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 #if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
  16     #pragma interface "dcbuffer.h"
  17 #endif
  18
  19 #include "wx/dcmemory.h"
  20 #include "wx/dcclient.h"
  21
  22 // flags for wxBufferedDC ctor/Init()
  23 enum
  24 {
  25     // this is more efficient and hence default
  26     wxBUFFER_DC_OVERWRITE_BG = 0,
  27
  28     // preserve the old background: more time consuming
  29     wxBUFFER_DC_PRESERVE_BG = 1,
  30
  31
  32     // flags used by default
  33     wxBUFFER_DC_DEFAULT = wxBUFFER_DC_OVERWRITE_BG
  34 };
  35
  36 // ----------------------------------------------------------------------------
  37 // Double buffering helper.
  38 // ----------------------------------------------------------------------------
  39
  40 class WXDLLIMPEXP_ADV wxBufferedDC : public wxMemoryDC
  41 {
  42 public:
  43     // Default ctor, must subsequently call Init for two stage construction.
  44     wxBufferedDC() : m_dc( 0 )
  45     {
  46     }
  47
  48     // Construct a wxBufferedDC using a user supplied buffer.
  49     wxBufferedDC(wxDC *dc, const wxBitmap &buffer);
  50
  51     // Construct a wxBufferedDC with an internal buffer of 'area'
  52     // (where area is usually something like the size of the window
  53     // being buffered)
  54     wxBufferedDC(wxDC *dc, const wxSize &area, int flags = wxBUFFER_DC_DEFAULT);
  55
  56     // default copy ctor ok.
  57
  58     // The usually desired  action in the dtor is to blit the buffer.
  59     virtual ~wxBufferedDC() { if ( m_dc ) UnMask(); }
  60
  61     // These reimplement the actions of the ctors for two stage creation, but
  62     // are not used by the ctors themselves to save a few cpu cycles.
  63     void Init(wxDC *dc, const wxBitmap &bitmap);
  64     void Init(wxDC *dc, const wxSize &area, int flags = wxBUFFER_DC_DEFAULT);
  65
  66     // Blits the buffer to the dc, and detaches the dc from the buffer (so it
  67     // can be effectively used once only).
  68     //
  69     // Usually called in the dtor or by the dtor of derived classes if the
  70     // BufferedDC must blit before the derived class (which may own the dc it's
  71     // blitting to) is destroyed.
  72     void UnMask();
  73
  74 private:
  75     // check that the bitmap is valid and use it
  76     void UseBuffer()
  77     {
  78         wxASSERT_MSG( m_buffer.Ok(), _T("invalid bitmap in wxBufferedDC") );
  79
  80         SelectObject(m_buffer);
  81     }
  82
  83     // preserve the background if necessary
  84     void SaveBg(const wxSize& area, int flags)
  85     {
  86         if ( flags & wxBUFFER_DC_PRESERVE_BG )
  87         {
  88             Blit(0, 0, area.GetWidth(), area.GetHeight(), m_dc, 0, 0);
  89         }
  90     }
  91
  92     // the underlying DC to which we copy everything drawn on this one in
  93     // UnMask()
  94     //
  95     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
  96     //     could probably be a reference.
  97     wxDC *m_dc;
  98
  99     // the buffer (selected in this DC)
 100     wxBitmap m_buffer;
 101
 102     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 103 };
 104
 105
 106 // ----------------------------------------------------------------------------
 107 // Double buffered PaintDC.
 108 // ----------------------------------------------------------------------------
 109
 110 // Creates a double buffered wxPaintDC, optionally allowing the
 111 // user to specify their own buffer to use.
 112 class WXDLLIMPEXP_ADV wxBufferedPaintDC : public wxBufferedDC
 113 {
 114 public:
 115     // this ctor creates a bitmap of the size of the window for buffering
 116     wxBufferedPaintDC(wxWindow *window, int flags = wxBUFFER_DC_DEFAULT)
 117         : m_paintdc(window)
 118     {
 119         Init(&m_paintdc, window->GetClientSize(), flags);
 120
 121         Prepare(window);
 122     }
 123
 124     // the bitmap must be valid here
 125     wxBufferedPaintDC(wxWindow *window, const wxBitmap& buffer)
 126         : m_paintdc(window)
 127     {
 128         Init(&m_paintdc, buffer);
 129
 130         Prepare(window);
 131     }
 132
 133     // default copy ctor ok.
 134
 135     virtual ~wxBufferedPaintDC()
 136     {
 137         // We must UnMask here, else by the time the base class
 138         // does it, the PaintDC will have already been destroyed.
 139         UnMask();
 140     }
 141
 142 private:
 143     // prepare the underlying DC
 144     void Prepare(wxWindow *window)
 145     {
 146         window->PrepareDC(m_paintdc);
 147     }
 148
 149     wxPaintDC m_paintdc;
 150
 151     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 152 };
 153
 154 #endif  // _WX_DCBUFFER_H_
 155