Add default ctor to wxMSW private WindowHDC helper class.

Allow to use objects of this class without any valid HWND, this is useful for
the derived classes which may, or may not, need the corresponding HDC.

See #14194.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71208 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/include/wx/msw/private.h b/include/wx/msw/private.h
index 2875d294c727f57cb7ce6aaac01e0f9b7dda4247..622c3b1544f036fbf6d2121c0490b159b791a949 100644 (file)
--- a/include/wx/msw/private.h
+++ b/include/wx/msw/private.h
@@ -417,8 +417,9 @@ private:
 class WindowHDC
 {
 public:
+    WindowHDC() : m_hwnd(NULL), m_hdc(NULL) { }
     WindowHDC(HWND hwnd) { m_hdc = ::GetDC(m_hwnd = hwnd); }
-   ~WindowHDC() { ::ReleaseDC(m_hwnd, m_hdc); }
+   ~WindowHDC() { if ( m_hwnd && m_hdc ) { ::ReleaseDC(m_hwnd, m_hdc); } }
 
     operator HDC() const { return m_hdc; }