create greyed image for wxBitmapButton in MSW automatically, as in wxGTK (replaces patch 1734018)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47483 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/bmpbuttn.h

@@ -19,7 +19,7 @@
 class WXDLLEXPORT wxBitmapButton : public wxBitmapButtonBase
 {
 public:
-    wxBitmapButton() { }
+    wxBitmapButton() { Init(); }
 
     wxBitmapButton(wxWindow *parent,
                    wxWindowID id,
@@ -30,6 +30,8 @@ public:
                    const wxValidator& validator = wxDefaultValidator,
                    const wxString& name = wxButtonNameStr)
     {
+        Init();
+
         Create(parent, id, bitmap, pos, size, style, validator, name);
     }
 
@@ -42,6 +44,13 @@ public:
                 const wxValidator& validator = wxDefaultValidator,
                 const wxString& name = wxButtonNameStr);
 
+    // override some base class methods to automatically synthesize the
+    // disabled bitmap if it wasn't set by the user
+    virtual void SetBitmapLabel(const wxBitmap& bitmap);
+    virtual void SetBitmapFocus(const wxBitmap& focus);
+    virtual void SetBitmapDisabled(const wxBitmap& disabled);
+    virtual void SetBitmapHover(const wxBitmap& hover);
+
     // Implementation
     virtual bool SetBackgroundColour(const wxColour& colour);
     virtual bool MSWOnDraw(WXDRAWITEMSTRUCT *item);
@@ -50,9 +59,15 @@ public:
     virtual void DrawButtonDisable( WXHDC dc, int left, int top, int right, int bottom, bool with_marg );
 
 protected:
+    // common part of all ctors
+    void Init()
+    {
+        m_disabledSetByUser =
+        m_hoverSetByUser = false;
+    }
+
     // reimplement some base class virtuals
     virtual wxSize DoGetBestSize() const;
-    virtual void OnSetBitmap();
 
     // invalidate m_brushDisabled when system colours change
     void OnSysColourChanged(wxSysColourChangedEvent& event);
@@ -64,6 +79,13 @@ protected:
     // the brush we use to draw disabled buttons
     wxBrush m_brushDisabled;
 
+    // true if m_bmpDisabled was set by user, false if we created it ourselves
+    // from m_bmpNormal
+    bool m_disabledSetByUser;
+
+    // true if m_bmpHover was set by user, false if it was set from m_bmpFocus
+    bool m_hoverSetByUser;
+
 
     DECLARE_EVENT_TABLE()
     DECLARE_DYNAMIC_CLASS_NO_COPY(wxBitmapButton)