1fcft_from_name(3)                    fcft                    fcft_from_name(3)
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3
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NAME

6       fcft_from_name - instantiate a new font
7

SYNOPSIS

9       #include <fcft/fcft.h>
10
11       struct fcft_font *fcft_from_name(
12           size_t count, const char *names[static count], const char *at‐
13           tributes);
14

DESCRIPTION

16       fcft_from_name() instantiates a new fcft font object from the FontCon‐
17       fig formatted font names. The first element in names is the primary
18       font, and the remaining elements (if any) are fallback fonts.
19
20       You must supply at least one font name.
21
22       All aspects of the font (size, DPI, variant etc) are configured through
23       the font name, using colon separated attribute=value pairs (e.g.
24       "Serif:size=26:slant=italic").
25
26       attributes is a convenient way to apply a set of attributes to all
27       fonts in names. attributes may be NULL, in which case no extra at‐
28       tributes are appended to the strings in names.
29
30       The primary font will be instantiated immediately, and any failure to
31       do so will result in an error. Fallback fonts are instantiated on de‐
32       mand, and any failure to do so will result in the that fallback font
33       being ignored, and the next one in the list is tried instead.
34

RETURN VALUE

36       On success, fcft_from_name() returns a pointer to an allocated
37       fcft_font object. On error, NULL is returned.
38
39           struct fcft_font {
40               int height;
41               int descent;
42               int ascent;
43
44               struct {
45                   int x;
46                   int y;
47               } max_advance;
48
49               struct {
50                   int x;
51                   int y;
52               } space_advance;
53
54               struct {
55                   int position;
56                   int thickness;
57               } underline;
58
59               struct {
60                   int position;
61                   int thickness;
62               } strikeout;
63           };
64
65       height is the line height, in pixels.
66
67       descent is the distance between the baseline and the font's lowest de‐
68       scending glyph, in pixels. In fcft's case, it is generally positive (a
69       negative value means the descent stretches up from the baseline).
70
71       ascent is the distance between the baseline and the font's highest as‐
72       cending glyph, in pixels. Generally a positive number (a negative value
73       means the ascent stretches down below the baseline).
74
75       ascent + descent is often the same as height, but not necessarily.
76       height may be larger, meaning the font intentionally adds extra (verti‐
77       cal) space between lines. Or it may be smaller, in which case lines
78       overlap.
79
80       max_advance is the amount, in pixels, the font's widest glyph advances
81       the pen position; x for a horizontal layout, and y for a vertical lay‐
82       out.
83
84       space_advance is the amount, in pixels, the glyph for space (0x20) ad‐
85       vances the pen position; x for a horizontal layout, and y for a verti‐
86       cal layout.
87
88       underline describes how to render underlines. position is the distance,
89       in pixels, from the baseline. A positive value means above the base‐
90       line, and a negative value means below the baseline. thickness is the
91       line's thickness, in pixels.
92
93       strikeout describes how to render strikeouts. See underline for a de‐
94       scription of its members.
95

EXAMPLE

97       In this example, we instantiate Times New Roman at a point size of 8 as
98       the primary font.
99
100       We also tell it to use Serif Bold (point size 10) as a fallback font
101       (note that it is usually better to let FontConfig handle fallback to
102       generic fonts like this).
103
104       Furthermore, both fonts will be Italic, and will be using DPI=140.
105
106       We then proceed to render the string hello world. You are assumed to
107       know how to create and use a pixman image. This example only shows how
108       one can use fcft to instantiate a font, rasterize glyphs and then blend
109       them onto a target pixman image.
110
111           #include <stdlib.h>
112           #include <wchar.h>
113           #include <fcft/fcft.h>
114
115           int
116           main(void)
117           {
118               setlocale(LC_CTYPE, "en_US.UTF-8");
119
120               if (!fcft_set_scaling_filter(FCFT_SCALING_FILTER_LANCZOS3))
121                  return EXIT_FAILURE;
122
123               struct fcft_font *font = fcft_from_name(
124                   2,
125                   (const char *[]){
126                       "Times New Roman:size=8",
127                       "Serif:size=10:weight=bold",
128                   },
129                   "slant=italic:dpi=140");
130
131               if (font == NULL)
132                   return EXIT_FAILURE;
133
134               /* Here you need to instantiate a 'target' pixman image, to blend
135                  with */
136               pixman_image_t *canvas = ...;
137
138               /* String to print */
139               static const wchar_t *const hello = L"hello world";
140
141               /*
142                * Pen position in canvas. The numbers chosen here are more or less
143                * random. Note however, that the composite calls below assume 'y'
144                * is the font's baseline (and thus the glyphs will be rendered
145                * above 'y')
146                */
147               struct {
148                   int x;
149                   int y;
150               } pen = {.x = 25, .y = 50};
151
152               /* Glyphs will be rendered in white */
153               pixman_image_t *color = pixman_image_create_solid_fill(
154                   &(struct pixman_color_t){
155                       .red = 0xffff,
156                       .green = 0xffff,
157                       .blue = 0xffff,
158                       .alpha = 0xffff,
159                   });
160
161               for (size_t i = 0; i < wcslen(hello); i++) {
162                   const struct fcft_glyph *glyph = fcft_glyph_rasterize(
163                       font, hello[i], FCFT_SUBPIXEL_DEFAULT);
164
165                   if (glyph == NULL)
166                       continue;
167
168                   /* Kerning */
169                   long x_kern = 0;
170                   if (i > 0) {
171                       fcft_kerning(font, hello[i - 1], hello[i], &x_kern, NULL);
172
173                   pen.x += x_kern;
174
175                   if (pixman_image_get_format(glyph->pix) == PIXMAN_a8r8g8b8) {
176                       /* Glyph is a pre-rendered image; typically a color emoji */
177                       pixman_image_composite32(
178                           PIXMAP_OP_OVER, glyph->pix, NULL, canvas, 0, 0, 0, 0,
179                           pen.x + glyph->x, pen.y + font->ascent - glyph->y,
180                           glyph->width, glyph->height);
181                   }
182
183                   else {
184                       /* Glyph is an alpha mask */
185                       pixman_image_composite32(
186                           PIXMAN_OP_OVER, color, glyph->pix, canvas, 0, 0, 0, 0,
187                           pen.x + glyph->x, pen.y + font->ascent - glyph->y,
188                           glyph->width, glyph->height);
189                   }
190
191                   /* Advance pen position */
192                   pen.x += glyph->advance.x;
193               }
194
195               pixman_image_unref(src);
196
197               fcft_destroy(font);
198               return EXIT_SUCCESS;
199           }
200

SEE ALSO

202       fcft_clone(), fcft_destroy(), fcft_glyph_rasterize(), fcft_kerning(),
203       fcft_size_adjust()
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206
2072.5.0                             2021-11-13                 fcft_from_name(3)
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