wxCocoa: Added wxNativePixelFormat and defined wxPIXEL_FORMAT_ALPHA

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@24715 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/rawbmp.h

@@ -154,6 +154,11 @@ typedef wxPixelFormat<unsigned char, 24, 0, 1, 2> wxImagePixelFormat;
     typedef wxPixelFormat<unsigned char, 32, 1, 2, 3> wxNativePixelFormat;
 
     #define wxPIXEL_FORMAT_ALPHA 0
+#elif defined(__WXCOCOA__)
+    // Cocoa is standard RGB or RGBA (normally it is RGBA)
+    typedef wxPixelFormat<unsigned char, 24, 0, 1, 2> wxNativePixelFormat;
+
+    #define wxPIXEL_FORMAT_ALPHA 3
 #endif
 
 // the (most common) native format for bitmaps with alpha channel