From a3b5ac6cc2dd6878a40ae7095aea232409c167be Mon Sep 17 00:00:00 2001
From: Nick Gammon <nick@gammon.com.au>
Date: Wed, 17 Feb 2010 16:53:55 +1100
Subject: [PATCH] Fixed bug in WindowBlendImage mode 4 (dissolve)

---
 miniwindow.cpp        | 32 +++++++++++++++++++++++++++++---
 scripting/methods.cpp | 10 +++++++---
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/miniwindow.cpp b/miniwindow.cpp
index bb533f78..f1f3dcac 100644
--- a/miniwindow.cpp
+++ b/miniwindow.cpp
@@ -2089,9 +2089,35 @@ long CMiniWindow::BlendImage(LPCTSTR ImageId,
     case  2: Blend_It (Blend_Average);      break;
     case  3: Blend_It (Blend_Interpolate);  break;
 
-    case  4:  // dissolve - randomly choose pixels based on opacity
-      for (i = 0; i < count; i++) 
-        pB [i] = (genrand () < Opacity) ? pA [i] : pB [i];
+     case  4:  // dissolve - randomly choose pixels based on opacity
+       {
+
+       for (row = 0; row < iHeight; row++)
+        {
+        long base = row * perline;
+        unsigned char rA, gA, bA, rB, gB, bB; 
+        for (i = 0; i < perline - 2; ) 
+          {
+          double rnd = genrand ();
+          bA = pA [base + i];     
+          gA = pA [base + i + 1]; 
+          rA = pA [base + i + 2]; 
+
+          bB = pB [base + i];  
+          gB = pB [base + i + 1];
+          rB = pB [base + i + 2];
+
+          pB [base + i] = (rnd < Opacity) ? rA : rB;;
+          i++;
+          pB [base + i] = (rnd < Opacity) ? gA : gB;
+          i++;
+          pB [base + i] = (rnd < Opacity) ? bA : bB;
+          i++;
+
+          }
+         }  // end for each row
+
+       }
       break;
 
     // darkening modes
diff --git a/scripting/methods.cpp b/scripting/methods.cpp
index 92df14de..188691ef 100644
--- a/scripting/methods.cpp
+++ b/scripting/methods.cpp
@@ -13775,9 +13775,13 @@ long r, g, b;
     case  3: Blend_It (Blend_Interpolate);  break;
 
     case  4:  // dissolve - randomly choose pixels based on opacity
-        r = (genrand () < Opacity) ? rA : rB;
-        g = (genrand () < Opacity) ? gA : gB;
-        b = (genrand () < Opacity) ? bA : bB;
+      {
+       double rnd = genrand ();
+
+        r = (rnd < Opacity) ? rA : rB;
+        g = (rnd < Opacity) ? gA : gB;
+        b = (rnd < Opacity) ? bA : bB;
+      }
       break;