Add wxPanel::SetBackgroundBitmap().

This method provides a simple way to set a background bitmap without defining
an EVT_ERASE_BACKGROUND handler and, more importantly, one that works
correctly in wxMSW for a window with children as it paints the background of
transparent children too.

Add a test of this method to the erase sample.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67253 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/panelg.h

@@ -12,6 +12,8 @@
 #ifndef _WX_GENERIC_PANELG_H_
 #define _WX_GENERIC_PANELG_H_
 
+#include "wx/bitmap.h"
+
 class WXDLLIMPEXP_CORE wxPanel : public wxPanelBase
 {
 public:
@@ -40,7 +42,18 @@ public:
     )
 #endif // WXWIN_COMPATIBILITY_2_8
 
+protected:
+    virtual void DoSetBackgroundBitmap(const wxBitmap& bmp);
+
 private:
+    // Event handler for erasing the background which is only used when we have
+    // a valid background bitmap.
+    void OnEraseBackground(wxEraseEvent& event);
+
+
+    // The bitmap used for painting the background if valid.
+    wxBitmap m_bitmapBg;
+
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxPanel);
 };
 

include/wx/msw/panel.h

@@ -11,6 +11,8 @@
 #ifndef _WX_MSW_PANEL_H_
 #define _WX_MSW_PANEL_H_
 
+class WXDLLIMPEXP_FWD_CORE wxBrush;
+
 // ----------------------------------------------------------------------------
 // wxPanel
 // ----------------------------------------------------------------------------
@@ -18,7 +20,7 @@
 class WXDLLIMPEXP_CORE wxPanel : public wxPanelBase
 {
 public:
-    wxPanel() { }
+    wxPanel() { Init(); }
 
     wxPanel(wxWindow *parent,
             wxWindowID winid = wxID_ANY,
@@ -27,6 +29,8 @@ public:
             long style = wxTAB_TRAVERSAL | wxNO_BORDER,
             const wxString& name = wxPanelNameStr)
     {
+        Init();
+
         Create(parent, winid, pos, size, style, name);
     }
 
@@ -48,7 +52,18 @@ public:
     )
 #endif // WXWIN_COMPATIBILITY_2_8
 
+protected:
+    void Init()
+    {
+        m_backgroundBrush = NULL;
+    }
+
+    virtual void DoSetBackgroundBitmap(const wxBitmap& bmp);
+    virtual WXHBRUSH MSWGetCustomBgBrush();
+
 private:
+    wxBrush *m_backgroundBrush;
+
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxPanel);
 };
 

include/wx/panel.h

@@ -52,6 +52,18 @@ public:
                 const wxString& name = wxPanelNameStr);
 
 
+    // Use the given bitmap to tile the background of this panel. This bitmap
+    // will show through any transparent children.
+    //
+    // Notice that you must not prevent the base class EVT_ERASE_BACKGROUND
+    // handler from running (i.e. not to handle this event yourself) for this
+    // to work.
+    void SetBackgroundBitmap(const wxBitmap& bmp)
+    {
+        DoSetBackgroundBitmap(bmp);
+    }
+
+
     // implementation from now on
     // --------------------------
 
@@ -59,6 +71,9 @@ public:
 
     WX_DECLARE_CONTROL_CONTAINER();
 
+protected:
+    virtual void DoSetBackgroundBitmap(const wxBitmap& bmp) = 0;
+
 private:
     wxDECLARE_EVENT_TABLE();
 
@@ -70,6 +85,7 @@ private:
 #elif defined(__WXMSW__)
     #include "wx/msw/panel.h"
 #else
+    #define wxHAS_GENERIC_PANEL
     #include "wx/generic/panelg.h"
 #endif
 

include/wx/univ/panel.h

@@ -44,6 +44,13 @@ public:
     )
 #endif // WXWIN_COMPATIBILITY_2_8
 
+protected:
+    virtual void DoSetBackgroundBitmap(const wxBitmap& bmp)
+    {
+        // We have support for background bitmap even at the base class level.
+        SetBackground(bmp, wxALIGN_NOT, wxTILE);
+    }
+
 private:
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxPanel);
 };