third_party/harfbuzz/src/harfbuzz-shape.h

   1 /*
   2  * Copyright (C) 2006  Red Hat, Inc.
   3  *
   4  * This is part of HarfBuzz, an OpenType Layout engine 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  * Red Hat Author(s): Owen Taylor
  25  */
  26
  27 #include <stdint.h>
  28
  29 /* Base Types */
  30
  31 typedef hb_uint16 HB_CodePoint; /* UTF-16 codepoint (not character ) */
  32 typedef char HB_Boolean;
  33 typedef hb_uint32 HB_Fixed; /* 26.6 */
  34 typedef hb_uint32 HB_Glyph;
  35 typedef hb_uint32 HB_Unichar;
  36
  37 /* Metrics reported by the font backend for use of the shaper */
  38 typedef struct _HB_GlyphMetrics HB_GlyphMetrics;
  39 struct _HB_GlyphMetrics
  40 {
  41     HB_Fixed advance;
  42
  43     /* Do we need ink/logical extents for the glyph here? */
  44 };
  45
  46 /*
  47  * HB_Font: Abstract font interface.
  48  *  First pass of this might just have FT_Face *getFace();
  49  */
  50 typedef struct _HB_Font HB_Font;
  51 typedef struct _HB_FontClass HB_FontClass;
  52
  53 struct HB_FontClass {
  54     HB_Glyph   (*charToGlyph)(HB_Font *font, HB_Unichar chr);
  55     void       (*getMetrics)(HB_Font *font, HB_Glyph glyph, HB_GlyphMetrics *metrics);
  56     HB_Boolean (*getSFontTable)(HB_Font *font, void **cookie, char **start, int *len);
  57     HB_Boolean (*freeSFontTable)(void **cookie);
  58 };
  59
  60 struct _HB_Font {
  61     HB_FontClass *clazz;
  62 };
  63
  64 /*
  65  * Language tags, of the form en-us; represented as interned, canonicalized
  66  * strings. hb_language_from_string("en_US"), hb_language_from_string("en-us")
  67  * both return the same (pointer-comparable) HB_Language).
  68  */
  69 typedef struct HB_Language_ *HB_Language;
  70
  71 HB_Language hb_language_from_string(const char *str);
  72 const char *hb_language_to_string(HB_Language language);
  73
  74 /* Special treatment for the edges of runs.
  75  */
  76 typedef enum {
  77     HB_RUN_EDGE_LINE_VISUAL_EDGE    = 1 << 0,
  78     HB_RUN_EDGE_LINE_LOGICAL_EDGE   = 1 << 1,
  79     HB_RUN_EDGE_LINE_ADD_HYPHEN     = 1 << 2  /* ???? */
  80 } HB_RunEdge;
  81
  82 /* Defines optional informaiton in HB_ShapeInput; this allows extension
  83  * of HB_ShapeInput while keeping binary compatibility
  84  */
  85 typedef enum {
  86     HB_SHAPE_START_TYPE = 1 << 0,
  87     HB_SHAPE_END_TYPE   = 1 << 1
  88 } HB_ShapeFlags;
  89
  90 /* Attributes types are described by "interned strings"; this is a little
  91  * annoying if you want to write a switch statement, but keeps things
  92  * simple.
  93  */
  94 typedef struct _HB_AttributeType *HB_AttributeType;
  95
  96 HB_AttributeType hb_attribute_type_from_string(const char *str);
  97 const char *hb_attribute_type_to_string(HB_AttributeType attribute_type);
  98
  99 struct HB_Attribute {
 100     HB_AttributeType type;
 101     int start;
 102     int end;
 103 };
 104
 105
 106 /**
 107  * You could handle this like HB_Language, but an enum seems a little nicer;
 108  * another approach would be to use OpenType script tags.
 109  */
 110 typedef enum {
 111     HB_SCRIPT_LATIN
 112     /* ... */
 113 } HB_ShapeScript;
 114
 115 /* This is just the subset of direction information needed by the shaper */
 116 typedef enum {
 117     HB_DIRECTION_LTR,
 118     HB_DIRECTION_RTL,
 119     HB_DIRECTION_TTB
 120 } HB_Direction;
 121
 122 typedef struct _HB_ShapeInput HB_ShapeInput;
 123 struct _HB_ShapeInput {
 124     /* Defines what fields the caller has initialized - fields not in
 125      * the enum are mandatory.
 126      */
 127     HB_ShapeFlags flags;
 128
 129     HB_CodePoint *text;
 130     int length;       /* total length of text to shape */
 131     int shape_offset; /* start of section to shape */
 132     int shape_length; /* number of code points to shape */
 133
 134     HB_Direction direction;
 135     HB_ShapeScript script;
 136     HB_Language language;
 137
 138     HB_AttributeType *attributes;
 139     int n_attributes;
 140
 141     HB_RunEdge start_type;
 142     HB_RunEdge end_type;
 143 };
 144
 145 struct HB_GlyphItem {
 146     HB_Glyph glyph;
 147
 148     HB_Fixed x_offset;
 149     HB_Fixed y_offset;
 150     HB_Fixed advance;
 151
 152     /* Add kashida information, etc, here */
 153 };
 154
 155 typedef enum {
 156     HB_RESULT_SUCCESS,
 157     HB_RESULT_NO_MEMORY,
 158     HB_SHAPE_RESULT_FAILED
 159 } HB_Result;
 160
 161 /*
 162  * Buffer for output
 163  */
 164 typedef struct _HB_GlyphBuffer HB_GlyphBuffer;
 165 struct _HB_GlyphBuffer {
 166     int glyph_item_size;
 167     int total_glyphs;
 168
 169     int *log_clusters; /* Uniscribe style */
 170     int cluster_space;
 171
 172     int glyph_space;
 173     void *glyph_buffer;
 174 };
 175
 176 /* Making this self-allocating simplifies writing shapers and
 177  * also keeps things easier for caller. item_size passed in
 178  * must be at least sizeof(HB_GlyphItem) but can be bigger,
 179  * to accomodate application structures that extend HB_GlyphItem.
 180  * The allocated items will be zero-initialized.
 181  *
 182  * (Hack: Harfbuzz could choose to use even a *bigger* item size
 183  * and stick internal information before the public item structure.
 184  * This hack could possibly be used to unify this with HB_Buffer)
 185  */
 186 HB_GlyphBuffer *hb_glyph_buffer_new             (size_t item_size);
 187 void            hb_glyph_buffer_clear           (HB_GlyphBuffer *buf);
 188 HB_Result       hb_glyph_buffer_extend_glyphs   (HB_GlyphBuffer *buf, int n_items);
 189 HB_Result       hb_glyph_buffer_extend_clusters (HB_GlyphBuffer *buf, int n_clusters);
 190 void            hb_glyph_buffer_free            (HB_GlyphBuffer *buf);
 191
 192
 193 /* Accessor for a particular glyph */
 194 #define HB_GLYPH_BUFFER_ITEM(buffer, index)
 195
 196 /*
 197  * Main shaping function
 198  */
 199 HB_Result hb_shape(HB_ShapeInput *input, HB_GlyphBuffer *output);