include/wx/dcbuffer.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/dcbuffer.h
   3 // Purpose:     wxBufferedDC class
   4 // Author:      Ron Lee <ron@debian.org>
   5 // Modified by: Vadim Zeitlin (refactored, added bg preservation)
   6 // Created:     16/03/02
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Ron Lee
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_DCBUFFER_H_
  13 #define _WX_DCBUFFER_H_
  14
  15 #include "wx/dcmemory.h"
  16 #include "wx/dcclient.h"
  17 #include "wx/window.h"
  18
  19 // ----------------------------------------------------------------------------
  20 // Double buffering helper.
  21 // ----------------------------------------------------------------------------
  22
  23 // Assumes the buffer bitmap covers the entire scrolled window,
  24 // and prepares the window DC accordingly
  25 #define wxBUFFER_VIRTUAL_AREA       0x01
  26
  27 // Assumes the buffer bitmap only covers the client area;
  28 // does not prepare the window DC
  29 #define wxBUFFER_CLIENT_AREA        0x02
  30
  31 class wxBufferedDC : public wxMemoryDC
  32 {
  33 public:
  34     // Default ctor, must subsequently call Init for two stage construction.
  35     wxBufferedDC() : m_dc( 0 ), m_style(0)
  36     {
  37     }
  38
  39     // Construct a wxBufferedDC using a user supplied buffer.
  40     wxBufferedDC(wxDC *dc, const wxBitmap &buffer, int style = wxBUFFER_CLIENT_AREA)
  41         : m_dc( dc ),
  42           m_buffer( buffer ),
  43           m_style(style)
  44     {
  45         UseBuffer();
  46     }
  47
  48     // Construct a wxBufferedDC with an internal buffer of 'area'
  49     // (where area is usually something like the size of the window
  50     // being buffered)
  51     wxBufferedDC(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  52         : m_dc( dc ),
  53           m_buffer( area.GetWidth(), area.GetHeight() ),
  54           m_style(style)
  55
  56     {
  57         UseBuffer();
  58     }
  59
  60     // default copy ctor ok.
  61
  62     // The usually desired  action in the dtor is to blit the buffer.
  63     virtual ~wxBufferedDC()
  64     {
  65         if ( m_dc ) UnMask();
  66     }
  67
  68     // These reimplement the actions of the ctors for two stage creation, but
  69     // are not used by the ctors themselves to save a few cpu cycles.
  70     void Init(wxDC *dc, const wxBitmap &buffer, int style = wxBUFFER_CLIENT_AREA)
  71     {
  72         wxASSERT_MSG( m_dc == 0 && m_buffer == wxNullBitmap,
  73                       _T("wxBufferedDC already initialised") );
  74         m_dc = dc;
  75         m_buffer = buffer;
  76         m_style = style;
  77         UseBuffer();
  78     }
  79
  80     void Init(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  81     {
  82         Init(dc, wxBitmap(area.GetWidth(), area.GetHeight()), style);
  83     }
  84
  85     // Blits the buffer to the dc, and detaches the dc from the buffer (so it
  86     // can be effectively used once only).
  87     //
  88     // Usually called in the dtor or by the dtor of derived classes if the
  89     // BufferedDC must blit before the derived class (which may own the dc it's
  90     // blitting to) is destroyed.
  91     void UnMask()
  92     {
  93         wxASSERT_MSG( m_dc != 0,
  94                       _T("No underlying DC associated with wxBufferedDC (anymore)") );
  95
  96         wxCoord x=0, y=0;
  97
  98         if (m_style & wxBUFFER_CLIENT_AREA)
  99             GetDeviceOrigin(& x, & y);
 100
 101         m_dc->Blit( 0, 0,
 102                     m_buffer.GetWidth(), m_buffer.GetHeight(), this,
 103                     -x, -y );
 104         m_dc = NULL;
 105     }
 106
 107     // Set and get the style
 108     void SetStyle(int style) { m_style = style; }
 109     int GetStyle() const { return m_style; }
 110
 111 private:
 112     // check that the bitmap is valid and use it
 113     void UseBuffer()
 114     {
 115         wxASSERT_MSG( m_buffer.Ok(), _T("invalid bitmap in wxBufferedDC") );
 116
 117         SelectObject(m_buffer);
 118     }
 119
 120     // the underlying DC to which we copy everything drawn on this one in
 121     // UnMask()
 122     //
 123     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
 124     //     could probably be a reference.
 125     wxDC *m_dc;
 126
 127     // the buffer (selected in this DC)
 128     wxBitmap m_buffer;
 129
 130     // the buffering style
 131     int m_style;
 132
 133     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 134 };
 135
 136
 137 // ----------------------------------------------------------------------------
 138 // Double buffered PaintDC.
 139 // ----------------------------------------------------------------------------
 140
 141 // Creates a double buffered wxPaintDC, optionally allowing the
 142 // user to specify their own buffer to use.
 143 class wxBufferedPaintDC : public wxBufferedDC
 144 {
 145 public:
 146     // If no bitmap is supplied by the user, a temporary one will be created.
 147     wxBufferedPaintDC(wxWindow *window, const wxBitmap& buffer, int style = wxBUFFER_CLIENT_AREA)
 148         : m_paintdc(window)
 149     {
 150         // If we're buffering the virtual window, scale the paint DC as well
 151         if (style & wxBUFFER_VIRTUAL_AREA)
 152             window->PrepareDC( m_paintdc );
 153
 154         if( buffer != wxNullBitmap )
 155             Init(&m_paintdc, buffer, style);
 156         else
 157             Init(&m_paintdc, window->GetClientSize(), style);
 158     }
 159
 160     // If no bitmap is supplied by the user, a temporary one will be created.
 161     wxBufferedPaintDC(wxWindow *window, int style = wxBUFFER_CLIENT_AREA)
 162         : m_paintdc(window)
 163     {
 164         // If we're using the virtual window, scale the paint DC as well
 165         if (style & wxBUFFER_VIRTUAL_AREA)
 166             window->PrepareDC( m_paintdc );
 167
 168         Init(&m_paintdc, window->GetClientSize(), style);
 169     }
 170
 171     // default copy ctor ok.
 172
 173     virtual ~wxBufferedPaintDC()
 174     {
 175         // We must UnMask here, else by the time the base class
 176         // does it, the PaintDC will have already been destroyed.
 177         UnMask();
 178     }
 179
 180 private:
 181     wxPaintDC m_paintdc;
 182
 183     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 184 };
 185
 186 #endif  // _WX_DCBUFFER_H_
 187