Add wxEnhMetaFile::Detach().

Allow getting the handle from this class, this is useful if it needs to be
passed to some other library, for example.

Closes #15706.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76117 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -51,6 +51,7 @@ wxMSW:
 - Fix loading of bitmap with non-pre-multiplied alpha (Artur Wieczorek).
 - Support multiline strings in wxDC::DrawRotatedText() (Artur Wieczorek).
 - Fix stretchable spacers in vertical toolbars (Artur Wieczorek).
+- Add wxEnhMetaFile::Detach() (Luca Bacci).
 
 wxOSX/Cocoa:
 

include/wx/msw/enhmeta.h

@@ -52,13 +52,21 @@ public:
     // this method
     bool SetClipboard(int width = 0, int height = 0);
 
+    // Detach the HENHMETAFILE from this object, i.e. don't delete the handle
+    // in the dtor -- the caller is now responsible for doing this, e.g. using
+    // Free() method below.
+    WXHANDLE Detach() { WXHANDLE h = m_hMF; m_hMF = 0; return h; }
+
+    // Destroy the given HENHMETAFILE object.
+    static void Free(WXHANDLE handle);
+
     // implementation
     WXHANDLE GetHENHMETAFILE() const { return m_hMF; }
     void SetHENHMETAFILE(WXHANDLE hMF) { Free(); m_hMF = hMF; }
 
 protected:
     void Init();
-    void Free();
+    void Free() { Free(m_hMF); }
     void Assign(const wxEnhMetaFile& mf);
 
     // we don't use these functions (but probably should) but have to implement

src/msw/enhmeta.cpp

@@ -120,11 +120,12 @@ void wxEnhMetaFile::Assign(const wxEnhMetaFile& mf)
     }
 }
 
-void wxEnhMetaFile::Free()
+/* static */
+void wxEnhMetaFile::Free(WXHANDLE handle)
 {
-    if ( m_hMF )
+    if ( handle )
     {
-        if ( !::DeleteEnhMetaFile(GetEMF()) )
+        if ( !::DeleteEnhMetaFile((HENHMETAFILE) handle) )
         {
             wxLogLastError(wxT("DeleteEnhMetaFile"));
         }