Mac compilation warnings

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20895 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/image/image.cpp

@@ -36,6 +36,7 @@
 #endif
 #include "wx/rawbmp.h"
 
+#define wxHAVE_RAW_BITMAP
 
 // derived classes
 
@@ -284,7 +285,8 @@ public:
                 p.Red() = r;
                 p.Green() = g;
                 p.Blue() = b;
-                p.Alpha() = (x*255.)/REAL_SIZE;
+                p.Alpha() =
+                    (wxAlphaPixelFormat::ChannelType)((x*255.)/REAL_SIZE);
 
                 ++p; // same as p.OffsetX(1)
             }