From 1a9a3ce9a39580a537b1cd25b4e207ac760075d6 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 23 Oct 2006 22:06:01 +0000
Subject: [PATCH] use wxBitmap object as m_buffer and not a pointer to it
 (replaces patch 1582878)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42309 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 include/wx/dcbuffer.h   | 21 +++++++++------------
 src/common/dcbufcmn.cpp | 20 ++++++++------------
 2 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/include/wx/dcbuffer.h b/include/wx/dcbuffer.h
index 6e26da6f97..5b553769b7 100644
--- a/include/wx/dcbuffer.h
+++ b/include/wx/dcbuffer.h
@@ -43,7 +43,6 @@ public:
     // Default ctor, must subsequently call Init for two stage construction.
     wxBufferedDC()
         : m_dc(NULL),
-          m_buffer(NULL),
           m_style(0)
     {
     }
@@ -52,8 +51,7 @@ public:
     wxBufferedDC(wxDC *dc,
                  const wxBitmap& buffer = wxNullBitmap,
                  int style = wxBUFFER_CLIENT_AREA)
-        : m_dc(NULL),
-          m_buffer(NULL)
+        : m_dc(NULL)
     {
         Init(dc, buffer, style);
     }
@@ -62,9 +60,7 @@ public:
     // (where area is usually something like the size of the window
     // being buffered)
     wxBufferedDC(wxDC *dc, const wxSize& area, int style = wxBUFFER_CLIENT_AREA)
-        : m_dc(NULL),
-          m_buffer(NULL)
-
+        : m_dc(NULL)
     {
         Init(dc, area, style);
     }
@@ -83,7 +79,7 @@ public:
     {
         InitCommon(dc, style);
 
-        m_buffer = &buffer;
+        m_buffer = buffer;
 
         UseBuffer();
     }
@@ -103,7 +99,8 @@ public:
     // blitting to) is destroyed.
     void UnMask()
     {
-        wxCHECK_RET( m_dc, _T("No underlying DC in wxBufferedDC") );
+        wxCHECK_RET( m_dc, _T("no underlying wxDC?") );
+        wxASSERT_MSG( m_buffer.IsOk(), _T("invalid backing store") );
 
         wxCoord x = 0,
                 y = 0;
@@ -111,7 +108,7 @@ public:
         if ( m_style & wxBUFFER_CLIENT_AREA )
             GetDeviceOrigin(&x, &y);
 
-        m_dc->Blit(0, 0, m_buffer->GetWidth(), m_buffer->GetHeight(),
+        m_dc->Blit(0, 0, m_buffer.GetWidth(), m_buffer.GetHeight(),
                    this, -x, -y );
         m_dc = NULL;
     }
@@ -124,7 +121,7 @@ private:
     // common part of Init()s
     void InitCommon(wxDC *dc, int style)
     {
-        wxASSERT_MSG( !m_dc && !m_buffer, _T("wxBufferedDC already initialised") );
+        wxASSERT_MSG( !m_dc, _T("wxBufferedDC already initialised") );
         wxCHECK_RET( dc, _T("can't associate NULL DC with wxBufferedDC") );
 
         m_dc = dc;
@@ -144,8 +141,8 @@ private:
     //     could probably be a reference.
     wxDC *m_dc;
 
-    // the buffer (selected in this DC)
-    const wxBitmap *m_buffer;
+    // the buffer (selected in this DC), initially invalid
+    wxBitmap m_buffer;
 
     // the buffering style
     int m_style;
diff --git a/src/common/dcbufcmn.cpp b/src/common/dcbufcmn.cpp
index eeea10859f..f4f289ed08 100644
--- a/src/common/dcbufcmn.cpp
+++ b/src/common/dcbufcmn.cpp
@@ -29,25 +29,21 @@
 
 #include "wx/dcbuffer.h"
 
-
 // ============================================================================
 // implementation
 // ============================================================================
 
-// ============================================================================
-// wxSharedDCBufferManager
-//   Helper class to free shared buffer when the app exists.
-// ============================================================================
+// ----------------------------------------------------------------------------
+// wxSharedDCBufferManager: helper class maintaining backing store bitmap
+// ----------------------------------------------------------------------------
 
 class wxSharedDCBufferManager
 {
-    friend class wxBufferedDC;
 public:
-
     wxSharedDCBufferManager() { }
     ~wxSharedDCBufferManager() { }
 
-    wxBitmap* GetBuffer(int w, int h)
+    wxBitmap GetBuffer(int w, int h)
     {
         if ( !m_buffer.IsOk() ||
              w > m_buffer.GetWidth() ||
@@ -59,11 +55,11 @@ public:
             m_buffer = wxBitmap(w, h);
         }
 
-        return &m_buffer;
+        return m_buffer;
     }
 
 private:
-    wxBitmap    m_buffer;
+    wxBitmap m_buffer;
 };
 
 static wxSharedDCBufferManager gs_sharedDCBufferManager;
@@ -75,7 +71,7 @@ static wxSharedDCBufferManager gs_sharedDCBufferManager;
 
 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
 {
-    if ( !m_buffer )
+    if ( !m_buffer.IsOk() )
     {
         if ( w == -1 || h == -1 )
             m_dc->GetSize(&w, &h);
@@ -83,6 +79,6 @@ void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
         m_buffer = gs_sharedDCBufferManager.GetBuffer(w, h);
     }
 
-    SelectObject(*m_buffer);
+    SelectObject(m_buffer);
 }
 
-- 
2.45.2