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[autofit] Support vertical stretching of tilde below base glyph. (2/2)

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* src/autofit/afadjust.h (AF_ADJUST_TILDE_BOTTOM): New macro.
* src/autofit/afadjust.c (af_reverse_character_map_new): Updated.

* src/autofit/aflatin.c (af_find_lowest_contour,
  af_latin_remove_bottom_tilde_points_from_edges,
  af_latin_stretch_bottom_tilde, af_latin_align_bottom_tilde): New functions
  in analogy to the top tilde versions.
  (af_glyph_hints_apply_vertical_separation_adjustments): Add support in
  analogy to the top tilde code.
  (af_latin_hints_apply): Updated.
This commit is contained in:
Werner Lemberg
2025-04-22 12:43:55 +02:00
parent ec28f4880b
commit ba94c9547e
3 changed files with 270 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
src/autofit/afadjust.c
View File

@@ -682,11 +682,12 @@
"down", /* AF_ADJUST_DOWN */
"",
"",
"top tilde", /* AF_ADJUST_TILDE_TOP */
"top tilde", /* AF_ADJUST_TILDE_TOP */
"bottom tilde", /* AF_ADJUST_TILDE_BOTTOM */
};
size_t flag_names_size = sizeof ( flag_names ) / sizeof ( char* );
char flag_str[32];
char flag_str[64];
int need_comma;
size_t j;

4
src/autofit/afadjust.h
View File

@@ -52,6 +52,10 @@ FT_BEGIN_HEADER
/* stays legible at small sizes, not degenerating to a horizontal line. */
#define AF_ADJUST_TILDE_TOP 0x10
/* The bottommost contour is a tilde. Enlarge it vertically so that it */
/* stays legible at small sizes, not degenerating to a horizontal line. */
#define AF_ADJUST_TILDE_BOTTOM 0x20
/* No adjustment, i.e., no flag is set. */
#define AF_ADJUST_NONE 0x00

267
src/autofit/aflatin.c
View File

@@ -2826,6 +2826,50 @@
}
static FT_Int
af_find_lowest_contour( AF_GlyphHints hints )
{
FT_Int lowest_contour = 0;
FT_Pos lowest_min_y = FT_INT_MAX;
FT_Int contour;
for ( contour = 0; contour < hints->num_contours; contour++ )
{
FT_Pos current_min_y;
AF_Point point = hints->contours[contour];
AF_Point first_point = point;
if ( !point )
continue;
if ( first_point->next->next == first_point )
continue;
current_min_y = point->y;
do
{
if ( point->y < current_min_y )
current_min_y = point->y;
point = point->next;
} while ( point != first_point );
if ( current_min_y < lowest_min_y )
{
lowest_min_y = current_min_y;
lowest_contour = contour;
}
}
return lowest_contour;
}
static void
af_remove_segments_containing_point( AF_GlyphHints hints,
AF_Point point )
@@ -2915,6 +2959,24 @@
}
static void
af_latin_remove_bottom_tilde_points_from_edges( AF_GlyphHints hints )
{
FT_Int lowest_contour = af_find_lowest_contour( hints );
AF_Point first_point = hints->contours[lowest_contour];
AF_Point p = first_point;
do
{
p = p->next;
af_remove_segments_containing_point( hints, p );
} while ( p != first_point );
}
static void
af_latin_stretch_top_tilde( AF_GlyphHints hints )
{
@@ -2923,7 +2985,7 @@
AF_Point first_point = p;
FT_Pos min_y, max_y;
FT_Pos min_y, max_y;
FT_Pos min_measurement;
FT_Bool measurement_taken = FALSE;
@@ -3047,6 +3109,115 @@
}
static void
af_latin_stretch_bottom_tilde( AF_GlyphHints hints )
{
FT_Int lowest_contour = af_find_lowest_contour( hints );
AF_Point p = hints->contours[lowest_contour];
AF_Point first_point = p;
FT_Pos min_y, max_y;
FT_Pos min_measurement;
FT_Bool measurement_taken = FALSE;
FT_Pos height;
FT_Pos extremum_threshold;
FT_Pos target_height;
min_y = max_y = p->y;
do
{
p = p->next;
if ( p->y < min_y )
min_y = p->y;
if ( p->y > max_y )
max_y = p->y;
} while ( p != first_point );
FT_TRACE4(( "af_latin_stretch_bottom_tilde: min y: %ld, max y: %ld\n",
min_y, max_y ));
height = max_y - min_y;
extremum_threshold = height / 8;
do
{
p = p->next;
if ( !( p->flags & AF_FLAG_CONTROL ) &&
p->prev->y == p->y && p->next->y == p->y &&
p->y != min_y && p->y != max_y &&
p->prev->flags & AF_FLAG_CONTROL &&
p->next->flags & AF_FLAG_CONTROL )
{
AF_Point prev_on = p->prev;
AF_Point next_on = p->next;
FT_Pos measurement;
while ( prev_on->flags & AF_FLAG_CONTROL )
prev_on = prev_on->prev;
while ( next_on->flags & AF_FLAG_CONTROL )
next_on = next_on->next;
if ( next_on->y > p->y && prev_on->y > p->y )
measurement = p->y - min_y;
else if ( next_on->y < p->y && prev_on->y < p->y )
measurement = max_y - p->y;
else
continue;
if ( measurement < extremum_threshold )
continue;
if ( !measurement_taken || measurement < min_measurement )
{
measurement_taken = TRUE;
min_measurement = measurement;
}
}
} while ( p != first_point );
if ( !measurement_taken )
min_measurement = 0;
FT_TRACE4(( "af_latin_stretch_bottom_tilde: min measurement %ld\n",
min_measurement ));
if ( height < 64 * 4 )
{
p = first_point;
do
{
p = p->next;
if ( !( p->flags & AF_FLAG_CONTROL ) )
p->flags |= AF_FLAG_TOUCH_Y;
} while ( p != first_point );
}
target_height = min_measurement + 64;
if ( height >= target_height )
return;
p = first_point;
do
{
p = p->next;
p->y = ( ( p->y - max_y ) * target_height / height ) + max_y;
} while ( p != first_point );
}
/*
As part of `af_latin_stretch_top_tilde`, normally all points in the
tilde are marked as touched, so the existing grid fitting will leave the
@@ -3109,6 +3280,43 @@
}
static void
af_latin_align_bottom_tilde( AF_GlyphHints hints )
{
FT_Int lowest_contour = af_find_lowest_contour( hints );
AF_Point p = hints->contours[lowest_contour];
AF_Point first_point = p;
FT_Pos min_y = p->y;
FT_Pos max_y = p->y;
FT_Pos max_y_rounded;
FT_Pos delta;
FT_Pos height;
do
{
p = p->next;
if ( p->y < min_y )
min_y = p->y;
if ( p->y > max_y )
max_y = p->y;
} while ( p != first_point );
max_y_rounded = FT_PIX_ROUND( max_y );
delta = max_y_rounded - max_y;
height = max_y - min_y;
if ( height < 64 * 3 )
delta -= ( FT_PIX_ROUND( height ) - height ) / 2;
af_move_contour_vertically( first_point, delta );
}
/* Return 1 if the given contour overlaps horizontally with the bounding */
/* box of all other contours combined. This is a helper for function */
/* `af_glyph_hints_apply_vertical_separation_adjustments`. */
@@ -3391,15 +3599,24 @@
FT_Pos lowest_min_y = FT_INT_MAX;
FT_Pos lowest_max_y;
FT_Int contour;
FT_Int contour;
FT_Bool horizontal_overlap;
FT_Pos min_distance = 64;
FT_Pos adjustment_amount;
FT_Bool is_tilde = FALSE;
FT_Bool grid_aligned_after_adjustment;
FT_Pos height;
AF_Point point;
AF_Point first_point;
if ( db_entry )
is_tilde = db_entry->flags & AF_ADJUST_TILDE_BOTTOM;
FT_TRACE4(( "af_glyph_hints_apply_vertical_separation_adjustments:\n"
" Applying vertical adjustment: AF_ADJUST_DOWN\n" ));
@@ -3443,6 +3660,19 @@
hints->contour_y_maxima[contour] = current_max_y;
}
horizontal_overlap =
af_check_contour_horizontal_overlap( hints, lowest_contour );
if ( !horizontal_overlap )
{
FT_TRACE4(( " Bottom contour does not horizontally overlap"
" with other contours.\n"
" Skipping adjustment.\n" ));
return;
}
point = hints->contours[lowest_contour];
first_point = point;
lowest_max_y = hints->contour_y_maxima[lowest_contour];
for ( contour = 0; contour < hints->num_contours; contour++ )
@@ -3475,6 +3705,21 @@
adjustment_amount = 64 - min_distance;
grid_aligned_after_adjustment =
( ( lowest_max_y - adjustment_amount ) % 64 == 0 );
height = lowest_max_y - lowest_min_y;
if ( is_tilde && grid_aligned_after_adjustment && height < 3 * 64 )
{
FT_Pos centering_adjustment =
( FT_PIX_ROUND( height ) - height ) / 2;
adjustment_amount += centering_adjustment;
FT_TRACE4(( " Additional centering: %ld\n",
centering_adjustment ));
}
FT_TRACE4(( " Calculated adjustment amount: %ld\n",
adjustment_amount ));
@@ -4411,7 +4656,8 @@
{
const AF_ReverseMapEntry *entry;
FT_Bool is_top_tilde = FALSE;
FT_Bool is_top_tilde = FALSE;
FT_Bool is_bottom_tilde = FALSE;
entry = af_reverse_character_map_lookup( metrics->root.reverse_charmap,
@@ -4423,7 +4669,10 @@
db_entry = af_adjustment_database_lookup( entry->codepoint );
if ( db_entry )
is_top_tilde = db_entry->flags & AF_ADJUST_TILDE_TOP;
{
is_top_tilde = db_entry->flags & AF_ADJUST_TILDE_TOP;
is_bottom_tilde = db_entry->flags & AF_ADJUST_TILDE_BOTTOM;
}
}
if ( is_top_tilde )
@@ -4434,6 +4683,14 @@
af_latin_align_top_tilde( hints );
af_latin_trace_height( 12, hints );
}
if ( is_bottom_tilde )
{
af_latin_trace_height( 20, hints );
af_latin_stretch_bottom_tilde( hints );
af_latin_trace_height( 21, hints );
af_latin_align_bottom_tilde( hints );
af_latin_trace_height( 22, hints );
}
axis = &metrics->axis[AF_DIMENSION_VERT];
error = af_latin_hints_detect_features( hints,
@@ -4442,6 +4699,8 @@
AF_DIMENSION_VERT );
if ( is_top_tilde )
af_latin_remove_top_tilde_points_from_edges( hints );
if ( is_bottom_tilde )
af_latin_remove_bottom_tilde_points_from_edges( hints );
if ( error )
goto Exit;