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 // implementation
  34 // ============================================================================
  35
  36 // ----------------------------------------------------------------------------
  37 // wxSharedDCBufferManager: helper class maintaining backing store bitmap
  38 // ----------------------------------------------------------------------------
  39
  40 class wxSharedDCBufferManager
  41 {
  42 public:
  43     wxSharedDCBufferManager() { }
  44     ~wxSharedDCBufferManager() { }
  45
  46     wxBitmap GetBuffer(int w, int h)
  47     {
  48         if ( !m_buffer.IsOk() ||
  49              w > m_buffer.GetWidth() ||
  50              h > m_buffer.GetHeight() )
  51         {
  52             // Create slightly larger bitmap so we don't need to
  53             // be reallocating constantly when the user enlarges
  54             // the frame for the first time.
  55             m_buffer = wxBitmap(w, h);
  56         }
  57
  58         return m_buffer;
  59     }
  60
  61 private:
  62     wxBitmap m_buffer;
  63 };
  64
  65 static wxSharedDCBufferManager gs_sharedDCBufferManager;
  66
  67
  68 // ============================================================================
  69 // wxBufferedDC
  70 // ============================================================================
  71
  72 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
  73 {
  74     if ( !m_buffer.IsOk() )
  75     {
  76         if ( w == -1 || h == -1 )
  77             m_dc->GetSize(&w, &h);
  78
  79         m_buffer = gs_sharedDCBufferManager.GetBuffer(w, h);
  80     }
  81
  82     SelectObject(m_buffer);
  83 }
  84