1 /* GDK - The GIMP Drawing Kit
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
21 * Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
22 * file for a list of people on the GTK+ Team. See the ChangeLog
23 * files for a list of changes. These files are distributed with
24 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
33 * @Short_description: RGBA colors
36 * The #GdkRGBA struct is a convenient way to pass rgba colors around.
37 * It's based on cairo's way to deal with colors and mirrors its behavior.
38 * All values are in the range from 0.0 to 1.0 inclusive. So the color
39 * (0.0, 0.0, 0.0, 0.0) represents transparent black and
40 * (1.0, 1.0, 1.0, 1.0) is opaque white. Other values will be clamped
41 * to this range when drawing.
44 G_DEFINE_BOXED_TYPE (GdkRGBA, gdk_rgba,
45 gdk_rgba_copy, gdk_rgba_free)
49 * @red: The intensity of the red channel from 0.0 to 1.0 inclusive
50 * @green: The intensity of the green channel from 0.0 to 1.0 inclusive
51 * @blue: The intensity of the blue channel from 0.0 to 1.0 inclusive
52 * @alpha: The opacity of the color from 0.0 for completely translucent to
55 * The GdkRGBA structure is used to represent a (possibly translucent)
56 * color, in a way that is compatible with cairos notion of color.
63 * Makes a copy of a #GdkRGBA structure.
65 * The result must be freed through gdk_rgba_free().
67 * Returns: A newly allocated #GdkRGBA, with the same contents as @rgba
72 gdk_rgba_copy (const GdkRGBA *rgba)
74 return g_slice_dup (GdkRGBA, rgba);
81 * Frees a #GdkRGBA struct created with gdk_rgba_copy()
86 gdk_rgba_free (GdkRGBA *rgba)
88 g_slice_free (GdkRGBA, rgba);
91 #define SKIP_WHITESPACES(s) while (*(s) == ' ') (s)++;
93 /* Parses a single color component from a rgb() or rgba() specification
94 * according to CSS3 rules. Compared to exact CSS3 parsing we are liberal
95 * in what we accept as follows:
97 * - For non-percentage values, we accept floats in the range 0-255
98 * not just [0-9]+ integers
99 * - For percentage values we accept any float, not just
100 * [ 0-9]+ | [0-9]* '.' [0-9]+
101 * - We accept mixed percentages and non-percentages in a single
102 * rgb() or rgba() specification.
105 parse_rgb_value (const char *str,
111 number = g_ascii_strtod (str, endp);
115 SKIP_WHITESPACES (p);
119 *endp = (char *)(p + 1);
120 return CLAMP(number / 100., 0., 1.);
124 return CLAMP(number / 255., 0., 1.);
130 * @rgba: the #GdkRGBA struct to fill in
131 * @spec: the string specifying the color
133 * Parses a textual representation of a color, filling in
134 * the <structfield>red</structfield>, <structfield>green</structfield>,
135 * <structfield>blue</structfield> and <structfield>alpha</structfield>
136 * fields of the @rgba struct.
138 * The string can be either one of:
141 * A standard name (Taken from the X11 rgb.txt file).
144 * A hex value in the form '#rgb' '#rrggbb' '#rrrgggbbb' or '#rrrrggggbbbb'
147 * A RGB color in the form 'rgb(r,g,b)' (In this case the color will
151 * A RGBA color in the form 'rgba(r,g,b,a)'
155 * Where 'r', 'g', 'b' and 'a' are respectively the red, green, blue and
156 * alpha color values. In the last two cases, r g and b are either integers
157 * in the range 0 to 255 or precentage values in the range 0% to 100%, and
158 * a is a floating point value in the range 0 to 1.
160 * Returns: %TRUE if the parsing succeeded
165 gdk_rgba_parse (GdkRGBA *rgba,
170 gchar *str = (gchar *) spec;
172 if (strncmp (str, "rgba", 4) == 0)
177 else if (strncmp (str, "rgb", 3) == 0)
185 PangoColor pango_color;
187 /* Resort on PangoColor for rgb.txt color
188 * map and '#' prefixed colors
190 if (pango_color_parse (&pango_color, str))
194 rgba->red = pango_color.red / 65535.;
195 rgba->green = pango_color.green / 65535.;
196 rgba->blue = pango_color.blue / 65535.;
206 SKIP_WHITESPACES (str);
214 SKIP_WHITESPACES (str);
215 r = parse_rgb_value (str, &str);
216 SKIP_WHITESPACES (str);
224 SKIP_WHITESPACES (str);
225 g = parse_rgb_value (str, &str);
226 SKIP_WHITESPACES (str);
234 SKIP_WHITESPACES (str);
235 b = parse_rgb_value (str, &str);
236 SKIP_WHITESPACES (str);
245 SKIP_WHITESPACES (str);
246 a = g_ascii_strtod (str, &str);
247 SKIP_WHITESPACES (str);
255 rgba->red = CLAMP (r, 0, 1);
256 rgba->green = CLAMP (g, 0, 1);
257 rgba->blue = CLAMP (b, 0, 1);
258 rgba->alpha = CLAMP (a, 0, 1);
264 #undef SKIP_WHITESPACES
268 * @p: (type GdkRGBA): a #GdkRGBA pointer
270 * A hash function suitable for using for a hash
271 * table that stores #GdkRGBAs.
273 * Return value: The hash value for @p
278 gdk_rgba_hash (gconstpointer p)
280 const GdkRGBA *rgba = p;
282 return ((guint) (rgba->red * 65535) +
283 ((guint) (rgba->green * 65535) << 11) +
284 ((guint) (rgba->blue * 65535) << 22) +
285 ((guint) (rgba->alpha * 65535) >> 6));
290 * @p1: (type GdkRGBA): a #GdkRGBA pointer
291 * @p2: (type GdkRGBA): another #GdkRGBA pointer
293 * Compares two RGBA colors.
295 * Return value: %TRUE if the two colors compare equal
300 gdk_rgba_equal (gconstpointer p1,
303 const GdkRGBA *rgba1, *rgba2;
308 if (rgba1->red == rgba2->red &&
309 rgba1->green == rgba2->green &&
310 rgba1->blue == rgba2->blue &&
311 rgba1->alpha == rgba2->alpha)
318 * gdk_rgba_to_string:
321 * Returns a textual specification of @rgba in the form
322 * <literal>rgb (r, g, b)</literal> or
323 * <literal>rgba (r, g, b, a)</literal>,
324 * where 'r', 'g', 'b' and 'a' represent the red, green,
325 * blue and alpha values respectively. r, g, and b are
326 * represented as integers in the range 0 to 255, and a
327 * is represented as floating point value in the range 0 to 1.
329 * These string forms are string forms those supported by
330 * the CSS3 colors module, and can be parsed by gdk_rgba_parse().
332 * Note that this string representation may loose some
333 * precision, since r, g and b are represented as 8-bit
334 * integers. If this is a concern, you should use a
335 * different representation.
337 * Returns: A newly allocated text string
342 gdk_rgba_to_string (const GdkRGBA *rgba)
344 if (rgba->alpha > 0.999)
346 return g_strdup_printf ("rgb(%d,%d,%d)",
347 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
348 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
349 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.));
353 gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
355 g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
357 return g_strdup_printf ("rgba(%d,%d,%d,%s)",
358 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
359 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
360 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.),