src/common/dcbufcmn.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/dcbufcmn.cpp
   3 // Purpose:     Buffered DC implementation
   4 // Author:      Ron Lee, Jaakko Salli
   5 // Modified by:
   6 // Created:     Sep-20-2006
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) wxWidgets team
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // For compilers that support precompilation, includes "wx.h".
  21 #include "wx/wxprec.h"
  22
  23 #ifdef __BORLANDC__
  24     #pragma hdrstop
  25 #endif
  26
  27 #ifndef WX_PRECOMP
  28 #endif
  29
  30 #include "wx/dcbuffer.h"
  31
  32
  33 // ============================================================================
  34 // implementation
  35 // ============================================================================
  36
  37 // ============================================================================
  38 // wxSharedDCBufferManager
  39 //   Helper class to free shared buffer when the app exists.
  40 // ============================================================================
  41
  42 class wxSharedDCBufferManager
  43 {
  44     friend class wxBufferedDC;
  45 public:
  46
  47     wxSharedDCBufferManager() { }
  48     ~wxSharedDCBufferManager() { }
  49
  50     wxBitmap* GetBuffer(int w, int h)
  51     {
  52         if ( !m_buffer.IsOk() ||
  53              w > m_buffer.GetWidth() ||
  54              h > m_buffer.GetHeight() )
  55         {
  56             // Create slightly larger bitmap so we don't need to
  57             // be reallocating constantly when the user enlarges
  58             // the frame for the first time.
  59             m_buffer = wxBitmap(w, h);
  60         }
  61
  62         return &m_buffer;
  63     }
  64
  65 private:
  66     wxBitmap    m_buffer;
  67 };
  68
  69 static wxSharedDCBufferManager gs_sharedDCBufferManager;
  70
  71
  72 // ============================================================================
  73 // wxBufferedDC
  74 // ============================================================================
  75
  76 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
  77 {
  78     if ( !m_buffer )
  79     {
  80         if ( w == -1 || h == -1 )
  81             m_dc->GetSize(&w, &h);
  82
  83         m_buffer = gs_sharedDCBufferManager.GetBuffer(w, h);
  84     }
  85
  86     SelectObject(*m_buffer);
  87 }
  88