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__) || defined(__WXDFB__)
  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 WXDLLEXPORT wxBufferedDC : public wxMemoryDC
  41 {
  42 public:
  43     // Default ctor, must subsequently call Init for two stage construction.
  44     wxBufferedDC()
  45         : m_dc(NULL),
  46           m_buffer(NULL),
  47           m_style(0)
  48     {
  49     }
  50
  51     // Construct a wxBufferedDC using a user supplied buffer.
  52     wxBufferedDC(wxDC *dc,
  53                  const wxBitmap& buffer = wxNullBitmap,
  54                  int style = wxBUFFER_CLIENT_AREA)
  55         : m_dc(NULL),
  56           m_buffer(NULL)
  57     {
  58         Init(dc, buffer, style);
  59     }
  60
  61     // Construct a wxBufferedDC with an internal buffer of 'area'
  62     // (where area is usually something like the size of the window
  63     // being buffered)
  64     wxBufferedDC(wxDC *dc, const wxSize& area, int style = wxBUFFER_CLIENT_AREA)
  65         : m_dc(NULL),
  66           m_buffer(NULL)
  67
  68     {
  69         Init(dc, area, style);
  70     }
  71
  72     // The usually desired  action in the dtor is to blit the buffer.
  73     virtual ~wxBufferedDC()
  74     {
  75         if ( m_dc )
  76             UnMask();
  77     }
  78
  79     // These reimplement the actions of the ctors for two stage creation
  80     void Init(wxDC *dc,
  81               const wxBitmap& buffer = wxNullBitmap,
  82               int style = wxBUFFER_CLIENT_AREA)
  83     {
  84         InitCommon(dc, style);
  85
  86         m_buffer = &buffer;
  87
  88         UseBuffer();
  89     }
  90
  91     void Init(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  92     {
  93         InitCommon(dc, style);
  94
  95         UseBuffer(area.x, area.y);
  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         wxCHECK_RET( m_dc, _T("No underlying DC in wxBufferedDC") );
 107
 108         wxCoord x = 0,
 109                 y = 0;
 110
 111         if ( m_style & wxBUFFER_CLIENT_AREA )
 112             GetDeviceOrigin(&x, &y);
 113
 114         m_dc->Blit(0, 0, m_buffer->GetWidth(), m_buffer->GetHeight(),
 115                    this, -x, -y );
 116         m_dc = NULL;
 117     }
 118
 119     // Set and get the style
 120     void SetStyle(int style) { m_style = style; }
 121     int GetStyle() const { return m_style; }
 122
 123 private:
 124     // common part of Init()s
 125     void InitCommon(wxDC *dc, int style)
 126     {
 127         wxASSERT_MSG( !m_dc && !m_buffer, _T("wxBufferedDC already initialised") );
 128         wxCHECK_RET( dc, _T("can't associate NULL DC with wxBufferedDC") );
 129
 130         m_dc = dc;
 131         m_style = style;
 132
 133         // inherit the same layout direction as the original DC
 134         SetLayoutDirection(dc->GetLayoutDirection());
 135     }
 136
 137     // check that the bitmap is valid and use it
 138     void UseBuffer(wxCoord w = -1, wxCoord h = -1);
 139
 140     // the underlying DC to which we copy everything drawn on this one in
 141     // UnMask()
 142     //
 143     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
 144     //     could probably be a reference.
 145     wxDC *m_dc;
 146
 147     // the buffer (selected in this DC)
 148     const wxBitmap *m_buffer;
 149
 150     // the buffering style
 151     int m_style;
 152
 153     DECLARE_DYNAMIC_CLASS(wxBufferedDC)
 154     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 155 };
 156
 157
 158 // ----------------------------------------------------------------------------
 159 // Double buffered PaintDC.
 160 // ----------------------------------------------------------------------------
 161
 162 // Creates a double buffered wxPaintDC, optionally allowing the
 163 // user to specify their own buffer to use.
 164 class WXDLLEXPORT wxBufferedPaintDC : public wxBufferedDC
 165 {
 166 public:
 167     // If no bitmap is supplied by the user, a temporary one will be created.
 168     wxBufferedPaintDC(wxWindow *window, const wxBitmap& buffer, int style = wxBUFFER_CLIENT_AREA)
 169         : m_paintdc(window)
 170     {
 171         // If we're buffering the virtual window, scale the paint DC as well
 172         if (style & wxBUFFER_VIRTUAL_AREA)
 173             window->PrepareDC( m_paintdc );
 174
 175         if( buffer != wxNullBitmap )
 176             Init(&m_paintdc, buffer, style);
 177         else
 178             Init(&m_paintdc, window->GetClientSize(), style);
 179     }
 180
 181     // If no bitmap is supplied by the user, a temporary one will be created.
 182     wxBufferedPaintDC(wxWindow *window, int style = wxBUFFER_CLIENT_AREA)
 183         : m_paintdc(window)
 184     {
 185         // If we're using the virtual window, scale the paint DC as well
 186         if (style & wxBUFFER_VIRTUAL_AREA)
 187             window->PrepareDC( m_paintdc );
 188
 189         Init(&m_paintdc, window->GetClientSize(), style);
 190     }
 191
 192     // default copy ctor ok.
 193
 194     virtual ~wxBufferedPaintDC()
 195     {
 196         // We must UnMask here, else by the time the base class
 197         // does it, the PaintDC will have already been destroyed.
 198         UnMask();
 199     }
 200
 201 private:
 202     wxPaintDC m_paintdc;
 203
 204     DECLARE_ABSTRACT_CLASS(wxBufferedPaintDC)
 205     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 206 };
 207
 208
 209
 210 //
 211 // wxAutoBufferedPaintDC is a wxPaintDC in toolkits which have double-
 212 // buffering by default. Otherwise it is a wxBufferedPaintDC. Thus,
 213 // you can only expect it work with a simple constructor that
 214 // accepts single wxWindow* argument.
 215 //
 216 #if wxALWAYS_NATIVE_DOUBLE_BUFFER
 217     #define wxAutoBufferedPaintDCBase           wxPaintDC
 218 #else
 219     #define wxAutoBufferedPaintDCBase           wxBufferedPaintDC
 220 #endif
 221
 222
 223 #ifdef __WXDEBUG__
 224
 225 class wxAutoBufferedPaintDC : public wxAutoBufferedPaintDCBase
 226 {
 227 public:
 228
 229     wxAutoBufferedPaintDC(wxWindow* win)
 230         : wxAutoBufferedPaintDCBase(win)
 231     {
 232         TestWinStyle(win);
 233     }
 234
 235     virtual ~wxAutoBufferedPaintDC() { }
 236
 237 private:
 238
 239     void TestWinStyle(wxWindow* win)
 240     {
 241         // Help the user to get the double-buffering working properly.
 242         wxASSERT_MSG( win->GetBackgroundStyle() == wxBG_STYLE_CUSTOM,
 243                       wxT("In constructor, you need to call SetBackgroundStyle(wxBG_STYLE_CUSTOM), ")
 244                       wxT("and also, if needed, paint the background manually in the paint event handler."));
 245     }
 246
 247     DECLARE_NO_COPY_CLASS(wxAutoBufferedPaintDC)
 248 };
 249
 250 #else // !__WXDEBUG__
 251
 252 // In release builds, just use typedef
 253 typedef wxAutoBufferedPaintDCBase wxAutoBufferedPaintDC;
 254
 255 #endif
 256
 257
 258 // Check if the window is natively double buffered and will return a wxPaintDC
 259 // if it is, a wxBufferedPaintDC otherwise.  It is the caller's responsibility
 260 // to delete the wxDC pointer when finished with it.
 261 inline wxDC* wxAutoBufferedPaintDCFactory(wxWindow* window)
 262 {
 263     if ( window->IsDoubleBuffered() )
 264         return new wxPaintDC(window);
 265     else
 266         return new wxBufferedPaintDC(window);
 267 }
 268
 269 #endif  // _WX_DCBUFFER_H_