Add wxBitmap::NewFromPNGData() for creating bitmaps from PNG data.

This simple function can be used to create a wxBitmap from the raw image data
in PNG format. It is just a thin wrapper around wxImage load functions under
almost all platforms but has two advantages:

1. It can be implemented natively for some platforms (currently only OS X).
2. It can be used in a single expression as it doesn't require creating a
   temporary wxMemoryInputStream and this will be required by wxBITMAP_PNG()
   macro that will be added soon.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72476 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/core/bitmap.cpp

@@ -1736,6 +1736,18 @@ bool wxBundleResourceHandler::LoadFile(wxBitmap *bitmap,
     return false ;
 }
 
+/* static */
+wxBitmap wxBitmapHelpers::NewFromPNGData(const void* data, size_t size)
+{
+    wxCFRef<CGDataProviderRef>
+        provider(CGDataProviderCreateWithData(NULL, data, size, NULL) );
+    wxCFRef<CGImageRef>
+        image(CGImageCreateWithPNGDataProvider(provider, NULL, true,
+                                                kCGRenderingIntentDefault));
+
+    return wxBitmap(image);
+}
+
 void wxBitmap::InitStandardHandlers()
 {
 #if wxOSX_USE_COCOA_OR_CARBON