added wxWindow::IsDoubleBuffered() and improve wxBufferedDC (patch 1565330)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41810 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/dcbufcmn.cpp

@@ -0,0 +1,136 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        src/common/dcbufcmn.cpp
+// Purpose:     Buffered DC implementation
+// Author:      Ron Lee, Jaakko Salli
+// Modified by:
+// Created:     Sep-20-2006
+// RCS-ID:      $Id$
+// Copyright:   (c) wxWidgets team
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+// ============================================================================
+// declarations
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+// For compilers that support precompilation, includes "wx.h".
+#include "wx/wxprec.h"
+
+#ifdef __BORLANDC__
+    #pragma hdrstop
+#endif
+
+#ifndef WX_PRECOMP
+#endif
+
+#include "wx/dcbuffer.h"
+
+
+// ============================================================================
+// implementation
+// ============================================================================
+
+// ============================================================================
+// wxSharedDCBufferManager
+//   Helper class to free shared buffer when the app exists.
+// ============================================================================
+
+class wxSharedDCBufferManager
+{
+    friend class wxBufferedDC;
+public:
+
+    wxSharedDCBufferManager()
+    {
+        m_buffer = NULL;
+    }
+
+    ~wxSharedDCBufferManager()
+    {
+        delete m_buffer;
+    }
+
+    wxBitmap* GetBuffer(wxWindow* win, const wxSize& area)
+    {
+        int width = area.x;
+        int height = area.y;
+
+        if ( width <= 0 )
+            win->GetClientSize(&width, &height);
+
+        if ( !m_buffer ||
+             width > m_buffer->GetWidth() ||
+             height > m_buffer->GetHeight() )
+        {
+            delete m_buffer;
+
+            // Create slightly larger bitmap so we don't need to
+            // be reallocating constantly when the user enlarges
+            // the frame for the first time.
+            m_buffer = new wxBitmap(width+20, height+20);
+        }
+
+        return m_buffer;
+    }
+
+private:
+    wxBitmap*   m_buffer;
+};
+
+static wxSharedDCBufferManager gs_sharedDCBufferManager;
+
+// ============================================================================
+// wxBufferedDC
+// ============================================================================
+
+// Blits the buffer to the dc, and detaches the dc from the buffer (so it
+// can be effectively used once only).
+//
+// Usually called in the dtor or by the dtor of derived classes if the
+// BufferedDC must blit before the derived class (which may own the dc it's
+// blitting to) is destroyed.
+void wxBufferedDC::UnMask()
+{
+    if ( m_buffer )
+    {
+        wxASSERT_MSG( m_mainDc != NULL,
+                      _T("No underlying DC associated with wxBufferedDC (anymore)") );
+
+        wxDC* bufferDc = DetachDC();
+
+        wxASSERT( bufferDc->IsKindOf(CLASSINFO(wxMemoryDC)) );
+
+        wxCoord x=0, y=0;
+
+        if (m_style & wxBUFFER_CLIENT_AREA)
+            bufferDc->GetDeviceOrigin(& x, & y);
+
+        m_mainDc->Blit( 0, 0,
+                        m_buffer->GetWidth(), m_buffer->GetHeight(), bufferDc,
+                        -x, -y );
+        m_mainDc = NULL;
+        m_buffer = NULL;
+        delete bufferDc;
+    }
+}
+
+void wxBufferedDC::PrepareBuffer(wxWindow* win, const wxSize& area)
+{
+    m_buffer = gs_sharedDCBufferManager.GetBuffer(win, area);
+}
+
+void wxBufferedDC::UseBuffer()
+{
+    wxASSERT(m_buffer);
+
+    wxMemoryDC* memoryDc = new wxMemoryDC(m_mainDc);
+    memoryDc->SelectObject(*m_buffer);
+
+    AttachDC(memoryDc);
+}
+
+