1 /****************************************************************************
2 *
3 * ftsynth.c
4 *
5 * FreeType synthesizing code for emboldening and slanting (body).
6 *
7 * Copyright (C) 2000-2023 by
8 * David Turner, Robert Wilhelm, and Werner Lemberg.
9 *
10 * This file is part of the FreeType project, and may only be used,
11 * modified, and distributed under the terms of the FreeType project
12 * license, LICENSE.TXT. By continuing to use, modify, or distribute
13 * this file you indicate that you have read the license and
14 * understand and accept it fully.
15 *
16 */
17
18
19 #include <freetype/ftsynth.h>
20 #include <freetype/internal/ftdebug.h>
21 #include <freetype/internal/ftobjs.h>
22 #include <freetype/ftoutln.h>
23 #include <freetype/ftbitmap.h>
24
25
26 /**************************************************************************
27 *
28 * The macro FT_COMPONENT is used in trace mode. It is an implicit
29 * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
30 * messages during execution.
31 */
32 #undef FT_COMPONENT
33 #define FT_COMPONENT synth
34
35
36 /*************************************************************************/
37 /*************************************************************************/
38 /**** ****/
39 /**** EXPERIMENTAL OBLIQUING SUPPORT ****/
40 /**** ****/
41 /*************************************************************************/
42 /*************************************************************************/
43
44 /* documentation is in ftsynth.h */
45
46 FT_EXPORT_DEF( void )
47 FT_GlyphSlot_Oblique( FT_GlyphSlot slot )
48 {
49 /* Value '0x0366A' corresponds to a shear angle of about 12 degrees. */
50 FT_GlyphSlot_Slant( slot, 0x0366A, 0 );
51 }
52
53
54 /* documentation is in ftsynth.h */
55
56 FT_EXPORT_DEF( void )
57 FT_GlyphSlot_Slant( FT_GlyphSlot slot,
58 FT_Fixed xslant,
59 FT_Fixed yslant )
60 {
61 FT_Matrix transform;
62 FT_Outline* outline;
63
64
65 if ( !slot )
66 return;
67
68 outline = &slot->outline;
69
70 /* only oblique outline glyphs */
71 if ( slot->format != FT_GLYPH_FORMAT_OUTLINE )
72 return;
73
74 /* we don't touch the advance width */
75
76 /* For italic, simply apply a shear transform */
77 transform.xx = 0x10000L;
78 transform.yx = -yslant;
79
80 transform.xy = xslant;
81 transform.yy = 0x10000L;
82
83 FT_Outline_Transform( outline, &transform );
84 }
85
86
87 /*************************************************************************/
88 /*************************************************************************/
89 /**** ****/
90 /**** EXPERIMENTAL EMBOLDENING SUPPORT ****/
91 /**** ****/
92 /*************************************************************************/
93 /*************************************************************************/
94
95
96 /* documentation is in ftsynth.h */
97
98 FT_EXPORT_DEF( void )
99 FT_GlyphSlot_Embolden( FT_GlyphSlot slot )
100 {
101 FT_GlyphSlot_AdjustWeight( slot, 0x0AAA, 0x0AAA );
102 }
103
104
105 FT_EXPORT_DEF( void )
106 FT_GlyphSlot_AdjustWeight( FT_GlyphSlot slot,
107 FT_Fixed xdelta,
108 FT_Fixed ydelta )
109 {
110 FT_Library library;
111 FT_Size size;
112 FT_Error error;
113 FT_Pos xstr, ystr;
114
115
116 if ( !slot )
117 return;
118
119 library = slot->library;
120 size = slot->face->size;
121
122 if ( slot->format != FT_GLYPH_FORMAT_OUTLINE &&
123 slot->format != FT_GLYPH_FORMAT_BITMAP )
124 return;
125
126 /* express deltas in pixels in 26.6 format */
127 xstr = (FT_Pos)size->metrics.x_ppem * xdelta / 1024;
128 ystr = (FT_Pos)size->metrics.y_ppem * ydelta / 1024;
129
130 if ( slot->format == FT_GLYPH_FORMAT_OUTLINE )
131 FT_Outline_EmboldenXY( &slot->outline, xstr, ystr );
132
133 else /* slot->format == FT_GLYPH_FORMAT_BITMAP */
134 {
135 /* round to full pixels */
136 xstr &= ~63;
137 if ( xstr == 0 )
138 xstr = 1 << 6;
139 ystr &= ~63;
140
141 /*
142 * XXX: overflow check for 16-bit system, for compatibility
143 * with FT_GlyphSlot_Embolden() since FreeType 2.1.10.
144 * unfortunately, this function return no informations
145 * about the cause of error.
146 */
147 if ( ( ystr >> 6 ) > FT_INT_MAX || ( ystr >> 6 ) < FT_INT_MIN )
148 {
149 FT_TRACE1(( "FT_GlyphSlot_Embolden:" ));
150 FT_TRACE1(( "too strong emboldening parameter ystr=%ld\n", ystr ));
151 return;
152 }
153 error = FT_GlyphSlot_Own_Bitmap( slot );
154 if ( error )
155 return;
156
157 error = FT_Bitmap_Embolden( library, &slot->bitmap, xstr, ystr );
158 if ( error )
159 return;
160 }
161
162 if ( slot->advance.x )
163 slot->advance.x += xstr;
164
165 if ( slot->advance.y )
166 slot->advance.y += ystr;
167
168 slot->metrics.width += xstr;
169 slot->metrics.height += ystr;
170 slot->metrics.horiAdvance += xstr;
171 slot->metrics.vertAdvance += ystr;
172 slot->metrics.horiBearingY += ystr;
173
174 /* XXX: 16-bit overflow case must be excluded before here */
175 if ( slot->format == FT_GLYPH_FORMAT_BITMAP )
176 slot->bitmap_top += (FT_Int)( ystr >> 6 );
177 }
178
179
180 /* END */