[goffice] GOFormat: new functions to access colour palette.

[Morten Welinder <mortenw src gnome org>]

commit 3ac7797d1764acf1f38ff2bbbf709890f18be247
Author: Morten Welinder <terra gnome org>
Date:   Sun Mar 30 09:24:20 2014 -0400

    GOFormat: new functions to access colour palette.

 goffice/utils/go-format.c |   73 +++++++++++++++++++++++++++++++++++++++-----
 goffice/utils/go-format.h |    6 ++++
 2 files changed, 70 insertions(+), 9 deletions(-)
---
diff --git a/goffice/utils/go-format.c b/goffice/utils/go-format.c
index e97535d..5d6fa56 100644
--- a/goffice/utils/go-format.c
+++ b/goffice/utils/go-format.c
@@ -714,15 +714,15 @@ go_format_foreach (GHFunc func, gpointer user_data)
 static struct {
        char const *name;
        GOColor go_color;
-} const format_colors[] = {
-       { N_("Black"),   GO_COLOR_BLACK },
-       { N_("Blue"),    GO_COLOR_BLUE },
-       { N_("Cyan"),    GO_COLOR_CYAN },
-       { N_("Green"),   GO_COLOR_GREEN },
-       { N_("Magenta"), GO_COLOR_VIOLET },
-       { N_("Red"),     GO_COLOR_RED },
-       { N_("White"),   GO_COLOR_WHITE },
-       { N_("Yellow"),  GO_COLOR_YELLOW }
+} const format_colors[8] = {
+       { N_("Black"),   GO_COLOR_BLACK },   /* Color 1 */
+       { N_("White"),   GO_COLOR_WHITE },   /* Color 2 */
+       { N_("Red"),     GO_COLOR_RED },     /* Color 3 */
+       { N_("Green"),   GO_COLOR_GREEN },   /* Color 4 */
+       { N_("Blue"),    GO_COLOR_BLUE },    /* Color 5 */
+       { N_("Yellow"),  GO_COLOR_YELLOW },  /* Color 6 */
+       { N_("Magenta"), GO_COLOR_VIOLET },  /* Color 7 */
+       { N_("Cyan"),    GO_COLOR_CYAN }    /* Color 8 */
 };
 
 static const GOColor
@@ -786,6 +786,61 @@ format_numbered_colors[56 + 1] = {
        GO_COLOR_FROM_RGB (0x33, 0x33, 0x33)
 };
 
+GOColor
+go_format_palette_color_of_index (int i)
+{
+       g_return_val_if_fail (i >= 1, 0);
+
+       return (i < (int)G_N_ELEMENTS (format_numbered_colors))
+               ? format_numbered_colors[i]
+               : 0;
+}
+
+char *
+go_format_palette_name_of_index (int i)
+{
+       g_return_val_if_fail (i >= 1, NULL);
+       g_return_val_if_fail (i < (int)G_N_ELEMENTS (format_numbered_colors), NULL);
+
+       if (i <= 8)
+               return g_strdup (format_colors[i - 1].name);
+       else
+               return g_strdup_printf ("Color%d", i);
+}
+
+
+static int
+color_dist (GOColor c1, GOColor c2)
+{
+       /* Simple 2-norm in rgb space. */
+       int dr = (int)GO_COLOR_UINT_R(c1) - (int)GO_COLOR_UINT_R(c2);
+       int dg = (int)GO_COLOR_UINT_G(c1) - (int)GO_COLOR_UINT_G(c2);
+       int db = (int)GO_COLOR_UINT_B(c1) - (int)GO_COLOR_UINT_B(c2);
+
+       return dr * dr + dg * dg + db * db;
+}
+
+int
+go_format_palette_index_from_color (GOColor c, gboolean *exact)
+{
+       int mindist = G_MAXINT;
+       unsigned ui;
+       int res = -1;
+
+       for (ui = 1; ui < G_N_ELEMENTS (format_numbered_colors); ui++) {
+               GOColor c2 = format_numbered_colors[ui];
+               int d = color_dist (c, c2);
+               if (d < mindist) {
+                       mindist = d;
+                       res = ui;
+               }
+       }
+
+       if (exact)
+               *exact = (mindist == 0);
+
+       return res;
+}
 
 /*
  * go_format_parse_color :
diff --git a/goffice/utils/go-format.h b/goffice/utils/go-format.h
index 61b9751..5eec5e0 100644
--- a/goffice/utils/go-format.h
+++ b/goffice/utils/go-format.h
@@ -279,6 +279,12 @@ GOFormatCurrency const *go_format_locale_currency (void);
 
 /*************************************************************************/
 
+GOColor go_format_palette_color_of_index (int i);
+int go_format_palette_index_from_color (GOColor c, gboolean *exact);
+char *go_format_palette_name_of_index (int i);
+
+/*************************************************************************/
+
 void _go_number_format_init (void);
 void _go_number_format_shutdown (void);
 void _go_currency_date_format_init     (void);