added preliminary emboldening code.. still _very_
experimental
This commit is contained in:
David Turner
parent
38cb5af01f
commit
d8b4514d43
18
include/freetype/ftsynth.h
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18
include/freetype/ftsynth.h
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#ifndef FTSYNTH_H
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#define FTSYNTH_H
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#include <freetype/freetype.h>
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/* this code is completely experimental - use with care */
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/* it will probably be completely rewritten in the future */
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/* or even integrated within the library... */
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FT_EXPORT_DEF(FT_Error) FT_Embolden_Outline( FT_Face original,
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FT_Outline* outline,
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FT_Pos* advance );
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FT_EXPORT_DEF(FT_Error) FT_Oblique_Outline( FT_Face original,
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FT_Outline* outline,
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FT_Pos* advance );
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#endif /* FTEMBOLD_H */
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371
src/base/ftsynth.c
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371
src/base/ftsynth.c
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#include <freetype/ftsynth.h>
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#define FT_BOLD_THRESHOLD 0x0100
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/*************************************************************************/
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/*************************************************************************/
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/**** ****/
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/**** EXPERIMENTAL OBLIQUING SUPPORT ****/
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/**** ****/
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/*************************************************************************/
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/*************************************************************************/
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FT_EXPORT_DEF(FT_Error) FT_Oblique_Outline( FT_GlyphSlot original,
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FT_Outline* outline,
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FT_Pos* advance )
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{
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FT_Matrix transform;
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FT_UNUSED(original);
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/* For italic, simply apply a shear transform, with an angle */
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/* of about 12 degrees.. */
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transform.xx = 0x10000;
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transform.yx = 0x00000;
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transform.xy = 0x06000;
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transform.yy = 0x10000;
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FT_Transform_Outline( outline, &transform );
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/* we don't touch the advance width */
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FT_UNUSED(advance);
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return 0;
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}
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/*************************************************************************/
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/*************************************************************************/
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/**** ****/
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/**** EXPERIMENTAL EMBOLDENING/OUTLINING SUPPORT ****/
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/**** ****/
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/*************************************************************************/
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/*************************************************************************/
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/* Compute the norm of a vector */
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#ifdef FT_CONFIG_OPTION_OLD_CALCS
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#include <freetype/internal/ftcalc.h>
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static
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FT_Pos ft_norm( FT_Vector* vec )
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{
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FT_Int64 t1, t2;
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MUL_64( vec->x, vec->x, t1 );
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MUL_64( vec->y, vec->y, t2 );
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ADD_64( t1, t2, t1 );
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return (FT_Pos)SQRT_64( t1 );
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}
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#else /* FT_CONFIG_OPTION_OLD_CALCS */
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static
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FT_Pos ft_norm( FT_Vector* vec )
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{
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FT_F26Dot6 u, v, d;
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FT_Int shift;
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FT_ULong H, L, L2, hi, lo, med;
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u = vec->x; if ( u < 0 ) u = -u;
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v = vec->y; if ( v < 0 ) v = -v;
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if ( u < v )
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{
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d = u;
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u = v;
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v = d;
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}
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/* check that we are not trying to normalize zero! */
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if ( u == 0 )
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return 0;
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/* compute (u*u + v*v) on 64 bits with two 32-bit registers [H:L] */
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hi = (FT_ULong)u >> 16;
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lo = (FT_ULong)u & 0xFFFF;
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med = hi * lo;
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H = hi * hi + ( med >> 15 );
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med <<= 17;
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L = lo * lo + med;
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if ( L < med )
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H++;
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hi = (FT_ULong)v >> 16;
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lo = (FT_ULong)v & 0xFFFF;
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med = hi * lo;
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H += hi * hi + ( med >> 15 );
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med <<= 17;
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L2 = lo * lo + med;
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if ( L2 < med )
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H++;
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L += L2;
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if ( L < L2 )
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H++;
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/* if the value is smaller than 32 bits */
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shift = 0;
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if ( H == 0 )
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{
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while ( ( L & 0xC0000000UL ) == 0 )
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{
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L <<= 2;
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shift++;
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}
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return ( FT_Sqrt32( L ) >> shift );
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}
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else
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{
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while ( H )
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{
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L = ( L >> 2 ) | ( H << 30 );
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H >>= 2;
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shift++;
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}
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return ( FT_Sqrt32( L ) << shift );
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}
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}
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#endif /* FT_CONFIG_OPTION_OLD_CALCS */
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static
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int ft_test_extrema( FT_Outline* outline,
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int n )
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{
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FT_Vector *prev, *cur, *next;
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FT_Pos product;
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FT_Int c, first, last;
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/* we need to compute the `previous' and `next' point */
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/* for these extrema. */
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cur = outline->points + n;
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prev = cur - 1;
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next = cur + 1;
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first = 0;
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for ( c = 0; c < outline->n_contours; c++ )
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{
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last = outline->contours[c];
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if ( n == first )
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prev = outline->points + last;
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if ( n == last )
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next = outline->points + first;
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first = last + 1;
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}
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product = FT_MulDiv( cur->x - prev->x, /* in.x */
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next->y - cur->y, /* out.y */
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0x40 )
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-
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FT_MulDiv( cur->y - prev->y, /* in.y */
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next->x - cur->x, /* out.x */
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0x40 );
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if ( product )
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product = product > 0 ? 1 : -1;
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return product;
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}
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/* Compute the orientation of path filling. It differs between TrueType */
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/* and Type1 formats. We could use the `ft_outline_reverse_fill' flag, */
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/* but it is better to re-compute it directly (it seems that this flag */
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/* isn't correctly set for some weird composite glyphs currently). */
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/* */
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/* We do this by computing bounding box points, and computing their */
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/* curvature. */
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/* */
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/* The function returns either 1 or -1. */
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/* */
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static
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int ft_get_orientation( FT_Outline* outline )
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{
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FT_BBox box;
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FT_BBox indices;
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int n, last;
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indices.xMin = -1;
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indices.yMin = -1;
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indices.xMax = -1;
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indices.yMax = -1;
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box.xMin = box.yMin = 32767;
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box.xMax = box.yMax = -32768;
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/* is it empty ? */
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if ( outline->n_contours < 1 )
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return 1;
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last = outline->contours[outline->n_contours - 1];
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for ( n = 0; n <= last; n++ )
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{
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FT_Pos x, y;
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x = outline->points[n].x;
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if ( x < box.xMin )
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{
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box.xMin = x;
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indices.xMin = n;
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}
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if ( x > box.xMax )
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{
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box.xMax = x;
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indices.xMax = n;
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}
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y = outline->points[n].y;
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if ( y < box.yMin )
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{
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box.yMin = y;
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indices.yMin = n;
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}
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if ( y > box.yMax )
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{
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box.yMax = y;
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indices.yMax = n;
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}
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}
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/* test orientation of the xmin */
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n = ft_test_extrema( outline, indices.xMin );
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if (n)
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goto Exit;
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n = ft_test_extrema( outline, indices.yMin );
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if (n)
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goto Exit;
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n = ft_test_extrema( outline, indices.xMax );
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if (n)
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goto Exit;
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n = ft_test_extrema( outline, indices.yMax );
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if (!n)
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n = 1;
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Exit:
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return n;
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}
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FT_EXPORT_FUNC(FT_Error) FT_Embolden_Outline( FT_GlyphSlot original,
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FT_Outline* outline,
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FT_Pos* advance )
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{
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FT_Vector u, v;
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FT_Vector* points;
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FT_Vector cur, prev, next;
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FT_Pos distance;
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FT_Face face = FT_SLOT_FACE(original);
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int c, n, first, orientation;
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FT_UNUSED( advance );
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/* compute control distance */
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distance = FT_MulFix( face->units_per_EM / 60,
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face->size->metrics.y_scale );
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orientation = ft_get_orientation( &original->outline );
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points = original->outline.points;
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first = 0;
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for ( c = 0; c < outline->n_contours; c++ )
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{
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int last = outline->contours[c];
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prev = points[last];
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for ( n = first; n <= last; n++ )
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{
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FT_Pos norm, delta, d;
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FT_Vector in, out;
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cur = points[n];
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if ( n < last ) next = points[n + 1];
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else next = points[first];
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/* compute the in and out vectors */
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in.x = cur.x - prev.x;
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in.y = cur.y - prev.y;
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out.x = next.x - cur.x;
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out.y = next.y - cur.y;
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/* compute U and V */
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norm = ft_norm( &in );
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u.x = orientation * FT_DivFix( in.y, norm );
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u.y = orientation * -FT_DivFix( in.x, norm );
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norm = ft_norm( &out );
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v.x = orientation * FT_DivFix( out.y, norm );
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v.y = orientation * -FT_DivFix( out.x, norm );
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d = distance;
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if ( ( outline->tags[n] & FT_Curve_Tag_On ) == 0 )
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d *= 2;
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/* Check discriminant for parallel vectors */
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delta = FT_MulFix( u.x, v.y ) - FT_MulFix( u.y, v.x );
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if ( delta > FT_BOLD_THRESHOLD || delta < -FT_BOLD_THRESHOLD )
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{
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/* Move point -- compute A and B */
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FT_Pos x, y, A, B;
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A = d + FT_MulFix( cur.x, u.x ) + FT_MulFix( cur.y, u.y );
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B = d + FT_MulFix( cur.x, v.x ) + FT_MulFix( cur.y, v.y );
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x = FT_MulFix( A, v.y ) - FT_MulFix( B, u.y );
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y = FT_MulFix( B, u.x ) - FT_MulFix( A, v.x );
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outline->points[n].x = distance + FT_DivFix( x, delta );
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outline->points[n].y = distance + FT_DivFix( y, delta );
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}
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else
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{
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/* Vectors are nearly parallel */
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FT_Pos x, y;
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x = distance + cur.x + FT_MulFix( d, u.x + v.x ) / 2;
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y = distance + cur.y + FT_MulFix( d, u.y + v.y ) / 2;
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outline->points[n].x = x;
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outline->points[n].y = y;
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}
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prev = cur;
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}
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first = last + 1;
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}
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if ( advance )
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*advance = ( *advance + distance * 4 ) & -64;
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return 0;
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}
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