gtk2/gdk/gdkrgba.c
Owen W. Taylor d2b64a1db2 Switch to CSS interpretation of rgb() and rgba() colors
CSS3 defines a somewhat odd syntax for rgba() colors - the rgb values
are integers from 0 to 255 or percentages and the a value is a
float from 0 to 1. To avoid increasing the total amount of confusion
in the world, make gdk_rgb_to_string() and gdk_rgb_parse() follow
this syntax rather than using floats for r, g, and b.

https://bugzilla.gnome.org/show_bug.cgi?id=633762
2010-11-05 22:19:50 +09:00

331 lines
7.7 KiB
C

/* GDK - The GIMP Drawing Kit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
#include "config.h"
#include "gdkrgba.h"
#include <string.h>
/**
* SECTION:rgba_colors
* @Short_description: RGBA colors
* @Title: RGBA Colors
*/
G_DEFINE_BOXED_TYPE (GdkRGBA, gdk_rgba,
gdk_rgba_copy, gdk_rgba_free)
/**
* gdk_rgba_copy:
* @rgba: a #GdkRGBA
*
* Makes a copy of a #GdkRGBA structure, the result must be freed
* through gdk_rgba_free().
*
* Returns: A newly allocated #GdkRGBA
**/
GdkRGBA *
gdk_rgba_copy (GdkRGBA *rgba)
{
GdkRGBA *copy;
copy = g_slice_new (GdkRGBA);
copy->red = rgba->red;
copy->green = rgba->green;
copy->blue = rgba->blue;
copy->alpha = rgba->alpha;
return copy;
}
/**
* gdk_rgba_free:
* @rgba: a #GdkRGBA
*
* Frees a #GdkRGBA struct created with gdk_rgba_copy()
**/
void
gdk_rgba_free (GdkRGBA *rgba)
{
g_slice_free (GdkRGBA, rgba);
}
#define SKIP_WHITESPACES(s) while (*(s) == ' ') (s)++;
/* Parses a single color component from a rgb() or rgba() specification
* according to CSS3 rules. Compared to exact CSS3 parsing we are liberal
* in what we accept as follows:
*
* - For non-percentage values, we accept floats in the range 0-255
* not just [0-9]+ integers
* - For percentage values we accept any float, not just
* [ 0-9]+ | [0-9]* '.' [0-9]+
* - We accept mixed percentages and non-percentages in a single
* rgb() or rgba() specification.
*/
static double
parse_rgb_value (const char *str,
char **endp)
{
double number;
const char *p;
number = g_ascii_strtod (str, endp);
p = *endp;
SKIP_WHITESPACES (p);
if (*p == '%')
{
*endp = (char *)(p + 1);
return CLAMP(number / 100., 0., 1.);
}
else
{
return CLAMP(number / 255., 0., 1.);
}
}
/**
* gdk_rgba_parse:
* @spec: the string specifying the color
* @rgba: the #GdkRGBA struct to fill in
*
* Parses a textual representation of a color, filling in
* the <structfield>red</structfield>, <structfield>green</structfield>,
* <structfield>blue</structfield> and <structfield>alpha</structfield>
* fields of the @rgba struct.
*
* The string can be either one of:
* <itemizedlist>
* <listitem>
* A standard name (Taken from the X11 rgb.txt file).
* </listitem>
* <listitem>
* A hex value in the form '#rgb' '#rrggbb' '#rrrgggbbb' or '#rrrrggggbbbb'
* </listitem>
* <listitem>
* A RGB color in the form 'rgb(r,g,b)' (In this case the color will
* have full opacity)
* </listitem>
* <listitem>
* A RGBA color in the form 'rgba(r,g,b,a)'
* </listitem>
* </itemizedlist>
*
* Where 'r', 'g', 'b' and 'a' are respectively the red, green, blue and
* alpha color values. In the last two cases, r g and b are either integers
* in the range 0 to 255 or precentage values in the range 0% to 100%, and
* a is a floating point value in the range 0 to 1.
*
* Returns: %TRUE if the parsing succeeded
**/
gboolean
gdk_rgba_parse (const gchar *spec,
GdkRGBA *rgba)
{
gboolean has_alpha;
gdouble r, g, b, a;
gchar *str = (gchar *) spec;
if (strncmp (str, "rgba", 4) == 0)
{
has_alpha = TRUE;
str += 4;
}
else if (strncmp (str, "rgb", 3) == 0)
{
has_alpha = FALSE;
a = 1;
str += 3;
}
else
{
PangoColor pango_color;
/* Resort on PangoColor for rgb.txt color
* map and '#' prefixed colors */
if (pango_color_parse (&pango_color, str))
{
if (rgba)
{
rgba->red = pango_color.red / 65535.;
rgba->green = pango_color.green / 65535.;
rgba->blue = pango_color.blue / 65535.;
rgba->alpha = 1;
}
return TRUE;
}
else
return FALSE;
}
SKIP_WHITESPACES (str);
if (*str != '(')
return FALSE;
str++;
/* Parse red */
SKIP_WHITESPACES (str);
r = parse_rgb_value (str, &str);
SKIP_WHITESPACES (str);
if (*str != ',')
return FALSE;
str++;
/* Parse green */
SKIP_WHITESPACES (str);
g = parse_rgb_value (str, &str);
SKIP_WHITESPACES (str);
if (*str != ',')
return FALSE;
str++;
/* Parse blue */
SKIP_WHITESPACES (str);
b = parse_rgb_value (str, &str);
SKIP_WHITESPACES (str);
if (has_alpha)
{
if (*str != ',')
return FALSE;
str++;
SKIP_WHITESPACES (str);
a = g_ascii_strtod (str, &str);
SKIP_WHITESPACES (str);
}
if (*str != ')')
return FALSE;
if (rgba)
{
rgba->red = CLAMP (r, 0, 1);
rgba->green = CLAMP (g, 0, 1);
rgba->blue = CLAMP (b, 0, 1);
rgba->alpha = CLAMP (a, 0, 1);
}
return TRUE;
}
#undef SKIP_WHITESPACES
/**
* gdk_rgba_hash:
* @p: a #GdkRGBA pointer.
*
* A hash function suitable for using for a hash
* table that stores #GdkRGBA<!-- -->s.
*
* Return value: The hash function applied to @p
**/
guint
gdk_rgba_hash (gconstpointer p)
{
const GdkRGBA *rgba = p;
return ((guint) (rgba->red * 65535) +
((guint) (rgba->green * 65535) << 11) +
((guint) (rgba->blue * 65535) << 22) +
((guint) (rgba->alpha * 65535) >> 6));
}
/**
* gdk_rgba_equal:
* @p1: a #GdkRGBA pointer.
* @p2: another #GdkRGBA pointer.
*
* Compares two RGBA colors.
*
* Return value: %TRUE if the two colors compare equal
**/
gboolean
gdk_rgba_equal (gconstpointer p1,
gconstpointer p2)
{
const GdkRGBA *rgba1, *rgba2;
rgba1 = p1;
rgba2 = p2;
if (rgba1->red == rgba2->red &&
rgba1->green == rgba2->green &&
rgba1->blue == rgba2->blue &&
rgba1->alpha == rgba2->alpha)
return TRUE;
return FALSE;
}
/**
* gdk_rgba_to_string:
* @rgba: a #GdkRGBA
*
* Returns a textual specification of @rgba in the form <literal>rgb
* (r, g, b)</literal> or <literal>rgba (r, g, b, a)</literal>,
* where 'r', 'g', 'b' and 'a' represent the red, green, blue and alpha values
* respectively. r, g, and b are integers in the range 0 to 255, and a
* is a floating point value in the range 0 to 1.
*
* (These string forms are string forms those supported by the CSS3 colors module)
*
* Returns: A newly allocated text string
**/
gchar *
gdk_rgba_to_string (const GdkRGBA *rgba)
{
if (rgba->alpha > 0.999)
{
return g_strdup_printf ("rgb(%d,%d,%d)",
(int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
(int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
(int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.));
}
else
{
gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
return g_strdup_printf ("rgba(%d,%d,%d,%s)",
(int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
(int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
(int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.),
alpha);
}
}