made GetClippingBox() work even for clipping region (pre)set by Windows and not only for clipping regions set using our own SetClippingXXX() functions

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@27106 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/dc.h

@@ -118,6 +118,13 @@ public:
     {
         m_hDC = dc;
         m_bOwnsDC = bOwnsDC;
+
+        // we might have a pre existing clipping region, make sure that we
+        // return it if asked -- but avoid calling ::GetClipBox() right now as
+        // it could be unnecessary wasteful
+        m_clipping = true;
+        m_clipX1 =
+        m_clipX2 = 0;
     }
 
     const wxBitmap& GetSelectedBitmap() const { return m_selectedBitmap; }
@@ -182,6 +189,8 @@ protected:
     {
         GetClippingBox(x, y, width, height);
     }
+    virtual void DoGetClippingBox(wxCoord *x, wxCoord *y,
+                                  wxCoord *w, wxCoord *h) const;
 
     virtual void DoGetSize(int *width, int *height) const;
     virtual void DoGetSizeMM(int* width, int* height) const;

src/msw/dc.cpp

@@ -383,6 +383,23 @@ void wxDC::UpdateClipBox()
     m_clipY2 = (wxCoord) YDEV2LOG(rect.bottom);
 }
 
+void
+wxDC::DoGetClippingBox(wxCoord *x, wxCoord *y, wxCoord *w, wxCoord *h) const
+{
+    // check if we should try to retrieve the clipping region possibly not set
+    // by our SetClippingRegion() but preset by Windows:this can only happen
+    // when we're associated with an existing HDC usign SetHDC(), see there
+    if ( m_clipping && !m_clipX1 && !m_clipX2 )
+    {
+        UpdateClipBox();
+
+        if ( !m_clipX1 && !m_clipX2 )
+            m_clipping = false;
+    }
+
+    return wxDCBase::DoGetClippingBox(x, y, w, h);
+}
+
 // common part of DoSetClippingRegion() and DoSetClippingRegionAsRegion()
 void wxDC::SetClippingHrgn(WXHRGN hrgn)
 {
@@ -465,7 +482,7 @@ void wxDC::DestroyClippingRegion()
         ::DeleteObject(rgn);
     }
 
-    m_clipping = false;
+    wxDCBase::DestroyClippingRegion();
 }
 
 // ---------------------------------------------------------------------------