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, see <http://www.gnu.org/licenses/>.
19 * Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
20 * file for a list of people on the GTK+ Team. See the ChangeLog
21 * files for a list of changes. These files are distributed with
22 * 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 gchar *str,
111 *number = g_ascii_strtod (str, endp);
112 if (errno == ERANGE || *endp == str ||
113 isinf (*number) || isnan (*number))
118 SKIP_WHITESPACES (p);
122 *endp = (char *)(p + 1);
123 *number = CLAMP(*number / 100., 0., 1.);
127 *number = CLAMP(*number / 255., 0., 1.);
135 * @rgba: the #GdkRGBA struct to fill in
136 * @spec: the string specifying the color
138 * Parses a textual representation of a color, filling in
139 * the <structfield>red</structfield>, <structfield>green</structfield>,
140 * <structfield>blue</structfield> and <structfield>alpha</structfield>
141 * fields of the @rgba struct.
143 * The string can be either one of:
146 * A standard name (Taken from the X11 rgb.txt file).
149 * A hex value in the form '#rgb' '#rrggbb' '#rrrgggbbb' or '#rrrrggggbbbb'
152 * A RGB color in the form 'rgb(r,g,b)' (In this case the color will
156 * A RGBA color in the form 'rgba(r,g,b,a)'
160 * Where 'r', 'g', 'b' and 'a' are respectively the red, green, blue and
161 * alpha color values. In the last two cases, r g and b are either integers
162 * in the range 0 to 255 or precentage values in the range 0% to 100%, and
163 * a is a floating point value in the range 0 to 1.
165 * Returns: %TRUE if the parsing succeeded
170 gdk_rgba_parse (GdkRGBA *rgba,
175 gchar *str = (gchar *) spec;
178 if (strncmp (str, "rgba", 4) == 0)
183 else if (strncmp (str, "rgb", 3) == 0)
191 PangoColor pango_color;
193 /* Resort on PangoColor for rgb.txt color
194 * map and '#' prefixed colors
196 if (pango_color_parse (&pango_color, str))
200 rgba->red = pango_color.red / 65535.;
201 rgba->green = pango_color.green / 65535.;
202 rgba->blue = pango_color.blue / 65535.;
212 SKIP_WHITESPACES (str);
220 SKIP_WHITESPACES (str);
221 if (!parse_rgb_value (str, &str, &r))
223 SKIP_WHITESPACES (str);
231 SKIP_WHITESPACES (str);
232 if (!parse_rgb_value (str, &str, &g))
234 SKIP_WHITESPACES (str);
242 SKIP_WHITESPACES (str);
243 if (!parse_rgb_value (str, &str, &b))
245 SKIP_WHITESPACES (str);
254 SKIP_WHITESPACES (str);
255 a = g_ascii_strtod (str, &p);
256 if (errno == ERANGE || p == str ||
257 isinf (a) || isnan (a))
260 SKIP_WHITESPACES (str);
268 SKIP_WHITESPACES (str);
275 rgba->red = CLAMP (r, 0, 1);
276 rgba->green = CLAMP (g, 0, 1);
277 rgba->blue = CLAMP (b, 0, 1);
278 rgba->alpha = CLAMP (a, 0, 1);
284 #undef SKIP_WHITESPACES
288 * @p: (type GdkRGBA): a #GdkRGBA pointer
290 * A hash function suitable for using for a hash
291 * table that stores #GdkRGBAs.
293 * Return value: The hash value for @p
298 gdk_rgba_hash (gconstpointer p)
300 const GdkRGBA *rgba = p;
302 return ((guint) (rgba->red * 65535) +
303 ((guint) (rgba->green * 65535) << 11) +
304 ((guint) (rgba->blue * 65535) << 22) +
305 ((guint) (rgba->alpha * 65535) >> 6));
310 * @p1: (type GdkRGBA): a #GdkRGBA pointer
311 * @p2: (type GdkRGBA): another #GdkRGBA pointer
313 * Compares two RGBA colors.
315 * Return value: %TRUE if the two colors compare equal
320 gdk_rgba_equal (gconstpointer p1,
323 const GdkRGBA *rgba1, *rgba2;
328 if (rgba1->red == rgba2->red &&
329 rgba1->green == rgba2->green &&
330 rgba1->blue == rgba2->blue &&
331 rgba1->alpha == rgba2->alpha)
338 * gdk_rgba_to_string:
341 * Returns a textual specification of @rgba in the form
342 * <literal>rgb (r, g, b)</literal> or
343 * <literal>rgba (r, g, b, a)</literal>,
344 * where 'r', 'g', 'b' and 'a' represent the red, green,
345 * blue and alpha values respectively. r, g, and b are
346 * represented as integers in the range 0 to 255, and a
347 * is represented as floating point value in the range 0 to 1.
349 * These string forms are string forms those supported by
350 * the CSS3 colors module, and can be parsed by gdk_rgba_parse().
352 * Note that this string representation may loose some
353 * precision, since r, g and b are represented as 8-bit
354 * integers. If this is a concern, you should use a
355 * different representation.
357 * Returns: A newly allocated text string
362 gdk_rgba_to_string (const GdkRGBA *rgba)
364 if (rgba->alpha > 0.999)
366 return g_strdup_printf ("rgb(%d,%d,%d)",
367 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
368 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
369 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.));
373 gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
375 g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
377 return g_strdup_printf ("rgba(%d,%d,%d,%s)",
378 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
379 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
380 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.),