ref: 5cf01aa2b26727abd97ef202a3687cd7a43819c3
dir: /src/autofit/aflatin.c/
/****************************************************************************
*
* aflatin.c
*
* Auto-fitter hinting routines for latin writing system (body).
*
* Copyright (C) 2003-2022 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 <freetype/ftadvanc.h>
#include <freetype/internal/ftdebug.h>
#include "afglobal.h"
#include "aflatin.h"
#include "aferrors.h"
/**************************************************************************
*
* 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 aflatin
/* needed for computation of round vs. flat segments */
#define FLAT_THRESHOLD( x ) ( x / 14 )
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N G L O B A L M E T R I C S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/* Find segments and links, compute all stem widths, and initialize */
/* standard width and height for the glyph with given charcode. */
FT_LOCAL_DEF( void )
af_latin_metrics_init_widths( AF_LatinMetrics metrics,
FT_Face face )
{
/* scan the array of segments in each direction */
AF_GlyphHintsRec hints[1];
FT_TRACE5(( "\n" ));
FT_TRACE5(( "latin standard widths computation (style `%s')\n",
af_style_names[metrics->root.style_class->style] ));
FT_TRACE5(( "=====================================================\n" ));
FT_TRACE5(( "\n" ));
af_glyph_hints_init( hints, face->memory );
metrics->axis[AF_DIMENSION_HORZ].width_count = 0;
metrics->axis[AF_DIMENSION_VERT].width_count = 0;
{
FT_Error error;
FT_ULong glyph_index;
int dim;
AF_LatinMetricsRec dummy[1];
AF_Scaler scaler = &dummy->root.scaler;
AF_StyleClass style_class = metrics->root.style_class;
AF_ScriptClass script_class = af_script_classes[style_class->script];
/* If HarfBuzz is not available, we need a pointer to a single */
/* unsigned long value. */
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
void* shaper_buf;
#else
FT_ULong shaper_buf_;
void* shaper_buf = &shaper_buf_;
#endif
const char* p;
#ifdef FT_DEBUG_LEVEL_TRACE
FT_ULong ch = 0;
#endif
p = script_class->standard_charstring;
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
shaper_buf = af_shaper_buf_create( face );
#endif
/*
* We check a list of standard characters to catch features like
* `c2sc' (small caps from caps) that don't contain lowercase letters
* by definition, or other features that mainly operate on numerals.
* The first match wins.
*/
glyph_index = 0;
while ( *p )
{
unsigned int num_idx;
#ifdef FT_DEBUG_LEVEL_TRACE
const char* p_old;
#endif
while ( *p == ' ' )
p++;
#ifdef FT_DEBUG_LEVEL_TRACE
p_old = p;
GET_UTF8_CHAR( ch, p_old );
#endif
/* reject input that maps to more than a single glyph */
p = af_shaper_get_cluster( p, &metrics->root, shaper_buf, &num_idx );
if ( num_idx > 1 )
continue;
/* otherwise exit loop if we have a result */
glyph_index = af_shaper_get_elem( &metrics->root,
shaper_buf,
0,
NULL,
NULL );
if ( glyph_index )
break;
}
af_shaper_buf_destroy( face, shaper_buf );
if ( !glyph_index )
{
FT_TRACE5(( "standard character missing;"
" using fallback stem widths\n" ));
goto Exit;
}
FT_TRACE5(( "standard character: U+%04lX (glyph index %ld)\n",
ch, glyph_index ));
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE );
if ( error || face->glyph->outline.n_points <= 0 )
goto Exit;
FT_ZERO( dummy );
dummy->units_per_em = metrics->units_per_em;
scaler->x_scale = 0x10000L;
scaler->y_scale = 0x10000L;
scaler->x_delta = 0;
scaler->y_delta = 0;
scaler->face = face;
scaler->render_mode = FT_RENDER_MODE_NORMAL;
scaler->flags = 0;
af_glyph_hints_rescale( hints, (AF_StyleMetrics)dummy );
error = af_glyph_hints_reload( hints, &face->glyph->outline );
if ( error )
goto Exit;
for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
{
AF_LatinAxis axis = &metrics->axis[dim];
AF_AxisHints axhints = &hints->axis[dim];
AF_Segment seg, limit, link;
FT_UInt num_widths = 0;
error = af_latin_hints_compute_segments( hints,
(AF_Dimension)dim );
if ( error )
goto Exit;
/*
* We assume that the glyphs selected for the stem width
* computation are `featureless' enough so that the linking
* algorithm works fine without adjustments of its scoring
* function.
*/
af_latin_hints_link_segments( hints,
0,
NULL,
(AF_Dimension)dim );
seg = axhints->segments;
limit = FT_OFFSET( seg, axhints->num_segments );
for ( ; seg < limit; seg++ )
{
link = seg->link;
/* we only consider stem segments there! */
if ( link && link->link == seg && link > seg )
{
FT_Pos dist;
dist = seg->pos - link->pos;
if ( dist < 0 )
dist = -dist;
if ( num_widths < AF_LATIN_MAX_WIDTHS )
axis->widths[num_widths++].org = dist;
}
}
/* this also replaces multiple almost identical stem widths */
/* with a single one (the value 100 is heuristic) */
af_sort_and_quantize_widths( &num_widths, axis->widths,
dummy->units_per_em / 100 );
axis->width_count = num_widths;
}
Exit:
for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
{
AF_LatinAxis axis = &metrics->axis[dim];
FT_Pos stdw;
stdw = ( axis->width_count > 0 ) ? axis->widths[0].org
: AF_LATIN_CONSTANT( metrics, 50 );
/* let's try 20% of the smallest width */
axis->edge_distance_threshold = stdw / 5;
axis->standard_width = stdw;
axis->extra_light = 0;
#ifdef FT_DEBUG_LEVEL_TRACE
{
FT_UInt i;
FT_TRACE5(( "%s widths:\n",
dim == AF_DIMENSION_VERT ? "horizontal"
: "vertical" ));
FT_TRACE5(( " %ld (standard)", axis->standard_width ));
for ( i = 1; i < axis->width_count; i++ )
FT_TRACE5(( " %ld", axis->widths[i].org ));
FT_TRACE5(( "\n" ));
}
#endif
}
}
FT_TRACE5(( "\n" ));
af_glyph_hints_done( hints );
}
static void
af_latin_sort_blue( FT_UInt count,
AF_LatinBlue* table )
{
FT_UInt i, j;
AF_LatinBlue swap;
/* we sort from bottom to top */
for ( i = 1; i < count; i++ )
{
for ( j = i; j > 0; j-- )
{
FT_Pos a, b;
if ( table[j - 1]->flags & ( AF_LATIN_BLUE_TOP |
AF_LATIN_BLUE_SUB_TOP ) )
a = table[j - 1]->ref.org;
else
a = table[j - 1]->shoot.org;
if ( table[j]->flags & ( AF_LATIN_BLUE_TOP |
AF_LATIN_BLUE_SUB_TOP ) )
b = table[j]->ref.org;
else
b = table[j]->shoot.org;
if ( b >= a )
break;
swap = table[j];
table[j] = table[j - 1];
table[j - 1] = swap;
}
}
}
/* Find all blue zones. Flat segments give the reference points, */
/* round segments the overshoot positions. */
static int
af_latin_metrics_init_blues( AF_LatinMetrics metrics,
FT_Face face )
{
FT_Pos flats [AF_BLUE_STRING_MAX_LEN];
FT_Pos rounds[AF_BLUE_STRING_MAX_LEN];
FT_UInt num_flats;
FT_UInt num_rounds;
AF_LatinBlue blue;
FT_Error error;
AF_LatinAxis axis = &metrics->axis[AF_DIMENSION_VERT];
FT_Outline outline;
AF_StyleClass sc = metrics->root.style_class;
AF_Blue_Stringset bss = sc->blue_stringset;
const AF_Blue_StringRec* bs = &af_blue_stringsets[bss];
FT_Pos flat_threshold = FLAT_THRESHOLD( metrics->units_per_em );
/* If HarfBuzz is not available, we need a pointer to a single */
/* unsigned long value. */
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
void* shaper_buf;
#else
FT_ULong shaper_buf_;
void* shaper_buf = &shaper_buf_;
#endif
/* we walk over the blue character strings as specified in the */
/* style's entry in the `af_blue_stringset' array */
FT_TRACE5(( "latin blue zones computation\n" ));
FT_TRACE5(( "============================\n" ));
FT_TRACE5(( "\n" ));
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
shaper_buf = af_shaper_buf_create( face );
#endif
for ( ; bs->string != AF_BLUE_STRING_MAX; bs++ )
{
const char* p = &af_blue_strings[bs->string];
FT_Pos* blue_ref;
FT_Pos* blue_shoot;
FT_Pos ascender;
FT_Pos descender;
#ifdef FT_DEBUG_LEVEL_TRACE
{
FT_Bool have_flag = 0;
FT_TRACE5(( "blue zone %d", axis->blue_count ));
if ( bs->properties )
{
FT_TRACE5(( " (" ));
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
{
FT_TRACE5(( "top" ));
have_flag = 1;
}
else if ( AF_LATIN_IS_SUB_TOP_BLUE( bs ) )
{
FT_TRACE5(( "sub top" ));
have_flag = 1;
}
if ( AF_LATIN_IS_NEUTRAL_BLUE( bs ) )
{
if ( have_flag )
FT_TRACE5(( ", " ));
FT_TRACE5(( "neutral" ));
have_flag = 1;
}
if ( AF_LATIN_IS_X_HEIGHT_BLUE( bs ) )
{
if ( have_flag )
FT_TRACE5(( ", " ));
FT_TRACE5(( "small top" ));
have_flag = 1;
}
if ( AF_LATIN_IS_LONG_BLUE( bs ) )
{
if ( have_flag )
FT_TRACE5(( ", " ));
FT_TRACE5(( "long" ));
}
FT_TRACE5(( ")" ));
}
FT_TRACE5(( ":\n" ));
}
#endif /* FT_DEBUG_LEVEL_TRACE */
num_flats = 0;
num_rounds = 0;
ascender = 0;
descender = 0;
while ( *p )
{
FT_ULong glyph_index;
FT_Long y_offset;
FT_Int best_point, best_contour_first, best_contour_last;
FT_Vector* points;
FT_Pos best_y_extremum; /* same as points.y */
FT_Bool best_round = 0;
unsigned int i, num_idx;
#ifdef FT_DEBUG_LEVEL_TRACE
const char* p_old;
FT_ULong ch;
#endif
while ( *p == ' ' )
p++;
#ifdef FT_DEBUG_LEVEL_TRACE
p_old = p;
GET_UTF8_CHAR( ch, p_old );
#endif
p = af_shaper_get_cluster( p, &metrics->root, shaper_buf, &num_idx );
if ( !num_idx )
{
FT_TRACE5(( " U+%04lX unavailable\n", ch ));
continue;
}
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
best_y_extremum = FT_INT_MIN;
else
best_y_extremum = FT_INT_MAX;
/* iterate over all glyph elements of the character cluster */
/* and get the data of the `biggest' one */
for ( i = 0; i < num_idx; i++ )
{
FT_Pos best_y;
FT_Bool round = 0;
/* load the character in the face -- skip unknown or empty ones */
glyph_index = af_shaper_get_elem( &metrics->root,
shaper_buf,
i,
NULL,
&y_offset );
if ( glyph_index == 0 )
{
FT_TRACE5(( " U+%04lX unavailable\n", ch ));
continue;
}
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE );
outline = face->glyph->outline;
/* reject glyphs that don't produce any rendering */
if ( error || outline.n_points <= 2 )
{
#ifdef FT_DEBUG_LEVEL_TRACE
if ( num_idx == 1 )
FT_TRACE5(( " U+%04lX contains no (usable) outlines\n", ch ));
else
FT_TRACE5(( " component %d of cluster starting with U+%04lX"
" contains no (usable) outlines\n", i, ch ));
#endif
continue;
}
/* now compute min or max point indices and coordinates */
points = outline.points;
best_point = -1;
best_y = 0; /* make compiler happy */
best_contour_first = 0; /* ditto */
best_contour_last = 0; /* ditto */
{
FT_Int nn;
FT_Int first = 0;
FT_Int last = -1;
for ( nn = 0; nn < outline.n_contours; first = last + 1, nn++ )
{
FT_Int old_best_point = best_point;
FT_Int pp;
last = outline.contours[nn];
/* Avoid single-point contours since they are never */
/* rasterized. In some fonts, they correspond to mark */
/* attachment points that are way outside of the glyph's */
/* real outline. */
if ( last <= first )
continue;
if ( AF_LATIN_IS_TOP_BLUE( bs ) ||
AF_LATIN_IS_SUB_TOP_BLUE( bs ) )
{
for ( pp = first; pp <= last; pp++ )
{
if ( best_point < 0 || points[pp].y > best_y )
{
best_point = pp;
best_y = points[pp].y;
ascender = FT_MAX( ascender, best_y + y_offset );
}
else
descender = FT_MIN( descender, points[pp].y + y_offset );
}
}
else
{
for ( pp = first; pp <= last; pp++ )
{
if ( best_point < 0 || points[pp].y < best_y )
{
best_point = pp;
best_y = points[pp].y;
descender = FT_MIN( descender, best_y + y_offset );
}
else
ascender = FT_MAX( ascender, points[pp].y + y_offset );
}
}
if ( best_point != old_best_point )
{
best_contour_first = first;
best_contour_last = last;
}
}
}
/* now check whether the point belongs to a straight or round */
/* segment; we first need to find in which contour the extremum */
/* lies, then inspect its previous and next points */
if ( best_point >= 0 )
{
FT_Pos best_x = points[best_point].x;
FT_Int prev, next;
FT_Int best_segment_first, best_segment_last;
FT_Int best_on_point_first, best_on_point_last;
FT_Pos dist;
best_segment_first = best_point;
best_segment_last = best_point;
if ( FT_CURVE_TAG( outline.tags[best_point] ) == FT_CURVE_TAG_ON )
{
best_on_point_first = best_point;
best_on_point_last = best_point;
}
else
{
best_on_point_first = -1;
best_on_point_last = -1;
}
/* look for the previous and next points on the contour */
/* that are not on the same Y coordinate, then threshold */
/* the `closeness'... */
prev = best_point;
next = prev;
do
{
if ( prev > best_contour_first )
prev--;
else
prev = best_contour_last;
dist = FT_ABS( points[prev].y - best_y );
/* accept a small distance or a small angle (both values are */
/* heuristic; value 20 corresponds to approx. 2.9 degrees) */
if ( dist > 5 )
if ( FT_ABS( points[prev].x - best_x ) <= 20 * dist )
break;
best_segment_first = prev;
if ( FT_CURVE_TAG( outline.tags[prev] ) == FT_CURVE_TAG_ON )
{
best_on_point_first = prev;
if ( best_on_point_last < 0 )
best_on_point_last = prev;
}
} while ( prev != best_point );
do
{
if ( next < best_contour_last )
next++;
else
next = best_contour_first;
dist = FT_ABS( points[next].y - best_y );
if ( dist > 5 )
if ( FT_ABS( points[next].x - best_x ) <= 20 * dist )
break;
best_segment_last = next;
if ( FT_CURVE_TAG( outline.tags[next] ) == FT_CURVE_TAG_ON )
{
best_on_point_last = next;
if ( best_on_point_first < 0 )
best_on_point_first = next;
}
} while ( next != best_point );
if ( AF_LATIN_IS_LONG_BLUE( bs ) )
{
/* If this flag is set, we have an additional constraint to */
/* get the blue zone distance: Find a segment of the topmost */
/* (or bottommost) contour that is longer than a heuristic */
/* threshold. This ensures that small bumps in the outline */
/* are ignored (for example, the `vertical serifs' found in */
/* many Hebrew glyph designs). */
/* If this segment is long enough, we are done. Otherwise, */
/* search the segment next to the extremum that is long */
/* enough, has the same direction, and a not too large */
/* vertical distance from the extremum. Note that the */
/* algorithm doesn't check whether the found segment is */
/* actually the one (vertically) nearest to the extremum. */
/* heuristic threshold value */
FT_Pos length_threshold = metrics->units_per_em / 25;
dist = FT_ABS( points[best_segment_last].x -
points[best_segment_first].x );
if ( dist < length_threshold &&
best_segment_last - best_segment_first + 2 <=
best_contour_last - best_contour_first )
{
/* heuristic threshold value */
FT_Pos height_threshold = metrics->units_per_em / 4;
FT_Int first;
FT_Int last;
FT_Bool hit;
/* we intentionally declare these two variables */
/* outside of the loop since various compilers emit */
/* incorrect warning messages otherwise, talking about */
/* `possibly uninitialized variables' */
FT_Int p_first = 0; /* make compiler happy */
FT_Int p_last = 0;
FT_Bool left2right;
/* compute direction */
prev = best_point;
do
{
if ( prev > best_contour_first )
prev--;
else
prev = best_contour_last;
if ( points[prev].x != best_x )
break;
} while ( prev != best_point );
/* skip glyph for the degenerate case */
if ( prev == best_point )
continue;
left2right = FT_BOOL( points[prev].x < points[best_point].x );
first = best_segment_last;
last = first;
hit = 0;
do
{
FT_Bool l2r;
FT_Pos d;
if ( !hit )
{
/* no hit; adjust first point */
first = last;
/* also adjust first and last on point */
if ( FT_CURVE_TAG( outline.tags[first] ) ==
FT_CURVE_TAG_ON )
{
p_first = first;
p_last = first;
}
else
{
p_first = -1;
p_last = -1;
}
hit = 1;
}
if ( last < best_contour_last )
last++;
else
last = best_contour_first;
if ( FT_ABS( best_y - points[first].y ) > height_threshold )
{
/* vertical distance too large */
hit = 0;
continue;
}
/* same test as above */
dist = FT_ABS( points[last].y - points[first].y );
if ( dist > 5 )
if ( FT_ABS( points[last].x - points[first].x ) <=
20 * dist )
{
hit = 0;
continue;
}
if ( FT_CURVE_TAG( outline.tags[last] ) == FT_CURVE_TAG_ON )
{
p_last = last;
if ( p_first < 0 )
p_first = last;
}
l2r = FT_BOOL( points[first].x < points[last].x );
d = FT_ABS( points[last].x - points[first].x );
if ( l2r == left2right &&
d >= length_threshold )
{
/* all constraints are met; update segment after */
/* finding its end */
do
{
if ( last < best_contour_last )
last++;
else
last = best_contour_first;
d = FT_ABS( points[last].y - points[first].y );
if ( d > 5 )
if ( FT_ABS( points[next].x - points[first].x ) <=
20 * dist )
{
if ( last > best_contour_first )
last--;
else
last = best_contour_last;
break;
}
p_last = last;
if ( FT_CURVE_TAG( outline.tags[last] ) ==
FT_CURVE_TAG_ON )
{
p_last = last;
if ( p_first < 0 )
p_first = last;
}
} while ( last != best_segment_first );
best_y = points[first].y;
best_segment_first = first;
best_segment_last = last;
best_on_point_first = p_first;
best_on_point_last = p_last;
break;
}
} while ( last != best_segment_first );
}
}
/* for computing blue zones, we add the y offset as returned */
/* by the currently used OpenType feature -- for example, */
/* superscript glyphs might be identical to subscript glyphs */
/* with a vertical shift */
best_y += y_offset;
#ifdef FT_DEBUG_LEVEL_TRACE
if ( num_idx == 1 )
FT_TRACE5(( " U+%04lX: best_y = %5ld", ch, best_y ));
else
FT_TRACE5(( " component %d of cluster starting with U+%04lX:"
" best_y = %5ld", i, ch, best_y ));
#endif
/* now set the `round' flag depending on the segment's kind: */
/* */
/* - if the horizontal distance between the first and last */
/* `on' point is larger than a heuristic threshold */
/* we have a flat segment */
/* - if either the first or the last point of the segment is */
/* an `off' point, the segment is round, otherwise it is */
/* flat */
if ( best_on_point_first >= 0 &&
best_on_point_last >= 0 &&
( FT_ABS( points[best_on_point_last].x -
points[best_on_point_first].x ) ) >
flat_threshold )
round = 0;
else
round = FT_BOOL(
FT_CURVE_TAG( outline.tags[best_segment_first] ) !=
FT_CURVE_TAG_ON ||
FT_CURVE_TAG( outline.tags[best_segment_last] ) !=
FT_CURVE_TAG_ON );
if ( round && AF_LATIN_IS_NEUTRAL_BLUE( bs ) )
{
/* only use flat segments for a neutral blue zone */
FT_TRACE5(( " (round, skipped)\n" ));
continue;
}
FT_TRACE5(( " (%s)\n", round ? "round" : "flat" ));
}
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
{
if ( best_y > best_y_extremum )
{
best_y_extremum = best_y;
best_round = round;
}
}
else
{
if ( best_y < best_y_extremum )
{
best_y_extremum = best_y;
best_round = round;
}
}
} /* end for loop */
if ( !( best_y_extremum == FT_INT_MIN ||
best_y_extremum == FT_INT_MAX ) )
{
if ( best_round )
rounds[num_rounds++] = best_y_extremum;
else
flats[num_flats++] = best_y_extremum;
}
} /* end while loop */
if ( num_flats == 0 && num_rounds == 0 )
{
/*
* we couldn't find a single glyph to compute this blue zone,
* we will simply ignore it then
*/
FT_TRACE5(( " empty\n" ));
continue;
}
/* we have computed the contents of the `rounds' and `flats' tables, */
/* now determine the reference and overshoot position of the blue -- */
/* we simply take the median value after a simple sort */
af_sort_pos( num_rounds, rounds );
af_sort_pos( num_flats, flats );
blue = &axis->blues[axis->blue_count];
blue_ref = &blue->ref.org;
blue_shoot = &blue->shoot.org;
axis->blue_count++;
if ( num_flats == 0 )
{
*blue_ref =
*blue_shoot = rounds[num_rounds / 2];
}
else if ( num_rounds == 0 )
{
*blue_ref =
*blue_shoot = flats[num_flats / 2];
}
else
{
*blue_ref = flats [num_flats / 2];
*blue_shoot = rounds[num_rounds / 2];
}
/* there are sometimes problems: if the overshoot position of top */
/* zones is under its reference position, or the opposite for bottom */
/* zones. We must thus check everything there and correct the errors */
if ( *blue_shoot != *blue_ref )
{
FT_Pos ref = *blue_ref;
FT_Pos shoot = *blue_shoot;
FT_Bool over_ref = FT_BOOL( shoot > ref );
if ( ( AF_LATIN_IS_TOP_BLUE( bs ) ||
AF_LATIN_IS_SUB_TOP_BLUE( bs) ) ^ over_ref )
{
*blue_ref =
*blue_shoot = ( shoot + ref ) / 2;
FT_TRACE5(( " [overshoot smaller than reference,"
" taking mean value]\n" ));
}
}
blue->ascender = ascender;
blue->descender = descender;
blue->flags = 0;
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
blue->flags |= AF_LATIN_BLUE_TOP;
if ( AF_LATIN_IS_SUB_TOP_BLUE( bs ) )
blue->flags |= AF_LATIN_BLUE_SUB_TOP;
if ( AF_LATIN_IS_NEUTRAL_BLUE( bs ) )
blue->flags |= AF_LATIN_BLUE_NEUTRAL;
/*
* The following flag is used later to adjust the y and x scales
* in order to optimize the pixel grid alignment of the top of small
* letters.
*/
if ( AF_LATIN_IS_X_HEIGHT_BLUE( bs ) )
blue->flags |= AF_LATIN_BLUE_ADJUSTMENT;
FT_TRACE5(( " -> reference = %ld\n", *blue_ref ));
FT_TRACE5(( " overshoot = %ld\n", *blue_shoot ));
} /* end for loop */
af_shaper_buf_destroy( face, shaper_buf );
if ( axis->blue_count )
{
/* we finally check whether blue zones are ordered; */
/* `ref' and `shoot' values of two blue zones must not overlap */
FT_UInt i;
AF_LatinBlue blue_sorted[AF_BLUE_STRINGSET_MAX_LEN + 2];
for ( i = 0; i < axis->blue_count; i++ )
blue_sorted[i] = &axis->blues[i];
/* sort bottoms of blue zones... */
af_latin_sort_blue( axis->blue_count, blue_sorted );
/* ...and adjust top values if necessary */
for ( i = 0; i < axis->blue_count - 1; i++ )
{
FT_Pos* a;
FT_Pos* b;
#ifdef FT_DEBUG_LEVEL_TRACE
FT_Bool a_is_top = 0;
#endif
if ( blue_sorted[i]->flags & ( AF_LATIN_BLUE_TOP |
AF_LATIN_BLUE_SUB_TOP ) )
{
a = &blue_sorted[i]->shoot.org;
#ifdef FT_DEBUG_LEVEL_TRACE
a_is_top = 1;
#endif
}
else
a = &blue_sorted[i]->ref.org;
if ( blue_sorted[i + 1]->flags & ( AF_LATIN_BLUE_TOP |
AF_LATIN_BLUE_SUB_TOP ) )
b = &blue_sorted[i + 1]->shoot.org;
else
b = &blue_sorted[i + 1]->ref.org;
if ( *a > *b )
{
*a = *b;
FT_TRACE5(( "blue zone overlap:"
" adjusting %s %ld to %ld\n",
a_is_top ? "overshoot" : "reference",
blue_sorted[i] - axis->blues,
*a ));
}
}
FT_TRACE5(( "\n" ));
return 0;
}
else
{
/* disable hinting for the current style if there are no blue zones */
AF_FaceGlobals globals = metrics->root.globals;
FT_UShort* gstyles = globals->glyph_styles;
FT_Long i;
FT_TRACE5(( "no blue zones found:"
" hinting disabled for this style\n" ));
for ( i = 0; i < globals->glyph_count; i++ )
{
if ( ( gstyles[i] & AF_STYLE_MASK ) == sc->style )
gstyles[i] = AF_STYLE_NONE_DFLT;
}
FT_TRACE5(( "\n" ));
return 1;
}
}
/* Check whether all ASCII digits have the same advance width. */
FT_LOCAL_DEF( void )
af_latin_metrics_check_digits( AF_LatinMetrics metrics,
FT_Face face )
{
FT_Bool started = 0, same_width = 1;
FT_Fixed advance = 0, old_advance = 0;
/* If HarfBuzz is not available, we need a pointer to a single */
/* unsigned long value. */
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
void* shaper_buf;
#else
FT_ULong shaper_buf_;
void* shaper_buf = &shaper_buf_;
#endif
/* in all supported charmaps, digits have character codes 0x30-0x39 */
const char digits[] = "0 1 2 3 4 5 6 7 8 9";
const char* p;
p = digits;
#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ
shaper_buf = af_shaper_buf_create( face );
#endif
while ( *p )
{
FT_ULong glyph_index;
unsigned int num_idx;
/* reject input that maps to more than a single glyph */
p = af_shaper_get_cluster( p, &metrics->root, shaper_buf, &num_idx );
if ( num_idx > 1 )
continue;
glyph_index = af_shaper_get_elem( &metrics->root,
shaper_buf,
0,
&advance,
NULL );
if ( !glyph_index )
continue;
if ( started )
{
if ( advance != old_advance )
{
same_width = 0;
break;
}
}
else
{
old_advance = advance;
started = 1;
}
}
af_shaper_buf_destroy( face, shaper_buf );
metrics->root.digits_have_same_width = same_width;
}
/* Initialize global metrics. */
FT_LOCAL_DEF( FT_Error )
af_latin_metrics_init( AF_LatinMetrics metrics,
FT_Face face )
{
FT_Error error = FT_Err_Ok;
FT_CharMap oldmap = face->charmap;
metrics->units_per_em = face->units_per_EM;
if ( !FT_Select_Charmap( face, FT_ENCODING_UNICODE ) )
{
af_latin_metrics_init_widths( metrics, face );
if ( af_latin_metrics_init_blues( metrics, face ) )
{
/* use internal error code to indicate missing blue zones */
error = -1;
goto Exit;
}
af_latin_metrics_check_digits( metrics, face );
}
Exit:
FT_Set_Charmap( face, oldmap );
return error;
}
/* Adjust scaling value, then scale and shift widths */
/* and blue zones (if applicable) for given dimension. */
static void
af_latin_metrics_scale_dim( AF_LatinMetrics metrics,
AF_Scaler scaler,
AF_Dimension dim )
{
FT_Fixed scale;
FT_Pos delta;
AF_LatinAxis axis;
FT_UInt nn;
if ( dim == AF_DIMENSION_HORZ )
{
scale = scaler->x_scale;
delta = scaler->x_delta;
}
else
{
scale = scaler->y_scale;
delta = scaler->y_delta;
}
axis = &metrics->axis[dim];
if ( axis->org_scale == scale && axis->org_delta == delta )
return;
axis->org_scale = scale;
axis->org_delta = delta;
/*
* correct X and Y scale to optimize the alignment of the top of small
* letters to the pixel grid
*/
{
AF_LatinAxis Axis = &metrics->axis[AF_DIMENSION_VERT];
AF_LatinBlue blue = NULL;
for ( nn = 0; nn < Axis->blue_count; nn++ )
{
if ( Axis->blues[nn].flags & AF_LATIN_BLUE_ADJUSTMENT )
{
blue = &Axis->blues[nn];
break;
}
}
if ( blue )
{
FT_Pos scaled;
FT_Pos threshold;
FT_Pos fitted;
FT_UInt limit;
FT_UInt ppem;
scaled = FT_MulFix( blue->shoot.org, scale );
ppem = metrics->root.scaler.face->size->metrics.x_ppem;
limit = metrics->root.globals->increase_x_height;
threshold = 40;
/* if the `increase-x-height' property is active, */
/* we round up much more often */
if ( limit &&
ppem <= limit &&
ppem >= AF_PROP_INCREASE_X_HEIGHT_MIN )
threshold = 52;
fitted = ( scaled + threshold ) & ~63;
if ( scaled != fitted )
{
#if 0
if ( dim == AF_DIMENSION_HORZ )
{
if ( fitted < scaled )
scale -= scale / 50; /* scale *= 0.98 */
}
else
#endif
if ( dim == AF_DIMENSION_VERT )
{
FT_Pos max_height;
FT_Pos dist;
FT_Fixed new_scale;
new_scale = FT_MulDiv( scale, fitted, scaled );
/* the scaling should not change the result by more than two pixels */
max_height = metrics->units_per_em;
for ( nn = 0; nn < Axis->blue_count; nn++ )
{
max_height = FT_MAX( max_height, Axis->blues[nn].ascender );
max_height = FT_MAX( max_height, -Axis->blues[nn].descender );
}
dist = FT_ABS( FT_MulFix( max_height, new_scale - scale ) );
dist &= ~127;
if ( dist == 0 )
{
FT_TRACE5(( "af_latin_metrics_scale_dim:"
" x height alignment (style `%s'):\n",
af_style_names[metrics->root.style_class->style] ));
FT_TRACE5(( " "
" vertical scaling changed"
" from %.5f to %.5f (by %ld%%)\n",
scale / 65536.0,
new_scale / 65536.0,
( fitted - scaled ) * 100 / scaled ));
FT_TRACE5(( "\n" ));
scale = new_scale;
}
#ifdef FT_DEBUG_LEVEL_TRACE
else
{
FT_TRACE5(( "af_latin_metrics_scale_dim:"
" x height alignment (style `%s'):\n",
af_style_names[metrics->root.style_class->style] ));
FT_TRACE5(( " "
" excessive vertical scaling abandoned\n" ));
FT_TRACE5(( "\n" ));
}
#endif
}
}
}
}
axis->scale = scale;
axis->delta = delta;
if ( dim == AF_DIMENSION_HORZ )
{
metrics->root.scaler.x_scale = scale;
metrics->root.scaler.x_delta = delta;
}
else
{
metrics->root.scaler.y_scale = scale;
metrics->root.scaler.y_delta = delta;
}
FT_TRACE5(( "%s widths (style `%s')\n",
dim == AF_DIMENSION_HORZ ? "horizontal" : "vertical",
af_style_names[metrics->root.style_class->style] ));
/* scale the widths */
for ( nn = 0; nn < axis->width_count; nn++ )
{
AF_Width width = axis->widths + nn;
width->cur = FT_MulFix( width->org, scale );
width->fit = width->cur;
FT_TRACE5(( " %ld scaled to %.2f\n",
width->org,
width->cur / 64.0 ));
}
FT_TRACE5(( "\n" ));
/* an extra-light axis corresponds to a standard width that is */
/* smaller than 5/8 pixels */
axis->extra_light =
FT_BOOL( FT_MulFix( axis->standard_width, scale ) < 32 + 8 );
#ifdef FT_DEBUG_LEVEL_TRACE
if ( axis->extra_light )
{
FT_TRACE5(( "`%s' style is extra light (at current resolution)\n",
af_style_names[metrics->root.style_class->style] ));
FT_TRACE5(( "\n" ));
}
#endif
if ( dim == AF_DIMENSION_VERT )
{
#ifdef FT_DEBUG_LEVEL_TRACE
if ( axis->blue_count )
FT_TRACE5(( "blue zones (style `%s')\n",
af_style_names[metrics->root.style_class->style] ));
#endif
/* scale the blue zones */
for ( nn = 0; nn < axis->blue_count; nn++ )
{
AF_LatinBlue blue = &axis->blues[nn];
FT_Pos dist;
blue->ref.cur = FT_MulFix( blue->ref.org, scale ) + delta;
blue->ref.fit = blue->ref.cur;
blue->shoot.cur = FT_MulFix( blue->shoot.org, scale ) + delta;
blue->shoot.fit = blue->shoot.cur;
blue->flags &= ~AF_LATIN_BLUE_ACTIVE;
/* a blue zone is only active if it is less than 3/4 pixels tall */
dist = FT_MulFix( blue->ref.org - blue->shoot.org, scale );
if ( dist <= 48 && dist >= -48 )
{
#if 0
FT_Pos delta1;
#endif
FT_Pos delta2;
/* use discrete values for blue zone widths */
#if 0
/* generic, original code */
delta1 = blue->shoot.org - blue->ref.org;
delta2 = delta1;
if ( delta1 < 0 )
delta2 = -delta2;
delta2 = FT_MulFix( delta2, scale );
if ( delta2 < 32 )
delta2 = 0;
else if ( delta2 < 64 )
delta2 = 32 + ( ( ( delta2 - 32 ) + 16 ) & ~31 );
else
delta2 = FT_PIX_ROUND( delta2 );
if ( delta1 < 0 )
delta2 = -delta2;
blue->ref.fit = FT_PIX_ROUND( blue->ref.cur );
blue->shoot.fit = blue->ref.fit + delta2;
#else
/* simplified version due to abs(dist) <= 48 */
delta2 = dist;
if ( dist < 0 )
delta2 = -delta2;
if ( delta2 < 32 )
delta2 = 0;
else if ( delta2 < 48 )
delta2 = 32;
else
delta2 = 64;
if ( dist < 0 )
delta2 = -delta2;
blue->ref.fit = FT_PIX_ROUND( blue->ref.cur );
blue->shoot.fit = blue->ref.fit - delta2;
#endif
blue->flags |= AF_LATIN_BLUE_ACTIVE;
}
}
/* use sub-top blue zone only if it doesn't overlap with */
/* another (non-sup-top) blue zone; otherwise, the */
/* effect would be similar to a neutral blue zone, which */
/* is not desired here */
for ( nn = 0; nn < axis->blue_count; nn++ )
{
AF_LatinBlue blue = &axis->blues[nn];
FT_UInt i;
if ( !( blue->flags & AF_LATIN_BLUE_SUB_TOP ) )
continue;
if ( !( blue->flags & AF_LATIN_BLUE_ACTIVE ) )
continue;
for ( i = 0; i < axis->blue_count; i++ )
{
AF_LatinBlue b = &axis->blues[i];
if ( b->flags & AF_LATIN_BLUE_SUB_TOP )
continue;
if ( !( b->flags & AF_LATIN_BLUE_ACTIVE ) )
continue;
if ( b->ref.fit <= blue->shoot.fit &&
b->shoot.fit >= blue->ref.fit )
{
blue->flags &= ~AF_LATIN_BLUE_ACTIVE;
break;
}
}
}
#ifdef FT_DEBUG_LEVEL_TRACE
for ( nn = 0; nn < axis->blue_count; nn++ )
{
AF_LatinBlue blue = &axis->blues[nn];
FT_TRACE5(( " reference %d: %ld scaled to %.2f%s\n",
nn,
blue->ref.org,
blue->ref.fit / 64.0,
( blue->flags & AF_LATIN_BLUE_ACTIVE ) ? ""
: " (inactive)" ));
FT_TRACE5(( " overshoot %d: %ld scaled to %.2f%s\n",
nn,
blue->shoot.org,
blue->shoot.fit / 64.0,
( blue->flags & AF_LATIN_BLUE_ACTIVE ) ? ""
: " (inactive)" ));
}
#endif
}
}
/* Scale global values in both directions. */
FT_LOCAL_DEF( void )
af_latin_metrics_scale( AF_LatinMetrics metrics,
AF_Scaler scaler )
{
metrics->root.scaler.render_mode = scaler->render_mode;
metrics->root.scaler.face = scaler->face;
metrics->root.scaler.flags = scaler->flags;
af_latin_metrics_scale_dim( metrics, scaler, AF_DIMENSION_HORZ );
af_latin_metrics_scale_dim( metrics, scaler, AF_DIMENSION_VERT );
}
/* Extract standard_width from writing system/script specific */
/* metrics class. */
FT_LOCAL_DEF( void )
af_latin_get_standard_widths( AF_LatinMetrics metrics,
FT_Pos* stdHW,
FT_Pos* stdVW )
{
if ( stdHW )
*stdHW = metrics->axis[AF_DIMENSION_VERT].standard_width;
if ( stdVW )
*stdVW = metrics->axis[AF_DIMENSION_HORZ].standard_width;
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N G L Y P H A N A L Y S I S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/* Walk over all contours and compute its segments. */
FT_LOCAL_DEF( FT_Error )
af_latin_hints_compute_segments( AF_GlyphHints hints,
AF_Dimension dim )
{
AF_LatinMetrics metrics = (AF_LatinMetrics)hints->metrics;
AF_AxisHints axis = &hints->axis[dim];
FT_Memory memory = hints->memory;
FT_Error error = FT_Err_Ok;
AF_Segment segment = NULL;
AF_SegmentRec seg0;
AF_Point* contour = hints->contours;
AF_Point* contour_limit = contour + hints->num_contours;
AF_Direction major_dir, segment_dir;
FT_Pos flat_threshold = FLAT_THRESHOLD( metrics->units_per_em );
FT_ZERO( &seg0 );
seg0.score = 32000;
seg0.flags = AF_EDGE_NORMAL;
major_dir = (AF_Direction)FT_ABS( axis->major_dir );
segment_dir = major_dir;
axis->num_segments = 0;
/* set up (u,v) in each point */
if ( dim == AF_DIMENSION_HORZ )
{
AF_Point point = hints->points;
AF_Point limit = point + hints->num_points;
for ( ; point < limit; point++ )
{
point->u = point->fx;
point->v = point->fy;
}
}
else
{
AF_Point point = hints->points;
AF_Point limit = point + hints->num_points;
for ( ; point < limit; point++ )
{
point->u = point->fy;
point->v = point->fx;
}
}
/* do each contour separately */
for ( ; contour < contour_limit; contour++ )
{
AF_Point point = contour[0];
AF_Point last = point->prev;
int on_edge = 0;
/* we call values measured along a segment (point->v) */
/* `coordinates', and values orthogonal to it (point->u) */
/* `positions' */
FT_Pos min_pos = 32000;
FT_Pos max_pos = -32000;
FT_Pos min_coord = 32000;
FT_Pos max_coord = -32000;
FT_UShort min_flags = AF_FLAG_NONE;
FT_UShort max_flags = AF_FLAG_NONE;
FT_Pos min_on_coord = 32000;
FT_Pos max_on_coord = -32000;
FT_Bool passed;
AF_Segment prev_segment = NULL;
FT_Pos prev_min_pos = min_pos;
FT_Pos prev_max_pos = max_pos;
FT_Pos prev_min_coord = min_coord;
FT_Pos prev_max_coord = max_coord;
FT_UShort prev_min_flags = min_flags;
FT_UShort prev_max_flags = max_flags;
FT_Pos prev_min_on_coord = min_on_coord;
FT_Pos prev_max_on_coord = max_on_coord;
if ( FT_ABS( last->out_dir ) == major_dir &&
FT_ABS( point->out_dir ) == major_dir )
{
/* we are already on an edge, try to locate its start */
last = point;
for (;;)
{
point = point->prev;
if ( FT_ABS( point->out_dir ) != major_dir )
{
point = point->next;
break;
}
if ( point == last )
break;
}
}
last = point;
passed = 0;
for (;;)
{
FT_Pos u, v;
if ( on_edge )
{
/* get minimum and maximum position */
u = point->u;
if ( u < min_pos )
min_pos = u;
if ( u > max_pos )
max_pos = u;
/* get minimum and maximum coordinate together with flags */
v = point->v;
if ( v < min_coord )
{
min_coord = v;
min_flags = point->flags;
}
if ( v > max_coord )
{
max_coord = v;
max_flags = point->flags;
}
/* get minimum and maximum coordinate of `on' points */
if ( !( point->flags & AF_FLAG_CONTROL ) )
{
v = point->v;
if ( v < min_on_coord )
min_on_coord = v;
if ( v > max_on_coord )
max_on_coord = v;
}
if ( point->out_dir != segment_dir || point == last )
{
/* check whether the new segment's start point is identical to */
/* the previous segment's end point; for example, this might */
/* happen for spikes */
if ( !prev_segment || segment->first != prev_segment->last )
{
/* points are different: we are just leaving an edge, thus */
/* record a new segment */
segment->last = point;
segment->pos = (FT_Short)( ( min_pos + max_pos ) >> 1 );
segment->delta = (FT_Short)( ( max_pos - min_pos ) >> 1 );
/* a segment is round if either its first or last point */
/* is a control point, and the length of the on points */
/* inbetween doesn't exceed a heuristic limit */
if ( ( min_flags | max_flags ) & AF_FLAG_CONTROL &&
( max_on_coord - min_on_coord ) < flat_threshold )
segment->flags |= AF_EDGE_ROUND;
segment->min_coord = (FT_Short)min_coord;
segment->max_coord = (FT_Short)max_coord;
segment->height = segment->max_coord - segment->min_coord;
prev_segment = segment;
prev_min_pos = min_pos;
prev_max_pos = max_pos;
prev_min_coord = min_coord;
prev_max_coord = max_coord;
prev_min_flags = min_flags;
prev_max_flags = max_flags;
prev_min_on_coord = min_on_coord;
prev_max_on_coord = max_on_coord;
}
else
{
/* points are the same: we don't create a new segment but */
/* merge the current segment with the previous one */
if ( prev_segment->last->in_dir == point->in_dir )
{
/* we have identical directions (this can happen for */
/* degenerate outlines that move zig-zag along the main */
/* axis without changing the coordinate value of the other */
/* axis, and where the segments have just been merged): */
/* unify segments */
/* update constraints */
if ( prev_min_pos < min_pos )
min_pos = prev_min_pos;
if ( prev_max_pos > max_pos )
max_pos = prev_max_pos;
if ( prev_min_coord < min_coord )
{
min_coord = prev_min_coord;
min_flags = prev_min_flags;
}
if ( prev_max_coord > max_coord )
{
max_coord = prev_max_coord;
max_flags = prev_max_flags;
}
if ( prev_min_on_coord < min_on_coord )
min_on_coord = prev_min_on_coord;
if ( prev_max_on_coord > max_on_coord )
max_on_coord = prev_max_on_coord;
prev_segment->last = point;
prev_segment->pos = (FT_Short)( ( min_pos +
max_pos ) >> 1 );
prev_segment->delta = (FT_Short)( ( max_pos -
min_pos ) >> 1 );
if ( ( min_flags | max_flags ) & AF_FLAG_CONTROL &&
( max_on_coord - min_on_coord ) < flat_threshold )
prev_segment->flags |= AF_EDGE_ROUND;
else
prev_segment->flags &= ~AF_EDGE_ROUND;
prev_segment->min_coord = (FT_Short)min_coord;
prev_segment->max_coord = (FT_Short)max_coord;
prev_segment->height = prev_segment->max_coord -
prev_segment->min_coord;
}
else
{
/* we have different directions; use the properties of the */
/* longer segment and discard the other one */
if ( FT_ABS( prev_max_coord - prev_min_coord ) >
FT_ABS( max_coord - min_coord ) )
{
/* discard current segment */
if ( min_pos < prev_min_pos )
prev_min_pos = min_pos;
if ( max_pos > prev_max_pos )
prev_max_pos = max_pos;
prev_segment->last = point;
prev_segment->pos = (FT_Short)( ( prev_min_pos +
prev_max_pos ) >> 1 );
prev_segment->delta = (FT_Short)( ( prev_max_pos -
prev_min_pos ) >> 1 );
}
else
{
/* discard previous segment */
if ( prev_min_pos < min_pos )
min_pos = prev_min_pos;
if ( prev_max_pos > max_pos )
max_pos = prev_max_pos;
segment->last = point;
segment->pos = (FT_Short)( ( min_pos + max_pos ) >> 1 );
segment->delta = (FT_Short)( ( max_pos - min_pos ) >> 1 );
if ( ( min_flags | max_flags ) & AF_FLAG_CONTROL &&
( max_on_coord - min_on_coord ) < flat_threshold )
segment->flags |= AF_EDGE_ROUND;
segment->min_coord = (FT_Short)min_coord;
segment->max_coord = (FT_Short)max_coord;
segment->height = segment->max_coord -
segment->min_coord;
*prev_segment = *segment;
prev_min_pos = min_pos;
prev_max_pos = max_pos;
prev_min_coord = min_coord;
prev_max_coord = max_coord;
prev_min_flags = min_flags;
prev_max_flags = max_flags;
prev_min_on_coord = min_on_coord;
prev_max_on_coord = max_on_coord;
}
}
axis->num_segments--;
}
on_edge = 0;
segment = NULL;
/* fall through */
}
}
/* now exit if we are at the start/end point */
if ( point == last )
{
if ( passed )
break;
passed = 1;
}
/* if we are not on an edge, check whether the major direction */
/* coincides with the current point's `out' direction, or */
/* whether we have a single-point contour */
if ( !on_edge &&
( FT_ABS( point->out_dir ) == major_dir ||
point == point->prev ) )
{
/*
* For efficiency, we restrict the number of segments to 1000,
* which is a heuristic value: it is very unlikely that a glyph
* with so many segments can be hinted in a sensible way.
* Reasons:
*
* - The glyph has really 1000 segments; this implies that it has
* at least 2000 outline points. Assuming 'normal' fonts that
* have superfluous points optimized away, viewing such a glyph
* only makes sense at large magnifications where hinting
* isn't applied anyway.
*
* - We have a broken glyph. Hinting doesn't make sense in this
* case either.
*/
if ( axis->num_segments > 1000 )
{
FT_TRACE0(( "af_latin_hints_compute_segments:"
" more than 1000 segments in this glyph;\n" ));
FT_TRACE0(( " "
" hinting is suppressed\n" ));
axis->num_segments = 0;
return FT_Err_Ok;
}
/* this is the start of a new segment! */
segment_dir = (AF_Direction)point->out_dir;
error = af_axis_hints_new_segment( axis, memory, &segment );
if ( error )
goto Exit;
/* clear all segment fields */
segment[0] = seg0;
segment->dir = (FT_Char)segment_dir;
segment->first = point;
segment->last = point;
/* `af_axis_hints_new_segment' reallocates memory, */
/* thus we have to refresh the `prev_segment' pointer */
if ( prev_segment )
prev_segment = segment - 1;
min_pos = max_pos = point->u;
min_coord = max_coord = point->v;
min_flags = max_flags = point->flags;
if ( point->flags & AF_FLAG_CONTROL )
{
min_on_coord = 32000;
max_on_coord = -32000;
}
else
min_on_coord = max_on_coord = point->v;
on_edge = 1;
if ( point == point->prev )
{
/* we have a one-point segment: this is a one-point */
/* contour with `in' and `out' direction set to */
/* AF_DIR_NONE */
segment->pos = (FT_Short)min_pos;
if (point->flags & AF_FLAG_CONTROL)
segment->flags |= AF_EDGE_ROUND;
segment->min_coord = (FT_Short)point->v;
segment->max_coord = (FT_Short)point->v;
segment->height = 0;
on_edge = 0;
segment = NULL;
}
}
point = point->next;
}
} /* contours */
/* now slightly increase the height of segments if this makes */
/* sense -- this is used to better detect and ignore serifs */
{
AF_Segment segments = axis->segments;
AF_Segment segments_end = FT_OFFSET( segments, axis->num_segments );
for ( segment = segments; segment < segments_end; segment++ )
{
AF_Point first = segment->first;
AF_Point last = segment->last;
FT_Pos first_v = first->v;
FT_Pos last_v = last->v;
if ( first_v < last_v )
{
AF_Point p;
p = first->prev;
if ( p->v < first_v )
segment->height = (FT_Short)( segment->height +
( ( first_v - p->v ) >> 1 ) );
p = last->next;
if ( p->v > last_v )
segment->height = (FT_Short)( segment->height +
( ( p->v - last_v ) >> 1 ) );
}
else
{
AF_Point p;
p = first->prev;
if ( p->v > first_v )
segment->height = (FT_Short)( segment->height +
( ( p->v - first_v ) >> 1 ) );
p = last->next;
if ( p->v < last_v )
segment->height = (FT_Short)( segment->height +
( ( last_v - p->v ) >> 1 ) );
}
}
}
Exit:
return error;
}
/* Link segments to form stems and serifs. If `width_count' and */
/* `widths' are non-zero, use them to fine-tune the scoring function. */
FT_LOCAL_DEF( void )
af_latin_hints_link_segments( AF_GlyphHints hints,
FT_UInt width_count,
AF_WidthRec* widths,
AF_Dimension dim )
{
AF_AxisHints axis = &hints->axis[dim];
AF_Segment segments = axis->segments;
AF_Segment segment_limit = FT_OFFSET( segments, axis->num_segments );
FT_Pos len_threshold, len_score, dist_score, max_width;
AF_Segment seg1, seg2;
if ( width_count )
max_width = widths[width_count - 1].org;
else
max_width = 0;
/* a heuristic value to set up a minimum value for overlapping */
len_threshold = AF_LATIN_CONSTANT( hints->metrics, 8 );
if ( len_threshold == 0 )
len_threshold = 1;
/* a heuristic value to weight lengths */
len_score = AF_LATIN_CONSTANT( hints->metrics, 6000 );
/* a heuristic value to weight distances (no call to */
/* AF_LATIN_CONSTANT needed, since we work on multiples */
/* of the stem width) */
dist_score = 3000;
/* now compare each segment to the others */
for ( seg1 = segments; seg1 < segment_limit; seg1++ )
{
if ( seg1->dir != axis->major_dir )
continue;
/* search for stems having opposite directions, */
/* with seg1 to the `left' of seg2 */
for ( seg2 = segments; seg2 < segment_limit; seg2++ )
{
FT_Pos pos1 = seg1->pos;
FT_Pos pos2 = seg2->pos;
if ( seg1->dir + seg2->dir == 0 && pos2 > pos1 )
{
/* compute distance between the two segments */
FT_Pos min = seg1->min_coord;
FT_Pos max = seg1->max_coord;
FT_Pos len;
if ( min < seg2->min_coord )
min = seg2->min_coord;
if ( max > seg2->max_coord )
max = seg2->max_coord;
/* compute maximum coordinate difference of the two segments */
/* (this is, how much they overlap) */
len = max - min;
if ( len >= len_threshold )
{
/*
* The score is the sum of two demerits indicating the
* `badness' of a fit, measured along the segments' main axis
* and orthogonal to it, respectively.
*
* - The less overlapping along the main axis, the worse it
* is, causing a larger demerit.
*
* - The nearer the orthogonal distance to a stem width, the
* better it is, causing a smaller demerit. For simplicity,
* however, we only increase the demerit for values that
* exceed the largest stem width.
*/
FT_Pos dist = pos2 - pos1;
FT_Pos dist_demerit, score;
if ( max_width )
{
/* distance demerits are based on multiples of `max_width'; */
/* we scale by 1024 for getting more precision */
FT_Pos delta = ( dist << 10 ) / max_width - ( 1 << 10 );
if ( delta > 10000 )
dist_demerit = 32000;
else if ( delta > 0 )
dist_demerit = delta * delta / dist_score;
else
dist_demerit = 0;
}
else
dist_demerit = dist; /* default if no widths available */
score = dist_demerit + len_score / len;
/* and we search for the smallest score */
if ( score < seg1->score )
{
seg1->score = score;
seg1->link = seg2;
}
if ( score < seg2->score )
{
seg2->score = score;
seg2->link = seg1;
}
}
}
}
}
/* now compute the `serif' segments, cf. explanations in `afhints.h' */
for ( seg1 = segments; seg1 < segment_limit; seg1++ )
{
seg2 = seg1->link;
if ( seg2 )
{
if ( seg2->link != seg1 )
{
seg1->link = NULL;
seg1->serif = seg2->link;
}
}
}
}
/* Link segments to edges, using feature analysis for selection. */
FT_LOCAL_DEF( FT_Error )
af_latin_hints_compute_edges( AF_GlyphHints hints,
AF_Dimension dim )
{
AF_AxisHints axis = &hints->axis[dim];
FT_Error error = FT_Err_Ok;
FT_Memory memory = hints->memory;
AF_LatinAxis laxis = &((AF_LatinMetrics)hints->metrics)->axis[dim];
AF_StyleClass style_class = hints->metrics->style_class;
AF_ScriptClass script_class = af_script_classes[style_class->script];
FT_Bool top_to_bottom_hinting = 0;
AF_Segment segments = axis->segments;
AF_Segment segment_limit = FT_OFFSET( segments, axis->num_segments );
AF_Segment seg;
#if 0
AF_Direction up_dir;
#endif
FT_Fixed scale;
FT_Pos edge_distance_threshold;
FT_Pos segment_length_threshold;
FT_Pos segment_width_threshold;
axis->num_edges = 0;
scale = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
: hints->y_scale;
#if 0
up_dir = ( dim == AF_DIMENSION_HORZ ) ? AF_DIR_UP
: AF_DIR_RIGHT;
#endif
if ( dim == AF_DIMENSION_VERT )
top_to_bottom_hinting = script_class->top_to_bottom_hinting;
/*
* We ignore all segments that are less than 1 pixel in length
* to avoid many problems with serif fonts. We compute the
* corresponding threshold in font units.
*/
if ( dim == AF_DIMENSION_HORZ )
segment_length_threshold = FT_DivFix( 64, hints->y_scale );
else
segment_length_threshold = 0;
/*
* Similarly, we ignore segments that have a width delta
* larger than 0.5px (i.e., a width larger than 1px).
*/
segment_width_threshold = FT_DivFix( 32, scale );
/**********************************************************************
*
* We begin by generating a sorted table of edges for the current
* direction. To do so, we simply scan each segment and try to find
* an edge in our table that corresponds to its position.
*
* If no edge is found, we create and insert a new edge in the
* sorted table. Otherwise, we simply add the segment to the edge's
* list which gets processed in the second step to compute the
* edge's properties.
*
* Note that the table of edges is sorted along the segment/edge
* position.
*
*/
/* assure that edge distance threshold is at most 0.25px */
edge_distance_threshold = FT_MulFix( laxis->edge_distance_threshold,
scale );
if ( edge_distance_threshold > 64 / 4 )
edge_distance_threshold = 64 / 4;
edge_distance_threshold = FT_DivFix( edge_distance_threshold,
scale );
for ( seg = segments; seg < segment_limit; seg++ )
{
AF_Edge found = NULL;
FT_Int ee;
/* ignore too short segments, too wide ones, and, in this loop, */
/* one-point segments without a direction */
if ( seg->height < segment_length_threshold ||
seg->delta > segment_width_threshold ||
seg->dir == AF_DIR_NONE )
continue;
/* A special case for serif edges: If they are smaller than */
/* 1.5 pixels we ignore them. */
if ( seg->serif &&
2 * seg->height < 3 * segment_length_threshold )
continue;
/* look for an edge corresponding to the segment */
for ( ee = 0; ee < axis->num_edges; ee++ )
{
AF_Edge edge = axis->edges + ee;
FT_Pos dist;
dist = seg->pos - edge->fpos;
if ( dist < 0 )
dist = -dist;
if ( dist < edge_distance_threshold && edge->dir == seg->dir )
{
found = edge;
break;
}
}
if ( !found )
{
AF_Edge edge;
/* insert a new edge in the list and */
/* sort according to the position */
error = af_axis_hints_new_edge( axis, seg->pos,
(AF_Direction)seg->dir,
top_to_bottom_hinting,
memory, &edge );
if ( error )
goto Exit;
/* add the segment to the new edge's list */
FT_ZERO( edge );
edge->first = seg;
edge->last = seg;
edge->dir = seg->dir;
edge->fpos = seg->pos;
edge->opos = FT_MulFix( seg->pos, scale );
edge->pos = edge->opos;
seg->edge_next = seg;
}
else
{
/* if an edge was found, simply add the segment to the edge's */
/* list */
seg->edge_next = found->first;
found->last->edge_next = seg;
found->last = seg;
}
}
/* we loop again over all segments to catch one-point segments */
/* without a direction: if possible, link them to existing edges */
for ( seg = segments; seg < segment_limit; seg++ )
{
AF_Edge found = NULL;
FT_Int ee;
if ( seg->dir != AF_DIR_NONE )
continue;
/* look for an edge corresponding to the segment */
for ( ee = 0; ee < axis->num_edges; ee++ )
{
AF_Edge edge = axis->edges + ee;
FT_Pos dist;
dist = seg->pos - edge->fpos;
if ( dist < 0 )
dist = -dist;
if ( dist < edge_distance_threshold )
{
found = edge;
break;
}
}
/* one-point segments without a match are ignored */
if ( found )
{
seg->edge_next = found->first;
found->last->edge_next = seg;
found->last = seg;
}
}
/*******************************************************************
*
* Good, we now compute each edge's properties according to the
* segments found on its position. Basically, these are
*
* - the edge's main direction
* - stem edge, serif edge or both (which defaults to stem then)
* - rounded edge, straight or both (which defaults to straight)
* - link for edge
*
*/
/* first of all, set the `edge' field in each segment -- this is */
/* required in order to compute edge links */
/*
* Note that removing this loop and setting the `edge' field of each
* segment directly in the code above slows down execution speed for
* some reasons on platforms like the Sun.
*/
{
AF_Edge edges = axis->edges;
AF_Edge edge_limit = FT_OFFSET( edges, axis->num_edges );
AF_Edge edge;
for ( edge = edges; edge < edge_limit; edge++ )
{
seg = edge->first;
if ( seg )
do
{
seg->edge = edge;
seg = seg->edge_next;
} while ( seg != edge->first );
}
/* now compute each edge properties */
for ( edge = edges; edge < edge_limit; edge++ )
{
FT_Int is_round = 0; /* does it contain round segments? */
FT_Int is_straight = 0; /* does it contain straight segments? */
#if 0
FT_Pos ups = 0; /* number of upwards segments */
FT_Pos downs = 0; /* number of downwards segments */
#endif
seg = edge->first;
do
{
FT_Bool is_serif;
/* check for roundness of segment */
if ( seg->flags & AF_EDGE_ROUND )
is_round++;
else
is_straight++;
#if 0
/* check for segment direction */
if ( seg->dir == up_dir )
ups += seg->max_coord - seg->min_coord;
else
downs += seg->max_coord - seg->min_coord;
#endif
/* check for links -- if seg->serif is set, then seg->link must */
/* be ignored */
is_serif = FT_BOOL( seg->serif &&
seg->serif->edge &&
seg->serif->edge != edge );
if ( ( seg->link && seg->link->edge ) || is_serif )
{
AF_Edge edge2;
AF_Segment seg2;
edge2 = edge->link;
seg2 = seg->link;
if ( is_serif )
{
seg2 = seg->serif;
edge2 = edge->serif;
}
if ( edge2 )
{
FT_Pos edge_delta;
FT_Pos seg_delta;
edge_delta = edge->fpos - edge2->fpos;
if ( edge_delta < 0 )
edge_delta = -edge_delta;
seg_delta = seg->pos - seg2->pos;
if ( seg_delta < 0 )
seg_delta = -seg_delta;
if ( seg_delta < edge_delta )
edge2 = seg2->edge;
}
else
edge2 = seg2->edge;
if ( is_serif )
{
edge->serif = edge2;
edge2->flags |= AF_EDGE_SERIF;
}
else
edge->link = edge2;
}
seg = seg->edge_next;
} while ( seg != edge->first );
/* set the round/straight flags */
edge->flags = AF_EDGE_NORMAL;
if ( is_round > 0 && is_round >= is_straight )
edge->flags |= AF_EDGE_ROUND;
#if 0
/* set the edge's main direction */
edge->dir = AF_DIR_NONE;
if ( ups > downs )
edge->dir = (FT_Char)up_dir;
else if ( ups < downs )
edge->dir = (FT_Char)-up_dir;
else if ( ups == downs )
edge->dir = 0; /* both up and down! */
#endif
/* get rid of serifs if link is set */
/* XXX: This gets rid of many unpleasant artefacts! */
/* Example: the `c' in cour.pfa at size 13 */
if ( edge->serif && edge->link )
edge->serif = NULL;
}
}
Exit:
return error;
}
/* Detect segments and edges for given dimension. */
FT_LOCAL_DEF( FT_Error )
af_latin_hints_detect_features( AF_GlyphHints hints,
FT_UInt width_count,
AF_WidthRec* widths,
AF_Dimension dim )
{
FT_Error error;
error = af_latin_hints_compute_segments( hints, dim );
if ( !error )
{
af_latin_hints_link_segments( hints, width_count, widths, dim );
error = af_latin_hints_compute_edges( hints, dim );
}
return error;
}
/* Compute all edges which lie within blue zones. */
static void
af_latin_hints_compute_blue_edges( AF_GlyphHints hints,
AF_LatinMetrics metrics )
{
AF_AxisHints axis = &hints->axis[AF_DIMENSION_VERT];
AF_Edge edge = axis->edges;
AF_Edge edge_limit = FT_OFFSET( edge, axis->num_edges );
AF_LatinAxis latin = &metrics->axis[AF_DIMENSION_VERT];
FT_Fixed scale = latin->scale;
/* compute which blue zones are active, i.e. have their scaled */
/* size < 3/4 pixels */
/* for each horizontal edge search the blue zone which is closest */
for ( ; edge < edge_limit; edge++ )
{
FT_UInt bb;
AF_Width best_blue = NULL;
FT_Bool best_blue_is_neutral = 0;
FT_Pos best_dist; /* initial threshold */
/* compute the initial threshold as a fraction of the EM size */
/* (the value 40 is heuristic) */
best_dist = FT_MulFix( metrics->units_per_em / 40, scale );
/* assure a minimum distance of 0.5px */
if ( best_dist > 64 / 2 )
best_dist = 64 / 2;
for ( bb = 0; bb < latin->blue_count; bb++ )
{
AF_LatinBlue blue = latin->blues + bb;
FT_Bool is_top_blue, is_neutral_blue, is_major_dir;
/* skip inactive blue zones (i.e., those that are too large) */
if ( !( blue->flags & AF_LATIN_BLUE_ACTIVE ) )
continue;
/* if it is a top zone, check for right edges (against the major */
/* direction); if it is a bottom zone, check for left edges (in */
/* the major direction) -- this assumes the TrueType convention */
/* for the orientation of contours */
is_top_blue =
(FT_Byte)( ( blue->flags & ( AF_LATIN_BLUE_TOP |
AF_LATIN_BLUE_SUB_TOP ) ) != 0 );
is_neutral_blue =
(FT_Byte)( ( blue->flags & AF_LATIN_BLUE_NEUTRAL ) != 0);
is_major_dir =
FT_BOOL( edge->dir == axis->major_dir );
/* neutral blue zones are handled for both directions */
if ( is_top_blue ^ is_major_dir || is_neutral_blue )
{
FT_Pos dist;
/* first of all, compare it to the reference position */
dist = edge->fpos - blue->ref.org;
if ( dist < 0 )
dist = -dist;
dist = FT_MulFix( dist, scale );
if ( dist < best_dist )
{
best_dist = dist;
best_blue = &blue->ref;
best_blue_is_neutral = is_neutral_blue;
}
/* now compare it to the overshoot position and check whether */
/* the edge is rounded, and whether the edge is over the */
/* reference position of a top zone, or under the reference */
/* position of a bottom zone (provided we don't have a */
/* neutral blue zone) */
if ( edge->flags & AF_EDGE_ROUND &&
dist != 0 &&
!is_neutral_blue )
{
FT_Bool is_under_ref = FT_BOOL( edge->fpos < blue->ref.org );
if ( is_top_blue ^ is_under_ref )
{
dist = edge->fpos - blue->shoot.org;
if ( dist < 0 )
dist = -dist;
dist = FT_MulFix( dist, scale );
if ( dist < best_dist )
{
best_dist = dist;
best_blue = &blue->shoot;
best_blue_is_neutral = is_neutral_blue;
}
}
}
}
}
if ( best_blue )
{
edge->blue_edge = best_blue;
if ( best_blue_is_neutral )
edge->flags |= AF_EDGE_NEUTRAL;
}
}
}
/* Initalize hinting engine. */
static FT_Error
af_latin_hints_init( AF_GlyphHints hints,
AF_LatinMetrics metrics )
{
FT_Render_Mode mode;
FT_UInt32 scaler_flags, other_flags;
FT_Face face = metrics->root.scaler.face;
af_glyph_hints_rescale( hints, (AF_StyleMetrics)metrics );
/*
* correct x_scale and y_scale if needed, since they may have
* been modified by `af_latin_metrics_scale_dim' above
*/
hints->x_scale = metrics->axis[AF_DIMENSION_HORZ].scale;
hints->x_delta = metrics->axis[AF_DIMENSION_HORZ].delta;
hints->y_scale = metrics->axis[AF_DIMENSION_VERT].scale;
hints->y_delta = metrics->axis[AF_DIMENSION_VERT].delta;
/* compute flags depending on render mode, etc. */
mode = metrics->root.scaler.render_mode;
scaler_flags = hints->scaler_flags;
other_flags = 0;
/*
* We snap the width of vertical stems for the monochrome and
* horizontal LCD rendering targets only.
*/
if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD )
other_flags |= AF_LATIN_HINTS_HORZ_SNAP;
/*
* We snap the width of horizontal stems for the monochrome and
* vertical LCD rendering targets only.
*/
if ( mode == FT_RENDER_MODE_MONO || mode == FT_RENDER_MODE_LCD_V )
other_flags |= AF_LATIN_HINTS_VERT_SNAP;
/*
* We adjust stems to full pixels unless in `light' or `lcd' mode.
*/
if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
if ( mode == FT_RENDER_MODE_MONO )
other_flags |= AF_LATIN_HINTS_MONO;
/*
* In `light' or `lcd' mode we disable horizontal hinting completely.
* We also do it if the face is italic.
*
* However, if warping is enabled (which only works in `light' hinting
* mode), advance widths get adjusted, too.
*/
if ( mode == FT_RENDER_MODE_LIGHT || mode == FT_RENDER_MODE_LCD ||
( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;
hints->scaler_flags = scaler_flags;
hints->other_flags = other_flags;
return FT_Err_Ok;
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N G L Y P H G R I D - F I T T I N G *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/* Snap a given width in scaled coordinates to one of the */
/* current standard widths. */
static FT_Pos
af_latin_snap_width( AF_Width widths,
FT_UInt count,
FT_Pos width )
{
FT_UInt n;
FT_Pos best = 64 + 32 + 2;
FT_Pos reference = width;
FT_Pos scaled;
for ( n = 0; n < count; n++ )
{
FT_Pos w;
FT_Pos dist;
w = widths[n].cur;
dist = width - w;
if ( dist < 0 )
dist = -dist;
if ( dist < best )
{
best = dist;
reference = w;
}
}
scaled = FT_PIX_ROUND( reference );
if ( width >= reference )
{
if ( width < scaled + 48 )
width = reference;
}
else
{
if ( width > scaled - 48 )
width = reference;
}
return width;
}
/* Compute the snapped width of a given stem, ignoring very thin ones. */
/* There is a lot of voodoo in this function; changing the hard-coded */
/* parameters influence the whole hinting process. */
static FT_Pos
af_latin_compute_stem_width( AF_GlyphHints hints,
AF_Dimension dim,
FT_Pos width,
FT_Pos base_delta,
FT_UInt base_flags,
FT_UInt stem_flags )
{
AF_LatinMetrics metrics = (AF_LatinMetrics)hints->metrics;
AF_LatinAxis axis = &metrics->axis[dim];
FT_Pos dist = width;
FT_Int sign = 0;
FT_Int vertical = ( dim == AF_DIMENSION_VERT );
if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ) ||
axis->extra_light )
return width;
if ( dist < 0 )
{
dist = -width;
sign = 1;
}
if ( ( vertical && !AF_LATIN_HINTS_DO_VERT_SNAP( hints ) ) ||
( !vertical && !AF_LATIN_HINTS_DO_HORZ_SNAP( hints ) ) )
{
/* smooth hinting process: very lightly quantize the stem width */
/* leave the widths of serifs alone */
if ( ( stem_flags & AF_EDGE_SERIF ) &&
vertical &&
( dist < 3 * 64 ) )
goto Done_Width;
else if ( base_flags & AF_EDGE_ROUND )
{
if ( dist < 80 )
dist = 64;
}
else if ( dist < 56 )
dist = 56;
if ( axis->width_count > 0 )
{
FT_Pos delta;
/* compare to standard width */
delta = dist - axis->widths[0].cur;
if ( delta < 0 )
delta = -delta;
if ( delta < 40 )
{
dist = axis->widths[0].cur;
if ( dist < 48 )
dist = 48;
goto Done_Width;
}
if ( dist < 3 * 64 )
{
delta = dist & 63;
dist &= -64;
if ( delta < 10 )
dist += delta;
else if ( delta < 32 )
dist += 10;
else if ( delta < 54 )
dist += 54;
else
dist += delta;
}
else
{
/* A stem's end position depends on two values: the start */
/* position and the stem length. The former gets usually */
/* rounded to the grid, while the latter gets rounded also if it */
/* exceeds a certain length (see below in this function). This */
/* `double rounding' can lead to a great difference to the */
/* original, unhinted position; this normally doesn't matter for */
/* large PPEM values, but for small sizes it can easily make */
/* outlines collide. For this reason, we adjust the stem length */
/* by a small amount depending on the PPEM value in case the */
/* former and latter rounding both point into the same */
/* direction. */
FT_Pos bdelta = 0;
if ( ( ( width > 0 ) && ( base_delta > 0 ) ) ||
( ( width < 0 ) && ( base_delta < 0 ) ) )
{
FT_UInt ppem = metrics->root.scaler.face->size->metrics.x_ppem;
if ( ppem < 10 )
bdelta = base_delta;
else if ( ppem < 30 )
bdelta = ( base_delta * (FT_Pos)( 30 - ppem ) ) / 20;
if ( bdelta < 0 )
bdelta = -bdelta;
}
dist = ( dist - bdelta + 32 ) & ~63;
}
}
}
else
{
/* strong hinting process: snap the stem width to integer pixels */
FT_Pos org_dist = dist;
dist = af_latin_snap_width( axis->widths, axis->width_count, dist );
if ( vertical )
{
/* in the case of vertical hinting, always round */
/* the stem heights to integer pixels */
if ( dist >= 64 )
dist = ( dist + 16 ) & ~63;
else
dist = 64;
}
else
{
if ( AF_LATIN_HINTS_DO_MONO( hints ) )
{
/* monochrome horizontal hinting: snap widths to integer pixels */
/* with a different threshold */
if ( dist < 64 )
dist = 64;
else
dist = ( dist + 32 ) & ~63;
}
else
{
/* for horizontal anti-aliased hinting, we adopt a more subtle */
/* approach: we strengthen small stems, round stems whose size */
/* is between 1 and 2 pixels to an integer, otherwise nothing */
if ( dist < 48 )
dist = ( dist + 64 ) >> 1;
else if ( dist < 128 )
{
/* We only round to an integer width if the corresponding */
/* distortion is less than 1/4 pixel. Otherwise this */
/* makes everything worse since the diagonals, which are */
/* not hinted, appear a lot bolder or thinner than the */
/* vertical stems. */
FT_Pos delta;
dist = ( dist + 22 ) & ~63;
delta = dist - org_dist;
if ( delta < 0 )
delta = -delta;
if ( delta >= 16 )
{
dist = org_dist;
if ( dist < 48 )
dist = ( dist + 64 ) >> 1;
}
}
else
/* round otherwise to prevent color fringes in LCD mode */
dist = ( dist + 32 ) & ~63;
}
}
}
Done_Width:
if ( sign )
dist = -dist;
return dist;
}
/* Align one stem edge relative to the previous stem edge. */
static void
af_latin_align_linked_edge( AF_GlyphHints hints,
AF_Dimension dim,
AF_Edge base_edge,
AF_Edge stem_edge )
{
FT_Pos dist, base_delta;
FT_Pos fitted_width;
dist = stem_edge->opos - base_edge->opos;
base_delta = base_edge->pos - base_edge->opos;
fitted_width = af_latin_compute_stem_width( hints, dim,
dist, base_delta,
base_edge->flags,
stem_edge->flags );
stem_edge->pos = base_edge->pos + fitted_width;
FT_TRACE5(( " LINK: edge %ld (opos=%.2f) linked to %.2f,"
" dist was %.2f, now %.2f\n",
stem_edge - hints->axis[dim].edges, stem_edge->opos / 64.0,
stem_edge->pos / 64.0, dist / 64.0, fitted_width / 64.0 ));
}
/* Shift the coordinates of the `serif' edge by the same amount */
/* as the corresponding `base' edge has been moved already. */
static void
af_latin_align_serif_edge( AF_GlyphHints hints,
AF_Edge base,
AF_Edge serif )
{
FT_UNUSED( hints );
serif->pos = base->pos + ( serif->opos - base->opos );
}
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** E D G E H I N T I N G ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/* The main grid-fitting routine. */
static void
af_latin_hint_edges( AF_GlyphHints hints,
AF_Dimension dim )
{
AF_AxisHints axis = &hints->axis[dim];
AF_Edge edges = axis->edges;
AF_Edge edge_limit = FT_OFFSET( edges, axis->num_edges );
FT_PtrDist n_edges;
AF_Edge edge;
AF_Edge anchor = NULL;
FT_Int has_serifs = 0;
AF_StyleClass style_class = hints->metrics->style_class;
AF_ScriptClass script_class = af_script_classes[style_class->script];
FT_Bool top_to_bottom_hinting = 0;
#ifdef FT_DEBUG_LEVEL_TRACE
FT_UInt num_actions = 0;
#endif
FT_TRACE5(( "latin %s edge hinting (style `%s')\n",
dim == AF_DIMENSION_VERT ? "horizontal" : "vertical",
af_style_names[hints->metrics->style_class->style] ));
if ( dim == AF_DIMENSION_VERT )
top_to_bottom_hinting = script_class->top_to_bottom_hinting;
/* we begin by aligning all stems relative to the blue zone */
/* if needed -- that's only for horizontal edges */
if ( dim == AF_DIMENSION_VERT && AF_HINTS_DO_BLUES( hints ) )
{
for ( edge = edges; edge < edge_limit; edge++ )
{
AF_Width blue;
AF_Edge edge1, edge2; /* these edges form the stem to check */
if ( edge->flags & AF_EDGE_DONE )
continue;
edge1 = NULL;
edge2 = edge->link;
/*
* If a stem contains both a neutral and a non-neutral blue zone,
* skip the neutral one. Otherwise, outlines with different
* directions might be incorrectly aligned at the same vertical
* position.
*
* If we have two neutral blue zones, skip one of them.
*
*/
if ( edge->blue_edge && edge2 && edge2->blue_edge )
{
FT_Byte neutral = edge->flags & AF_EDGE_NEUTRAL;
FT_Byte neutral2 = edge2->flags & AF_EDGE_NEUTRAL;
if ( neutral2 )
{
edge2->blue_edge = NULL;
edge2->flags &= ~AF_EDGE_NEUTRAL;
}
else if ( neutral )
{
edge->blue_edge = NULL;
edge->flags &= ~AF_EDGE_NEUTRAL;
}
}
blue = edge->blue_edge;
if ( blue )
edge1 = edge;
/* flip edges if the other edge is aligned to a blue zone */
else if ( edge2 && edge2->blue_edge )
{
blue = edge2->blue_edge;
edge1 = edge2;
edge2 = edge;
}
if ( !edge1 )
continue;
#ifdef FT_DEBUG_LEVEL_TRACE
if ( !anchor )
FT_TRACE5(( " BLUE_ANCHOR: edge %ld (opos=%.2f) snapped to %.2f,"
" was %.2f (anchor=edge %ld)\n",
edge1 - edges, edge1->opos / 64.0, blue->fit / 64.0,
edge1->pos / 64.0, edge - edges ));
else
FT_TRACE5(( " BLUE: edge %ld (opos=%.2f) snapped to %.2f,"
" was %.2f\n",
edge1 - edges, edge1->opos / 64.0, blue->fit / 64.0,
edge1->pos / 64.0 ));
num_actions++;
#endif
edge1->pos = blue->fit;
edge1->flags |= AF_EDGE_DONE;
if ( edge2 && !edge2->blue_edge )
{
af_latin_align_linked_edge( hints, dim, edge1, edge2 );
edge2->flags |= AF_EDGE_DONE;
#ifdef FT_DEBUG_LEVEL_TRACE
num_actions++;
#endif
}
if ( !anchor )
anchor = edge;
}
}
/* now we align all other stem edges, trying to maintain the */
/* relative order of stems in the glyph */
for ( edge = edges; edge < edge_limit; edge++ )
{
AF_Edge edge2;
if ( edge->flags & AF_EDGE_DONE )
continue;
/* skip all non-stem edges */
edge2 = edge->link;
if ( !edge2 )
{
has_serifs++;
continue;
}
/* now align the stem */
/* this should not happen, but it's better to be safe */
if ( edge2->blue_edge )
{
FT_TRACE5(( " ASSERTION FAILED for edge %ld\n", edge2 - edges ));
af_latin_align_linked_edge( hints, dim, edge2, edge );
edge->flags |= AF_EDGE_DONE;
#ifdef FT_DEBUG_LEVEL_TRACE
num_actions++;
#endif
continue;
}
if ( !anchor )
{
/* if we reach this if clause, no stem has been aligned yet */
FT_Pos org_len, org_center, cur_len;
FT_Pos cur_pos1, error1, error2, u_off, d_off;
org_len = edge2->opos - edge->opos;
cur_len = af_latin_compute_stem_width( hints, dim,
org_len, 0,
edge->flags,
edge2->flags );
/* some voodoo to specially round edges for small stem widths; */
/* the idea is to align the center of a stem, then shifting */
/* the stem edges to suitable positions */
if ( cur_len <= 64 )
{
/* width <= 1px */
u_off = 32;
d_off = 32;
}
else
{
/* 1px < width < 1.5px */
u_off = 38;
d_off = 26;
}
if ( cur_len < 96 )
{
org_center = edge->opos + ( org_len >> 1 );
cur_pos1 = FT_PIX_ROUND( org_center );
error1 = org_center - ( cur_pos1 - u_off );
if ( error1 < 0 )
error1 = -error1;
error2 = org_center - ( cur_pos1 + d_off );
if ( error2 < 0 )
error2 = -error2;
if ( error1 < error2 )
cur_pos1 -= u_off;
else
cur_pos1 += d_off;
edge->pos = cur_pos1 - cur_len / 2;
edge2->pos = edge->pos + cur_len;
}
else
edge->pos = FT_PIX_ROUND( edge->opos );
anchor = edge;
edge->flags |= AF_EDGE_DONE;
FT_TRACE5(( " ANCHOR: edge %ld (opos=%.2f) and %ld (opos=%.2f)"
" snapped to %.2f and %.2f\n",
edge - edges, edge->opos / 64.0,
edge2 - edges, edge2->opos / 64.0,
edge->pos / 64.0, edge2->pos / 64.0 ));
af_latin_align_linked_edge( hints, dim, edge, edge2 );
#ifdef FT_DEBUG_LEVEL_TRACE
num_actions += 2;
#endif
}
else
{
FT_Pos org_pos, org_len, org_center, cur_len;
FT_Pos cur_pos1, cur_pos2, delta1, delta2;
org_pos = anchor->pos + ( edge->opos - anchor->opos );
org_len = edge2->opos - edge->opos;
org_center = org_pos + ( org_len >> 1 );
cur_len = af_latin_compute_stem_width( hints, dim,
org_len, 0,
edge->flags,
edge2->flags );
if ( edge2->flags & AF_EDGE_DONE )
{
FT_TRACE5(( " ADJUST: edge %ld (pos=%.2f) moved to %.2f\n",
edge - edges, edge->pos / 64.0,
( edge2->pos - cur_len ) / 64.0 ));
edge->pos = edge2->pos - cur_len;
}
else if ( cur_len < 96 )
{
FT_Pos u_off, d_off;
cur_pos1 = FT_PIX_ROUND( org_center );
if ( cur_len <= 64 )
{
u_off = 32;
d_off = 32;
}
else
{
u_off = 38;
d_off = 26;
}
delta1 = org_center - ( cur_pos1 - u_off );
if ( delta1 < 0 )
delta1 = -delta1;
delta2 = org_center - ( cur_pos1 + d_off );
if ( delta2 < 0 )
delta2 = -delta2;
if ( delta1 < delta2 )
cur_pos1 -= u_off;
else
cur_pos1 += d_off;
edge->pos = cur_pos1 - cur_len / 2;
edge2->pos = cur_pos1 + cur_len / 2;
FT_TRACE5(( " STEM: edge %ld (opos=%.2f) linked to %ld (opos=%.2f)"
" snapped to %.2f and %.2f\n",
edge - edges, edge->opos / 64.0,
edge2 - edges, edge2->opos / 64.0,
edge->pos / 64.0, edge2->pos / 64.0 ));
}
else
{
org_pos = anchor->pos + ( edge->opos - anchor->opos );
org_len = edge2->opos - edge->opos;
org_center = org_pos + ( org_len >> 1 );
cur_len = af_latin_compute_stem_width( hints, dim,
org_len, 0,
edge->flags,
edge2->flags );
cur_pos1 = FT_PIX_ROUND( org_pos );
delta1 = cur_pos1 + ( cur_len >> 1 ) - org_center;
if ( delta1 < 0 )
delta1 = -delta1;
cur_pos2 = FT_PIX_ROUND( org_pos + org_len ) - cur_len;
delta2 = cur_pos2 + ( cur_len >> 1 ) - org_center;
if ( delta2 < 0 )
delta2 = -delta2;
edge->pos = ( delta1 < delta2 ) ? cur_pos1 : cur_pos2;
edge2->pos = edge->pos + cur_len;
FT_TRACE5(( " STEM: edge %ld (opos=%.2f) linked to %ld (opos=%.2f)"
" snapped to %.2f and %.2f\n",
edge - edges, edge->opos / 64.0,
edge2 - edges, edge2->opos / 64.0,
edge->pos / 64.0, edge2->pos / 64.0 ));
}
#ifdef FT_DEBUG_LEVEL_TRACE
num_actions++;
#endif
edge->flags |= AF_EDGE_DONE;
edge2->flags |= AF_EDGE_DONE;
if ( edge > edges &&
( top_to_bottom_hinting ? ( edge->pos > edge[-1].pos )
: ( edge->pos < edge[-1].pos ) ) )
{
/* don't move if stem would (almost) disappear otherwise; */
/* the ad-hoc value 16 corresponds to 1/4px */
if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
{
#ifdef FT_DEBUG_LEVEL_TRACE
FT_TRACE5(( " BOUND: edge %ld (pos=%.2f) moved to %.2f\n",
edge - edges,
edge->pos / 64.0,
edge[-1].pos / 64.0 ));
num_actions++;
#endif
edge->pos = edge[-1].pos;
}
}
}
}
/* make sure that lowercase m's maintain their symmetry */
/* In general, lowercase m's have six vertical edges if they are sans */
/* serif, or twelve if they are with serifs. This implementation is */
/* based on that assumption, and seems to work very well with most */
/* faces. However, if for a certain face this assumption is not */
/* true, the m is just rendered like before. In addition, any stem */
/* correction will only be applied to symmetrical glyphs (even if the */
/* glyph is not an m), so the potential for unwanted distortion is */
/* relatively low. */
/* We don't handle horizontal edges since we can't easily assure that */
/* the third (lowest) stem aligns with the base line; it might end up */
/* one pixel higher or lower. */
n_edges = edge_limit - edges;
if ( dim == AF_DIMENSION_HORZ && ( n_edges == 6 || n_edges == 12 ) )
{
AF_Edge edge1, edge2, edge3;
FT_Pos dist1, dist2, span, delta;
if ( n_edges == 6 )
{
edge1 = edges;
edge2 = edges + 2;
edge3 = edges + 4;
}
else
{
edge1 = edges + 1;
edge2 = edges + 5;
edge3 = edges + 9;
}
dist1 = edge2->opos - edge1->opos;
dist2 = edge3->opos - edge2->opos;
span = dist1 - dist2;
if ( span < 0 )
span = -span;
if ( span < 8 )
{
delta = edge3->pos - ( 2 * edge2->pos - edge1->pos );
edge3->pos -= delta;
if ( edge3->link )
edge3->link->pos -= delta;
/* move the serifs along with the stem */
if ( n_edges == 12 )
{
( edges + 8 )->pos -= delta;
( edges + 11 )->pos -= delta;
}
edge3->flags |= AF_EDGE_DONE;
if ( edge3->link )
edge3->link->flags |= AF_EDGE_DONE;
}
}
if ( has_serifs || !anchor )
{
/*
* now hint the remaining edges (serifs and single) in order
* to complete our processing
*/
for ( edge = edges; edge < edge_limit; edge++ )
{
FT_Pos delta;
if ( edge->flags & AF_EDGE_DONE )
continue;
delta = 1000;
if ( edge->serif )
{
delta = edge->serif->opos - edge->opos;
if ( delta < 0 )
delta = -delta;
}
if ( delta < 64 + 16 )
{
af_latin_align_serif_edge( hints, edge->serif, edge );
FT_TRACE5(( " SERIF: edge %ld (opos=%.2f) serif to %ld (opos=%.2f)"
" aligned to %.2f\n",
edge - edges, edge->opos / 64.0,
edge->serif - edges, edge->serif->opos / 64.0,
edge->pos / 64.0 ));
}
else if ( !anchor )
{
edge->pos = FT_PIX_ROUND( edge->opos );
anchor = edge;
FT_TRACE5(( " SERIF_ANCHOR: edge %ld (opos=%.2f)"
" snapped to %.2f\n",
edge-edges, edge->opos / 64.0, edge->pos / 64.0 ));
}
else
{
AF_Edge before, after;
for ( before = edge - 1; before >= edges; before-- )
if ( before->flags & AF_EDGE_DONE )
break;
for ( after = edge + 1; after < edge_limit; after++ )
if ( after->flags & AF_EDGE_DONE )
break;
if ( before >= edges && before < edge &&
after < edge_limit && after > edge )
{
if ( after->opos == before->opos )
edge->pos = before->pos;
else
edge->pos = before->pos +
FT_MulDiv( edge->opos - before->opos,
after->pos - before->pos,
after->opos - before->opos );
FT_TRACE5(( " SERIF_LINK1: edge %ld (opos=%.2f) snapped to %.2f"
" from %ld (opos=%.2f)\n",
edge - edges, edge->opos / 64.0,
edge->pos / 64.0,
before - edges, before->opos / 64.0 ));
}
else
{
edge->pos = anchor->pos +
( ( edge->opos - anchor->opos + 16 ) & ~31 );
FT_TRACE5(( " SERIF_LINK2: edge %ld (opos=%.2f)"
" snapped to %.2f\n",
edge - edges, edge->opos / 64.0, edge->pos / 64.0 ));
}
}
#ifdef FT_DEBUG_LEVEL_TRACE
num_actions++;
#endif
edge->flags |= AF_EDGE_DONE;
if ( edge > edges &&
( top_to_bottom_hinting ? ( edge->pos > edge[-1].pos )
: ( edge->pos < edge[-1].pos ) ) )
{
/* don't move if stem would (almost) disappear otherwise; */
/* the ad-hoc value 16 corresponds to 1/4px */
if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
{
#ifdef FT_DEBUG_LEVEL_TRACE
FT_TRACE5(( " BOUND: edge %ld (pos=%.2f) moved to %.2f\n",
edge - edges,
edge->pos / 64.0,
edge[-1].pos / 64.0 ));
num_actions++;
#endif
edge->pos = edge[-1].pos;
}
}
if ( edge + 1 < edge_limit &&
edge[1].flags & AF_EDGE_DONE &&
( top_to_bottom_hinting ? ( edge->pos < edge[1].pos )
: ( edge->pos > edge[1].pos ) ) )
{
/* don't move if stem would (almost) disappear otherwise; */
/* the ad-hoc value 16 corresponds to 1/4px */
if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
{
#ifdef FT_DEBUG_LEVEL_TRACE
FT_TRACE5(( " BOUND: edge %ld (pos=%.2f) moved to %.2f\n",
edge - edges,
edge->pos / 64.0,
edge[1].pos / 64.0 ));
num_actions++;
#endif
edge->pos = edge[1].pos;
}
}
}
}
#ifdef FT_DEBUG_LEVEL_TRACE
if ( !num_actions )
FT_TRACE5(( " (none)\n" ));
FT_TRACE5(( "\n" ));
#endif
}
/* Apply the complete hinting algorithm to a latin glyph. */
static FT_Error
af_latin_hints_apply( FT_UInt glyph_index,
AF_GlyphHints hints,
FT_Outline* outline,
AF_LatinMetrics metrics )
{
FT_Error error;
int dim;
AF_LatinAxis axis;
error = af_glyph_hints_reload( hints, outline );
if ( error )
goto Exit;
/* analyze glyph outline */
if ( AF_HINTS_DO_HORIZONTAL( hints ) )
{
axis = &metrics->axis[AF_DIMENSION_HORZ];
error = af_latin_hints_detect_features( hints,
axis->width_count,
axis->widths,
AF_DIMENSION_HORZ );
if ( error )
goto Exit;
}
if ( AF_HINTS_DO_VERTICAL( hints ) )
{
axis = &metrics->axis[AF_DIMENSION_VERT];
error = af_latin_hints_detect_features( hints,
axis->width_count,
axis->widths,
AF_DIMENSION_VERT );
if ( error )
goto Exit;
/* apply blue zones to base characters only */
if ( !( metrics->root.globals->glyph_styles[glyph_index] & AF_NONBASE ) )
af_latin_hints_compute_blue_edges( hints, metrics );
}
/* grid-fit the outline */
for ( dim = 0; dim < AF_DIMENSION_MAX; dim++ )
{
if ( ( dim == AF_DIMENSION_HORZ && AF_HINTS_DO_HORIZONTAL( hints ) ) ||
( dim == AF_DIMENSION_VERT && AF_HINTS_DO_VERTICAL( hints ) ) )
{
af_latin_hint_edges( hints, (AF_Dimension)dim );
af_glyph_hints_align_edge_points( hints, (AF_Dimension)dim );
af_glyph_hints_align_strong_points( hints, (AF_Dimension)dim );
af_glyph_hints_align_weak_points( hints, (AF_Dimension)dim );
}
}
af_glyph_hints_save( hints, outline );
Exit:
return error;
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N S C R I P T C L A S S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
AF_DEFINE_WRITING_SYSTEM_CLASS(
af_latin_writing_system_class,
AF_WRITING_SYSTEM_LATIN,
sizeof ( AF_LatinMetricsRec ),
(AF_WritingSystem_InitMetricsFunc) af_latin_metrics_init, /* style_metrics_init */
(AF_WritingSystem_ScaleMetricsFunc)af_latin_metrics_scale, /* style_metrics_scale */
(AF_WritingSystem_DoneMetricsFunc) NULL, /* style_metrics_done */
(AF_WritingSystem_GetStdWidthsFunc)af_latin_get_standard_widths, /* style_metrics_getstdw */
(AF_WritingSystem_InitHintsFunc) af_latin_hints_init, /* style_hints_init */
(AF_WritingSystem_ApplyHintsFunc) af_latin_hints_apply /* style_hints_apply */
)
/* END */