[babl] Adding HSV Conversion

[Michael Murà <mmure src gnome org>]

commit 70345c0a98a8450bf9f747b4ca50218659c1a4d4
Author: Maxime Nicco <maxime nicco gmail fr>
Date:   Wed Jul 25 11:32:31 2012 +0200

    Adding HSV Conversion
    
    implement conversion between rvba and hsvba float

 extensions/Makefile.am |    2 +
 extensions/naive-HSV.c |  222 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 224 insertions(+), 0 deletions(-)
---
diff --git a/extensions/Makefile.am b/extensions/Makefile.am
index 4d2d4cb..7ed4af7 100644
--- a/extensions/Makefile.am
+++ b/extensions/Makefile.am
@@ -24,6 +24,7 @@ ext_LTLIBRARIES = \
 	float.la    \
 	fast-float.la    \
 	naive-CMYK.la   \
+	naive-HSV.la   \
 	sse-fixups.la
 
 cairo_la_SOURCES = cairo.c
@@ -33,6 +34,7 @@ gggl_lies_la_SOURCES = gggl-lies.c
 gggl_la_SOURCES = gggl.c
 gimp_8bit_la_SOURCES = gimp-8bit.c
 naive_CMYK_la_SOURCES = naive-CMYK.c
+naive_HSV_la_SOURCES = naive-HSV.c
 sse_fixups_la_SOURCES = sse-fixups.c
 float_la_SOURCES = float.c
 fast_float_la_SOURCES = fast-float.c
diff --git a/extensions/naive-HSV.c b/extensions/naive-HSV.c
new file mode 100644
index 0000000..d200de1
--- /dev/null
+++ b/extensions/naive-HSV.c
@@ -0,0 +1,222 @@
+/* babl - dynamically extendable universal pixel conversion library.
+ * Copyright (C) 2005, Ãyvind KolÃs.
+ *
+ * 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 3 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, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+ /*
+ * Adding support for HSV colorspace
+ *
+ * Maxime Nicco <maxime nicco gmail fr>
+ */
+
+#include "config.h"
+#include <math.h>
+#include <string.h>
+
+#include "babl.h"
+
+#define MIN(a,b) (a > b) ? b : a;
+#define MAX(a,b) (a < b) ? b : a;
+
+static long  rgba_to_hsva (char *src,
+                           char *dst,
+                           long  n);
+
+static long  hsva_to_rgba (char *src,
+                           char *dst,
+                           long  n);
+
+int init (void);
+
+int
+init (void)
+{
+  babl_component_new ("hue", NULL);
+  babl_component_new ("saturation", NULL);
+  babl_component_new ("value", NULL);
+  babl_component_new ("alpha", NULL);
+
+  babl_model_new (
+    "name", "HSVA",
+    babl_component ("hue"),
+    babl_component ("saturation"),
+    babl_component ("value"),
+    babl_component ("alpha"),
+    NULL
+  );
+
+  babl_conversion_new (
+    babl_model ("RGBA"),
+    babl_model ("HSVA"),
+    "linear", rgba_to_hsva,
+    NULL
+  );
+
+  babl_conversion_new (
+    babl_model ("HSVA"),
+    babl_model ("RGBA"),
+    "linear", hsva_to_rgba,
+    NULL
+  );
+  babl_format_new (
+    "name", "HSVA float",
+    babl_model ("HSVA"),
+    babl_type ("float"),
+    babl_component ("hue"),
+    babl_component ("saturation"),
+    babl_component ("value"),
+    babl_component ("alpha"),
+    NULL
+  );
+
+  return 0;
+}
+
+
+static long
+rgba_to_hsva (char *src,
+              char *dst,
+              long  n)
+{
+  while (n--)
+  {
+    double red   = ((double *) src)[0];
+    double green = ((double *) src)[1];
+    double blue  = ((double *) src)[2];
+    double alpha = ((double *) src)[3];
+
+    double hue, saturation, value;
+
+    double  min;
+    double  chroma;
+
+     if (red > green)
+    {
+      value = MAX (red, blue);
+      min = MIN (green, blue);
+    }
+    else
+    {
+      value = MAX (green, blue);
+      min = MIN (red, blue);
+    }
+
+    chroma = value - min;
+
+    if (value == 0.0)
+      saturation = 0.0;
+    else
+      saturation = chroma / value;
+
+    if (saturation == 0.0)
+    {
+      hue = 0.0;
+    }
+    else
+    {
+      if (red == value)
+      {
+        hue = (green - blue) / chroma;
+        
+        if(hue < 0.0)
+          hue += 6.0;
+      }
+      else if (green == value)
+        hue = 2.0 + (blue - red) / chroma;
+      else
+        hue = 4.0 + (red - green) / chroma;
+
+      hue *= 60.0;
+    }
+
+    ((double *) dst)[0] = hue;
+    ((double *) dst)[1] = saturation;
+    ((double *) dst)[2] = value;
+    ((double *) dst)[3] = alpha;
+
+    src += 4 * sizeof (double);
+    dst += 4 * sizeof (double);
+  }
+  return n;
+}
+
+static long
+hsva_to_rgba (char *src,
+              char *dst,
+              long  n)
+{
+  while (n--)
+  {
+    double hue        = ((double *) src)[0];
+    double saturation = ((double *) src)[1];
+    double value      = ((double *) src)[2];
+    double alpha      = ((double *) src)[3];
+
+    double red = 0, green = 0, blue = 0;
+
+    double chroma, h_tmp, x, min;
+
+    chroma = saturation * value;
+    h_tmp = hue / 60.0;
+    x = chroma * (1.0 - fabs(fmod(h_tmp, 2.0) - 1.0));
+
+    if (h_tmp < 1.0)
+    {
+      red   = chroma;
+      green = x;
+    }
+    else if (h_tmp < 2.0)
+    {
+      red   = x;
+      green = chroma;
+    }
+    else if (h_tmp < 3.0)
+    {
+      green = chroma;
+      blue  = x;
+    }
+    else if (h_tmp < 4.0)
+    {
+      green = x;
+      blue  = chroma;
+    }
+    else if (h_tmp < 5.0)
+    {
+      red  = x;
+      blue = chroma;
+    }
+    else if (h_tmp < 6.0)
+    {
+      red  = chroma;
+      blue = x;
+    }
+
+    min = value-chroma;
+
+    red += min;
+    green += min;
+    blue += min;
+
+    ((double *) dst)[0] = red;
+    ((double *) dst)[1] = green;
+    ((double *) dst)[2] = blue;
+    ((double *) dst)[3] = alpha;
+
+    src += 4 * sizeof (double);
+    dst += 4 * sizeof (double);
+  }
+  return n;
+}