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author Matti Hamalainen <ccr@tnsp.org>
date Mon, 05 Aug 2013 12:25:43 +0300
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1 /* ============================================================================
2 * Freetype GL - A C OpenGL Freetype engine
3 * Platform: Any
4 * WWW: http://code.google.com/p/freetype-gl/
5 * ----------------------------------------------------------------------------
6 * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright notice,
12 * this list of conditions and the following disclaimer.
13 *
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
20 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
21 * EVENT SHALL NICOLAS P. ROUGIER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
22 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * The views and conclusions contained in the software and documentation are
30 * those of the authors and should not be interpreted as representing official
31 * policies, either expressed or implied, of Nicolas P. Rougier.
32 * ============================================================================
33 */
34 #ifndef __TEXTURE_FONT_H__
35 #define __TEXTURE_FONT_H__
36
37 #include <stdlib.h>
38
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42
43 #include "vector.h"
44 #include "texture-atlas.h"
45
46 /**
47 * @file texture-font.h
48 * @author Nicolas Rougier (Nicolas.Rougier@inria.fr)
49 *
50 * @defgroup texture-font Texture font
51 *
52 * Texture font.
53 *
54 * Example Usage:
55 * @code
56 * #include "texture-font.h"
57 *
58 * int main( int arrgc, char *argv[] )
59 * {
60 * return 0;
61 * }
62 * @endcode
63 *
64 * @{
65 */
66
67
68
69 /**
70 * A structure that hold a kerning value relatively to a charcode.
71 *
72 * This structure cannot be used alone since the (necessary) right charcode is
73 * implicitely held by the owner of this structure.
74 */
75 typedef struct
76 {
77 /**
78 * Left character code in the kern pair.
79 */
80 wchar_t charcode;
81
82 /**
83 * Kerning value (in fractional pixels).
84 */
85 float kerning;
86
87 } kerning_t;
88
89
90
91
92 /*
93 * Glyph metrics:
94 * --------------
95 *
96 * xmin xmax
97 * | |
98 * |<-------- width -------->|
99 * | |
100 * | +-------------------------+----------------- ymax
101 * | | ggggggggg ggggg | ^ ^
102 * | | g:::::::::ggg::::g | | |
103 * | | g:::::::::::::::::g | | |
104 * | | g::::::ggggg::::::gg | | |
105 * | | g:::::g g:::::g | | |
106 * offset_x -|-------->| g:::::g g:::::g | offset_y |
107 * | | g:::::g g:::::g | | |
108 * | | g::::::g g:::::g | | |
109 * | | g:::::::ggggg:::::g | | |
110 * | | g::::::::::::::::g | | height
111 * | | gg::::::::::::::g | | |
112 * baseline ---*---------|---- gggggggg::::::g-----*-------- |
113 * / | | g:::::g | |
114 * origin | | gggggg g:::::g | |
115 * | | g:::::gg gg:::::g | |
116 * | | g::::::ggg:::::::g | |
117 * | | gg:::::::::::::g | |
118 * | | ggg::::::ggg | |
119 * | | gggggg | v
120 * | +-------------------------+----------------- ymin
121 * | |
122 * |------------- advance_x ---------->|
123 */
124
125 /**
126 * A structure that describe a glyph.
127 */
128 typedef struct
129 {
130 /**
131 * Wide character this glyph represents
132 */
133 wchar_t charcode;
134
135 /**
136 * Glyph id (used for display lists)
137 */
138 unsigned int id;
139
140 /**
141 * Glyph's width in pixels.
142 */
143 size_t width;
144
145 /**
146 * Glyph's height in pixels.
147 */
148 size_t height;
149
150 /**
151 * Glyph's left bearing expressed in integer pixels.
152 */
153 int offset_x;
154
155 /**
156 * Glyphs's top bearing expressed in integer pixels.
157 *
158 * Remember that this is the distance from the baseline to the top-most
159 * glyph scanline, upwards y coordinates being positive.
160 */
161 int offset_y;
162
163 /**
164 * For horizontal text layouts, this is the horizontal distance (in
165 * fractional pixels) used to increment the pen position when the glyph is
166 * drawn as part of a string of text.
167 */
168 float advance_x;
169
170 /**
171 * For vertical text layouts, this is the vertical distance (in fractional
172 * pixels) used to increment the pen position when the glyph is drawn as
173 * part of a string of text.
174 */
175 float advance_y;
176
177 /**
178 * First normalized texture coordinate (x) of top-left corner
179 */
180 float s0;
181
182 /**
183 * Second normalized texture coordinate (y) of top-left corner
184 */
185 float t0;
186
187 /**
188 * First normalized texture coordinate (x) of bottom-right corner
189 */
190 float s1;
191
192 /**
193 * Second normalized texture coordinate (y) of bottom-right corner
194 */
195 float t1;
196
197 /**
198 * A vector of kerning pairs relative to this glyph.
199 */
200 vector_t * kerning;
201
202 /**
203 * Glyph outline type (0 = None, 1 = line, 2 = inner, 3 = outer)
204 */
205 int outline_type;
206
207 /**
208 * Glyph outline thickness
209 */
210 float outline_thickness;
211
212 } texture_glyph_t;
213
214
215
216 /**
217 * Texture font structure.
218 */
219 typedef struct
220 {
221 /**
222 * Vector of glyphs contained in this font.
223 */
224 vector_t * glyphs;
225
226 /**
227 * Atlas structure to store glyphs data.
228 */
229 texture_atlas_t * atlas;
230
231 /**
232 * Font filename
233 */
234 char * filename;
235
236 /**
237 * Font size
238 */
239 float size;
240
241 /**
242 * Whether to use autohint when rendering font
243 */
244 int hinting;
245
246 /**
247 * Outline type (0 = None, 1 = line, 2 = inner, 3 = outer)
248 */
249 int outline_type;
250
251 /**
252 * Outline thickness
253 */
254 float outline_thickness;
255
256 /**
257 * Whether to use our own lcd filter.
258 */
259 int filtering;
260
261 /**
262 * Whether to use kerning if available
263 */
264 int kerning;
265
266 /**
267 * LCD filter weights
268 */
269 unsigned char lcd_weights[5];
270
271 /**
272 * This field is simply used to compute a default line spacing (i.e., the
273 * baseline-to-baseline distance) when writing text with this font. Note
274 * that it usually is larger than the sum of the ascender and descender
275 * taken as absolute values. There is also no guarantee that no glyphs
276 * extend above or below subsequent baselines when using this distance.
277 */
278 float height;
279
280 /**
281 * This field is the distance that must be placed between two lines of
282 * text. The baseline-to-baseline distance should be computed as:
283 * ascender - descender + linegap
284 */
285 float linegap;
286
287 /**
288 * The ascender is the vertical distance from the horizontal baseline to
289 * the highest 'character' coordinate in a font face. Unfortunately, font
290 * formats define the ascender differently. For some, it represents the
291 * ascent of all capital latin characters (without accents), for others it
292 * is the ascent of the highest accented character, and finally, other
293 * formats define it as being equal to bbox.yMax.
294 */
295 float ascender;
296
297 /**
298 * The descender is the vertical distance from the horizontal baseline to
299 * the lowest 'character' coordinate in a font face. Unfortunately, font
300 * formats define the descender differently. For some, it represents the
301 * descent of all capital latin characters (without accents), for others it
302 * is the ascent of the lowest accented character, and finally, other
303 * formats define it as being equal to bbox.yMin. This field is negative
304 * for values below the baseline.
305 */
306 float descender;
307
308 /**
309 * The position of the underline line for this face. It is the center of
310 * the underlining stem. Only relevant for scalable formats.
311 */
312 float underline_position;
313
314 /**
315 * The thickness of the underline for this face. Only relevant for scalable
316 * formats.
317 */
318 float underline_thickness;
319
320 } texture_font_t;
321
322
323
324 /**
325 * This function creates a new texture font from given filename and size. The
326 * texture atlas is used to store glyph on demand. Note the depth of the atlas
327 * will determine if the font is rendered as alpha channel only (depth = 1) or
328 * RGB (depth = 3) that correspond to subpixel rendering (if available on your
329 * freetype implementation).
330 *
331 * @param atlas A texture atlas
332 * @param filename A font filename
333 * @param size Size of font to be created (in points)
334 *
335 * @return A new empty font (no glyph inside yet)
336 *
337 */
338 texture_font_t *
339 texture_font_new( texture_atlas_t * atlas,
340 const char * filename,
341 const float size );
342
343
344 /**
345 * Delete a texture font. Note that this does not delete the glyph from the
346 * texture atlas.
347 *
348 * @param self a valid texture font
349 */
350 void
351 texture_font_delete( texture_font_t * self );
352
353
354 /**
355 * Request a new glyph from the font. If it has not been created yet, it will
356 * be.
357 *
358 * @param self A valid texture font
359 * @param charcode Character codepoint to be loaded.
360 *
361 * @return A pointer on the new glyph or 0 if the texture atlas is not big
362 * enough
363 *
364 */
365 texture_glyph_t *
366 texture_font_get_glyph( texture_font_t * self,
367 wchar_t charcode );
368
369
370 /**
371 * Request the loading of several glyphs at once.
372 *
373 * @param self a valid texture font
374 * @param charcodes character codepoints to be loaded.
375 *
376 * @return Number of missed glyph if the texture is not big enough to hold
377 * every glyphs.
378 */
379 size_t
380 texture_font_load_glyphs( texture_font_t * self,
381 const wchar_t * charcodes );
382
383 /**
384 * Get the kerning between two horizontal glyphs.
385 *
386 * @param self a valid texture glyph
387 * @param charcode codepoint of the peceding glyph
388 *
389 * @return x kerning value
390 */
391 float
392 texture_glyph_get_kerning( const texture_glyph_t * self,
393 const wchar_t charcode );
394
395
396 /**
397 * Creates a new empty glyph
398 *
399 * @return a new empty glyph (not valid)
400 */
401 texture_glyph_t *
402 texture_glyph_new( void );
403
404 /** @} */
405
406
407 #ifdef __cplusplus
408 }
409 #endif
410
411 #endif /* __TEXTURE_FONT_H__ */
412