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 #include "wx/dcbuffer.h"
  28
  29 #ifndef WX_PRECOMP
  30     #include "wx/module.h"
  31 #endif
  32
  33 // ============================================================================
  34 // implementation
  35 // ============================================================================
  36
  37 IMPLEMENT_DYNAMIC_CLASS(wxBufferedDC,wxMemoryDC)
  38 IMPLEMENT_ABSTRACT_CLASS(wxBufferedPaintDC,wxBufferedDC)
  39
  40 // ----------------------------------------------------------------------------
  41 // wxSharedDCBufferManager: helper class maintaining backing store bitmap
  42 // ----------------------------------------------------------------------------
  43
  44 class wxSharedDCBufferManager : public wxModule
  45 {
  46 public:
  47     wxSharedDCBufferManager() { }
  48
  49     virtual bool OnInit() { return true; }
  50     virtual void OnExit() { wxDELETE(ms_buffer); }
  51
  52     static wxBitmap* GetBuffer(int w, int h)
  53     {
  54         if ( ms_usingSharedBuffer )
  55             return new wxBitmap(w, h);
  56
  57         if ( !ms_buffer ||
  58                 w > ms_buffer->GetWidth() ||
  59                     h > ms_buffer->GetHeight() )
  60         {
  61             delete ms_buffer;
  62
  63             // we must always return a valid bitmap but creating a bitmap of
  64             // size 0 would fail, so create a 1*1 bitmap in this case
  65             if ( !w )
  66                 w = 1;
  67             if ( !h )
  68                 h = 1;
  69
  70             ms_buffer = new wxBitmap(w, h);
  71         }
  72
  73         ms_usingSharedBuffer = true;
  74         return ms_buffer;
  75     }
  76
  77     static void ReleaseBuffer(wxBitmap* buffer)
  78     {
  79         if ( buffer == ms_buffer )
  80         {
  81             wxASSERT_MSG( ms_usingSharedBuffer, wxT("shared buffer already released") );
  82             ms_usingSharedBuffer = false;
  83         }
  84         else
  85         {
  86             delete buffer;
  87         }
  88     }
  89
  90 private:
  91     static wxBitmap *ms_buffer;
  92     static bool ms_usingSharedBuffer;
  93
  94     DECLARE_DYNAMIC_CLASS(wxSharedDCBufferManager)
  95 };
  96
  97 wxBitmap* wxSharedDCBufferManager::ms_buffer = NULL;
  98 bool wxSharedDCBufferManager::ms_usingSharedBuffer = false;
  99
 100 IMPLEMENT_DYNAMIC_CLASS(wxSharedDCBufferManager, wxModule)
 101
 102 // ============================================================================
 103 // wxBufferedDC
 104 // ============================================================================
 105
 106 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
 107 {
 108     wxCHECK_RET( w >= -1 && h >= -1, "Invalid buffer size" );
 109
 110     if ( !m_buffer || !m_buffer->IsOk() )
 111     {
 112         if ( w == -1 || h == -1 )
 113             m_dc->GetSize(&w, &h);
 114
 115         m_buffer = wxSharedDCBufferManager::GetBuffer(w, h);
 116         m_style |= wxBUFFER_USES_SHARED_BUFFER;
 117     }
 118
 119     SelectObject(*m_buffer);
 120
 121     // now that the DC is valid we can inherit the attributes (fonts, colours,
 122     // layout direction, ...) from the original DC
 123     if ( m_dc && m_dc->IsOk() )
 124         CopyAttributes(*m_dc);
 125 }
 126
 127 void wxBufferedDC::UnMask()
 128 {
 129     wxCHECK_RET( m_dc, wxT("no underlying wxDC?") );
 130     wxASSERT_MSG( m_buffer && m_buffer->IsOk(), wxT("invalid backing store") );
 131
 132     wxCoord x = 0,
 133             y = 0;
 134
 135     // Ensure the scale matches the device
 136     SetUserScale(1.0, 1.0);
 137
 138     if ( m_style & wxBUFFER_CLIENT_AREA )
 139         GetDeviceOrigin(&x, &y);
 140
 141     // avoid blitting too much: if we were created for a bigger bitmap (and
 142     // reused for a smaller one later) we should only blit the real bitmap area
 143     // and not the full allocated back buffer
 144     int widthDC,
 145         heightDC;
 146
 147     m_dc->GetSize(&widthDC, &heightDC);
 148
 149     int widthBuf = m_buffer->GetWidth(),
 150         heightBuf = m_buffer->GetHeight();
 151
 152     m_dc->Blit(0, 0,
 153                wxMin(widthDC, widthBuf), wxMin(heightDC, heightBuf),
 154                this,
 155                -x, -y);
 156     m_dc = NULL;
 157
 158     if ( m_style & wxBUFFER_USES_SHARED_BUFFER )
 159         wxSharedDCBufferManager::ReleaseBuffer(m_buffer);
 160 }