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 // Set when not using specific buffer bitmap. Note that this
  41 // is private style and not returned by GetStyle.
  42 #define wxBUFFER_USES_SHARED_BUFFER 0x04
  43
  44 class WXDLLIMPEXP_CORE wxBufferedDC : public wxMemoryDC
  45 {
  46 public:
  47     // Default ctor, must subsequently call Init for two stage construction.
  48     wxBufferedDC()
  49         : m_dc(NULL),
  50           m_buffer(NULL),
  51           m_style(0)
  52     {
  53     }
  54
  55     // Construct a wxBufferedDC using a user supplied buffer.
  56     wxBufferedDC(wxDC *dc,
  57                  wxBitmap& buffer = wxNullBitmap,
  58                  int style = wxBUFFER_CLIENT_AREA)
  59         : m_dc(NULL), m_buffer(NULL)
  60     {
  61         Init(dc, buffer, style);
  62     }
  63
  64     // Construct a wxBufferedDC with an internal buffer of 'area'
  65     // (where area is usually something like the size of the window
  66     // being buffered)
  67     wxBufferedDC(wxDC *dc, const wxSize& area, int style = wxBUFFER_CLIENT_AREA)
  68         : m_dc(NULL), m_buffer(NULL)
  69     {
  70         Init(dc, area, style);
  71     }
  72
  73     // The usually desired  action in the dtor is to blit the buffer.
  74     virtual ~wxBufferedDC()
  75     {
  76         if ( m_dc )
  77             UnMask();
  78     }
  79
  80     // These reimplement the actions of the ctors for two stage creation
  81     void Init(wxDC *dc,
  82               wxBitmap& buffer = wxNullBitmap,
  83               int style = wxBUFFER_CLIENT_AREA)
  84     {
  85         InitCommon(dc, style);
  86
  87         m_buffer = &buffer;
  88
  89         UseBuffer();
  90     }
  91
  92     void Init(wxDC *dc, const wxSize &area, int style = wxBUFFER_CLIENT_AREA)
  93     {
  94         InitCommon(dc, style);
  95
  96         UseBuffer(area.x, area.y);
  97     }
  98
  99     // Blits the buffer to the dc, and detaches the dc from the buffer (so it
 100     // can be effectively used once only).
 101     //
 102     // Usually called in the dtor or by the dtor of derived classes if the
 103     // BufferedDC must blit before the derived class (which may own the dc it's
 104     // blitting to) is destroyed.
 105     void UnMask();
 106
 107     // Set and get the style
 108     void SetStyle(int style) { m_style = style; }
 109     int GetStyle() const { return m_style & ~wxBUFFER_USES_SHARED_BUFFER; }
 110
 111 private:
 112     // common part of Init()s
 113     void InitCommon(wxDC *dc, int style)
 114     {
 115         wxASSERT_MSG( !m_dc, _T("wxBufferedDC already initialised") );
 116
 117         m_dc = dc;
 118         m_style = style;
 119
 120         // inherit the same layout direction as the original DC
 121         if (dc && dc->IsOk())
 122             SetLayoutDirection(dc->GetLayoutDirection());
 123     }
 124
 125     // check that the bitmap is valid and use it
 126     void UseBuffer(wxCoord w = -1, wxCoord h = -1);
 127
 128     // the underlying DC to which we copy everything drawn on this one in
 129     // UnMask()
 130     //
 131     // NB: Without the existence of a wxNullDC, this must be a pointer, else it
 132     //     could probably be a reference.
 133     wxDC *m_dc;
 134
 135     // the buffer (selected in this DC), initially invalid
 136     wxBitmap *m_buffer;
 137
 138     // the buffering style
 139     int m_style;
 140
 141     DECLARE_DYNAMIC_CLASS(wxBufferedDC)
 142     DECLARE_NO_COPY_CLASS(wxBufferedDC)
 143 };
 144
 145
 146 // ----------------------------------------------------------------------------
 147 // Double buffered PaintDC.
 148 // ----------------------------------------------------------------------------
 149
 150 // Creates a double buffered wxPaintDC, optionally allowing the
 151 // user to specify their own buffer to use.
 152 class WXDLLIMPEXP_CORE wxBufferedPaintDC : public wxBufferedDC
 153 {
 154 public:
 155     // If no bitmap is supplied by the user, a temporary one will be created.
 156     wxBufferedPaintDC(wxWindow *window, wxBitmap& buffer, int style = wxBUFFER_CLIENT_AREA)
 157         : m_paintdc(window)
 158     {
 159         // If we're buffering the virtual window, scale the paint DC as well
 160         if (style & wxBUFFER_VIRTUAL_AREA)
 161             window->PrepareDC( m_paintdc );
 162
 163         if( buffer.IsOk() )
 164             Init(&m_paintdc, buffer, style);
 165         else
 166             Init(&m_paintdc, GetBufferedSize(window, style), style);
 167     }
 168
 169     // If no bitmap is supplied by the user, a temporary one will be created.
 170     wxBufferedPaintDC(wxWindow *window, int style = wxBUFFER_CLIENT_AREA)
 171         : m_paintdc(window)
 172     {
 173         // If we're using the virtual window, scale the paint DC as well
 174         if (style & wxBUFFER_VIRTUAL_AREA)
 175             window->PrepareDC( m_paintdc );
 176
 177         Init(&m_paintdc, GetBufferedSize(window, style), style);
 178     }
 179
 180     // default copy ctor ok.
 181
 182     virtual ~wxBufferedPaintDC()
 183     {
 184         // We must UnMask here, else by the time the base class
 185         // does it, the PaintDC will have already been destroyed.
 186         UnMask();
 187     }
 188
 189 protected:
 190     // return the size needed by the buffer: this depends on whether we're
 191     // buffering just the currently shown part or the total (scrolled) window
 192     static wxSize GetBufferedSize(wxWindow *window, int style)
 193     {
 194         return style & wxBUFFER_VIRTUAL_AREA ? window->GetVirtualSize()
 195                                              : window->GetClientSize();
 196     }
 197
 198 private:
 199     wxPaintDC m_paintdc;
 200
 201     DECLARE_ABSTRACT_CLASS(wxBufferedPaintDC)
 202     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 203 };
 204
 205
 206
 207 //
 208 // wxAutoBufferedPaintDC is a wxPaintDC in toolkits which have double-
 209 // buffering by default. Otherwise it is a wxBufferedPaintDC. Thus,
 210 // you can only expect it work with a simple constructor that
 211 // accepts single wxWindow* argument.
 212 //
 213 #if wxALWAYS_NATIVE_DOUBLE_BUFFER
 214     #define wxAutoBufferedPaintDCBase           wxPaintDC
 215 #else
 216     #define wxAutoBufferedPaintDCBase           wxBufferedPaintDC
 217 #endif
 218
 219
 220 #ifdef __WXDEBUG__
 221
 222 class WXDLLIMPEXP_CORE wxAutoBufferedPaintDC : public wxAutoBufferedPaintDCBase
 223 {
 224 public:
 225
 226     wxAutoBufferedPaintDC(wxWindow* win)
 227         : wxAutoBufferedPaintDCBase(win)
 228     {
 229         TestWinStyle(win);
 230     }
 231
 232     virtual ~wxAutoBufferedPaintDC() { }
 233
 234 private:
 235
 236     void TestWinStyle(wxWindow* win)
 237     {
 238         // Help the user to get the double-buffering working properly.
 239         wxASSERT_MSG( win->GetBackgroundStyle() == wxBG_STYLE_CUSTOM,
 240                       wxT("In constructor, you need to call SetBackgroundStyle(wxBG_STYLE_CUSTOM), ")
 241                       wxT("and also, if needed, paint the background manually in the paint event handler."));
 242     }
 243
 244     DECLARE_NO_COPY_CLASS(wxAutoBufferedPaintDC)
 245 };
 246
 247 #else // !__WXDEBUG__
 248
 249 // In release builds, just use typedef
 250 typedef wxAutoBufferedPaintDCBase wxAutoBufferedPaintDC;
 251
 252 #endif
 253
 254
 255 // Check if the window is natively double buffered and will return a wxPaintDC
 256 // if it is, a wxBufferedPaintDC otherwise.  It is the caller's responsibility
 257 // to delete the wxDC pointer when finished with it.
 258 inline wxDC* wxAutoBufferedPaintDCFactory(wxWindow* window)
 259 {
 260     if ( window->IsDoubleBuffered() )
 261         return new wxPaintDC(window);
 262     else
 263         return new wxBufferedPaintDC(window);
 264 }
 265
 266 #endif  // _WX_DCBUFFER_H_