coords_length && *coords_length)
 268     {
 269       hb_array_t<const Fixed> instanceCoords = instance->get_coordinates (axisCount)
 270                                                          .sub_array (0, *coords_length);
 271       for (unsigned int i = 0; i < instanceCoords.length; i++)
 272         coords[i] = instanceCoords.arrayZ[i].to_float ();
 273     }
 274     return axisCount;
 275   }
 276 
 277   protected:
 278   hb_array_t<const AxisRecord> get_axes () const
 279   { return hb_array (&(this+firstAxis), axisCount); }
 280 
 281   const InstanceRecord *get_instance (unsigned int i) const
 282   {
 283     if (unlikely (i >= instanceCount)) return nullptr;
 284    return &StructAtOffset<InstanceRecord> (&StructAfter<InstanceRecord> (get_axes ()),
 285                                            i * instanceSize);
 286   }
 287 
 288   protected:
 289   FixedVersion<>version;        /* Version of the fvar table
 290                                  * initially set to 0x00010000u */
 291   OffsetTo<AxisRecord>
 292                 firstAxis;      /* Offset in bytes from the beginning of the table
 293                                  * to the start of the AxisRecord array. */
 294   HBUINT16      reserved;       /* This field is permanently reserved. Set to 2. */
 295   HBUINT16      axisCount;      /* The number of variation axes in the font (the
 296                                  * number of records in the axes array). */
 297   HBUINT16      axisSize;       /* The size in bytes of each VariationAxisRecord —
 298                                  * set to 20 (0x0014) for this version. */
 299   HBUINT16      instanceCount;  /* The number of named instances defined in the font
 300                                  * (the number of records in the instances array). */
 301   HBUINT16      instanceSize;   /* The size in bytes of each InstanceRecord — set
 302                                  * to either axisCount * sizeof(Fixed) + 4, or to
 303                                  * axisCount * sizeof(Fixed) + 6. */
 304 
 305   public:
 306   DEFINE_SIZE_STATIC (16);
 307 };
 308 
 309 } /* namespace OT */
 310 
 311 
 312 #endif /* HB_OT_VAR_FVAR_TABLE_HH */