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 // Split platforms into two groups - those which have well-working
  20 // double-buffering by default, and those which do not.
  21 #if defined(__WXMAC__) || defined(__WXGTK20__)
  22     #define wxALWAYS_NATIVE_DOUBLE_BUFFER       1
  23 #else
  24     #define wxALWAYS_NATIVE_DOUBLE_BUFFER       0
  25 #endif
  26
  27
  28 // ----------------------------------------------------------------------------
  29 // Double buffering helper.
  30 // ----------------------------------------------------------------------------
  31
  32 // Assumes the buffer bitmap covers the entire scrolled window,
  33 // and prepares the window DC accordingly
  34 #define wxBUFFER_VIRTUAL_AREA       0x01
  35
  36 // Assumes the buffer bitmap only covers the client area;
  37 // does not prepare the window DC
  38 #define wxBUFFER_CLIENT_AREA        0x02
  39
  40 class wxBufferedDC : public wxMemoryDC
  41 {
  42 public:
  43     // Default ctor, must subsequently call Init for two stage construction.
  44     wxBufferedDC() : m_dc( 0 ), m_style(0)
  45     {
  46     }
  47
  48     // Construct a wxBufferedDC using a user supplied buffer.
  49     wxBufferedDC(wxDC *dc,
  50                  const wxBitmap &buffer = wxNullBitmap,
  51                  int style = wxBUFFER_CLIENT_AREA)
  52         : m_dc( dc ),
  53           m_buffer( buffer ),
  54           m_style(style)
  55     {
  56         UseBuffer();
  57     }
  58
  59     // Construct a wxBufferedDC with an internal buffer of 'area'
  60     // (where area is usually something like the size of the window
  61     // being buffered)
  62     wxBufferedDC(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  63         : m_dc( dc ),
  64           m_buffer( area.GetWidth(), area.GetHeight() ),
  65           m_style(style)
  66
  67     {
  68         UseBuffer();
  69     }
  70
  71     // default copy ctor ok.
  72
  73     // The usually desired  action in the dtor is to blit the buffer.
  74     virtual ~wxBufferedDC()
  75     {
  76         if ( m_dc ) UnMask();
  77     }
  78
  79     // These reimplement the actions of the ctors for two stage creation, but
  80     // are not used by the ctors themselves to save a few cpu cycles.
  81     void Init(wxDC *dc,
  82               const wxBitmap &buffer=wxNullBitmap,
  83               int style = wxBUFFER_CLIENT_AREA)
  84     {
  85         wxASSERT_MSG( m_dc == 0 && m_buffer == wxNullBitmap,
  86                       _T("wxBufferedDC already initialised") );
  87         m_dc = dc;
  88         m_buffer = buffer;
  89         m_style = style;
  90         UseBuffer();
  91     }
  92
  93     void Init(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  94     {
  95         Init(dc, wxBitmap(area.GetWidth(), area.GetHeight()), style);
  96     }
  97
  98     // Blits the buffer to the dc, and detaches the dc from the buffer (so it
  99     // can be effectively used once only).
 100     //
 101     // Usually called in the dtor or by the dtor of derived classes if the
 102     // BufferedDC must blit before the derived class (which may own the dc it's
 103     // blitting to) is destroyed.
 104     void UnMask()
 105     {
 106         wxASSERT_MSG( m_dc != 0,
 107                       _T("No underlying DC associated with wxBufferedDC (anymore)") );
 108
 109         wxCoord x=0, y=0;
 110
 111         if (m_style & wxBUFFER_CLIENT_AREA)
 112             GetDeviceOrigin(&x, &y);
 113
 114         m_dc->Blit( 0, 0,
 115                     m_buffer.GetWidth(), m_buffer.GetHeight(), this,
 116                     -x, -y );
 117         m_dc = NULL;
 118     }
 119
 120     // Set and get the style
 121     void SetStyle(int style) { m_style = style; }
 122     int GetStyle() const { return m_style; }
 123
 124 private:
 125     // check that the bitmap is valid and use it
 126     void UseBuffer()
 127     {
 128         if (!m_buffer.Ok())
 129         {
 130             wxCoord w, h;
 131             m_dc->GetSize(&w, &h);
 132             m_buffer = wxBitmap(w, h);
 133         }
 134
 135         SelectObject(m_buffer);
 136     }
 137
 138     // the underlying DC to which we copy everything drawn on this one in
 139     // UnMask()
 140     //
 141     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
 142     //     could probably be a reference.
 143     wxDC *m_dc;
 144
 145     // the buffer (selected in this DC)
 146     wxBitmap m_buffer;
 147
 148     // the buffering style
 149     int m_style;
 150
 151     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 152 };
 153
 154
 155 // ----------------------------------------------------------------------------
 156 // Double buffered PaintDC.
 157 // ----------------------------------------------------------------------------
 158
 159 // Creates a double buffered wxPaintDC, optionally allowing the
 160 // user to specify their own buffer to use.
 161 class wxBufferedPaintDC : public wxBufferedDC
 162 {
 163 public:
 164     // If no bitmap is supplied by the user, a temporary one will be created.
 165     wxBufferedPaintDC(wxWindow *window, const wxBitmap& buffer, int style = wxBUFFER_CLIENT_AREA)
 166         : m_paintdc(window)
 167     {
 168         // If we're buffering the virtual window, scale the paint DC as well
 169         if (style & wxBUFFER_VIRTUAL_AREA)
 170             window->PrepareDC( m_paintdc );
 171
 172         if( buffer != wxNullBitmap )
 173             Init(&m_paintdc, buffer, style);
 174         else
 175             Init(&m_paintdc, window->GetClientSize(), style);
 176     }
 177
 178     // If no bitmap is supplied by the user, a temporary one will be created.
 179     wxBufferedPaintDC(wxWindow *window, int style = wxBUFFER_CLIENT_AREA)
 180         : m_paintdc(window)
 181     {
 182         // If we're using the virtual window, scale the paint DC as well
 183         if (style & wxBUFFER_VIRTUAL_AREA)
 184             window->PrepareDC( m_paintdc );
 185
 186         Init(&m_paintdc, window->GetClientSize(), style);
 187     }
 188
 189     // default copy ctor ok.
 190
 191     virtual ~wxBufferedPaintDC()
 192     {
 193         // We must UnMask here, else by the time the base class
 194         // does it, the PaintDC will have already been destroyed.
 195         UnMask();
 196     }
 197
 198 private:
 199     wxPaintDC m_paintdc;
 200
 201     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 202 };
 203
 204
 205
 206 //
 207 // wxAutoBufferedPaintDC is a wxPaintDC in toolkits which have double-
 208 // buffering by default. Otherwise it is a wxBufferedPaintDC. Thus,
 209 // you can only expect it work with a simple constructor that
 210 // accepts single wxWindow* argument.
 211 //
 212 #if wxALWAYS_NATIVE_DOUBLE_BUFFER
 213     #define wxAutoBufferedPaintDCBase           wxPaintDC
 214 #else
 215     #define wxAutoBufferedPaintDCBase           wxBufferedPaintDC
 216 #endif
 217
 218
 219 #ifdef __WXDEBUG__
 220
 221 class wxAutoBufferedPaintDC : public wxAutoBufferedPaintDCBase
 222 {
 223 public:
 224
 225     wxAutoBufferedPaintDC(wxWindow* win)
 226         : wxAutoBufferedPaintDCBase(win)
 227     {
 228         TestWinStyle(win);
 229     }
 230
 231     virtual ~wxAutoBufferedPaintDC() { }
 232
 233 private:
 234
 235     void TestWinStyle(wxWindow* win)
 236     {
 237         // Help the user to get the double-buffering working properly.
 238         wxASSERT_MSG( win->GetBackgroundStyle() == wxBG_STYLE_CUSTOM,
 239                       wxT("In constructor, you need to call GetBackgroundStyle(wxBG_STYLE_CUSTOM), ")
 240                       wxT("and also, if needed, paint the background manually in the paint event handler."));
 241     }
 242
 243     DECLARE_NO_COPY_CLASS(wxAutoBufferedPaintDC)
 244 };
 245
 246 #else // !__WXDEBUG__
 247
 248 // In release builds, just use typedef
 249 typedef wxAutoBufferedPaintDCBase wxAutoBufferedPaintDC;
 250
 251 #endif
 252
 253
 254 // Check if the window is natively double buffered and will return a wxPaintDC
 255 // if it is, a wxBufferedPaintDC otherwise.  It is the caller's responsibility
 256 // to delete the wxDC pointer when finished with it.
 257 inline wxDC* wxAutoBufferedPaintDCFactory(wxWindow* window)
 258 {
 259     if ( window->IsDoubleBuffered() )
 260         return new wxPaintDC(window);
 261     else
 262         return new wxBufferedPaintDC(window);
 263 }
 264
 265
 266 #endif  // _WX_DCBUFFER_H_