added wxMessageOutputBest which tries to show the message to the user in the best possible way

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@34555 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msgout.h

@@ -43,7 +43,8 @@ public:
     // show a message to the user
     virtual void Printf(const wxChar* format, ...)  ATTRIBUTE_PRINTF_2 = 0;
 
-    // gets the current wxMessageOutput object
+    // gets the current wxMessageOutput object (may be NULL during
+    // initialization or shutdown)
     static wxMessageOutput* Get();
 
     // sets the global wxMessageOutput instance; returns the previous one
@@ -53,6 +54,20 @@ private:
     static wxMessageOutput* ms_msgOut;
 };
 
+// ----------------------------------------------------------------------------
+// implementation showing the message to the user in "best" possible way: uses
+// native message box if available (currently only under Windows) and stderr
+// otherwise; unlike wxMessageOutputMessageBox this class is always safe to use
+// ----------------------------------------------------------------------------
+
+class WXDLLIMPEXP_BASE wxMessageOutputBest : public wxMessageOutput
+{
+public:
+    wxMessageOutputBest() { }
+
+    virtual void Printf(const wxChar* format, ...) ATTRIBUTE_PRINTF_2;
+};
+
 // ----------------------------------------------------------------------------
 // implementation which sends output to stderr
 // ----------------------------------------------------------------------------

src/common/msgout.cpp

@@ -88,6 +88,26 @@ wxMessageOutput* wxMessageOutput::Set(wxMessageOutput* msgout)
     return old;
 }
 
+// ----------------------------------------------------------------------------
+// wxMessageOutputBest
+// ----------------------------------------------------------------------------
+
+void wxMessageOutputBest::Printf(const wxChar* format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    wxString out;
+
+    out.PrintfV(format, args);
+    va_end(args);
+
+#ifdef __WINDOWS__
+    ::MessageBox(NULL, out, _T("wxWidgets"), MB_ICONINFORMATION | MB_OK);
+#else // !__WINDOWS__
+    fprintf(stderr, "%s", (const char*) out.mb_str());
+#endif // __WINDOWS__/!__WINDOWS__
+}
+
 // ----------------------------------------------------------------------------
 // wxMessageOutputStderr
 // ----------------------------------------------------------------------------