Add wxListCtrl::SetHeaderAttr()

This method can be used to change the list view header appearance.

Add the method declaration, documentation, show it in the sample and implement
it for wxMSW (only, for now).

src/msw/listctrl.cpp

@@ -42,6 +42,7 @@
 #include "wx/vector.h"
 
 #include "wx/msw/private.h"
+#include "wx/msw/private/customdraw.h"
 #include "wx/msw/private/keyboard.h"
 
 // Currently gcc doesn't define NMLVFINDITEM, and DMC only defines
@@ -229,6 +230,34 @@ public:
     wxDECLARE_NO_COPY_CLASS(wxMSWListItemData);
 };
 
+// wxMSWListHeaderCustomDraw: custom draw helper for the header
+class wxMSWListHeaderCustomDraw : public wxMSWImpl::CustomDraw
+{
+public:
+    wxMSWListHeaderCustomDraw()
+    {
+    }
+
+    // Make this field public to let wxListCtrl update it directly when its
+    // header attributes change.
+    wxItemAttr m_attr;
+
+private:
+    virtual bool HasCustomDrawnItems() const wxOVERRIDE
+    {
+        // We only exist if the header does need to be custom drawn.
+        return true;
+    }
+
+    virtual const wxItemAttr*
+    GetItemAttr(DWORD_PTR WXUNUSED(dwItemSpec)) const wxOVERRIDE
+    {
+        // We use the same attribute for all items for now.
+        return &m_attr;
+    }
+};
+
+
 wxBEGIN_EVENT_TABLE(wxListCtrl, wxListCtrlBase)
     EVT_PAINT(wxListCtrl::OnPaint)
     EVT_CHAR_HOOK(wxListCtrl::OnCharHook)
@@ -255,6 +284,8 @@ void wxListCtrl::Init()
     m_textCtrl = NULL;
 
     m_hasAnyAttr = false;
+
+    m_headerCustomDraw = NULL;
 }
 
 bool wxListCtrl::Create(wxWindow *parent,
@@ -434,6 +465,8 @@ wxListCtrl::~wxListCtrl()
         delete m_imageListSmall;
     if (m_ownsImageListState)
         delete m_imageListState;
+
+    delete m_headerCustomDraw;
 }
 
 // ----------------------------------------------------------------------------
@@ -520,6 +553,68 @@ bool wxListCtrl::SetBackgroundColour(const wxColour& col)
     return true;
 }
 
+bool wxListCtrl::SetHeaderAttr(const wxItemAttr& attr)
+{
+    // We need to propagate the change of the font to the native header window
+    // as it also affects its layout.
+    bool fontChanged;
+
+    // Start or stop custom drawing the header.
+    if ( attr.IsDefault() )
+    {
+        if ( !m_headerCustomDraw )
+        {
+            // Nothing changed, skip refreshing the control below.
+            return true;
+        }
+
+        fontChanged = m_headerCustomDraw->m_attr.HasFont();
+
+        delete m_headerCustomDraw;
+        m_headerCustomDraw = NULL;
+    }
+    else // We do have custom attributes.
+    {
+        if ( !m_headerCustomDraw )
+            m_headerCustomDraw = new wxMSWListHeaderCustomDraw();
+
+        if ( m_headerCustomDraw->m_attr == attr )
+        {
+            // As above, skip refresh.
+            return true;
+        }
+
+        fontChanged = attr.GetFont() != m_headerCustomDraw->m_attr.GetFont();
+
+        m_headerCustomDraw->m_attr = attr;
+    }
+
+    if ( HWND hwndHdr = ListView_GetHeader(GetHwnd()) )
+    {
+        if ( fontChanged )
+        {
+            // Don't just reset the font if no font is specified, as the header
+            // uses the same font as the listview control and not the ugly
+            // default GUI font by default.
+            const wxFont& font = attr.HasFont() ? attr.GetFont() : GetFont();
+
+            // We need to tell the header about its new font to let it compute
+            // its new height.
+            ::SendMessage(hwndHdr, WM_SETFONT,
+                          (WPARAM)GetHfontOf(font), MAKELPARAM(TRUE, 0));
+        }
+
+        // Refreshing the listview makes it notice the change in height of its
+        // header and redraws it too. We probably could do something less than
+        // a full refresh, but it doesn't seem to be worth it, the header
+        // attributes won't be changed that often, so keep it simple for now.
+        Refresh();
+    }
+    //else: header not shown or not in report view?
+
+    return true;
+}
+
 // Gets information about this column
 bool wxListCtrl::GetColumn(int col, wxListItem& item) const
 {
@@ -2085,6 +2180,15 @@ bool wxListCtrl::MSWOnNotify(int idCtrl, WXLPARAM lParam, WXLPARAM *result)
                 // doesn't seem to have any negative consequences
                 return true;
 
+            case NM_CUSTOMDRAW:
+                if ( m_headerCustomDraw )
+                {
+                    *result = m_headerCustomDraw->HandleCustomDraw(lParam);
+                    if ( *result != CDRF_DODEFAULT )
+                        return true;
+                }
+                wxFALLTHROUGH;
+
             default:
                 ignore = true;
         }