RGB <-> HSV colorspace conversion lib

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10253 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 165 insertions, 0 deletions

diff --git a/apps/plugins/lib/SOURCES b/apps/plugins/lib/SOURCES
index 81cdc8c..f0e9ebc 100644
--- a/apps/plugins/lib/SOURCES
+++ b/apps/plugins/lib/SOURCES
@@ -1,5 +1,6 @@
 configfile.c
 playback_control.c
+rgb_hsv.c
 #if defined(HAVE_LCD_BITMAP) && (LCD_DEPTH < 4) && (CONFIG_LCD != LCD_IPOD2BPP)
 gray_core.c
 gray_draw.c
diff --git a/apps/plugins/lib/rgb_hsv.c b/apps/plugins/lib/rgb_hsv.c
new file mode 100644
index 0000000..0d424b9
--- /dev/null
+++ b/apps/plugins/lib/rgb_hsv.c
@@ -0,0 +1,129 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 Antoine Cellerier <dionoea -at- videolan -dot- org>
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "rgb_hsv.h"
+
+/***********************************************************************
+ * Colorspace transformations
+ ***********************************************************************
+ * r, g and b range from 0 to 255
+ * h ranges from 0 to 3599 (which in fact means 0.0 to 359.9).
+ *   360 is the same as 0 (it loops)
+ * s and v range from 0 to 255 (which in fact means 0.00 to 1.00)
+ ***********************************************************************/
+
+void rgb2hsv( int r, int g, int b, int *h, int *s, int *v )
+{
+    int max;
+    int min;
+
+    max = r > g ? r : g;
+    if( b > max ) max = b;
+
+    min = r < g ? r : g;
+    if( b < min ) min = b;
+
+    if( max == 0 )
+    {
+        *v = 0;
+        *h = 0; *s = 0; /* Random since it's black */
+        return;
+    }
+    else if( max == min )
+    {
+        *h = 0; /* Random since it's gray */
+    }
+    else if( max == r && g >= b )
+    {
+        *h = ( 10 * 60 * ( g - b )/( max - min ) );
+    }
+    else if( max == r && g < b )
+    {
+        *h = ( 10 * ( 60 * ( g - b )/( max - min ) + 360 ));
+    }
+    else if( max == g )
+    {
+        *h = ( 10 * ( 60 * ( b - r )/( max - min ) + 120 ));
+    }
+    else// if( max == b )
+    {
+        *h = ( 10 * ( 60 * ( r - g )/( max - min ) + 240 ));
+    }
+
+    /* Just in case ? */
+    while( *h < 0 ) *h += 3600;
+    while( *h >= 3600 ) *h-= 3600;
+
+    *s = (( max - min )*255)/max;
+    *v = max;
+}
+
+void hsv2rgb( int h, int s, int v, int *r, int *g, int *b )
+{
+    int f, p, q, t;
+    while( h < 0 ) h += 3600;
+    while( h >= 3600 ) h-= 3600;
+    f = h%600;
+    p = ( v * ( 255 - s ) ) / ( 255 );
+    q = ( v * ( 600*255 - f*s ) ) / ( 255 * 600 );
+    t = ( v * ( 600*255 - ( 600 - f ) * s ) ) / ( 255 * 600 );
+
+
+    if( s == 0 ) /* gray */
+    {
+        *r = v;
+        *g = *r;
+        *b = *r;
+        return;
+    }
+
+    switch( h/600 )
+    {
+        case 0:
+            *r = v;
+            *g = t;
+            *b = p;
+            break;
+        case 1:
+            *r = q;
+            *g = v;
+            *b = p;
+            break;
+        case 2:
+            *r = p;
+            *g = v;
+            *b = t;
+            break;
+        case 3:
+            *r = p;
+            *g = q;
+            *b = v;
+            break;
+        case 4:
+            *r = t;
+            *g = p;
+            *b = v;
+            break;
+        case 5:
+            *r = v;
+            *g = p;
+            *b = q;
+            break;
+    }
+}
diff --git a/apps/plugins/lib/rgb_hsv.h b/apps/plugins/lib/rgb_hsv.h
new file mode 100644
index 0000000..30bb206
--- /dev/null
+++ b/apps/plugins/lib/rgb_hsv.h
@@ -0,0 +1,35 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 Antoine Cellerier <dionoea -at- videolan -dot- org>
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#ifndef LIB_HSV_RGB_H
+#define LIB_HSV_RGB_H
+
+/***********************************************************************
+ * Colorspace transformations
+ ***********************************************************************
+ * r, g and b range from 0 to 255
+ * h ranges from 0 to 3599 (which in fact means 0.0 to 359.9).
+ *   360 is the same as 0 (it loops)
+ * s and v range from 0 to 255 (which in fact means 0.00 to 1.00)
+ ***********************************************************************/
+
+void rgb2hsv( int r, int g, int b, int *h, int *s, int *v );
+void hsv2rgb( int h, int s, int v, int *r, int *g, int *b );
+
+#endif