ref: 6d2596368a1fe6bb2e2e835e27319f7092393d36
dir: /src/base/ftsynth.c/
/***************************************************************************/
/* */
/* ftsynth.c */
/* */
/* FreeType synthesizing code for emboldening and slanting (body). */
/* */
/* Copyright 2000 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/ftsynth.h>
#define FT_BOLD_THRESHOLD 0x0100
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** EXPERIMENTAL OBLIQUING SUPPORT ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
FT_EXPORT_DEF( FT_Error ) FT_Oblique_Outline( FT_GlyphSlot original,
FT_Outline* outline,
FT_Pos* advance )
{
FT_Matrix transform;
FT_UNUSED( original );
/* we don't touch the advance width */
FT_UNUSED(advance);
/* For italic, simply apply a shear transform, with an angle */
/* of about 12 degrees. */
transform.xx = 0x10000;
transform.yx = 0x00000;
transform.xy = 0x06000;
transform.yy = 0x10000;
FT_Transform_Outline( outline, &transform );
return 0;
}
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** EXPERIMENTAL EMBOLDENING/OUTLINING SUPPORT ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
/* Compute the norm of a vector */
#ifdef FT_CONFIG_OPTION_OLD_CALCS
#include <freetype/internal/ftcalc.h>
static
FT_Pos ft_norm( FT_Vector* vec )
{
FT_Int64 t1, t2;
MUL_64( vec->x, vec->x, t1 );
MUL_64( vec->y, vec->y, t2 );
ADD_64( t1, t2, t1 );
return (FT_Pos)SQRT_64( t1 );
}
#else /* FT_CONFIG_OPTION_OLD_CALCS */
static
FT_Pos ft_norm( FT_Vector* vec )
{
FT_F26Dot6 u, v, d;
FT_Int shift;
FT_ULong H, L, L2, hi, lo, med;
u = vec->x; if ( u < 0 ) u = -u;
v = vec->y; if ( v < 0 ) v = -v;
if ( u < v )
{
d = u;
u = v;
v = d;
}
/* check that we are not trying to normalize zero! */
if ( u == 0 )
return 0;
/* compute (u*u + v*v) on 64 bits with two 32-bit registers [H:L] */
hi = (FT_ULong)u >> 16;
lo = (FT_ULong)u & 0xFFFF;
med = hi * lo;
H = hi * hi + ( med >> 15 );
med <<= 17;
L = lo * lo + med;
if ( L < med )
H++;
hi = (FT_ULong)v >> 16;
lo = (FT_ULong)v & 0xFFFF;
med = hi * lo;
H += hi * hi + ( med >> 15 );
med <<= 17;
L2 = lo * lo + med;
if ( L2 < med )
H++;
L += L2;
if ( L < L2 )
H++;
/* if the value is smaller than 32 bits */
shift = 0;
if ( H == 0 )
{
while ( ( L & 0xC0000000UL ) == 0 )
{
L <<= 2;
shift++;
}
return ( FT_Sqrt32( L ) >> shift );
}
else
{
while ( H )
{
L = ( L >> 2 ) | ( H << 30 );
H >>= 2;
shift++;
}
return ( FT_Sqrt32( L ) << shift );
}
}
#endif /* FT_CONFIG_OPTION_OLD_CALCS */
static
int ft_test_extrema( FT_Outline* outline,
int n )
{
FT_Vector *prev, *cur, *next;
FT_Pos product;
FT_Int c, first, last;
/* we need to compute the `previous' and `next' point */
/* for these extrema. */
cur = outline->points + n;
prev = cur - 1;
next = cur + 1;
first = 0;
for ( c = 0; c < outline->n_contours; c++ )
{
last = outline->contours[c];
if ( n == first )
prev = outline->points + last;
if ( n == last )
next = outline->points + first;
first = last + 1;
}
product = FT_MulDiv( cur->x - prev->x, /* in.x */
next->y - cur->y, /* out.y */
0x40 )
-
FT_MulDiv( cur->y - prev->y, /* in.y */
next->x - cur->x, /* out.x */
0x40 );
if ( product )
product = product > 0 ? 1 : -1;
return product;
}
/* Compute the orientation of path filling. It differs between TrueType */
/* and Type1 formats. We could use the `ft_outline_reverse_fill' flag, */
/* but it is better to re-compute it directly (it seems that this flag */
/* isn't correctly set for some weird composite glyphs currently). */
/* */
/* We do this by computing bounding box points, and computing their */
/* curvature. */
/* */
/* The function returns either 1 or -1. */
/* */
static
int ft_get_orientation( FT_Outline* outline )
{
FT_BBox box;
FT_BBox indices;
int n, last;
indices.xMin = -1;
indices.yMin = -1;
indices.xMax = -1;
indices.yMax = -1;
box.xMin = box.yMin = 32767;
box.xMax = box.yMax = -32768;
/* is it empty ? */
if ( outline->n_contours < 1 )
return 1;
last = outline->contours[outline->n_contours - 1];
for ( n = 0; n <= last; n++ )
{
FT_Pos x, y;
x = outline->points[n].x;
if ( x < box.xMin )
{
box.xMin = x;
indices.xMin = n;
}
if ( x > box.xMax )
{
box.xMax = x;
indices.xMax = n;
}
y = outline->points[n].y;
if ( y < box.yMin )
{
box.yMin = y;
indices.yMin = n;
}
if ( y > box.yMax )
{
box.yMax = y;
indices.yMax = n;
}
}
/* test orientation of the xmin */
n = ft_test_extrema( outline, indices.xMin );
if ( n )
goto Exit;
n = ft_test_extrema( outline, indices.yMin );
if ( n )
goto Exit;
n = ft_test_extrema( outline, indices.xMax );
if ( n )
goto Exit;
n = ft_test_extrema( outline, indices.yMax );
if ( !n )
n = 1;
Exit:
return n;
}
FT_EXPORT_FUNC(FT_Error) FT_Embolden_Outline( FT_GlyphSlot original,
FT_Outline* outline,
FT_Pos* advance )
{
FT_Vector u, v;
FT_Vector* points;
FT_Vector cur, prev, next;
FT_Pos distance;
FT_Face face = FT_SLOT_FACE( original );
int c, n, first, orientation;
FT_UNUSED( advance );
/* compute control distance */
distance = FT_MulFix( face->units_per_EM / 60,
face->size->metrics.y_scale );
orientation = ft_get_orientation( &original->outline );
points = original->outline.points;
first = 0;
for ( c = 0; c < outline->n_contours; c++ )
{
int last = outline->contours[c];
prev = points[last];
for ( n = first; n <= last; n++ )
{
FT_Pos norm, delta, d;
FT_Vector in, out;
cur = points[n];
if ( n < last ) next = points[n + 1];
else next = points[first];
/* compute the in and out vectors */
in.x = cur.x - prev.x;
in.y = cur.y - prev.y;
out.x = next.x - cur.x;
out.y = next.y - cur.y;
/* compute U and V */
norm = ft_norm( &in );
u.x = orientation * FT_DivFix( in.y, norm );
u.y = orientation * -FT_DivFix( in.x, norm );
norm = ft_norm( &out );
v.x = orientation * FT_DivFix( out.y, norm );
v.y = orientation * -FT_DivFix( out.x, norm );
d = distance;
if ( ( outline->tags[n] & FT_Curve_Tag_On ) == 0 )
d *= 2;
/* Check discriminant for parallel vectors */
delta = FT_MulFix( u.x, v.y ) - FT_MulFix( u.y, v.x );
if ( delta > FT_BOLD_THRESHOLD || delta < -FT_BOLD_THRESHOLD )
{
/* Move point -- compute A and B */
FT_Pos x, y, A, B;
A = d + FT_MulFix( cur.x, u.x ) + FT_MulFix( cur.y, u.y );
B = d + FT_MulFix( cur.x, v.x ) + FT_MulFix( cur.y, v.y );
x = FT_MulFix( A, v.y ) - FT_MulFix( B, u.y );
y = FT_MulFix( B, u.x ) - FT_MulFix( A, v.x );
outline->points[n].x = distance + FT_DivFix( x, delta );
outline->points[n].y = distance + FT_DivFix( y, delta );
}
else
{
/* Vectors are nearly parallel */
FT_Pos x, y;
x = distance + cur.x + FT_MulFix( d, u.x + v.x ) / 2;
y = distance + cur.y + FT_MulFix( d, u.y + v.y ) / 2;
outline->points[n].x = x;
outline->points[n].y = y;
}
prev = cur;
}
first = last + 1;
}
if ( advance )
*advance = ( *advance + distance * 4 ) & -64;
return 0;
}
/* END */