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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
This commit is contained in:
Owen W. Taylor
parent
fbdcf193ae
commit
5daab52661
@ -72,6 +72,43 @@ gdk_rgba_free (GdkRGBA *rgba)
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g_slice_free (GdkRGBA, rgba);
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}
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#define SKIP_WHITESPACES(s) while (*(s) == ' ') (s)++;
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/* Parses a single color component from a rgb() or rgba() specification
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* according to CSS3 rules. Compared to exact CSS3 parsing we are liberal
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* in what we accept as follows:
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*
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* - For non-percentage values, we accept floats in the range 0-255
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* not just [0-9]+ integers
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* - For percentage values we accept any float, not just
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* [ 0-9]+ | [0-9]* '.' [0-9]+
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* - We accept mixed percentages and non-percentages in a single
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* rgb() or rgba() specification.
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*/
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static double
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parse_rgb_value (const char *str,
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char **endp)
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{
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double number;
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const char *p;
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number = g_ascii_strtod (str, endp);
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p = *endp;
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SKIP_WHITESPACES (p);
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if (*p == '%')
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{
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*endp = (char *)(p + 1);
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return CLAMP(number / 100., 0., 1.);
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}
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else
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{
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return CLAMP(number / 255., 0., 1.);
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}
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}
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/**
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* gdk_rgba_parse:
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* @spec: the string specifying the color
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@ -100,8 +137,9 @@ gdk_rgba_free (GdkRGBA *rgba)
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* </itemizedlist>
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*
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* Where 'r', 'g', 'b' and 'a' are respectively the red, green, blue and
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* alpha color values, parsed in the last 2 cases as double numbers in
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* the range [0..1], any other value out of that range will be clamped.
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* alpha color values. In the last two cases, r g and b are either integers
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* in the range 0 to 255 or precentage values in the range 0% to 100%, and
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* a is a floating point value in the range 0 to 1.
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*
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* Returns: %TRUE if the parsing succeeded
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**/
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@ -113,8 +151,6 @@ gdk_rgba_parse (const gchar *spec,
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gdouble r, g, b, a;
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gchar *str = (gchar *) spec;
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#define SKIP_WHITESPACES(s) while (*(s) == ' ') (s)++;
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if (strncmp (str, "rgba", 4) == 0)
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{
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has_alpha = TRUE;
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@ -157,7 +193,7 @@ gdk_rgba_parse (const gchar *spec,
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/* Parse red */
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SKIP_WHITESPACES (str);
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r = g_ascii_strtod (str, &str);
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r = parse_rgb_value (str, &str);
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SKIP_WHITESPACES (str);
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if (*str != ',')
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@ -167,7 +203,7 @@ gdk_rgba_parse (const gchar *spec,
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/* Parse green */
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SKIP_WHITESPACES (str);
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g = g_ascii_strtod (str, &str);
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g = parse_rgb_value (str, &str);
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SKIP_WHITESPACES (str);
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if (*str != ',')
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@ -177,7 +213,7 @@ gdk_rgba_parse (const gchar *spec,
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/* Parse blue */
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SKIP_WHITESPACES (str);
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b = g_ascii_strtod (str, &str);
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b = parse_rgb_value (str, &str);
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SKIP_WHITESPACES (str);
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if (has_alpha)
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@ -195,8 +231,6 @@ gdk_rgba_parse (const gchar *spec,
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if (*str != ')')
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return FALSE;
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#undef SKIP_WHITESPACES
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if (rgba)
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{
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rgba->red = CLAMP (r, 0, 1);
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@ -208,6 +242,8 @@ gdk_rgba_parse (const gchar *spec,
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return TRUE;
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}
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#undef SKIP_WHITESPACES
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/**
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* gdk_rgba_hash:
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* @p: a #GdkRGBA pointer.
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@ -259,25 +295,36 @@ gdk_rgba_equal (gconstpointer p1,
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* gdk_rgba_to_string:
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* @rgba: a #GdkRGBA
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*
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* Returns a textual specification of @rgba in the form
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* <literal>rgba (r, g, b, a)</literal>, where 'r', 'g',
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* 'b' and 'a' represent the red, green, blue and alpha
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* values respectively.
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* Returns a textual specification of @rgba in the form <literal>rgb
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* (r, g, b)</literal> or <literal>rgba (r, g, b, a)</literal>,
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* where 'r', 'g', 'b' and 'a' represent the red, green, blue and alpha values
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* respectively. r, g, and b are integers in the range 0 to 255, and a
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* is a floating point value in the range 0 to 1.
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*
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* (These string forms are string forms those supported by the CSS3 colors module)
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*
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* Returns: A newly allocated text string
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**/
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gchar *
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gdk_rgba_to_string (const GdkRGBA *rgba)
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{
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gchar red[G_ASCII_DTOSTR_BUF_SIZE];
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gchar green[G_ASCII_DTOSTR_BUF_SIZE];
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gchar blue[G_ASCII_DTOSTR_BUF_SIZE];
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gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
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if (rgba->alpha > 0.999)
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{
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return g_strdup_printf ("rgb(%d,%d,%d)",
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(int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
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(int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
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(int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.));
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}
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else
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{
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gchar alpha[G_ASCII_DTOSTR_BUF_SIZE];
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g_ascii_dtostr (red, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->red, 0, 1));
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g_ascii_dtostr (green, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->green, 0, 1));
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g_ascii_dtostr (blue, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->blue, 0, 1));
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g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
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g_ascii_dtostr (alpha, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (rgba->alpha, 0, 1));
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return g_strdup_printf ("rgba(%s,%s,%s,%s)", red, green, blue, alpha);
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return g_strdup_printf ("rgba(%d,%d,%d,%s)",
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(int)(0.5 + CLAMP (rgba->red, 0., 1.) * 255.),
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(int)(0.5 + CLAMP (rgba->green, 0., 1.) * 255.),
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(int)(0.5 + CLAMP (rgba->blue, 0., 1.) * 255.),
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alpha);
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}
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}
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@ -14,23 +14,23 @@ test_color_parse (void)
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res = gdk_rgba_parse ("", &color);
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g_assert (!res);
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expected.red = 100/255.;
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expected.green = 90/255.;
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expected.blue = 80/255.;
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expected.alpha = 0.1;
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res = gdk_rgba_parse ("rgba(100,90,80,0.1)", &color);
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g_assert (res);
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g_assert (gdk_rgba_equal (&color, &expected));
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expected.red = 0.4;
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expected.green = 0.3;
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expected.blue = 0.2;
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expected.alpha = 0.1;
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res = gdk_rgba_parse ("rgba(0.4,0.3,0.2,0.1)", &color);
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res = gdk_rgba_parse ("rgba(40%,30%,20%,0.1)", &color);
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g_assert (res);
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g_assert (gdk_rgba_equal (&color, &expected));
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res = gdk_rgba_parse ("rgba ( 0.4 , 0.3 , 0.2 , 0.1 )", &color);
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g_assert (res);
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g_assert (gdk_rgba_equal (&color, &expected));
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expected.red = 0.4;
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expected.green = 0.3;
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expected.blue = 0.2;
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expected.alpha = 1.0;
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res = gdk_rgba_parse ("rgb(0.4,0.3,0.2)", &color);
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res = gdk_rgba_parse ("rgba( 40 % , 30 % , 20 % , 0.1 )", &color);
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g_assert (res);
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g_assert (gdk_rgba_equal (&color, &expected));
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@ -61,10 +61,13 @@ test_color_to_string (void)
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gchar *res_en;
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gchar *orig;
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/* Using /255. values for the r, g, b components should
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* make sure they round-trip exactly without rounding
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* from the double => integer => double conversions */
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rgba.red = 1.0;
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rgba.green = 0.5;
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rgba.blue = 0.1;
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rgba.alpha = 1.0;
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rgba.green = 128/255.;
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rgba.blue = 64/255.;
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rgba.alpha = 0.5;
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orig = g_strdup (setlocale (LC_ALL, NULL));
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res = gdk_rgba_to_string (&rgba);
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