ref: 730b7b1f79c447f6812fe95c8b2f9ec684752d81
dir: /src/autofit/aflatin.c/
/***************************************************************************/
/* */
/* aflatin.c */
/* */
/* Auto-fitter hinting routines for latin script (body). */
/* */
/* Copyright 2003, 2004, 2005 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 "aflatin.h"
#include "aferrors.h"
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N G L O B A L M E T R I C S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
static void
af_latin_metrics_init_widths( AF_LatinMetrics metrics,
FT_Face face )
{
/* scan the array of segments in each direction */
AF_GlyphHintsRec hints[1];
af_glyph_hints_init( hints, face->memory );
metrics->axis[AF_DIMENSION_HORZ].width_count = 0;
metrics->axis[AF_DIMENSION_VERT].width_count = 0;
/* For now, compute the standard width and height from the `o'. */
{
FT_Error error;
FT_UInt glyph_index;
int dim;
AF_ScriptMetricsRec dummy[1];
AF_Scaler scaler = &dummy->scaler;
glyph_index = FT_Get_Char_Index( face, 'o' );
if ( glyph_index == 0 )
goto Exit;
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE );
if ( error || face->glyph->outline.n_points <= 0 )
goto Exit;
FT_ZERO( dummy );
scaler->x_scale = scaler->y_scale = 0x10000L;
scaler->x_delta = scaler->y_delta = 0;
scaler->face = face;
scaler->render_mode = FT_RENDER_MODE_NORMAL;
scaler->flags = 0;
af_glyph_hints_rescale( hints, 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;
FT_Pos edge_distance_threshold = 32000;
error = af_latin_hints_compute_segments( hints,
(AF_Dimension)dim );
if ( error )
goto Exit;
af_latin_hints_link_segments( hints,
(AF_Dimension)dim );
seg = axhints->segments;
limit = 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;
}
}
af_sort_widths( num_widths, axis->widths );
axis->width_count = num_widths;
/* we will now try to find the smallest width */
if ( num_widths > 0 && axis->widths[0].org < edge_distance_threshold )
edge_distance_threshold = axis->widths[0].org;
/* Now, compute the edge distance threshold as a fraction of the */
/* smallest width in the font. Set it in `hinter->glyph' too! */
if ( edge_distance_threshold == 32000 )
edge_distance_threshold = 50;
/* let's try 20% */
axis->edge_distance_threshold = edge_distance_threshold / 5;
}
}
Exit:
af_glyph_hints_done( hints );
}
#define AF_LATIN_MAX_TEST_CHARACTERS 12
static const char* const af_latin_blue_chars[AF_LATIN_MAX_BLUES] =
{
"THEZOCQS",
"HEZLOCUS",
"fijkdbh",
"xzroesc",
"xzroesc",
"pqgjy"
};
static void
af_latin_metrics_init_blues( AF_LatinMetrics metrics,
FT_Face face )
{
FT_Pos flats [AF_LATIN_MAX_TEST_CHARACTERS];
FT_Pos rounds[AF_LATIN_MAX_TEST_CHARACTERS];
FT_Int num_flats;
FT_Int num_rounds;
FT_Int bb;
AF_LatinBlue blue;
FT_Error error;
AF_LatinAxis axis = &metrics->axis[AF_DIMENSION_VERT];
FT_GlyphSlot glyph = face->glyph;
/* we compute the blues simply by loading each character from the */
/* 'af_latin_blue_chars[blues]' string, then compute its top-most or */
/* bottom-most points (depending on `AF_IS_TOP_BLUE') */
AF_LOG(( "blue zones computation\n" ));
AF_LOG(( "------------------------------------------------\n" ));
for ( bb = 0; bb < AF_LATIN_BLUE_MAX; bb++ )
{
const char* p = af_latin_blue_chars[bb];
const char* limit = p + AF_LATIN_MAX_TEST_CHARACTERS;
FT_Pos* blue_ref;
FT_Pos* blue_shoot;
AF_LOG(( "blue %3d: ", bb ));
num_flats = 0;
num_rounds = 0;
for ( ; p < limit && *p; p++ )
{
FT_UInt glyph_index;
FT_Vector* extremum;
FT_Vector* points;
FT_Vector* point_limit;
FT_Vector* point;
FT_Bool round;
AF_LOG(( "'%c'", *p ));
/* load the character in the face -- skip unknown or empty ones */
glyph_index = FT_Get_Char_Index( face, (FT_UInt)*p );
if ( glyph_index == 0 )
continue;
error = FT_Load_Glyph( face, glyph_index, FT_LOAD_NO_SCALE );
if ( error || glyph->outline.n_points <= 0 )
continue;
/* now compute min or max point indices and coordinates */
points = glyph->outline.points;
point_limit = points + glyph->outline.n_points;
point = points;
extremum = point;
point++;
if ( AF_LATIN_IS_TOP_BLUE( bb ) )
{
for ( ; point < point_limit; point++ )
if ( point->y > extremum->y )
extremum = point;
}
else
{
for ( ; point < point_limit; point++ )
if ( point->y < extremum->y )
extremum = point;
}
AF_LOG(( "%5d", (int)extremum->y ));
/* now, check whether the point belongs to a straight or round */
/* segment; we first need to find in which contour the extremum */
/* lies, then see its previous and next points */
{
FT_Int idx = (FT_Int)( extremum - points );
FT_Int n;
FT_Int first, last, prev, next, end;
FT_Pos dist;
last = -1;
first = 0;
for ( n = 0; n < glyph->outline.n_contours; n++ )
{
end = glyph->outline.contours[n];
if ( end >= idx )
{
last = end;
break;
}
first = end + 1;
}
/* XXX: should never happen! */
if ( last < 0 )
continue;
/* now look for the previous and next points that are not on the */
/* same Y coordinate. Threshold the `closeness'... */
prev = idx;
next = prev;
do
{
if ( prev > first )
prev--;
else
prev = last;
dist = points[prev].y - extremum->y;
if ( dist < -5 || dist > 5 )
break;
} while ( prev != idx );
do
{
if ( next < last )
next++;
else
next = first;
dist = points[next].y - extremum->y;
if ( dist < -5 || dist > 5 )
break;
} while ( next != idx );
/* now, set the `round' flag depending on the segment's kind */
round = FT_BOOL(
FT_CURVE_TAG( glyph->outline.tags[prev] ) != FT_CURVE_TAG_ON ||
FT_CURVE_TAG( glyph->outline.tags[next] ) != FT_CURVE_TAG_ON );
AF_LOG(( "%c ", round ? 'r' : 'f' ));
}
if ( round )
rounds[num_rounds++] = extremum->y;
else
flats[num_flats++] = extremum->y;
}
AF_LOG(( "\n" ));
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
*/
AF_LOG(( "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( bb ) ^ over_ref )
*blue_shoot = *blue_ref = ( shoot + ref ) / 2;
}
blue->flags = 0;
if ( AF_LATIN_IS_TOP_BLUE( bb ) )
blue->flags |= AF_LATIN_BLUE_TOP;
/*
* The following flags 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 ( bb == AF_LATIN_BLUE_SMALL_TOP )
blue->flags |= AF_LATIN_BLUE_ADJUSTMENT;
AF_LOG(( "-- ref = %ld, shoot = %ld\n", *blue_ref, *blue_shoot ));
}
return;
}
FT_LOCAL_DEF( FT_Error )
af_latin_metrics_init( AF_LatinMetrics metrics,
FT_Face face )
{
FT_Error error = AF_Err_Ok;
FT_CharMap oldmap = face->charmap;
FT_UInt ee;
static const FT_Encoding latin_encodings[] =
{
FT_ENCODING_UNICODE,
FT_ENCODING_APPLE_ROMAN,
FT_ENCODING_ADOBE_STANDARD,
FT_ENCODING_ADOBE_LATIN_1,
FT_ENCODING_NONE /* end of list */
};
metrics->units_per_em = face->units_per_EM;
/* do we have a latin charmap in there? */
for ( ee = 0; latin_encodings[ee] != FT_ENCODING_NONE; ee++ )
{
error = FT_Select_Charmap( face, latin_encodings[ee] );
if ( !error )
break;
}
if ( !error )
{
af_latin_metrics_init_widths( metrics, face );
af_latin_metrics_init_blues( metrics, face );
}
FT_Set_Charmap( face, oldmap );
return AF_Err_Ok;
}
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_MulFix( blue->shoot.org, scaler->y_scale );
FT_Pos fitted = FT_PIX_ROUND( scaled );
if ( scaled != fitted )
{
if ( dim == AF_DIMENSION_HORZ )
{
if ( fitted < scaled )
scale -= scale/50; /* x_scale = x_scale*0.98 */
}
else
{
scale = FT_MulDiv( scale, fitted, scaled );
}
}
}
}
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;
}
/* scale the standard 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;
}
if ( dim == AF_DIMENSION_VERT )
{
/* 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 )
{
FT_Pos delta1, delta2;
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;
blue->flags |= AF_LATIN_BLUE_ACTIVE;
}
}
}
}
FT_LOCAL_DEF( void )
af_latin_metrics_scale( AF_LatinMetrics metrics,
AF_Scaler scaler )
{
af_latin_metrics_scale_dim( metrics, scaler, AF_DIMENSION_HORZ );
af_latin_metrics_scale_dim( metrics, scaler, AF_DIMENSION_VERT );
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** L A T I N G L Y P H A N A L Y S I S *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
FT_LOCAL_DEF( FT_Error )
af_latin_hints_compute_segments( AF_GlyphHints hints,
AF_Dimension dim )
{
AF_AxisHints axis = &hints->axis[dim];
FT_Memory memory = hints->memory;
FT_Error error = AF_Err_Ok;
AF_Segment segment = NULL;
AF_Point* contour = hints->contours;
AF_Point* contour_limit = contour + hints->num_contours;
AF_Direction major_dir, segment_dir;
#ifdef AF_HINT_METRICS
AF_Point min_point = 0;
AF_Point max_point = 0;
FT_Pos min_coord = 32000;
FT_Pos max_coord = -32000;
#endif
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;
FT_Pos min_pos = 32000; /* minimum segment pos != min_coord */
FT_Pos max_pos = -32000; /* maximum segment pos != max_coord */
FT_Bool passed;
#ifdef AF_HINT_METRICS
if ( point->u < min_coord )
{
min_coord = point->u;
min_point = point;
}
if ( point->u > max_coord )
{
max_coord = point->u;
max_point = point;
}
#endif
if ( point == last ) /* skip singletons -- just in case */
continue;
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 )
{
u = point->u;
if ( u < min_pos )
min_pos = u;
if ( u > max_pos )
max_pos = u;
if ( point->out_dir != segment_dir || point == last )
{
/* we are just leaving an edge; record a new segment! */
segment->last = point;
segment->pos = ( min_pos + max_pos ) >> 1;
/* a segment is round if either its first or last point */
/* is a control point */
if ( ( segment->first->flags | point->flags ) &
AF_FLAG_CONTROL )
segment->flags |= AF_EDGE_ROUND;
/* compute segment size */
min_pos = max_pos = point->v;
v = segment->first->v;
if ( v < min_pos )
min_pos = v;
if ( v > max_pos )
max_pos = v;
segment->min_coord = min_pos;
segment->max_coord = max_pos;
on_edge = 0;
segment = NULL;
/* fallthrough */
}
}
/* now exit if we are at the start/end point */
if ( point == last )
{
if ( passed )
break;
passed = 1;
}
if ( !on_edge && FT_ABS( point->out_dir ) == major_dir )
{
/* this is the start of a new segment! */
segment_dir = (AF_Direction)point->out_dir;
/* clear all segment fields */
error = af_axis_hints_new_segment( axis, memory, &segment );
if ( error )
goto Exit;
segment->dir = segment_dir;
segment->flags = AF_EDGE_NORMAL;
min_pos = max_pos = point->u;
segment->first = point;
segment->last = point;
segment->contour = contour;
segment->score = 32000;
segment->link = NULL;
on_edge = 1;
#ifdef AF_HINT_METRICS
if ( point == max_point )
max_point = 0;
if ( point == min_point )
min_point = 0;
#endif
}
point = point->next;
}
} /* contours */
#ifdef AF_HINT_METRICS
/* we need to ensure that there are edges on the left-most and */
/* right-most points of the glyph in order to hint the metrics; */
/* we do this by inserting fake segments when needed */
if ( dim == AF_DIMENSION_HORZ )
{
AF_Point point = hints->points;
AF_Point point_limit = point + hints->num_points;
FT_Pos min_pos = 32000;
FT_Pos max_pos = -32000;
min_point = 0;
max_point = 0;
/* compute minimum and maximum points */
for ( ; point < point_limit; point++ )
{
FT_Pos x = point->fx;
if ( x < min_pos )
{
min_pos = x;
min_point = point;
}
if ( x > max_pos )
{
max_pos = x;
max_point = point;
}
}
/* insert minimum segment */
if ( min_point )
{
/* clear all segment fields */
error = af_axis_hints_new_segment( axis, memory, &segment );
if ( error )
goto Exit;
segment->dir = segment_dir;
segment->flags = AF_EDGE_NORMAL;
segment->first = min_point;
segment->last = min_point;
segment->pos = min_pos;
segment->score = 32000;
segment->link = NULL;
segment = NULL;
}
/* insert maximum segment */
if ( max_point )
{
/* clear all segment fields */
error = af_axis_hints_new_segment( axis, memory, &segment );
if ( error )
goto Exit;
segment->dir = segment_dir;
segment->flags = AF_EDGE_NORMAL;
segment->first = max_point;
segment->last = max_point;
segment->pos = max_pos;
segment->score = 32000;
segment->link = NULL;
segment = NULL;
}
}
#endif /* AF_HINT_METRICS */
Exit:
return error;
}
FT_LOCAL_DEF( void )
af_latin_hints_link_segments( AF_GlyphHints hints,
AF_Dimension dim )
{
AF_AxisHints axis = &hints->axis[dim];
AF_Segment segments = axis->segments;
AF_Segment segment_limit = segments + axis->num_segments;
AF_Direction major_dir = axis->major_dir;
AF_Segment seg1, seg2;
/* now compare each segment to the others */
for ( seg1 = segments; seg1 < segment_limit; seg1++ )
{
/* the fake segments are introduced to hint the metrics -- */
/* we must never link them to anything */
if ( seg1->first == seg1->last || seg1->dir != major_dir )
continue;
for ( seg2 = segments; seg2 < segment_limit; seg2++ )
if ( seg2 != seg1 && seg1->dir + seg2->dir == 0 )
{
FT_Pos pos1 = seg1->pos;
FT_Pos pos2 = seg2->pos;
FT_Pos dist = pos2 - pos1;
if ( dist < 0 )
continue;
{
FT_Pos min = seg1->min_coord;
FT_Pos max = seg1->max_coord;
FT_Pos len, score;
if ( min < seg2->min_coord )
min = seg2->min_coord;
if ( max > seg2->max_coord )
max = seg2->max_coord;
len = max - min;
if ( len >= 8 )
{
score = dist + 3000 / len;
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 */
for ( seg1 = segments; seg1 < segment_limit; seg1++ )
{
seg2 = seg1->link;
if ( seg2 )
{
seg2->num_linked++;
if ( seg2->link != seg1 )
{
seg1->link = 0;
seg1->serif = seg2->link;
}
}
}
}
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 = AF_Err_Ok;
FT_Memory memory = hints->memory;
AF_LatinAxis laxis = &((AF_LatinMetrics)hints->metrics)->axis[dim];
AF_Segment segments = axis->segments;
AF_Segment segment_limit = segments + axis->num_segments;
AF_Segment seg;
AF_Direction up_dir;
FT_Fixed scale;
FT_Pos edge_distance_threshold;
axis->num_edges = 0;
scale = ( dim == AF_DIMENSION_HORZ ) ? hints->x_scale
: hints->y_scale;
up_dir = ( dim == AF_DIMENSION_HORZ ) ? AF_DIR_UP
: AF_DIR_RIGHT;
/*********************************************************************/
/* */
/* We will 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 will be processed in the second step to compute the */
/* edge's properties. */
/* */
/* Note that the edges table is sorted along the segment/edge */
/* position. */
/* */
/*********************************************************************/
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 = 0;
FT_Int ee;
/* 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;
}
}
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, 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->fpos = seg->pos;
edge->opos = edge->pos = FT_MulFix( seg->pos, scale );
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;
}
}
/*********************************************************************/
/* */
/* Good, we will now compute each edge's properties according to */
/* segments found on its position. Basically, these are: */
/* */
/* - 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 = 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? */
FT_Pos ups = 0; /* number of upwards segments */
FT_Pos downs = 0; /* number of downwards segments */
seg = edge->first;
do
{
FT_Bool is_serif;
/* check for roundness of segment */
if ( seg->flags & AF_EDGE_ROUND )
is_round++;
else
is_straight++;
/* check for segment direction */
if ( seg->dir == up_dir )
ups += seg->max_coord-seg->min_coord;
else
downs += seg->max_coord-seg->min_coord;
/* check for links -- if seg->serif is set, then seg->link must */
/* be ignored */
is_serif = (FT_Bool)( seg->serif && seg->serif->edge != edge );
if ( seg->link || 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;
/* set the edge's main direction */
edge->dir = AF_DIR_NONE;
if ( ups > downs )
edge->dir = up_dir;
else if ( ups < downs )
edge->dir = -up_dir;
else if ( ups == downs )
edge->dir = 0; /* both up and down! */
/* gets 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 = 0;
}
}
Exit:
return error;
}
FT_LOCAL_DEF( FT_Error )
af_latin_hints_detect_features( AF_GlyphHints hints,
AF_Dimension dim )
{
FT_Error error;
error = af_latin_hints_compute_segments( hints, dim );
if ( !error )
{
af_latin_hints_link_segments( hints, dim );
error = af_latin_hints_compute_edges( hints, dim );
}
return error;
}
FT_LOCAL_DEF( 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 = 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_Int bb;
AF_Width best_blue = NULL;
FT_Pos best_dist; /* initial threshold */
/* compute the initial threshold as a fraction of the EM size */
best_dist = FT_MulFix( metrics->units_per_em / 40, scale );
if ( best_dist > 64 / 2 )
best_dist = 64 / 2;
for ( bb = 0; bb < AF_LATIN_BLUE_MAX; bb++ )
{
AF_LatinBlue blue = latin->blues + bb;
FT_Bool is_top_blue, is_major_dir;
/* skip inactive blue zones (i.e., those that are too small) */
if ( !( blue->flags & AF_LATIN_BLUE_ACTIVE ) )
continue;
/* if it is a top zone, check for right edges -- if it is a bottom */
/* zone, check for left edges */
/* */
/* of course, that's for TrueType */
is_top_blue = ( blue->flags & AF_LATIN_BLUE_TOP ) != 0;
is_major_dir = FT_BOOL( edge->dir == axis->major_dir );
/* if it is a top zone, the edge must be against the major */
/* direction; if it is a bottom zone, it must be in the major */
/* direction */
if ( is_top_blue ^ is_major_dir )
{
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;
}
/* now, compare it to the overshoot position if the edge is */
/* rounded, and if the edge is over the reference position of a */
/* top zone, or under the reference position of a bottom zone */
if ( edge->flags & AF_EDGE_ROUND && dist != 0 )
{
FT_Bool is_under_ref = FT_BOOL( edge->fpos < blue->ref.org );
if ( is_top_blue ^ is_under_ref )
{
blue = latin->blues + bb;
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;
}
}
}
}
}
if ( best_blue )
edge->blue_edge = best_blue;
}
}
static FT_Error
af_latin_hints_init( AF_GlyphHints hints,
AF_LatinMetrics metrics )
{
FT_Render_Mode mode;
af_glyph_hints_rescale( hints, (AF_ScriptMetrics)metrics );
/*
* correct x_scale and y_scale when needed, since they may have
* been modified af_latin_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;
/*
* 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 )
hints->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 )
hints->other_flags |= AF_LATIN_HINTS_VERT_SNAP;
/*
* We adjust stems to full pixels only if we don't use the `light' mode.
*/
if ( mode != FT_RENDER_MODE_LIGHT )
hints->other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
if ( mode == FT_RENDER_MODE_MONO )
hints->other_flags |= AF_LATIN_HINTS_MONO;
return 0;
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** 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_Int count,
FT_Pos width )
{
int 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 */
static FT_Pos
af_latin_compute_stem_width( AF_GlyphHints hints,
AF_Dimension dim,
FT_Pos width,
AF_Edge_Flags base_flags,
AF_Edge_Flags 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 = AF_HINTS_DO_VERTICAL( hints );
if ( !AF_LATIN_HINTS_DO_STEM_ADJUST( hints ) )
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 */
if ( axis->width_count > 0 )
{
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
dist = ( dist + 32 ) & ~63;
}
}
else
{
/* strong hinting process: snap the stem width to integer pixels */
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 )
dist = ( dist + 22 ) & ~63;
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 = stem_edge->opos - base_edge->opos;
FT_Pos fitted_width = af_latin_compute_stem_width(
hints, dim, dist,
(AF_Edge_Flags)base_edge->flags,
(AF_Edge_Flags)stem_edge->flags );
stem_edge->pos = base_edge->pos + fitted_width;
}
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 ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
FT_LOCAL_DEF( 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 = edges + axis->num_edges;
FT_Int n_edges;
AF_Edge edge;
AF_Edge anchor = 0;
FT_Int has_serifs = 0;
/* we begin by aligning all stems relative to the blue zone */
/* if needed -- that's only for horizontal edges */
if ( dim == AF_DIMENSION_VERT )
{
for ( edge = edges; edge < edge_limit; edge++ )
{
AF_Width blue;
AF_Edge edge1, edge2;
if ( edge->flags & AF_EDGE_DONE )
continue;
blue = edge->blue_edge;
edge1 = NULL;
edge2 = edge->link;
if ( blue )
{
edge1 = edge;
}
else if ( edge2 && edge2->blue_edge )
{
blue = edge2->blue_edge;
edge1 = edge2;
edge2 = edge;
}
if ( !edge1 )
continue;
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;
}
if ( !anchor )
anchor = edge;
}
}
/* now we will align all 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 || edge2 < edge )
{
af_latin_align_linked_edge( hints, dim, edge2, edge );
edge->flags |= AF_EDGE_DONE;
continue;
}
if ( !anchor )
{
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,
(AF_Edge_Flags)edge->flags,
(AF_Edge_Flags)edge2->flags );
if ( cur_len <= 64 )
u_off = d_off = 32;
else
{
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 = cur_pos1 + cur_len / 2;
}
else
edge->pos = FT_PIX_ROUND( edge->opos );
anchor = edge;
edge->flags |= AF_EDGE_DONE;
af_latin_align_linked_edge( hints, dim, edge, edge2 );
}
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,
(AF_Edge_Flags)edge->flags,
(AF_Edge_Flags)edge2->flags );
if ( cur_len < 96 )
{
FT_Pos u_off, d_off;
cur_pos1 = FT_PIX_ROUND( org_center );
if (cur_len <= 64 )
u_off = 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;
}
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,
(AF_Edge_Flags)edge->flags,
(AF_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;
}
edge->flags |= AF_EDGE_DONE;
edge2->flags |= AF_EDGE_DONE;
if ( edge > edges && edge->pos < edge[-1].pos )
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++ )
{
if ( edge->flags & AF_EDGE_DONE )
continue;
if ( edge->serif )
af_latin_align_serif_edge( hints, edge->serif, edge );
else if ( !anchor )
{
edge->pos = FT_PIX_ROUND( edge->opos );
anchor = edge;
}
else
edge->pos = anchor->pos +
FT_PIX_ROUND( edge->opos - anchor->opos );
edge->flags |= AF_EDGE_DONE;
if ( edge > edges && edge->pos < edge[-1].pos )
edge->pos = edge[-1].pos;
if ( edge + 1 < edge_limit &&
edge[1].flags & AF_EDGE_DONE &&
edge->pos > edge[1].pos )
edge->pos = edge[1].pos;
}
}
}
static FT_Error
af_latin_hints_apply( AF_GlyphHints hints,
FT_Outline* outline,
AF_LatinMetrics metrics )
{
FT_Error error;
int dim;
error = af_glyph_hints_reload( hints, outline );
if ( error )
goto Exit;
/* analyze glyph outline */
if ( AF_HINTS_DO_HORIZONTAL( hints ) )
{
error = af_latin_hints_detect_features( hints, AF_DIMENSION_HORZ );
if ( error )
goto Exit;
}
if ( AF_HINTS_DO_VERTICAL( hints ) )
{
error = af_latin_hints_detect_features( hints, AF_DIMENSION_VERT );
if ( error )
goto Exit;
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 *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
static const AF_Script_UniRangeRec af_latin_uniranges[] =
{
{ 32, 127 }, /* XXX: TODO: Add new Unicode ranges here! */
{ 160, 255 },
{ 0, 0 }
};
FT_CALLBACK_TABLE_DEF const AF_ScriptClassRec
af_latin_script_class =
{
AF_SCRIPT_LATIN,
af_latin_uniranges,
sizeof( AF_LatinMetricsRec ),
(AF_Script_InitMetricsFunc) af_latin_metrics_init,
(AF_Script_ScaleMetricsFunc)af_latin_metrics_scale,
(AF_Script_DoneMetricsFunc) NULL,
(AF_Script_InitHintsFunc) af_latin_hints_init,
(AF_Script_ApplyHintsFunc) af_latin_hints_apply
};
/* END */