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- /***************************************************************************/
- /* */
- /* 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 */
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