Utility functions to pass wxWidgets pointers from Perl to C++ code.

C++ var_dir / set_var_dir() interface to access the UI resources
from the C++ code.

xs/src/slic3r/GUI/wxPerlIface.cpp

@@ -0,0 +1,97 @@
+// Derived from the following:
+
+/////////////////////////////////////////////////////////////////////////////
+// Name:        cpp/helpers.cpp
+// Purpose:     implementation for helpers.h
+// Author:      Mattia Barbon
+// Modified by:
+// Created:     29/10/2000
+// RCS-ID:      $Id: helpers.cpp 3397 2012-09-30 02:26:07Z mdootson $
+// Copyright:   (c) 2000-2011 Mattia Barbon
+// Licence:     This program is free software; you can redistribute it and/or
+//              modify it under the same terms as Perl itself
+/////////////////////////////////////////////////////////////////////////////
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+#include "EXTERN.h"
+#include "perl.h"
+#include "XSUB.h"
+#include "ppport.h"
+#undef do_open
+#undef do_close
+#ifdef __cplusplus
+}
+#endif
+
+//#include <xsinit.h>
+
+// ----------------------------------------------------------------------------
+// Utility functions for working with MAGIC
+// ----------------------------------------------------------------------------
+
+struct my_magic
+{
+    my_magic() : object( NULL ), deleteable( true ) { }
+
+    void*      object;
+    bool       deleteable;
+};
+
+//STATIC MGVTBL my_vtbl = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
+my_magic* wxPli_get_magic( pTHX_ SV* rv )
+{
+    // check for reference
+    if( !SvROK( rv ) )
+        return NULL;
+    SV* ref = SvRV( rv );
+
+    // if it isn't a SvPVMG, then it can't have MAGIC
+    // so it is deleteable
+    if( !ref || SvTYPE( ref ) < SVt_PVMG )
+        return NULL;
+
+    // search for '~' / PERL_MAGIC_ext magic, and check the value
+//    MAGIC* magic = mg_findext( ref, PERL_MAGIC_ext, &my_vtbl );
+    MAGIC* magic = mg_find( ref, '~' );
+    if( !magic )
+        return NULL;
+
+    return (my_magic*)magic->mg_ptr;
+}
+
+// gets 'this' pointer from a blessed scalar/hash reference
+void* wxPli_sv_2_object( pTHX_ SV* scalar, const char* classname ) 
+{
+    // is it correct to use undef as 'NULL'?
+    if( !SvOK( scalar ) ) 
+    {
+        return NULL;
+    }
+
+    if( !SvROK( scalar ) )
+        croak( "variable is not an object: it must have type %s", classname );
+
+    if( !classname || sv_derived_from( scalar, (char*) classname ) ) 
+    {
+        SV* ref = SvRV( scalar );
+
+        my_magic* mg = wxPli_get_magic( aTHX_ scalar );
+
+        // rationale: if this is an hash-ish object, it always
+        // has both mg and mg->object; if however this is a
+        // scalar-ish object that has been marked/unmarked deletable
+        // it has mg, but not mg->object
+        if( !mg || !mg->object )
+            return INT2PTR( void*, SvOK( ref ) ? SvIV( ref ) : 0 );
+
+        return mg->object;
+    }
+    else 
+    {
+        croak( "variable is not of type %s", classname );
+        return NULL; // dummy, for compiler
+    }
+}