Add wxPowerResourceBlocker for power management.

Add functions to acquire/release power resources, preventing/allowing back the
system to go to sleep or turn off the screen and a class wrapping them in a
safe way.

This patch implements the functions for MSW and OSX, adds documentation and
updates the sample to demonstrate the new functionality.

Closes #16413.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77511 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/power.h

@@ -95,6 +95,49 @@ typedef void (wxEvtHandler::*wxPowerEventFunction)(wxPowerEvent&);
     #undef wxHAS_POWER_EVENTS
 #endif // support for power events/no support
 
+// ----------------------------------------------------------------------------
+// wxPowerResourceBlocker
+// ----------------------------------------------------------------------------
+
+enum wxPowerResourceKind
+{
+    wxPOWER_RESOURCE_SCREEN,
+    wxPOWER_RESOURCE_SYSTEM
+};
+
+class WXDLLIMPEXP_BASE wxPowerResource
+{
+public:
+    static bool Acquire(wxPowerResourceKind kind,
+                        const wxString& reason = wxString());
+    static void Release(wxPowerResourceKind kind);
+};
+
+class wxPowerResourceBlocker
+{
+public:
+    explicit wxPowerResourceBlocker(wxPowerResourceKind kind,
+                                    const wxString& reason = wxString())
+        : m_kind(kind),
+          m_acquired(wxPowerResource::Acquire(kind, reason))
+    {
+    }
+
+    bool IsInEffect() const { return m_acquired; }
+
+    ~wxPowerResourceBlocker()
+    {
+        if ( m_acquired )
+            wxPowerResource::Release(m_kind);
+    }
+
+private:
+    const wxPowerResourceKind m_kind;
+    const bool m_acquired;
+
+    wxDECLARE_NO_COPY_CLASS(wxPowerResourceBlocker);
+};
+
 // ----------------------------------------------------------------------------
 // power management functions
 // ----------------------------------------------------------------------------