Value mode

diff --git a/io-xcf.c b/io-xcf.c
index 3dd4f12..8b364c1 100644 (file)
--- a/io-xcf.c
+++ b/io-xcf.c
@@ -429,6 +429,34 @@ saturation (guchar *rgb0, guchar *rgb1)
        
 }
 
+void
+value (guchar *rgb0, guchar *rgb1)
+{
+       //hue and saturation ov rgb0, value of rgb1
+       guchar min0 = MIN (MIN (rgb0[0], rgb0[1]), rgb0[2]);
+       guchar max0 = MAX (MAX (rgb0[0], rgb0[1]), rgb0[2]);
+       guchar min1 = MIN (MIN (rgb1[0], rgb1[1]), rgb1[2]);
+       guchar max1 = MAX (MAX (rgb1[0], rgb1[1]), rgb1[2]);
+       if (max0 == 0) {
+               rgb1[0] = 0x00;
+               rgb1[1] = 0x00;
+               rgb1[2] = 0x00;
+               return;
+       }
+       if (max0 == min0) {
+               rgb1[0] = max1;
+               rgb1[1] = max1;
+               rgb1[2] = max1;
+               return;
+       }
+
+       double p = max1 / max0;
+
+       rgb1[0] = (guchar)(rgb0[0] * p);
+       rgb1[1] = (guchar)(rgb0[1] * p);
+       rgb1[2] = (guchar)(rgb0[2] * p);
+}
+
 void
 composite (gchar *pixbuf_pixels, int rowstride, gchar *tile_pixels, int ox, int oy, int tw, int th, guint32 layer_mode)
 {
@@ -644,8 +672,18 @@ composite (gchar *pixbuf_pixels, int rowstride, gchar *tile_pixels, int ox, int
                                blend (dest, src);
                        }
                break;
-       case LAYERMODE_COLOR:
        case LAYERMODE_VALUE:
+               f = value;
+               for (j=0;j<th;j++)
+                       for (i=0;i<tw;i++) {
+                               guchar *dest = pixbuf_pixels + origin + j * rowstride + 4 * i;
+                               guchar *src = tile_pixels + j*tw*4 + i*4;
+                               f (dest, src);
+                               src[3] = MIN (dest[3], src[3]);
+                               blend (dest, src);
+                       }
+               break;
+       case LAYERMODE_COLOR:
        
        default:        //Pack layer on top of each other, without any blending at all
                for (j=0; j<th;j++) {