lib/tacontrol.h

   1 /* tacontrol.h */
   2
   3 /*
   4  * Copyright (C) 2014-2017 by Werner Lemberg.
   5  *
   6  * This file is part of the ttfautohint library, and may only be used,
   7  * modified, and distributed under the terms given in `COPYING'.  By
   8  * continuing to use, modify, or distribute this file you indicate that you
   9  * have read `COPYING' and understand and accept it fully.
  10  *
  11  * The file `COPYING' mentioned in the previous paragraph is distributed
  12  * with the ttfautohint library.
  13  */
  14
  15
  16 #ifndef TACONTROL_H_
  17 #define TACONTROL_H_
  18
  19 #ifdef __cplusplus
  20 extern "C" {
  21 #endif
  22
  23 #include <setjmp.h>  /* for flex error handling */
  24
  25
  26 /* see the section `Managing exceptions' in chapter 6 */
  27 /* (`The TrueType Instruction Set') of the OpenType reference */
  28 /* how `delta_shift' works */
  29
  30 #define CONTROL_DELTA_SHIFT 3 /* 1/8px */
  31 #define CONTROL_DELTA_FACTOR (1 << CONTROL_DELTA_SHIFT)
  32
  33 #define CONTROL_DELTA_SHIFT_MAX ((1.0 / CONTROL_DELTA_FACTOR) * 8)
  34 #define CONTROL_DELTA_SHIFT_MIN -CONTROL_DELTA_SHIFT_MAX
  35
  36
  37 /*
  38  * For the generated TrueType bytecode, we use
  39  *
  40  *   delta_base = 6   ,
  41  *
  42  * which gives us the following ppem ranges for the three delta
  43  * instructions:
  44  *
  45  *   DELTAP1    6-21ppem
  46  *   DELTAP2   22-37ppem
  47  *   DELTAP3   38-53ppem   .
  48  */
  49
  50 #define CONTROL_DELTA_PPEM_MIN 6
  51 #define CONTROL_DELTA_PPEM_MAX 53
  52
  53
  54 /*
  55  * The control type.
  56  */
  57
  58 typedef enum Control_Type_
  59 {
  60   Control_Delta_before_IUP,
  61   Control_Delta_after_IUP,
  62   Control_Single_Point_Segment_Left,
  63   Control_Single_Point_Segment_Right,
  64   Control_Single_Point_Segment_None,
  65   Control_Script_Feature
  66 } Control_Type;
  67
  68
  69 /*
  70  * A structure to hold control instructions.  A linked list of it gets
  71  * allocated by a successful call to `TA_control_parse_buffer'.  Use
  72  * `TA_control_free' to deallocate the list.
  73  *
  74  * `x_shift' and `y_shift' are in the range [-8;8] for delta exceptions
  75  * and in the range [SHRT_MIN;SHRT_MAX] for one-point segment offsets.
  76  *
  77  * The `Control' typedef is in `ta.h'.
  78  */
  79
  80 struct Control_
  81 {
  82   Control_Type type;
  83
  84   long font_idx;
  85   long glyph_idx;
  86   number_range* points;
  87   int x_shift;
  88   int y_shift;
  89   number_range* ppems;
  90
  91   int line_number;
  92
  93   struct Control_* next;
  94 };
  95
  96
  97 /*
  98  * A structure to hold a single control instruction.
  99  */
 100
 101 typedef struct Ctrl_
 102 {
 103   Control_Type type;
 104
 105   long font_idx;
 106   long glyph_idx;
 107   int ppem;
 108   int point_idx;
 109
 110   int x_shift;
 111   int y_shift;
 112
 113   int line_number;
 114 } Ctrl;
 115
 116
 117 /*
 118  * This structure is used for communication with `TA_control_parse'.
 119  */
 120
 121 typedef struct Control_Context_
 122 {
 123   /* The error code returned by the parser or lexer. */
 124   TA_Error error;
 125
 126   /* If no error, this holds the parsing result. */
 127   Control* result;
 128
 129   /*
 130    * The parser's or lexer's error message in case of error; might be the
 131    * empty string.
 132    */
 133   char errmsg[256];
 134
 135   /*
 136    * In case of error, `errline_num' gives the line number of the offending
 137    * line in `font->control_buf', starting with value 1; `errline_pos_left'
 138    * and `errline_pos_right' hold the left and right position of the
 139    * offending token in this line, also starting with value 1.  For
 140    * allocation errors or internal parser or lexer errors those values are
 141    * meaningless, though.
 142    */
 143   int errline_num;
 144   int errline_pos_left;
 145   int errline_pos_right;
 146
 147   /*
 148    * The current font index, useful for `TA_Err_Control_Invalid_Font_Index'.
 149    */
 150   long font_idx;
 151
 152   /*
 153    * The current glyph index, useful for
 154    * `TA_Err_Control_Invalid_Glyph_Index'.
 155    */
 156   long glyph_idx;
 157
 158   /*
 159    * If the returned error is `TA_Err_Control_Invalid_Range', these two
 160    * values set up the allowed range.
 161    */
 162   int number_set_min;
 163   int number_set_max;
 164
 165   /* private flex data */
 166   void* scanner;
 167   int eof;
 168   jmp_buf jump_buffer;
 169
 170   /* private bison data */
 171   FONT* font;
 172 } Control_Context;
 173
 174
 175 /*
 176  * Create and initialize a `Control' object.  In case of an allocation error,
 177  * the return value is NULL.  `point_set' and `ppem_set' are expected to be
 178  * in reverse list order; `TA_control_new' then reverts them to normal order.
 179  */
 180
 181 Control*
 182 TA_control_new(Control_Type type,
 183                long font_idx,
 184                long glyph_idx,
 185                number_range* point_set,
 186                double x_shift,
 187                double y_shift,
 188                number_range* ppem_set,
 189                int line_number);
 190
 191
 192 /*
 193  * Prepend `element' to `list' of `Control' objects.  If `element' is NULL,
 194  * return `list.
 195  */
 196
 197 Control*
 198 TA_control_prepend(Control* list,
 199                    Control* element);
 200
 201
 202 /*
 203  * Reverse a list of `Control' objects.
 204  */
 205
 206 Control*
 207 TA_control_reverse(Control* list);
 208
 209
 210 /*
 211  * Initialize the scanner data within a `Control_Context' object.
 212  * `font->control_buf' is the control instructions buffer to be parsed,
 213  * `font->control_len' its length.
 214  *
 215  * This function is defined in `tacontrol.flex'.
 216  */
 217
 218 void
 219 TA_control_scanner_init(Control_Context* context,
 220                         FONT* font);
 221
 222
 223 /*
 224  * Free the scanner data within a `Control_Context' object.
 225  *
 226  * This function is defined in `tacontrol.flex'.
 227  */
 228
 229 void
 230 TA_control_scanner_done(Control_Context* context);
 231
 232
 233 /*
 234  * Parse buffer with ttfautohint control instructions, stored in
 235  * `font->control_buf' with length `font->control_len'.
 236  *
 237  * The format of entries in such a control instructions buffer is given in
 238  * `ttfautohint.h' (option `control-file'); the following describes more
 239  * technical details, using the constants defined above.
 240  *
 241  * x shift and y shift values represent floating point numbers that get
 242  * rounded to multiples of 1/(2^CONTROL_DELTA_SHIFT) pixels.
 243  *
 244  * Values for x and y shifts must be in the range
 245  * [CONTROL_DELTA_SHIFT_MIN;CONTROL_DELTA_SHIFT_MAX].  Values for ppems must
 246  * be in the range [CONTROL_DELTA_PPEM_MIN;CONTROL_DELTA_PPEM_MAX].
 247  *
 248  * The returned error codes are 0 (TA_Err_Ok) or in the range 0x200-0x2FF;
 249  * see `ttfautohint-errors.h' for all possible values.
 250  *
 251  * `TA_control_parse_buffer' stores the parsed result in `font->control', to
 252  * be freed with `TA_control_free' after use.  If there is no control
 253  * instructions data (for example, an empty string or whitespace only)
 254  * nothing gets allocated, and `font->control' is set to NULL.
 255  *
 256  * In case of error, `error_string_p' holds an error message, `errlinenum_p'
 257  * gives the line number in the control instructions buffer where the error
 258  * occurred, `errline_p' the corresponding line, and `errpos_p' the position
 259  * in this line.  After use, `error_string_p' and `errline_p' must be
 260  * deallocated by the user.  Note that `errline_p' and `errpos_p' can be
 261  * NULL even in case of an error.  If there is no error, those four values
 262  * are undefined.
 263  */
 264
 265 TA_Error
 266 TA_control_parse_buffer(FONT* font,
 267                         char** error_string_p,
 268                         unsigned int* errlinenum_p,
 269                         char** errline_p,
 270                         char** errpos_p);
 271
 272
 273 /*
 274  * Apply coverage data from the control instructions file.
 275  */
 276
 277 void
 278 TA_control_apply_coverage(SFNT* sfnt,
 279                           FONT* font);
 280
 281 /*
 282  * Free the allocated data in `control'.
 283  */
 284
 285 void
 286 TA_control_free(Control* control);
 287
 288
 289 /*
 290  * Return a string representation of `font->control'.  After use, the string
 291  * should be deallocated with a call to `free'.  In case of an allocation
 292  * error, the return value is NULL.
 293  */
 294
 295 char*
 296 TA_control_show(FONT* font);
 297
 298
 299 /*
 300  * Build a tree providing sequential access to the control instructions data
 301  * in `font->control'.  This also sets `font->control_data_cur' to the first
 302  * element (or NULL if there isn't one).
 303  */
 304
 305 TA_Error
 306 TA_control_build_tree(FONT* font);
 307
 308
 309 /*
 310  * Free the control instructions data tree.
 311  */
 312
 313 void
 314 TA_control_free_tree(FONT* font);
 315
 316
 317 /*
 318  * Get next control instruction and store it in `font->control_data_cur'.
 319  */
 320
 321 void
 322 TA_control_get_next(FONT* font);
 323
 324
 325 /*
 326  * Access control instruction.  Return NULL if there is no more data.
 327  */
 328
 329 const Ctrl*
 330 TA_control_get_ctrl(FONT* font);
 331
 332
 333 /*
 334  * Collect one-point segment data for a given glyph index and store them in
 335  * `font->control_segment_dirs'.
 336  */
 337
 338 TA_Error
 339 TA_control_segment_dir_collect(FONT* font,
 340                                long font_idx,
 341                                long glyph_idx);
 342
 343 /*
 344  * Access next one-point segment data.  Returns 1 on success or 0 if no more
 345  * data.  In the latter case, it resets the internal iterator so that
 346  * calling this function another time starts at the beginning again.
 347  */
 348
 349 int
 350 TA_control_segment_dir_get_next(FONT* font,
 351                                 int* point_idx,
 352                                 TA_Direction* dir,
 353                                 int* left_offset,
 354                                 int* right_offset);
 355
 356
 357 #ifdef __cplusplus
 358 } /* extern "C" */
 359 #endif
 360
 361 #endif /* TACONTROL_H_ */
 362
 363 /* end of control.h */