wxUICanceller: Move upstream and make reusable

Signed-off-by: Simon Rozman <simon@rozman.si>

lib/EAPBase_UI/include/EAP_UI.h

@@ -463,6 +463,30 @@ protected:
 };
 
 
+///
+/// Closes active window if exists
+///
+class wxUICanceller
+{
+public:
+    ///
+    /// Send WM_CLOSE to the active window if it exists.
+    ///
+    /// \param[inout] hWndCurrent  Reference to a handle of the active window is stored. The variable should be shared between threads.
+    /// \param[in]    hWnd         Handle of a new window to be activated
+    ///
+    wxUICanceller(_Inout_ HWND volatile &hWndCurrent, _In_ HWND hWnd);
+
+    ///
+    /// Clears the active window handle.
+    ///
+    ~wxUICanceller();
+
+protected:
+    HWND volatile &m_hWndCurrent;
+};
+
+
 ///
 /// EAP general note
 ///

lib/EAPBase_UI/src/EAP_UI.cpp

@@ -600,3 +600,24 @@ wxInitializerPeer::~wxInitializerPeer()
 wxCriticalSection wxInitializerPeer::s_lock;
 unsigned long wxInitializerPeer::s_init_ref_count = 0;
 wxLocale *wxInitializerPeer::s_locale = NULL;
+
+
+//////////////////////////////////////////////////////////////////////
+// wxUICanceller
+//////////////////////////////////////////////////////////////////////
+
+wxUICanceller::wxUICanceller(_Inout_ HWND volatile &hWndCurrent, _In_ HWND hWnd) :
+    m_hWndCurrent(hWndCurrent)
+{
+    HWND hWndPrev = (HWND)InterlockedCompareExchangePointer((PVOID volatile *)&m_hWndCurrent, hWnd, NULL);
+    if (hWndPrev) {
+        PostMessage(hWndPrev, WM_CLOSE, 0, 0);
+        throw winstd::win_runtime_error(ERROR_CANCELLED, __FUNCTION__ " Aborted.");
+    }
+}
+
+
+wxUICanceller::~wxUICanceller()
+{
+    InterlockedExchangePointer((PVOID volatile *)&m_hWndCurrent, NULL);
+}