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 // Copyright:   (c) wxWidgets team
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // For compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #include "wx/dcbuffer.h"
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/module.h"
  30 #endif
  31
  32 // ============================================================================
  33 // implementation
  34 // ============================================================================
  35
  36 IMPLEMENT_DYNAMIC_CLASS(wxBufferedDC,wxMemoryDC)
  37 IMPLEMENT_ABSTRACT_CLASS(wxBufferedPaintDC,wxBufferedDC)
  38
  39 // ----------------------------------------------------------------------------
  40 // wxSharedDCBufferManager: helper class maintaining backing store bitmap
  41 // ----------------------------------------------------------------------------
  42
  43 class wxSharedDCBufferManager : public wxModule
  44 {
  45 public:
  46     wxSharedDCBufferManager() { }
  47
  48     virtual bool OnInit() { return true; }
  49     virtual void OnExit() { wxDELETE(ms_buffer); }
  50
  51     static wxBitmap* GetBuffer(int w, int h)
  52     {
  53         if ( ms_usingSharedBuffer )
  54             return new wxBitmap(w, h);
  55
  56         if ( !ms_buffer ||
  57                 w > ms_buffer->GetWidth() ||
  58                     h > ms_buffer->GetHeight() )
  59         {
  60             delete ms_buffer;
  61
  62             // we must always return a valid bitmap but creating a bitmap of
  63             // size 0 would fail, so create a 1*1 bitmap in this case
  64             if ( !w )
  65                 w = 1;
  66             if ( !h )
  67                 h = 1;
  68
  69             ms_buffer = new wxBitmap(w, h);
  70         }
  71
  72         ms_usingSharedBuffer = true;
  73         return ms_buffer;
  74     }
  75
  76     static void ReleaseBuffer(wxBitmap* buffer)
  77     {
  78         if ( buffer == ms_buffer )
  79         {
  80             wxASSERT_MSG( ms_usingSharedBuffer, wxT("shared buffer already released") );
  81             ms_usingSharedBuffer = false;
  82         }
  83         else
  84         {
  85             delete buffer;
  86         }
  87     }
  88
  89 private:
  90     static wxBitmap *ms_buffer;
  91     static bool ms_usingSharedBuffer;
  92
  93     DECLARE_DYNAMIC_CLASS(wxSharedDCBufferManager)
  94 };
  95
  96 wxBitmap* wxSharedDCBufferManager::ms_buffer = NULL;
  97 bool wxSharedDCBufferManager::ms_usingSharedBuffer = false;
  98
  99 IMPLEMENT_DYNAMIC_CLASS(wxSharedDCBufferManager, wxModule)
 100
 101 // ============================================================================
 102 // wxBufferedDC
 103 // ============================================================================
 104
 105 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
 106 {
 107     wxCHECK_RET( w >= -1 && h >= -1, "Invalid buffer size" );
 108
 109     if ( !m_buffer || !m_buffer->IsOk() )
 110     {
 111         if ( w == -1 || h == -1 )
 112             m_dc->GetSize(&w, &h);
 113
 114         m_buffer = wxSharedDCBufferManager::GetBuffer(w, h);
 115         m_style |= wxBUFFER_USES_SHARED_BUFFER;
 116         m_area.Set(w,h);
 117     }
 118     else
 119         m_area = m_buffer->GetSize();
 120
 121     SelectObject(*m_buffer);
 122
 123     // now that the DC is valid we can inherit the attributes (fonts, colours,
 124     // layout direction, ...) from the original DC
 125     if ( m_dc && m_dc->IsOk() )
 126         CopyAttributes(*m_dc);
 127 }
 128
 129 void wxBufferedDC::UnMask()
 130 {
 131     wxCHECK_RET( m_dc, wxT("no underlying wxDC?") );
 132     wxASSERT_MSG( m_buffer && m_buffer->IsOk(), wxT("invalid backing store") );
 133
 134     wxCoord x = 0,
 135             y = 0;
 136
 137     // Ensure the scale matches the device
 138     SetUserScale(1.0, 1.0);
 139
 140     if ( m_style & wxBUFFER_CLIENT_AREA )
 141         GetDeviceOrigin(&x, &y);
 142
 143     // It's possible that the buffer may be bigger than the area that needs to
 144     // be drawn (the client size of the window is smaller than the bitmap, or
 145     // a shared bitmap has been reused for a smaller area, etc.) so avoid
 146     // blitting too much if possible, but only use the real DC size if the
 147     // wxBUFFER_VIRTUAL_AREA style is not set.
 148     int width = m_area.GetWidth(),
 149         height = m_area.GetHeight();
 150
 151     if (! m_style & wxBUFFER_VIRTUAL_AREA)
 152     {
 153         int widthDC,
 154             heightDC;
 155         m_dc->GetSize(&widthDC, &heightDC);
 156         width = wxMin(width, widthDC);
 157         height = wxMin(height, heightDC);
 158     }
 159
 160     m_dc->Blit(0, 0, width, height, this, -x, -y);
 161     m_dc = NULL;
 162
 163     if ( m_style & wxBUFFER_USES_SHARED_BUFFER )
 164         wxSharedDCBufferManager::ReleaseBuffer(m_buffer);
 165 }