docs/latex/wx/bufferdc.tex

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %% Name:        bufferdc.tex
   3 %% Purpose:     wxBufferedDC documentation
   4 %% Author:      Vadim Zeitlin
   5 %% Modified by:
   6 %% Created:     07.02.04
   7 %% RCS-ID:      $Id$
   8 %% Copyright:   (c) 2004 Vadim Zeitlin
   9 %% License:     wxWindows license
  10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  11
  12 \section{\class{wxBufferedDC}}\label{wxbuffereddc}
  13
  14 This simple class provides a simple way to avoid flicker: when drawing on it,
  15 everything is in fact first drawn on an in-memory buffer (a
  16 \helpref{wxBitmap}{wxbitmap}) and then copied to the screen only once, when this
  17 object is destroyed.
  18
  19 It can be used in the same way as any other device context. wxBufferedDC itself
  20 typically replaces \helpref{wxClientDC}{wxclientdc}, if you want to use it in
  21 your \texttt{OnPaint()} handler, you should look at
  22 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} or \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}.
  23
  24 Please note that GTK+ 2.0 as well as OS X provide double buffering themselves
  25 +natively. Use \helpref{wxWindow::IsDoubleBuffered}{wxwindowisdoublebuffered} to
  26 +determine whether you need to use buffering or not.
  27
  28 \wxheading{Derived from}
  29
  30 \helpref{wxMemoryDC}{wxmemorydc}\\
  31 \helpref{wxDC}{wxdc}\\
  32 \helpref{wxObject}{wxobject}
  33
  34 \wxheading{Include files}
  35
  36 <wx/dcbuffer.h>
  37
  38 \wxheading{See also}
  39
  40 \helpref{wxDC}{wxdc},\rtfsp
  41 \helpref{wxMemoryDC}{wxmemorydc},\rtfsp
  42 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc},\rtfsp
  43 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
  44
  45
  46 \latexignore{\rtfignore{\wxheading{Members}}}
  47
  48 \membersection{wxBufferedDC::wxBufferedDC}\label{wxbuffereddcctor}
  49
  50 \func{}{wxBufferedDC}{\void}
  51
  52 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  53
  54 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  55
  56 If you use the first, default, constructor, you must call one of the
  57 \helpref{Init}{wxbuffereddcinit} methods later in order to use the object.
  58
  59 The other constructors initialize the object immediately and \texttt{Init()}
  60 must not be called after using them.
  61
  62 \wxheading{Parameters}
  63
  64 \docparam{dc}{The underlying DC: everything drawn to this object will be
  65 flushed to this DC when this object is destroyed.  You may pass NULL
  66 in order to just initialize the buffer, and not flush it.}
  67
  68 \docparam{area}{The size of the bitmap to be used for buffering (this bitmap is
  69 created internally when it is not given explicitly).}
  70
  71 \docparam{buffer}{Explicitly provided bitmap to be used for buffering: this is
  72 the most efficient solution as the bitmap doesn't have to be recreated each
  73 time but it also requires more memory as the bitmap is never freed. The bitmap
  74 should have appropriate size, anything drawn outside of its bounds is clipped.}
  75
  76 \docparam{style}{wxBUFFER\_CLIENT\_AREA to indicate that just the client area of
  77 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
  78 covers the virtual area (in which case PrepareDC is automatically called for the actual window
  79 device context).}
  80
  81 \membersection{wxBufferedDC::Init}\label{wxbuffereddcinit}
  82
  83 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  84
  85 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  86
  87 These functions initialize the object created using the default constructor.
  88 Please see \helpref{constructors documentation}{wxbuffereddcctor} for details.
  89
  90
  91 % VZ: UnMask() intentionally not documented, we might want to make it private
  92
  93
  94 \membersection{wxBufferedDC::\destruct{wxBufferedDC}}\label{wxbuffereddcdtor}
  95
  96 Copies everything drawn on the DC so far to the underlying DC associated with
  97 this object, if any.
  98
  99
 100 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 101
 102 \section{\class{wxBufferedPaintDC}}\label{wxbufferedpaintdc}
 103
 104 This is a subclass of \helpref{wxBufferedDC}{wxbuffereddc} which can be used
 105 inside of an \texttt{OnPaint()} event handler. Just create an object of this class instead
 106 of \helpref{wxPaintDC}{wxpaintdc} and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle}
 107 is called with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all
 108 you have to do to (mostly) avoid flicker. The only thing to watch out for is that if you are
 109 using this class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably
 110 do \textbf{not} want to call \helpref{PrepareDC}{wxscrolledwindowpreparedc} on it as it
 111 already does this internally for the real underlying wxPaintDC.
 112
 113 \wxheading{Derived from}
 114
 115 \helpref{wxBufferedDC}{wxbuffereddc}\\
 116 \helpref{wxMemoryDC}{wxmemorydc}\\
 117 \helpref{wxDC}{wxdc}\\
 118 \helpref{wxObject}{wxobject}
 119
 120 \wxheading{Include files}
 121
 122 <wx/dcbuffer.h>
 123
 124 \wxheading{See also}
 125
 126 \helpref{wxDC}{wxdc},\rtfsp
 127 \helpref{wxBufferedDC}{wxbuffereddc},\rtfsp
 128 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
 129
 130
 131 \latexignore{\rtfignore{\wxheading{Members}}}
 132
 133 \membersection{wxBufferedPaintDC::wxBufferedPaintDC}\label{wxbufferedpaintdcctor}
 134
 135 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 136
 137 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 138
 139 As with \helpref{wxBufferedDC}{wxbuffereddcctor}, you may either provide the
 140 bitmap to be used for buffering or let this object create one internally (in
 141 the latter case, the size of the client part of the window is used).
 142
 143 Pass wxBUFFER\_CLIENT\_AREA for the {\it style} parameter to indicate that just the client area of
 144 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
 145 covers the virtual area (in which case PrepareDC is automatically called for the actual window
 146 device context).
 147
 148 \membersection{wxBufferedPaintDC::\destruct{wxBufferedPaintDC}}\label{wxbufferedpaintdcdtor}
 149
 150 Copies everything drawn on the DC so far to the window associated with this
 151 object, using a \helpref{wxPaintDC}{wxpaintdc}.
 152
 153
 154 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 155
 156 \section{\class{wxAutoBufferedPaintDC}}\label{wxautobufferedpaintdc}
 157
 158 This wxDC derivative can be used inside of an \texttt{OnPaint()} event handler to achieve
 159 double-buffered drawing. Just create an object of this class instead of \helpref{wxPaintDC}{wxpaintdc}
 160 and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} is called
 161 with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all you have
 162 to do to (mostly) avoid flicker.
 163
 164 The difference between \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} and this class,
 165 is the lightweigthness - on platforms which have native double-buffering, wxAutoBufferedPaintDC is simply
 166 a typedef of wxPaintDC. Otherwise, it is a typedef of wxBufferedPaintDC.
 167
 168
 169 \wxheading{Derived from}
 170
 171 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}\\
 172 \helpref{wxPaintDC}{wxpaintdc}\\
 173 \helpref{wxDC}{wxdc}\\
 174 \helpref{wxObject}{wxobject}
 175
 176 \wxheading{Include files}
 177
 178 <wx/dcbuffer.h>
 179
 180 \wxheading{See also}
 181
 182 \helpref{wxDC}{wxdc},\rtfsp
 183 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}
 184
 185
 186 \latexignore{\rtfignore{\wxheading{Members}}}
 187
 188 \membersection{wxAutoBufferedPaintDC::wxAutoBufferedPaintDC}\label{wxautobufferedpaintdcctor}
 189
 190 \func{}{wxAutoBufferedPaintDC}{\param{wxWindow *}{window}}
 191
 192 Constructor. Pass a pointer to the window on which you wish to paint.
 193