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Code Issues 9 Releases Wiki Activity

add additional grid aligning step to tilde unflattening to fix issues

This commit is contained in:
Craig White 2024-04-13 23:04:08 -04:00
parent 984ff89185
commit afa11fc16a
1 changed files with 56 additions and 3 deletions
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59
src/autofit/aflatin.c
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@ -2889,8 +2889,7 @@ The n tilde on times new roman with forced autofitting on,
16.5-18 ppem font size exhibits this behaviour.
*/
void
af_latin_stretch_tildes( AF_GlyphHints hints,
FT_Int glyph_index )
af_latin_stretch_tildes( AF_GlyphHints hints )
{
FT_Int highest_contour = af_find_highest_contour( hints );
AF_Point p = hints->contours[highest_contour];
@ -3021,6 +3020,59 @@ af_latin_stretch_tildes( AF_GlyphHints hints,
while ( p != first_point );
}
/*
As part of af_latin_stretch_tildes, all points in the tilde
are marked as touched, so the existing grid fitting will leave
the tilde misaligned with the grid.
This function moves the tilde contour down to be grid fitted.
We assume that if moving the tilde down would cause it to touch or
overlap another countour, the vertical adjustment step will fix it
Because the vertical adjustment step comes after all other grid fitting
steps, the top edge of the contour under the tilde is usually aligned with
a horizontal gridline. The vertical gap enforced by the vertical adjustment
is exactly one pixel, so if the top edge of the contour below the tilde is on a
gridline, the resulting tilde contour will also be grid aligned.
But in cases where the gap is already big enough so that the vertical
adjustment does nothing, this function ensures that even without the
intervention of the vertical adjustment step, the tilde will be
grid aligned.
*/
void
af_latin_align_tildes( AF_GlyphHints hints ) {
FT_Int highest_contour = af_find_highest_contour( hints );
AF_Point p = hints->contours[highest_contour];
AF_Point first_point = p;
FT_Pos min_y, max_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_Pos mid_y = ( min_y + max_y ) / 2;
FT_Pos min_y_rounded = FT_PIX_ROUND( min_y );
FT_Pos delta = min_y_rounded - min_y;
do
{
p = p->next;
p->y += delta;
}
while ( p != first_point );
}
/*True if the given contour overlaps horizontally with the bounding box
Of all other contours combined.
This is a helper for af_glyph_hints_apply_vertical_separation_adjustments */
@ -4141,7 +4193,8 @@ af_glyph_hints_apply_vertical_separation_adjustments( AF_GlyphHints hints,
FT_Bool is_tilde = af_lookup_tilde_correction_type( metrics->root.reverse_charmap, glyph_index );
if ( is_tilde ) {
traceheight(0, hints);
af_latin_stretch_tildes( hints, glyph_index );
af_latin_stretch_tildes( hints );
af_latin_align_tildes( hints );
traceheight(1, hints);
}
axis = &metrics->axis[AF_DIMENSION_VERT];