Add wxDCTextBgColourChanger and wxDCTextBgModeChanger helpers

These classes are similar to the existing wxDCTextColourChanger and
allow temporarily changing other wxDC attributes.

Closes https://github.com/wxWidgets/wxWidgets/pull/1298

include/wx/dc.h

@@ -1405,6 +1405,78 @@ private:
     wxDECLARE_NO_COPY_CLASS(wxDCTextColourChanger);
 };
 
+// ----------------------------------------------------------------------------
+// helper class: you can use it to temporarily change the DC text background colour and
+// restore it automatically when the object goes out of scope
+// ----------------------------------------------------------------------------
+
+class WXDLLIMPEXP_CORE wxDCTextBgColourChanger
+{
+public:
+    wxDCTextBgColourChanger(wxDC& dc) : m_dc(dc) { }
+
+    wxDCTextBgColourChanger(wxDC& dc, const wxColour& col) : m_dc(dc)
+    {
+        Set(col);
+    }
+
+    ~wxDCTextBgColourChanger()
+    {
+        if ( m_colBgOld.IsOk() )
+            m_dc.SetTextBackground(m_colBgOld);
+    }
+
+    void Set(const wxColour& col)
+    {
+        if ( !m_colBgOld.IsOk() )
+            m_colBgOld = m_dc.GetTextBackground();
+        m_dc.SetTextBackground(col);
+    }
+
+private:
+    wxDC& m_dc;
+
+    wxColour m_colBgOld;
+
+    wxDECLARE_NO_COPY_CLASS(wxDCTextBgColourChanger);
+};
+
+// ----------------------------------------------------------------------------
+// helper class: you can use it to temporarily change the DC text background mode and
+// restore it automatically when the object goes out of scope
+// ----------------------------------------------------------------------------
+
+class WXDLLIMPEXP_CORE wxDCTextBgModeChanger
+{
+public:
+    wxDCTextBgModeChanger(wxDC& dc) : m_dc(dc), m_modeOld(wxBRUSHSTYLE_INVALID) { }
+
+    wxDCTextBgModeChanger(wxDC& dc, int mode) : m_dc(dc)
+    {
+        Set(mode);
+    }
+
+    ~wxDCTextBgModeChanger()
+    {
+        if ( m_modeOld != wxBRUSHSTYLE_INVALID )
+            m_dc.SetBackgroundMode(m_modeOld);
+    }
+
+    void Set(int mode)
+    {
+        if ( m_modeOld == wxBRUSHSTYLE_INVALID )
+            m_modeOld = m_dc.GetBackgroundMode();
+        m_dc.SetBackgroundMode(mode);
+    }
+
+private:
+    wxDC& m_dc;
+
+    int m_modeOld;
+
+    wxDECLARE_NO_COPY_CLASS(wxDCTextBgModeChanger);
+};
+
 // ----------------------------------------------------------------------------
 // helper class: you can use it to temporarily change the DC pen and
 // restore it automatically when the object goes out of scope