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 mirros 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 pass around color data. When using it
56 * as struct members or on the stack, you want to use the struct directly
57 * and not allocate it.
64 * Makes a copy of a #GdkRGBA structure, the result must be freed
65 * through gdk_rgba_free().
67 * Returns: A newly allocated #GdkRGBA
72 gdk_rgba_copy (const GdkRGBA *rgba)
76 copy = g_slice_new (GdkRGBA);
77 copy->red = rgba->red;
78 copy->green = rgba->green;
79 copy->blue = rgba->blue;
80 copy->alpha = rgba->alpha;
89 * Frees a #GdkRGBA struct created with gdk_rgba_copy()
94 gdk_rgba_free (GdkRGBA *rgba)
96 g_slice_free (GdkRGBA, rgba);
99 #define SKIP_WHITESPACES(s) while (*(s) == ' ') (s)++;
101 /* Parses a single color component from a rgb() or rgba() specification
102 * according to CSS3 rules. Compared to exact CSS3 parsing we are liberal
103 * in what we accept as follows:
105 * - For non-percentage values, we accept floats in the range 0-255
106 * not just [0-9]+ integers
107 * - For percentage values we accept any float, not just
108 * [ 0-9]+ | [0-9]* '.' [0-9]+
109 * - We accept mixed percentages and non-percentages in a single
110 * rgb() or rgba() specification.
113 parse_rgb_value (const char *str,
119 number = g_ascii_strtod (str, endp);
123 SKIP_WHITESPACES (p);
127 *endp = (char *)(p + 1);
128 return CLAMP(number / 100., 0., 1.);
132 return CLAMP(number / 255., 0., 1.);
138 * @rgba: the #GdkRGBA struct to fill in
139 * @spec: the string specifying the color
141 * Parses a textual representation of a color, filling in
142 * the <structfield>red</structfield>, <structfield>green</structfield>,
143 * <structfield>blue</structfield> and <structfield>alpha</structfield>
144 * fields of the @rgba struct.
146 * The string can be either one of:
149 * A standard name (Taken from the X11 rgb.txt file).
152 * A hex value in the form '#rgb' '#rrggbb' '#rrrgggbbb' or '#rrrrggggbbbb'
155 * A RGB color in the form 'rgb(r,g,b)' (In this case the color will
159 * A RGBA color in the form 'rgba(r,g,b,a)'
163 * Where 'r', 'g', 'b' and 'a' are respectively the red, green, blue and
164 * alpha color values. In the last two cases, r g and b are either integers
165 * in the range 0 to 255 or precentage values in the range 0% to 100%, and
166 * a is a floating point value in the range 0 to 1.
168 * Returns: %TRUE if the parsing succeeded
173 gdk_rgba_parse (GdkRGBA *rgba,
178 gchar *str = (gchar *) spec;
180 if (strncmp (str, "rgba", 4) == 0)
185 else if (strncmp (str, "rgb", 3) == 0)
193 PangoColor pango_color;
195 /* Resort on PangoColor for rgb.txt color
196 * map and '#' prefixed colors */
197 if (pango_color_parse (&pango_color, str))
201 rgba->red = pango_color.red / 65535.;
202 rgba->green = pango_color.green / 65535.;
203 rgba->blue = pango_color.blue / 65535.;
213 SKIP_WHITESPACES (str);
221 SKIP_WHITESPACES (str);
222 r = parse_rgb_value (str, &str);
223 SKIP_WHITESPACES (str);
231 SKIP_WHITESPACES (str);
232 g = parse_rgb_value (str, &str);
233 SKIP_WHITESPACES (str);
241 SKIP_WHITESPACES (str);
242 b = parse_rgb_value (str, &str);
243 SKIP_WHITESPACES (str);
252 SKIP_WHITESPACES (str);
253 a = g_ascii_strtod (str, &str);
254 SKIP_WHITESPACES (str);
262 rgba->red = CLAMP (r, 0, 1);
263 rgba->green = CLAMP (g, 0, 1);
264 rgba->blue = CLAMP (b, 0, 1);
265 rgba->alpha = CLAMP (a, 0, 1);
271 #undef SKIP_WHITESPACES
275 * @p: a #GdkRGBA pointer.
277 * A hash function suitable for using for a hash
278 * table that stores #GdkRGBA<!-- -->s.
280 * Return value: The hash function applied to @p
285 gdk_rgba_hash (gconstpointer p)
287 const GdkRGBA *rgba = p;
289 return ((guint) (rgba->red * 65535) +
290 ((guint) (rgba->green * 65535) << 11) +
291 ((guint) (rgba->blue * 65535) << 22) +
292 ((guint) (rgba->alpha * 65535) >> 6));
297 * @p1: a #GdkRGBA pointer.
298 * @p2: another #GdkRGBA pointer.
300 * Compares two RGBA colors.
302 * Return value: %TRUE if the two colors compare equal
307 gdk_rgba_equal (gconstpointer p1,
310 const GdkRGBA *rgba1, *rgba2;
315 if (rgba1->red == rgba2->red &&
316 rgba1->green == rgba2->green &&
317 rgba1->blue == rgba2->blue &&
318 rgba1->alpha == rgba2->alpha)
325 * gdk_rgba_to_string:
328 * Returns a textual specification of @rgba in the form <literal>rgb
329 * (r, g, b)</literal> or <literal>rgba (r, g, b, a)</literal>,
330 * where 'r', 'g', 'b' and 'a' represent the red, green, blue and alpha values
331 * respectively. r, g, and b are integers in the range 0 to 255, and a
332 * is a floating point value in the range 0 to 1.
334 * (These string forms are string forms those supported by the CSS3 colors module)
336 * Returns: A newly allocated text string
341 gdk_rgba_to_string (const GdkRGBA *rgba)
343 if (rgba->alpha > 0.999)
345 return g_strdup_printf ("rgb(%d,%d,%d)",
346 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
347 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
348 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.));
352 gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
354 g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
356 return g_strdup_printf ("rgba(%d,%d,%d,%s)",
357 (int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
358 (int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
359 (int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.),