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-rw-r--r--src/autofit/hbshim.c546
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diff --git a/src/autofit/hbshim.c b/src/autofit/hbshim.c
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--- a/src/autofit/hbshim.c
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-/***************************************************************************/
-/* */
-/* hbshim.c */
-/* */
-/* HarfBuzz interface for accessing OpenType features (body). */
-/* */
-/* Copyright 2013-2015 by */
-/* David Turner, Robert Wilhelm, and Werner Lemberg. */
-/* */
-/* This file is part of the FreeType project, and may only be used, */
-/* modified, and distributed under the terms of the FreeType project */
-/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
-/* this file you indicate that you have read the license and */
-/* understand and accept it fully. */
-/* */
-/***************************************************************************/
-
-
-#include <ft2build.h>
-#include FT_FREETYPE_H
-#include "afglobal.h"
-#include "aftypes.h"
-#include "hbshim.h"
-
-#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
-
-
- /*************************************************************************/
- /* */
- /* The macro FT_COMPONENT is used in trace mode. It is an implicit */
- /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */
- /* messages during execution. */
- /* */
-#undef FT_COMPONENT
-#define FT_COMPONENT trace_afharfbuzz
-
-
- /*
- * We use `sets' (in the HarfBuzz sense, which comes quite near to the
- * usual mathematical meaning) to manage both lookups and glyph indices.
- *
- * 1. For each coverage, collect lookup IDs in a set. Note that an
- * auto-hinter `coverage' is represented by one `feature', and a
- * feature consists of an arbitrary number of (font specific) `lookup's
- * that actually do the mapping job. Please check the OpenType
- * specification for more details on features and lookups.
- *
- * 2. Create glyph ID sets from the corresponding lookup sets.
- *
- * 3. The glyph set corresponding to AF_COVERAGE_DEFAULT is computed
- * with all lookups specific to the OpenType script activated. It
- * relies on the order of AF_DEFINE_STYLE_CLASS entries so that
- * special coverages (like `oldstyle figures') don't get overwritten.
- *
- */
-
-
- /* load coverage tags */
-#undef COVERAGE
-#define COVERAGE( name, NAME, description, \
- tag1, tag2, tag3, tag4 ) \
- static const hb_tag_t name ## _coverage[] = \
- { \
- HB_TAG( tag1, tag2, tag3, tag4 ), \
- HB_TAG_NONE \
- };
-
-
-#include "afcover.h"
-
-
- /* define mapping between coverage tags and AF_Coverage */
-#undef COVERAGE
-#define COVERAGE( name, NAME, description, \
- tag1, tag2, tag3, tag4 ) \
- name ## _coverage,
-
-
- static const hb_tag_t* coverages[] =
- {
-#include "afcover.h"
-
- NULL /* AF_COVERAGE_DEFAULT */
- };
-
-
- /* load HarfBuzz script tags */
-#undef SCRIPT
-#define SCRIPT( s, S, d, h, sc1, sc2, sc3 ) h,
-
-
- static const hb_script_t scripts[] =
- {
-#include "afscript.h"
- };
-
-
- FT_Error
- af_get_coverage( AF_FaceGlobals globals,
- AF_StyleClass style_class,
- FT_Byte* gstyles )
- {
- hb_face_t* face;
-
- hb_set_t* gsub_lookups; /* GSUB lookups for a given script */
- hb_set_t* gsub_glyphs; /* glyphs covered by GSUB lookups */
- hb_set_t* gpos_lookups; /* GPOS lookups for a given script */
- hb_set_t* gpos_glyphs; /* glyphs covered by GPOS lookups */
-
- hb_script_t script;
- const hb_tag_t* coverage_tags;
- hb_tag_t script_tags[] = { HB_TAG_NONE,
- HB_TAG_NONE,
- HB_TAG_NONE,
- HB_TAG_NONE };
-
- hb_codepoint_t idx;
-#ifdef FT_DEBUG_LEVEL_TRACE
- int count;
-#endif
-
-
- if ( !globals || !style_class || !gstyles )
- return FT_THROW( Invalid_Argument );
-
- face = hb_font_get_face( globals->hb_font );
-
- gsub_lookups = hb_set_create();
- gsub_glyphs = hb_set_create();
- gpos_lookups = hb_set_create();
- gpos_glyphs = hb_set_create();
-
- coverage_tags = coverages[style_class->coverage];
- script = scripts[style_class->script];
-
- /* Convert a HarfBuzz script tag into the corresponding OpenType */
- /* tag or tags -- some Indic scripts like Devanagari have an old */
- /* and a new set of features. */
- hb_ot_tags_from_script( script,
- &script_tags[0],
- &script_tags[1] );
-
- /* `hb_ot_tags_from_script' usually returns HB_OT_TAG_DEFAULT_SCRIPT */
- /* as the second tag. We change that to HB_TAG_NONE except for the */
- /* default script. */
- if ( style_class->script == globals->module->default_script &&
- style_class->coverage == AF_COVERAGE_DEFAULT )
- {
- if ( script_tags[0] == HB_TAG_NONE )
- script_tags[0] = HB_OT_TAG_DEFAULT_SCRIPT;
- else
- {
- if ( script_tags[1] == HB_TAG_NONE )
- script_tags[1] = HB_OT_TAG_DEFAULT_SCRIPT;
- else if ( script_tags[1] != HB_OT_TAG_DEFAULT_SCRIPT )
- script_tags[2] = HB_OT_TAG_DEFAULT_SCRIPT;
- }
- }
- else
- {
- if ( script_tags[1] == HB_OT_TAG_DEFAULT_SCRIPT )
- script_tags[1] = HB_TAG_NONE;
- }
-
- hb_ot_layout_collect_lookups( face,
- HB_OT_TAG_GSUB,
- script_tags,
- NULL,
- coverage_tags,
- gsub_lookups );
-
- if ( hb_set_is_empty( gsub_lookups ) )
- goto Exit; /* nothing to do */
-
- hb_ot_layout_collect_lookups( face,
- HB_OT_TAG_GPOS,
- script_tags,
- NULL,
- coverage_tags,
- gpos_lookups );
-
- FT_TRACE4(( "GSUB lookups (style `%s'):\n"
- " ",
- af_style_names[style_class->style] ));
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- count = 0;
-#endif
-
- for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_lookups, &idx ); )
- {
-#ifdef FT_DEBUG_LEVEL_TRACE
- FT_TRACE4(( " %d", idx ));
- count++;
-#endif
-
- /* get output coverage of GSUB feature */
- hb_ot_layout_lookup_collect_glyphs( face,
- HB_OT_TAG_GSUB,
- idx,
- NULL,
- NULL,
- NULL,
- gsub_glyphs );
- }
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- if ( !count )
- FT_TRACE4(( " (none)" ));
- FT_TRACE4(( "\n\n" ));
-#endif
-
- FT_TRACE4(( "GPOS lookups (style `%s'):\n"
- " ",
- af_style_names[style_class->style] ));
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- count = 0;
-#endif
-
- for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gpos_lookups, &idx ); )
- {
-#ifdef FT_DEBUG_LEVEL_TRACE
- FT_TRACE4(( " %d", idx ));
- count++;
-#endif
-
- /* get input coverage of GPOS feature */
- hb_ot_layout_lookup_collect_glyphs( face,
- HB_OT_TAG_GPOS,
- idx,
- NULL,
- gpos_glyphs,
- NULL,
- NULL );
- }
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- if ( !count )
- FT_TRACE4(( " (none)" ));
- FT_TRACE4(( "\n\n" ));
-#endif
-
- /*
- * We now check whether we can construct blue zones, using glyphs
- * covered by the feature only. In case there is not a single zone
- * (this is, not a single character is covered), we skip this coverage.
- *
- */
- if ( style_class->coverage != AF_COVERAGE_DEFAULT )
- {
- AF_Blue_Stringset bss = style_class->blue_stringset;
- const AF_Blue_StringRec* bs = &af_blue_stringsets[bss];
-
- FT_Bool found = 0;
-
-
- for ( ; bs->string != AF_BLUE_STRING_MAX; bs++ )
- {
- const char* p = &af_blue_strings[bs->string];
-
-
- while ( *p )
- {
- hb_codepoint_t ch;
-
-
- GET_UTF8_CHAR( ch, p );
-
- for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_lookups,
- &idx ); )
- {
- hb_codepoint_t gidx = FT_Get_Char_Index( globals->face, ch );
-
-
- if ( hb_ot_layout_lookup_would_substitute( face, idx,
- &gidx, 1, 1 ) )
- {
- found = 1;
- break;
- }
- }
- }
- }
-
- if ( !found )
- {
- FT_TRACE4(( " no blue characters found; style skipped\n" ));
- goto Exit;
- }
- }
-
- /*
- * Various OpenType features might use the same glyphs at different
- * vertical positions; for example, superscript and subscript glyphs
- * could be the same. However, the auto-hinter is completely
- * agnostic of OpenType features after the feature analysis has been
- * completed: The engine then simply receives a glyph index and returns a
- * hinted and usually rendered glyph.
- *
- * Consider the superscript feature of font `pala.ttf': Some of the
- * glyphs are `real', this is, they have a zero vertical offset, but
- * most of them are small caps glyphs shifted up to the superscript
- * position (this is, the `sups' feature is present in both the GSUB and
- * GPOS tables). The code for blue zones computation actually uses a
- * feature's y offset so that the `real' glyphs get correct hints. But
- * later on it is impossible to decide whether a glyph index belongs to,
- * say, the small caps or superscript feature.
- *
- * For this reason, we don't assign a style to a glyph if the current
- * feature covers the glyph in both the GSUB and the GPOS tables. This
- * is quite a broad condition, assuming that
- *
- * (a) glyphs that get used in multiple features are present in a
- * feature without vertical shift,
- *
- * and
- *
- * (b) a feature's GPOS data really moves the glyph vertically.
- *
- * Not fulfilling condition (a) makes a font larger; it would also
- * reduce the number of glyphs that could be addressed directly without
- * using OpenType features, so this assumption is rather strong.
- *
- * Condition (b) is much weaker, and there might be glyphs which get
- * missed. However, the OpenType features we are going to handle are
- * primarily located in GSUB, and HarfBuzz doesn't provide an API to
- * directly get the necessary information from the GPOS table. A
- * possible solution might be to directly parse the GPOS table to find
- * out whether a glyph gets shifted vertically, but this is something I
- * would like to avoid if not really necessary.
- *
- * Note that we don't follow this logic for the default coverage.
- * Complex scripts like Devanagari have mandatory GPOS features to
- * position many glyph elements, using mark-to-base or mark-to-ligature
- * tables; the number of glyphs missed due to condition (b) would be far
- * too large.
- *
- */
- if ( style_class->coverage != AF_COVERAGE_DEFAULT )
- hb_set_subtract( gsub_glyphs, gpos_glyphs );
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- FT_TRACE4(( " glyphs without GPOS data (`*' means already assigned)" ));
- count = 0;
-#endif
-
- for ( idx = HB_SET_VALUE_INVALID; hb_set_next( gsub_glyphs, &idx ); )
- {
-#ifdef FT_DEBUG_LEVEL_TRACE
- if ( !( count % 10 ) )
- FT_TRACE4(( "\n"
- " " ));
-
- FT_TRACE4(( " %d", idx ));
- count++;
-#endif
-
- /* glyph indices returned by `hb_ot_layout_lookup_collect_glyphs' */
- /* can be arbitrary: some fonts use fake indices for processing */
- /* internal to GSUB or GPOS, which is fully valid */
- if ( idx >= (hb_codepoint_t)globals->glyph_count )
- continue;
-
- if ( gstyles[idx] == AF_STYLE_UNASSIGNED )
- gstyles[idx] = (FT_Byte)style_class->style;
-#ifdef FT_DEBUG_LEVEL_TRACE
- else
- FT_TRACE4(( "*" ));
-#endif
- }
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- if ( !count )
- FT_TRACE4(( "\n"
- " (none)" ));
- FT_TRACE4(( "\n\n" ));
-#endif
-
- Exit:
- hb_set_destroy( gsub_lookups );
- hb_set_destroy( gsub_glyphs );
- hb_set_destroy( gpos_lookups );
- hb_set_destroy( gpos_glyphs );
-
- return FT_Err_Ok;
- }
-
-
- /* construct HarfBuzz features */
-#undef COVERAGE
-#define COVERAGE( name, NAME, description, \
- tag1, tag2, tag3, tag4 ) \
- static const hb_feature_t name ## _feature[] = \
- { \
- { \
- HB_TAG( tag1, tag2, tag3, tag4 ), \
- 1, 0, (unsigned int)-1 \
- } \
- };
-
-
-#include "afcover.h"
-
-
- /* define mapping between HarfBuzz features and AF_Coverage */
-#undef COVERAGE
-#define COVERAGE( name, NAME, description, \
- tag1, tag2, tag3, tag4 ) \
- name ## _feature,
-
-
- static const hb_feature_t* features[] =
- {
-#include "afcover.h"
-
- NULL /* AF_COVERAGE_DEFAULT */
- };
-
-
- FT_Error
- af_get_char_index( AF_StyleMetrics metrics,
- FT_ULong charcode,
- FT_ULong *codepoint,
- FT_Long *y_offset )
- {
- AF_StyleClass style_class;
-
- const hb_feature_t* feature;
-
- FT_ULong in_idx, out_idx;
-
-
- if ( !metrics )
- return FT_THROW( Invalid_Argument );
-
- in_idx = FT_Get_Char_Index( metrics->globals->face, charcode );
-
- style_class = metrics->style_class;
-
- feature = features[style_class->coverage];
-
- if ( feature )
- {
- FT_Int upem = (FT_Int)metrics->globals->face->units_per_EM;
-
- hb_font_t* font = metrics->globals->hb_font;
- hb_buffer_t* buf = hb_buffer_create();
-
- uint32_t c = (uint32_t)charcode;
-
- hb_glyph_info_t* ginfo;
- hb_glyph_position_t* gpos;
- unsigned int gcount;
-
-
- /* we shape at a size of units per EM; this means font units */
- hb_font_set_scale( font, upem, upem );
-
- /* XXX: is this sufficient for a single character of any script? */
- hb_buffer_set_direction( buf, HB_DIRECTION_LTR );
- hb_buffer_set_script( buf, scripts[style_class->script] );
-
- /* we add one character to `buf' ... */
- hb_buffer_add_utf32( buf, &c, 1, 0, 1 );
-
- /* ... and apply one feature */
- hb_shape( font, buf, feature, 1 );
-
- ginfo = hb_buffer_get_glyph_infos( buf, &gcount );
- gpos = hb_buffer_get_glyph_positions( buf, &gcount );
-
- out_idx = ginfo[0].codepoint;
-
- /* getting the same index indicates no substitution, */
- /* which means that the glyph isn't available in the feature */
- if ( in_idx == out_idx )
- {
- *codepoint = 0;
- *y_offset = 0;
- }
- else
- {
- *codepoint = out_idx;
- *y_offset = gpos[0].y_offset;
- }
-
- hb_buffer_destroy( buf );
-
-#ifdef FT_DEBUG_LEVEL_TRACE
- if ( gcount > 1 )
- FT_TRACE1(( "af_get_char_index:"
- " input character mapped to multiple glyphs\n" ));
-#endif
- }
- else
- {
- *codepoint = in_idx;
- *y_offset = 0;
- }
-
- return FT_Err_Ok;
- }
-
-
-#else /* !FT_CONFIG_OPTION_USE_HARFBUZZ */
-
-
- FT_Error
- af_get_coverage( AF_FaceGlobals globals,
- AF_StyleClass style_class,
- FT_Byte* gstyles )
- {
- FT_UNUSED( globals );
- FT_UNUSED( style_class );
- FT_UNUSED( gstyles );
-
- return FT_Err_Ok;
- }
-
-
- FT_Error
- af_get_char_index( AF_StyleMetrics metrics,
- FT_ULong charcode,
- FT_ULong *codepoint,
- FT_Long *y_offset )
- {
- FT_Face face;
-
-
- if ( !metrics )
- return FT_THROW( Invalid_Argument );
-
- face = metrics->globals->face;
-
- *codepoint = FT_Get_Char_Index( face, charcode );
- *y_offset = 0;
-
- return FT_Err_Ok;
- }
-
-
-#endif /* !FT_CONFIG_OPTION_USE_HARFBUZZ */
-
-
-/* END */