Avoid crash when trying to access m_window from wxScreenDC.

[wxWidgets.git] / src / msw / dib.cpp

diff --git a/src/msw/dib.cpp b/src/msw/dib.cpp
index efa5b11d4ab006df47b8fc78bc9daf63e3e6abe2..0c89e7e5add0de12fe4b3f1f5993db65889dabae 100644 (file)
--- a/src/msw/dib.cpp
+++ b/src/msw/dib.cpp
@@ -36,9 +36,10 @@
     #include "wx/string.h"
     #include "wx/log.h"
     #include "wx/intl.h"
+    #include "wx/bitmap.h"
+    #include "wx/image.h"
 #endif //WX_PRECOMP
 
-#include "wx/bitmap.h"
 #include "wx/file.h"
 
 #include <stdio.h>
@@ -48,7 +49,6 @@
     #include <memory.h>
 #endif
 
-#include "wx/image.h"
 #include "wx/msw/dib.h"
 
 #ifdef __WXWINCE__
@@ -775,14 +775,26 @@ wxImage wxDIB::ConvertToImage() const
             dst[1] = *src++;
             dst[0] = *src++;
 
-            dst += 3;
-
             if ( is32bit )
             {
                 if ( alpha )
-                    *alpha++ = *src;
+                {
+                    // wxImage uses non premultiplied alpha so undo
+                    // premultiplication done in Create() above
+                    const unsigned char a = *src;
+                    *alpha++ = a;
+                    if ( a > 0 )
+                    {
+                        dst[0] = (dst[0] * 255 - 127) / a;
+                        dst[1] = (dst[1] * 255 - 127) / a;
+                        dst[2] = (dst[2] * 255 - 127) / a;
+                    }
+                }
+
                 src++;
             }
+
+            dst += 3;
         }
 
         // pass to the previous line in the image