2 libdrawtext - a simple library for fast text rendering in OpenGL
3 Copyright (C) 2011-2019 John Tsiombikas <nuclear@member.fsf.org>
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
18 #ifndef LIBDRAWTEXT_H_
19 #define LIBDRAWTEXT_H_
27 /* draw buffering modes */
29 DTX_NBF = 0,/* unbuffered */
30 DTX_LBF, /* line buffered */
31 DTX_FBF /* fully buffered */
34 /* glyphmap resize filtering */
49 /* Open a truetype/opentype/whatever font.
51 * If sz is non-zero, the default ASCII glyphmap at the requested point size is
52 * automatically created as well, and ready to use.
54 * To use other unicode ranges and different font sizes you must first call
55 * dtx_prepare or dtx_prepare_range before issuing any drawing calls, otherwise
56 * nothing will be rendered.
58 struct dtx_font *dtx_open_font(const char *fname, int sz);
59 /* same as dtx_open_font, but open from a memory buffer instead of a file */
60 struct dtx_font *dtx_open_font_mem(void *ptr, int memsz, int fontsz);
61 /* open a font by loading a precompiled glyphmap (see: dtx_save_glyphmap)
62 * this works even when compiled without freetype support
64 struct dtx_font *dtx_open_font_glyphmap(const char *fname);
65 /* same as dtx_open_font_glyphmap, but open from a memory buffer instead of a file */
66 struct dtx_font *dtx_open_font_glyphmap_mem(void *ptr, int memsz);
67 /* close a font opened by either of the above */
68 void dtx_close_font(struct dtx_font *fnt);
70 /* prepare an ASCII glyphmap for the specified font size */
71 void dtx_prepare(struct dtx_font *fnt, int sz);
72 /* prepare an arbitrary unicode range glyphmap for the specified font size */
73 void dtx_prepare_range(struct dtx_font *fnt, int sz, int cstart, int cend);
75 /* convert all glyphmaps to distance fields for use with the distance field
76 * font rendering algorithm. This is a convenience function which calls
77 * dtx_calc_glyphmap_distfield and
78 * dtx_resize_glyphmap(..., scale_numer, scale_denom, DTX_LINEAR) for each
79 * glyphmap in this font.
81 int dtx_calc_font_distfield(struct dtx_font *fnt, int scale_numer, int scale_denom);
83 /* Finds the glyphmap that contains the specified character code and matches the requested size
84 * Returns null if it hasn't been created (you should call dtx_prepare/dtx_prepare_range).
86 struct dtx_glyphmap *dtx_get_font_glyphmap(struct dtx_font *fnt, int sz, int code);
88 /* Finds the glyphmap that contains the specified unicode range and matches the requested font size
89 * Will automatically generate one if it can't find it.
91 struct dtx_glyphmap *dtx_get_font_glyphmap_range(struct dtx_font *fnt, int sz, int cstart, int cend);
93 /* returns the number of glyphmaps in this font */
94 int dtx_get_num_glyphmaps(struct dtx_font *fnt);
95 /* returns the Nth glyphmap of this font */
96 struct dtx_glyphmap *dtx_get_glyphmap(struct dtx_font *fnt, int idx);
98 /* Creates and returns a glyphmap for a particular unicode range and font size.
99 * The generated glyphmap is added to the font's list of glyphmaps.
101 struct dtx_glyphmap *dtx_create_glyphmap_range(struct dtx_font *fnt, int sz, int cstart, int cend);
102 /* free a glyphmap */
103 void dtx_free_glyphmap(struct dtx_glyphmap *gmap);
105 /* converts a glyphmap to a distance field glyphmap, for use with the distance
106 * field font rendering algorithm.
108 * It is recommended to use a fairly large font size glyphmap for this, and
109 * then shrink the resulting distance field glyphmap as needed, with
110 * dtx_resize_glyphmap
112 int dtx_calc_glyphmap_distfield(struct dtx_glyphmap *gmap);
114 /* resize a glyphmap by the provided scale factor fraction snum/sdenom
115 * in order to maintain the power of 2 invariant, scaling fractions are only
116 * allowed to be of the form 1/x or x/1, where x is a power of 2
118 int dtx_resize_glyphmap(struct dtx_glyphmap *gmap, int snum, int sdenom, int filter);
120 /* returns a pointer to the raster image of a glyphmap (1 byte per pixel grayscale) */
121 unsigned char *dtx_get_glyphmap_image(struct dtx_glyphmap *gmap);
122 /* returns the width of the glyphmap image in pixels */
123 int dtx_get_glyphmap_width(struct dtx_glyphmap *gmap);
124 /* returns the height of the glyphmap image in pixels */
125 int dtx_get_glyphmap_height(struct dtx_glyphmap *gmap);
126 /* returns the point size represented by this glyphmap */
127 int dtx_get_glyphmap_ptsize(struct dtx_glyphmap *gmap);
129 /* The following functions can be used even when the library is compiled without
132 struct dtx_glyphmap *dtx_load_glyphmap(const char *fname);
133 struct dtx_glyphmap *dtx_load_glyphmap_stream(FILE *fp);
134 struct dtx_glyphmap *dtx_load_glyphmap_mem(void *ptr, int memsz);
135 int dtx_save_glyphmap(const char *fname, const struct dtx_glyphmap *gmap);
136 int dtx_save_glyphmap_stream(FILE *fp, const struct dtx_glyphmap *gmap);
138 /* adds a glyphmap to a font */
139 void dtx_add_glyphmap(struct dtx_font *fnt, struct dtx_glyphmap *gmap);
141 void dtxhack_replace_texture(struct dtx_glyphmap *gmap, unsigned int tex);
143 /* ---- options and flags ---- */
145 /* options for the OpenGL renderer */
146 DTX_GL_ATTR_VERTEX, /* vertex attribute location (default: -1 for standard gl_Vertex) */
147 DTX_GL_ATTR_TEXCOORD, /* texture uv attribute location (default: -1 for gl_MultiTexCoord0) */
148 DTX_GL_ATTR_COLOR, /* color attribute location (default: -1 for gl_Color) */
149 /* options for the raster renderer */
150 DTX_RASTER_THRESHOLD, /* opaque/transparent threshold (default: -1. fully opaque glyphs) */
151 DTX_RASTER_BLEND, /* glyph alpha blending (0 or 1) (default: 0 (off)) */
153 DTX_GL_BLEND, /* GL alpha blending (0 or 1) (default: 1 (on)) */
154 DTX_GL_ALPHATEST, /* GL alpha test threshold (0 - 255) (default: 0 (disabled)) */
156 /* generic options */
157 DTX_PADDING = 128, /* padding between glyphs in pixels (default: 8) */
158 DTX_SAVE_PPM, /* let dtx_save_glyphmap* save PPM instead of PGM (0 or 1) (default: 0 (PGM)) */
160 DTX_FORCE_32BIT_ENUM = 0x7fffffff /* this is not a valid option */
163 void dtx_set(enum dtx_option opt, int val);
164 int dtx_get(enum dtx_option opt);
167 /* ---- rendering ---- */
169 /* the dtx_target_ functions select which rendering mode to use.
172 void dtx_target_opengl(void);
173 /* pixels are expected to be RGBA ordered bytes, 4 per pixel
174 * text is rendered with pre-multiplied alpha
176 void dtx_target_raster(unsigned char *pixels, int width, int height);
179 /* data structures passed to user-supplied draw callback */
180 struct dtx_vertex { float x, y, s, t; };
182 unsigned char *pixels; /* pixel buffer pointer (8 bits per pixel) */
183 int width, height; /* dimensions of the pixel buffer */
184 void *udata; /* user-supplied pointer to data associated with this
185 * pixmap. On the first callback invocation this pointer
186 * will be null. The user may set it to associate any extra
187 * data to this pixmap (such as texture structures or
188 * identifiers). Libdrawtext will never modify this pointer.
192 /* user-defined glyph drawing callback type (set with dtx_target_user)
193 * It's called when the output buffer is flushed, with a pointer to the vertex
194 * buffer that needs to be drawn (every 3 vertices forming a triangle), the
195 * number of vertices in the buffer, and a pointer to the current glyphmap
196 * atlas pixmap (see struct dtx_pixmap above).
198 typedef void (*dtx_user_draw_func)(struct dtx_vertex *v, int vcount,
199 struct dtx_pixmap *pixmap, void *cls);
201 /* set user-supplied draw callback and optional closure pointer, which will
202 * be passed unchanged as the last argument on every invocation of the draw
205 void dtx_target_user(dtx_user_draw_func drawfunc, void *cls);
208 /* position of the origin of the first character to be printed */
209 void dtx_position(float x, float y);
210 /* TODO currently only used by the raster renderer, implement in gl too */
211 void dtx_color(float r, float g, float b, float a);
213 /* before drawing anything this function must set the font to use */
214 void dtx_use_font(struct dtx_font *fnt, int sz);
216 /* sets the buffering mode
217 * - DTX_NBUF: every call to dtx_string gets rendered immediately.
218 * - DTX_LBUF: renders when the buffer is full or the string contains a newline.
219 * - DTX_FBUF: renders only when the buffer is full (you must call dtx_flush explicitly).
221 void dtx_draw_buffering(int mode);
223 /* Sets the vertex attribute indices to use for passing vertex and texture coordinate
224 * data. By default both are -1 which means you don't have to use a shader, and if you
225 * do they are accessible through gl_Vertex and gl_MultiTexCoord0, as usual.
227 * NOTE: If you are using OpenGL ES 2.x or OpenGL >= 3.1 core (non-compatibility)
228 * context you must specify valid attribute indices.
230 * NOTE2: equivalent to:
231 * dtx_set(DTX_GL_ATTR_VERTEX, vert_attr);
232 * dtx_set(DTX_GL_ATTR_TEXCOORD, tex_attr);
234 void dtx_vertex_attribs(int vert_attr, int tex_attr);
236 /* draws a single glyph at the origin */
237 void dtx_glyph(int code);
238 /* draws a utf-8 string starting at the origin. \n \r and \t are handled appropriately. */
239 void dtx_string(const char *str);
240 void dtx_substring(const char *str, int start, int end);
242 void dtx_printf(const char *fmt, ...);
244 /* render any pending glyphs (see dtx_draw_buffering) */
245 void dtx_flush(void);
248 /* ---- encodings ---- */
250 /* returns a pointer to the next character in a utf-8 stream */
251 char *dtx_utf8_next_char(char *str);
253 /* returns a pointer to the previous character in a utf-8 stream */
254 char *dtx_utf8_prev_char(char *ptr, char *first);
256 /* returns the unicode character codepoint of the utf-8 character starting at str */
257 int dtx_utf8_char_code(const char *str);
259 /* returns the number of bytes of the utf-8 character starting at str */
260 int dtx_utf8_nbytes(const char *str);
262 /* returns the number of utf-8 characters in a zero-terminated utf-8 string */
263 int dtx_utf8_char_count(const char *str);
265 /* returns the number of utf-8 characters in the next N bytes starting from str */
266 int dtx_utf8_char_count_range(const char *str, int nbytes);
268 /* Converts a unicode code-point to a utf-8 character by filling in the buffer
269 * passed at the second argument, and returns the number of bytes taken by that
271 * It's valid to pass a null buffer pointer, in which case only the byte count is
272 * returned (useful to figure out how much memory to allocate for a buffer).
274 size_t dtx_utf8_from_char_code(int code, char *buf);
276 /* Converts a unicode utf-16 wchar_t string to utf-8, filling in the buffer passed
277 * at the second argument. Returns the size of the resulting string in bytes.
279 * It's valid to pass a null buffer pointer, in which case only the size gets
280 * calculated and returned, which is useful for figuring out how much memory to
281 * allocate for the utf-8 buffer.
283 size_t dtx_utf8_from_string(const wchar_t *str, char *buf);
286 /* ---- metrics ---- */
287 float dtx_line_height(void);
288 float dtx_baseline(void);
290 /* rendered dimensions of a single glyph */
291 void dtx_glyph_box(int code, struct dtx_box *box);
292 float dtx_glyph_width(int code);
293 float dtx_glyph_height(int code);
295 /* rendered dimensions of a string */
296 void dtx_string_box(const char *str, struct dtx_box *box);
297 void dtx_substring_box(const char *str, int start, int end, struct dtx_box *box);
298 float dtx_string_width(const char *str);
299 float dtx_string_height(const char *str);
301 /* returns the horizontal position of the n-th character of the rendered string
302 * (useful for placing cursors)
304 float dtx_char_pos(const char *str, int n);
306 int dtx_char_at_pt(const char *str, float pt);
312 #endif /* LIBDRAWTEXT_H_ */