Refactor wxMSW wxStaticBitmap to separate bitmaps and icons

Use different members for storing wxBitmap and wxIcon instead of using a
single pointer for storing a heap-allocated copy of either of them
because this is simpler, more efficient due to avoiding unnecessary
conversions and RTTI, and will be simpler to generalize to using
wxBitmapBundle instead of wxBitmap in the upcoming commits.

As a side effect, don't assert in GetIcon() or GetBitmap() if there is
no valid icon or bitmap, as this is inconsistent with the other ports
and wasn't even consistent between these functions in wxMSW itself.

There should be no other changes in behaviour.

include/wx/msw/statbmp.h

@@ -25,7 +25,20 @@ public:
 
     wxStaticBitmap(wxWindow *parent,
                    wxWindowID id,
-                   const wxGDIImage& label,
+                   const wxBitmap& label,
+                   const wxPoint& pos = wxDefaultPosition,
+                   const wxSize& size = wxDefaultSize,
+                   long style = 0,
+                   const wxString& name = wxASCII_STR(wxStaticBitmapNameStr))
+    {
+        Init();
+
+        Create(parent, id, label, pos, size, style, name);
+    }
+
+    wxStaticBitmap(wxWindow *parent,
+                   wxWindowID id,
+                   const wxIcon& label,
                    const wxPoint& pos = wxDefaultPosition,
                    const wxSize& size = wxDefaultSize,
                    long style = 0,
@@ -38,16 +51,34 @@ public:
 
     bool Create(wxWindow *parent,
                 wxWindowID id,
-                const wxGDIImage& label,
+                const wxBitmap& label,
                 const wxPoint& pos = wxDefaultPosition,
                 const wxSize& size = wxDefaultSize,
                 long style = 0,
-                const wxString& name = wxASCII_STR(wxStaticBitmapNameStr));
+                const wxString& name = wxASCII_STR(wxStaticBitmapNameStr))
+    {
+        m_bitmap = label;
+
+        return DoCreate(parent, id, pos, size, style, name);
+    }
+
+    bool Create(wxWindow *parent,
+                wxWindowID id,
+                const wxIcon& label,
+                const wxPoint& pos = wxDefaultPosition,
+                const wxSize& size = wxDefaultSize,
+                long style = 0,
+                const wxString& name = wxASCII_STR(wxStaticBitmapNameStr))
+    {
+        m_icon = label;
+
+        return DoCreate(parent, id, pos, size, style, name);
+    }
 
     virtual ~wxStaticBitmap() { Free(); }
 
-    virtual void SetIcon(const wxIcon& icon) wxOVERRIDE { SetImage(&icon); }
-    virtual void SetBitmap(const wxBitmap& bitmap) wxOVERRIDE { SetImage(&bitmap); }
+    virtual void SetIcon(const wxIcon& icon) wxOVERRIDE;
+    virtual void SetBitmap(const wxBitmap& bitmap) wxOVERRIDE;
     virtual wxBitmap GetBitmap() const wxOVERRIDE;
     virtual wxIcon GetIcon() const wxOVERRIDE;
 
@@ -59,15 +90,23 @@ public:
 protected:
     virtual wxSize DoGetBestClientSize() const wxOVERRIDE;
 
+private:
     // ctor/dtor helpers
     void Init();
     void Free();
 
-    // true if icon/bitmap is valid
-    bool ImageIsOk() const;
+    // common part of both Create() overloads
+    bool DoCreate(wxWindow *parent,
+                  wxWindowID id,
+                  const wxPoint& pos,
+                  const wxSize& size,
+                  long style,
+                  const wxString& name);
 
-    void SetImage(const wxGDIImage* image);
-    void SetImageNoCopy( wxGDIImage* image );
+    // update the image to correspond to the current m_icon or m_bitmap value,
+    // resize the control if the new size is different from the old one and
+    // update its style if the new "is icon" value differs from the old one
+    void DoUpdateImage(const wxSize& sizeOld, bool wasIcon);
 
     // draw the bitmap ourselves here if the OS can't do it correctly (if it
     // can we leave it to it)
@@ -75,14 +114,19 @@ protected:
 
     void WXHandleSize(wxSizeEvent& event);
 
-    // we can have either an icon or a bitmap
-    bool m_isIcon;
-    wxGDIImage *m_image;
+    // return the either m_icon or m_bitmap (may still be invalid of both of
+    // them are)
+    const wxGDIImage& GetImage() const;
+
+
+    // we can have either an icon or a bitmap: if m_icon is valid, it is used,
+    // otherwise m_bitmap is used if it is valid
+    wxIcon m_icon;
+    wxBitmap m_bitmap;
 
     // handle used in last call to STM_SETIMAGE
     WXHANDLE m_currentHandle;
 
-private:
     // Flag indicating whether we own m_currentHandle, i.e. should delete it.
     bool m_ownsCurrentHandle;