- Rewrite wxHeaderCtrl to be virtual-like: even if we don't need an infinite

number of columns in it, it turns out that getting column information from
  the associated control is much easier than copying it into the control.
- Provide wxHeaderCtrlSimple derived class which can be used easily if
  callback approach of wxHeaderCtrl is not needed.
- Because of wxHeaderCtrl virtualization, port-specific implementations of
  wxHeaderColumn are not needed any more and were removed.
- Use wxHeaderCtrl in the generic wxDataViewCtrl: this means that column
  events are broken right now in it as they haven't been implemented by
  wxHeaderCtrl yet, this will be fixed a.s.a.p.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57161 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/headerctrl.h

@@ -16,7 +16,11 @@
 
     It is used as part of wxGrid and (will be used in the near future) in
     in wxDataViewCtrl and report view of wxListCtrl but can be also used
-    independently.
+    independently. In general this class is meant to be used as part of another
+    control which already stores the column information somewhere as it can't
+    be used directly: instead you need to inherit from it and implement the
+    GetColumn() method to provide column information. See wxHeaderCtrlSimple
+    for a concrete control class which can be used directly.
 
     In addition to labeling the columns, the control has the following
     features:
@@ -85,7 +89,7 @@ public:
                  wxWindowID winid = wxID_ANY,
                  const wxPoint& pos = wxDefaultPosition,
                  const wxSize& size = wxDefaultSize,
-                 long style = 0,
+                 long style = wxHD_DEFAULT_STYLE,
                  const wxString& name = wxHeaderCtrlNameStr);
 
     /**
@@ -115,12 +119,25 @@ public:
                 wxWindowID winid = wxID_ANY,
                 const wxPoint& pos = wxDefaultPosition,
                 const wxSize& size = wxDefaultSize,
-                long style = 0,
+                long style = wxHD_DEFAULT_STYLE,
                 const wxString& name = wxHeaderCtrlNameStr);
 
+    /**
+        Set the number of columns in the control.
+
+        The control will use GetColumn() to get information about all the
+        new columns and refresh itself, i.e. this method also has the same
+        effect as calling UpdateColumn() for all columns but it should only be
+        used if the number of columns really changed.
+     */
+    void SetColumnCount(unsigned int count);
+
     /**
         Return the number of columns in the control.
 
+        @return
+            Number of columns as previously set by SetColumnCount().
+
         @see IsEmpty()
      */
     unsigned int GetColumnCount() const;
@@ -132,6 +149,59 @@ public:
      */
     bool IsEmpty() const;
 
+protected:
+    /**
+        Method to be implemented by the derived classes to return the
+        information for the given column.
+
+        @param idx
+            The column index, between 0 and the value last passed to
+            SetColumnCount().
+     */
+    virtual wxHeaderColumnBase& GetColumn(unsigned int idx) = 0;
+};
+
+
+/**
+    @class wxHeaderCtrlSimple
+
+    wxHeaderCtrlSimple is a concrete header control which can be used directly,
+    without inheriting from it as you need to do when using wxHeaderCtrl
+    itself.
+
+    When using it, you need to use simple AppendColumn(), InsertColumn() and
+    DeleteColumn() methods instead of setting the number of columns with
+    SetColumnCount() and returning the information about them from the
+    overridden GetColumn().
+
+    @library{wxcore}
+    @category{ctrl}
+
+    @see wxHeaderCtrl
+*/
+class wxHeaderCtrlSimple : public wxHeaderCtrl
+{
+public:
+    /**
+        Default constructor not creating the underlying window.
+
+        You must use Create() after creating the object using this constructor.
+     */
+    wxHeaderCtrlSimple();
+
+    /**
+        Constructor creating the window.
+
+        Please see the base class wxHeaderCtrl::Create() method for the
+        parameters description.
+     */
+    wxHeaderCtrlSimple(wxWindow *parent,
+                       wxWindowID winid = wxID_ANY,
+                       const wxPoint& pos = wxDefaultPosition,
+                       const wxSize& size = wxDefaultSize,
+                       long style = wxHD_DEFAULT_STYLE,
+                       const wxString& name = wxHeaderCtrlNameStr);
+
     /**
         Insert the column at the given position.