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 class wxBufferedDC : public wxMemoryDC
  24 {
  25 public:
  26     // Default ctor, must subsequently call Init for two stage construction.
  27     wxBufferedDC() : m_dc( 0 )
  28     {
  29     }
  30
  31     // Construct a wxBufferedDC using a user supplied buffer.
  32     wxBufferedDC(wxDC *dc, const wxBitmap &buffer)
  33         : m_dc( dc ),
  34           m_buffer( buffer )
  35     {
  36         UseBuffer();
  37     }
  38
  39     // Construct a wxBufferedDC with an internal buffer of 'area'
  40     // (where area is usually something like the size of the window
  41     // being buffered)
  42     wxBufferedDC(wxDC *dc, const wxSize &area)
  43         : m_dc( dc ),
  44           m_buffer( area.GetWidth(), area.GetHeight() )
  45     {
  46         UseBuffer();
  47     }
  48
  49     // default copy ctor ok.
  50
  51     // The usually desired  action in the dtor is to blit the buffer.
  52     virtual ~wxBufferedDC()
  53     {
  54         if ( m_dc ) UnMask();
  55     }
  56
  57     // These reimplement the actions of the ctors for two stage creation, but
  58     // are not used by the ctors themselves to save a few cpu cycles.
  59     void Init(wxDC *dc, const wxBitmap &buffer)
  60     {
  61         wxASSERT_MSG( m_dc == 0 && m_buffer == wxNullBitmap,
  62                       _T("wxBufferedDC already initialised") );
  63         m_dc = dc;
  64         m_buffer = buffer;
  65         UseBuffer();
  66     }
  67
  68     void Init(wxDC *dc, const wxSize &area)
  69     {
  70         Init(dc, wxBitmap(area.GetWidth(), area.GetHeight()));
  71     }
  72
  73     // Blits the buffer to the dc, and detaches the dc from the buffer (so it
  74     // can be effectively used once only).
  75     //
  76     // Usually called in the dtor or by the dtor of derived classes if the
  77     // BufferedDC must blit before the derived class (which may own the dc it's
  78     // blitting to) is destroyed.
  79     void UnMask()
  80     {
  81         wxASSERT_MSG( m_dc != 0,
  82                       _T("No underlying DC associated with wxBufferedDC (anymore)") );
  83
  84         wxCoord x, y;
  85         GetDeviceOrigin(& x, & y);
  86
  87         m_dc->Blit( 0, 0,
  88                     m_buffer.GetWidth(), m_buffer.GetHeight(), this,
  89                     -x, -y );
  90         m_dc = NULL;
  91     }
  92
  93 private:
  94     // check that the bitmap is valid and use it
  95     void UseBuffer()
  96     {
  97         wxASSERT_MSG( m_buffer.Ok(), _T("invalid bitmap in wxBufferedDC") );
  98
  99         SelectObject(m_buffer);
 100     }
 101
 102     // the underlying DC to which we copy everything drawn on this one in
 103     // UnMask()
 104     //
 105     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
 106     //     could probably be a reference.
 107     wxDC *m_dc;
 108
 109     // the buffer (selected in this DC)
 110     wxBitmap m_buffer;
 111
 112     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 113 };
 114
 115
 116 // ----------------------------------------------------------------------------
 117 // Double buffered PaintDC.
 118 // ----------------------------------------------------------------------------
 119
 120 // Creates a double buffered wxPaintDC, optionally allowing the
 121 // user to specify their own buffer to use.
 122 class wxBufferedPaintDC : public wxBufferedDC
 123 {
 124 public:
 125     // If no bitmap is supplied by the user, a temporary one wil; be created.
 126     wxBufferedPaintDC(wxWindow *window, const wxBitmap& buffer = wxNullBitmap)
 127         : m_paintdc(window)
 128     {
 129         if( buffer != wxNullBitmap )
 130             Init(&m_paintdc, buffer);
 131         else
 132             Init(&m_paintdc, window->GetClientSize());
 133     }
 134
 135     // default copy ctor ok.
 136
 137     virtual ~wxBufferedPaintDC()
 138     {
 139         // We must UnMask here, else by the time the base class
 140         // does it, the PaintDC will have already been destroyed.
 141         UnMask();
 142     }
 143
 144 private:
 145     wxPaintDC m_paintdc;
 146
 147     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 148 };
 149
 150 #endif  // _WX_DCBUFFER_H_
 151