ref: 83246e296ea433b65b9d295b5e08fedd39ff1ab7
dir: /libfreetype/ftsynth.c/
/***************************************************************************/
/* */
/* ftsynth.c */
/* */
/* FreeType synthesizing code for emboldening and slanting (body). */
/* */
/* Copyright 2000-2001 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 <ft2build.h>
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_CALC_H
#include FT_OUTLINE_H
#include FT_TRIGONOMETRY_H
#include FT_SYNTHESIS_H
#define FT_BOLD_THRESHOLD 0x0100
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** EXPERIMENTAL OBLIQUING SUPPORT ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
FT_EXPORT_DEF( void )
FT_GlyphSlot_Oblique( FT_GlyphSlot slot )
{
FT_Matrix transform;
FT_Outline* outline = &slot->outline;
/* only oblique outline glyphs */
if ( slot->format != FT_GLYPH_FORMAT_OUTLINE )
return;
/* we don't touch the advance width */
/* For italic, simply apply a shear transform, with an angle */
/* of about 12 degrees. */
transform.xx = 0x10000L;
transform.yx = 0x00000L;
transform.xy = 0x06000L;
transform.yy = 0x10000L;
FT_Outline_Transform( outline, &transform );
}
/*************************************************************************/
/*************************************************************************/
/**** ****/
/**** EXPERIMENTAL EMBOLDENING/OUTLINING SUPPORT ****/
/**** ****/
/*************************************************************************/
/*************************************************************************/
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_DEF( void )
FT_GlyphSlot_Embolden( FT_GlyphSlot slot )
{
FT_Vector* points;
FT_Vector v_prev, v_first, v_next, v_cur;
FT_Pos distance;
FT_Outline* outline = &slot->outline;
FT_Face face = FT_SLOT_FACE( slot );
FT_Angle rotate, angle_in, angle_out;
FT_Int c, n, first, orientation;
/* only embolden outline glyph images */
if ( slot->format != FT_GLYPH_FORMAT_OUTLINE )
return;
/* compute control distance */
distance = FT_MulFix( face->units_per_EM / 60,
face->size->metrics.y_scale );
orientation = ft_get_orientation( outline );
rotate = FT_ANGLE_PI2*orientation;
points = outline->points;
first = 0;
for ( c = 0; c < outline->n_contours; c++ )
{
int last = outline->contours[c];
v_first = points[first];
v_prev = points[last];
v_cur = v_first;
for ( n = first; n <= last; n++ )
{
FT_Pos d;
FT_Vector in, out;
FT_Fixed scale;
FT_Angle angle_diff;
if ( n < last ) v_next = points[n + 1];
else v_next = v_first;
/* compute the in and out vectors */
in.x = v_cur.x - v_prev.x;
in.y = v_cur.y - v_prev.y;
out.x = v_next.x - v_cur.x;
out.y = v_next.y - v_cur.y;
angle_in = FT_Atan2( in.x, in.y );
angle_out = FT_Atan2( out.x, out.y );
angle_diff = FT_Angle_Diff( angle_in, angle_out );
scale = FT_Cos( angle_diff/2 );
if ( scale < 0x400L && scale > -0x400L )
{
if ( scale >= 0 )
scale = 0x400L;
else
scale = -0x400L;
}
d = FT_DivFix( distance, scale );
FT_Vector_From_Polar( &in, d, angle_in + angle_diff/2 - rotate );
outline->points[n].x = v_cur.x + distance + in.x;
outline->points[n].y = v_cur.y + distance + in.y;
v_prev = v_cur;
v_cur = v_next;
}
first = last + 1;
}
slot->metrics.horiAdvance = ( slot->metrics.horiAdvance + distance*4 ) & -64;
}
/* END */