From e43825e73848079880f1b7ac250bb7dc96dff1f7 Mon Sep 17 00:00:00 2001
From: Stephane Delcroix <stephane@delcroix.org>
Date: Mon, 16 Mar 2009 13:02:03 +0100
Subject: [PATCH] implement softlight as gimp does and not as the docs state.
 Fix test02 for good

---
 io-xcf.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/io-xcf.c b/io-xcf.c
index 1a91e56..68ea51c 100644
--- a/io-xcf.c
+++ b/io-xcf.c
@@ -323,6 +323,7 @@ screen (guchar *rgb0, guchar *rgb1)
 void
 overlay (guchar *rgb0, guchar *rgb1)
 {
+	//FIXME
 	//LOG ("Overlay (%d %d %d) (%d %d %d) : ", rgb0[0], rgb0[1], rgb0[2], rgb1[0], rgb1[1], rgb1[2]);
 	rgb1[0] = MIN (0xff, ((0xff - rgb1[0]) * rgb0[0] * rgb0[0] / 0xff + rgb0[0] * (0xff - (0xff - rgb1[0]) * (0xff - rgb1[0]) / 0xff)) / 0xff);
 	rgb1[1] = MIN (0xff, ((0xff - rgb1[1]) * rgb0[1] * rgb0[1] / 0xff + rgb0[1] * (0xff - (0xff - rgb1[1]) * (0xff - rgb1[1]) / 0xff)) / 0xff);
@@ -404,6 +405,17 @@ hardlight (guchar *rgb0, guchar *rgb1) //if x2 < 0.5 then 2*x1*x2 else 1-2*(1-x1
 	rgb1[2] = rgb1[2] < 0x80 ? 2 * rgb0[2] * rgb1[2] / 0xff : 0xff - 2 * (0xff - rgb0[2]) * (0xff - rgb1[2])/ 0xff;
 }
 
+void
+softlight(guchar *rgb0, guchar *rgb1)
+{
+	//FIXME
+	//LOG ("Softlight (%d %d %d) (%d %d %d) : ", rgb0[0], rgb0[1], rgb0[2], rgb1[0], rgb1[1], rgb1[2]);
+	rgb1[0] = ((0xff - rgb0[0]) * rgb0[0] * rgb1[0] / 0xff + rgb0[0] * (0xff - (0xff - rgb1[0]) * (0xff - rgb0[0]) / 0x100)) / 0x100;
+	rgb1[1] = ((0xff - rgb0[1]) * rgb0[1] * rgb1[1] / 0xff + rgb0[1] * (0xff - (0xff - rgb1[1]) * (0xff - rgb0[1]) / 0x100)) / 0x100;
+	rgb1[2] = ((0xff - rgb0[2]) * rgb0[2] * rgb1[2] / 0xff + rgb0[2] * (0xff - (0xff - rgb1[2]) * (0xff - rgb0[2]) / 0x100)) / 0x100;
+	//LOG ("(%d %d %d)\n", rgb1[0], rgb1[1], rgb1[2]);	
+}
+
 void
 grainextract (guchar *rgb0, guchar *rgb1) //x1-x2+.5
 {
@@ -583,7 +595,6 @@ composite (gchar *pixbuf_pixels, int rowstride, gchar *tile_pixels, int ox, int
 			}
 		break;
 	case LAYERMODE_OVERLAY:
-	case LAYERMODE_SOFTLIGHT:
 		f = overlay;
 		for (j=0;j<th;j++)
 			for (i=0;i<tw;i++) {
@@ -594,6 +605,17 @@ composite (gchar *pixbuf_pixels, int rowstride, gchar *tile_pixels, int ox, int
 				blend (dest, src);
 			}
 		break;
+	case LAYERMODE_SOFTLIGHT:
+		f = softlight;
+		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_DIFFERENCE:
 		f = difference;
 		for (j=0;j<th;j++)
-- 
2.20.1