From 45458366591a550c47e54193c8070d957fdd465b Mon Sep 17 00:00:00 2001
From: Christopher James Lahey <clahey@ximian.com>
Date: Sun, 15 Apr 2001 00:31:40 +0000
Subject: Added widget/e-hsv-utils.lo.

2001-04-14  Christopher James Lahey  <clahey@ximian.com>

	* gal/Makefile.am: Added widget/e-hsv-utils.lo.

	* gal/widgets/Makefile.am: Added e-hsv-utils.c and e-hsv-utils.h.

	* gal/widgets/e-hsv-utils.c, gal/widgets/e-hsv-utils.h: Moved from
	gal/e-table/e-table-hsv-utils.c and
	gal/e-table/e-table-hsv-utils.h.  Handle modifying hue saturation
	and value of colors.

svn path=/trunk/; revision=9317
---
 widgets/misc/e-hsv-utils.c | 166 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 widgets/misc/e-hsv-utils.c

(limited to 'widgets/misc/e-hsv-utils.c')

diff --git a/widgets/misc/e-hsv-utils.c b/widgets/misc/e-hsv-utils.c
new file mode 100644
index 0000000000..31561436dd
--- /dev/null
+++ b/widgets/misc/e-hsv-utils.c
@@ -0,0 +1,166 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+/*
+ * e-hsv-utils.c: utilites for manipulating colours in HSV space
+ *
+ * Author:
+ *   Seth Nickell <seth@eazel.com>
+ *
+ * Copyright (C) 1995-2001 Seth Nickell, Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ */
+
+#include <config.h>
+
+#include "e-hsv-utils.h"
+
+/* tweak_hsv is a really tweaky function. it modifies its first argument, which
+   should be the colour you want tweaked. delta_h, delta_s and delta_v specify
+   how much you want their respective channels modified (and in what direction).
+   if it can't do the specified modification, it does it in the oppositon direction */
+void
+e_hsv_tweak (GdkColor *colour, gdouble delta_h, gdouble delta_s, gdouble delta_v) 
+{
+	gdouble h, s, v, r, g, b;
+
+	r = colour->red   / 65535.0f;
+	g = colour->green / 65535.0f;
+	b = colour->blue  / 65535.0f;
+	
+	e_rgb_to_hsv (r, g, b, &h, &s, &v);
+	
+	if (h + delta_h < 0) {
+		h -= delta_h;
+	} else {
+		h += delta_h;
+	}
+	
+	if (s + delta_s < 0) {
+		s -= delta_s;
+	} else {
+		s += delta_s;
+	}
+
+	if (v + delta_v < 0) {
+		v -= delta_v;
+	} else {
+		v += delta_v;
+	}
+
+	e_hsv_to_rgb (h, s, v, &r, &g, &b);
+	
+	colour->red   = r * 65535.0f;
+	colour->green = g * 65535.0f;
+	colour->blue  = b * 65535.0f;
+}
+
+/* Copy n' Paste code from the GTK+ colour selector (gtkcolorsel.c) */
+/* Originally lifted, I suspect, from "Foley, van Dam"              */
+void
+e_hsv_to_rgb (gdouble  h, gdouble  s, gdouble  v,
+	      gdouble *r, gdouble *g, gdouble *b)
+{
+  gint i;
+  gdouble f, w, q, t;
+
+  if (s == 0.0)
+    s = 0.000001;
+
+  if (h == -1.0)
+    {
+      *r = v;
+      *g = v;
+      *b = v;
+    }
+  else
+    {
+      if (h == 360.0)
+	h = 0.0;
+      h = h / 60.0;
+      i = (gint) h;
+      f = h - i;
+      w = v * (1.0 - s);
+      q = v * (1.0 - (s * f));
+      t = v * (1.0 - (s * (1.0 - f)));
+
+      switch (i)
+	{
+	case 0:
+	  *r = v;
+	  *g = t;
+	  *b = w;
+	  break;
+	case 1:
+	  *r = q;
+	  *g = v;
+	  *b = w;
+	  break;
+	case 2:
+	  *r = w;
+	  *g = v;
+	  *b = t;
+	  break;
+	case 3:
+	  *r = w;
+	  *g = q;
+	  *b = v;
+	  break;
+	case 4:
+	  *r = t;
+	  *g = w;
+	  *b = v;
+	  break;
+	case 5:
+	  *r = v;
+	  *g = w;
+	  *b = q;
+	  break;
+	}
+    }
+}
+
+void
+e_rgb_to_hsv (gdouble r, gdouble g, gdouble b,
+	      gdouble *h, gdouble *s, gdouble *v)
+{
+  double max, min, delta;
+
+  max = r;
+  if (g > max)
+    max = g;
+  if (b > max)
+    max = b;
+
+  min = r;
+  if (g < min)
+    min = g;
+  if (b < min)
+    min = b;
+
+  *v = max;
+
+  if (max != 0.0)
+    *s = (max - min) / max;
+  else
+    *s = 0.0;
+
+  if (*s == 0.0)
+    *h = -1.0;
+  else
+    {
+      delta = max - min;
+
+      if (r == max)
+	*h = (g - b) / delta;
+      else if (g == max)
+	*h = 2.0 + (b - r) / delta;
+      else if (b == max)
+	*h = 4.0 + (r - g) / delta;
+
+      *h = *h * 60.0;
+
+      if (*h < 0.0)
+	*h = *h + 360;
+    }
+}
+
+
-- 
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