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List:       kde-commits
Subject:    [kdelibs/KDE/4.7] khtml/imload: Fix sign extension causing image scaling to read from wrong location
From:       Maks Orlovich <maksim () kde ! org>
Date:       2012-02-08 13:16:44
Message-ID: 20120208131644.EEA8EA60B9 () git ! kde ! org
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Git commit 6f5f6ccf12ceabc0c1fc8a780bf9a87b8b344ff5 by Maks Orlovich.
Committed on 06/02/2012 at 13:11.
Pushed by orlovich into branch 'KDE/4.7'.

Fix sign extension causing image scaling to read from wrong locations
with very high ratios.

M  +12   -6    khtml/imload/scaledimageplane.h

http://commits.kde.org/kdelibs/6f5f6ccf12ceabc0c1fc8a780bf9a87b8b344ff5

diff --git a/khtml/imload/scaledimageplane.h b/khtml/imload/scaledimageplane.h
index 953c34c..35fec21 100644
--- a/khtml/imload/scaledimageplane.h
+++ b/khtml/imload/scaledimageplane.h
@@ -24,6 +24,8 @@
 #ifndef SCALED_IMAGE_PLANE_H
 #define SCALED_IMAGE_PLANE_H
 
+#include <cassert>
+
 #include "array2d.h"
 #include "imageplane.h"
 #include "rawimageplane.h"
@@ -48,21 +50,25 @@ private:
 
         //### I bet this has all sorts of imprecision problems w/high ratios
         unsigned int* origin = new unsigned int[scaled];
-        
+
         //### FIXME: replace with something that clamps on right edge later?
         double ratio    = double(orig)/double(scaled);
-        int    intRatio = int(ratio*65536.0 + 1);
-        int    pos      = 0;
-        
+
+        // Should be assured by ImageManager::isAcceptableScaleSize
+        assert(ratio < 65536);
+
+        unsigned intRatio = unsigned(ratio*65536.0 + 1);
+        unsigned pos      = 0;
+
         for (unsigned int pix = 0; pix < scaled; pix++)
         {
             origin[pix]  =  pos >> 16;
             pos          += intRatio;
         }
-        
+
         return origin;
     }
-    
+
     unsigned int* xScaleTable;
     unsigned int* yScaleTable;
 public:
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