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{Localization Support}
  29
  30 If you pass in a valid DC, wxBufferedDC will inherit its layout direction.
  31
  32 \wxheading{Derived from}
  33
  34 \helpref{wxMemoryDC}{wxmemorydc}\\
  35 \helpref{wxDC}{wxdc}\\
  36 \helpref{wxObject}{wxobject}
  37
  38 \wxheading{Include files}
  39
  40 <wx/dcbuffer.h>
  41
  42 \wxheading{See also}
  43
  44 \helpref{wxDC}{wxdc},\rtfsp
  45 \helpref{wxMemoryDC}{wxmemorydc},\rtfsp
  46 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc},\rtfsp
  47 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
  48
  49
  50 \latexignore{\rtfignore{\wxheading{Members}}}
  51
  52 \membersection{wxBufferedDC::wxBufferedDC}\label{wxbuffereddcctor}
  53
  54 \func{}{wxBufferedDC}{\void}
  55
  56 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  57
  58 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  59
  60 If you use the first, default, constructor, you must call one of the
  61 \helpref{Init}{wxbuffereddcinit} methods later in order to use the object.
  62
  63 The other constructors initialize the object immediately and \texttt{Init()}
  64 must not be called after using them.
  65
  66 \wxheading{Parameters}
  67
  68 \docparam{dc}{The underlying DC: everything drawn to this object will be
  69 flushed to this DC when this object is destroyed.  You may pass NULL
  70 in order to just initialize the buffer, and not flush it.}
  71
  72 \docparam{area}{The size of the bitmap to be used for buffering (this bitmap is
  73 created internally when it is not given explicitly).}
  74
  75 \docparam{buffer}{Explicitly provided bitmap to be used for buffering: this is
  76 the most efficient solution as the bitmap doesn't have to be recreated each
  77 time but it also requires more memory as the bitmap is never freed. The bitmap
  78 should have appropriate size, anything drawn outside of its bounds is clipped.}
  79
  80 \docparam{style}{wxBUFFER\_CLIENT\_AREA to indicate that just the client area of
  81 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
  82 covers the virtual area (in which case PrepareDC is automatically called for the actual window
  83 device context).}
  84
  85 \membersection{wxBufferedDC::Init}\label{wxbuffereddcinit}
  86
  87 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  88
  89 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  90
  91 These functions initialize the object created using the default constructor.
  92 Please see \helpref{constructors documentation}{wxbuffereddcctor} for details.
  93
  94
  95 % VZ: UnMask() intentionally not documented, we might want to make it private
  96
  97
  98 \membersection{wxBufferedDC::\destruct{wxBufferedDC}}\label{wxbuffereddcdtor}
  99
 100 Copies everything drawn on the DC so far to the underlying DC associated with
 101 this object, if any.
 102
 103
 104 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 105
 106 \section{\class{wxBufferedPaintDC}}\label{wxbufferedpaintdc}
 107
 108 This is a subclass of \helpref{wxBufferedDC}{wxbuffereddc} which can be used
 109 inside of an \texttt{OnPaint()} event handler. Just create an object of this class instead
 110 of \helpref{wxPaintDC}{wxpaintdc} and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle}
 111 is called with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all
 112 you have to do to (mostly) avoid flicker. The only thing to watch out for is that if you are
 113 using this class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably
 114 do \textbf{not} want to call \helpref{PrepareDC}{wxscrolledwindowpreparedc} on it as it
 115 already does this internally for the real underlying wxPaintDC.
 116
 117 \wxheading{Derived from}
 118
 119 \helpref{wxBufferedDC}{wxbuffereddc}\\
 120 \helpref{wxMemoryDC}{wxmemorydc}\\
 121 \helpref{wxDC}{wxdc}\\
 122 \helpref{wxObject}{wxobject}
 123
 124 \wxheading{Include files}
 125
 126 <wx/dcbuffer.h>
 127
 128 \wxheading{See also}
 129
 130 \helpref{wxDC}{wxdc},\rtfsp
 131 \helpref{wxBufferedDC}{wxbuffereddc},\rtfsp
 132 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
 133
 134
 135 \latexignore{\rtfignore{\wxheading{Members}}}
 136
 137 \membersection{wxBufferedPaintDC::wxBufferedPaintDC}\label{wxbufferedpaintdcctor}
 138
 139 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 140
 141 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 142
 143 As with \helpref{wxBufferedDC}{wxbuffereddcctor}, you may either provide the
 144 bitmap to be used for buffering or let this object create one internally (in
 145 the latter case, the size of the client part of the window is used).
 146
 147 Pass wxBUFFER\_CLIENT\_AREA for the {\it style} parameter to indicate that just the client area of
 148 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
 149 covers the virtual area (in which case PrepareDC is automatically called for the actual window
 150 device context).
 151
 152 \membersection{wxBufferedPaintDC::\destruct{wxBufferedPaintDC}}\label{wxbufferedpaintdcdtor}
 153
 154 Copies everything drawn on the DC so far to the window associated with this
 155 object, using a \helpref{wxPaintDC}{wxpaintdc}.
 156
 157
 158 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 159
 160 \section{\class{wxAutoBufferedPaintDC}}\label{wxautobufferedpaintdc}
 161
 162 This wxDC derivative can be used inside of an \texttt{OnPaint()} event handler to achieve
 163 double-buffered drawing. Just create an object of this class instead of \helpref{wxPaintDC}{wxpaintdc}
 164 and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} is called
 165 with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all you have
 166 to do to (mostly) avoid flicker.
 167
 168 The difference between \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} and this class,
 169 is the lightweigthness - on platforms which have native double-buffering, wxAutoBufferedPaintDC is simply
 170 a typedef of wxPaintDC. Otherwise, it is a typedef of wxBufferedPaintDC.
 171
 172
 173 \wxheading{Derived from}
 174
 175 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}\\
 176 \helpref{wxPaintDC}{wxpaintdc}\\
 177 \helpref{wxDC}{wxdc}\\
 178 \helpref{wxObject}{wxobject}
 179
 180 \wxheading{Include files}
 181
 182 <wx/dcbuffer.h>
 183
 184 \wxheading{See also}
 185
 186 \helpref{wxDC}{wxdc},\rtfsp
 187 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}
 188
 189
 190 \latexignore{\rtfignore{\wxheading{Members}}}
 191
 192 \membersection{wxAutoBufferedPaintDC::wxAutoBufferedPaintDC}\label{wxautobufferedpaintdcctor}
 193
 194 \func{}{wxAutoBufferedPaintDC}{\param{wxWindow *}{window}}
 195
 196 Constructor. Pass a pointer to the window on which you wish to paint.
 197