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. wxBufferedDC is aware of this however, and will bypass the buffering
  26 unless explicit buffer bitmap is given.
  27
  28 \wxheading{Derived from}
  29
  30 \helpref{wxDC}{wxdc}\\
  31 \helpref{wxObject}{wxobject}
  32
  33 \wxheading{Include files}
  34
  35 <wx/dcbuffer.h>
  36
  37 \wxheading{See also}
  38
  39 \helpref{wxDC}{wxdc},\rtfsp
  40 \helpref{wxMemoryDC}{wxmemorydc},\rtfsp
  41 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc},\rtfsp
  42 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
  43
  44
  45 \latexignore{\rtfignore{\wxheading{Members}}}
  46
  47 \membersection{wxBufferedDC::wxBufferedDC}\label{wxbuffereddcctor}
  48
  49 \func{}{wxBufferedDC}{\void}
  50
  51 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  52
  53 \func{}{wxBufferedDC}{\param{wxWindow*}{window}, \param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  54
  55 If you use the first, default, constructor, you must call one of the
  56 \helpref{Init}{wxbuffereddcinit} methods later in order to use the object.
  57
  58 The other constructors initialize the object immediately and \texttt{Init()}
  59 must not be called after using them.
  60
  61 \wxheading{Parameters}
  62
  63 \docparam{dc}{The underlying DC: everything drawn to this object will be
  64 flushed to this DC when this object is destroyed.  You may pass NULL
  65 in order to just initialize the buffer, and not flush it.}
  66
  67 \docparam{window}{The window on which the dc paints. May be NULL, but
  68 you should normally specify this so that the DC can be aware whether the
  69 surface is natively double-buffered or not.}
  70
  71 \docparam{area}{The size of the bitmap to be used for buffering (this bitmap is
  72 created internally when it is not given explicitly).}
  73
  74 \docparam{buffer}{Explicitly provided bitmap to be used for buffering: this is
  75 the most efficient solution as the bitmap doesn't have to be recreated each
  76 time but it also requires more memory as the bitmap is never freed. The bitmap
  77 should have appropriate size, anything drawn outside of its bounds is clipped.}
  78
  79 \docparam{style}{wxBUFFER\_CLIENT\_AREA to indicate that just the client area of
  80 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
  81 covers the virtual area (in which case PrepareDC is automatically called for the actual window
  82 device context).}
  83
  84 \membersection{wxBufferedDC::Init}\label{wxbuffereddcinit}
  85
  86 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  87
  88 \func{void}{Init}{\param{wxWindow*}{window}, \param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
  89
  90 These functions initialize the object created using the default constructor.
  91 Please see \helpref{constructors documentation}{wxbuffereddcctor} for details.
  92
  93
  94 % VZ: UnMask() intentionally not documented, we might want to make it private
  95
  96
  97 \membersection{wxBufferedDC::\destruct{wxBufferedDC}}\label{wxbuffereddcdtor}
  98
  99 Copies everything drawn on the DC so far to the underlying DC associated with
 100 this object, if any.
 101
 102
 103 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 104
 105 \section{\class{wxBufferedPaintDC}}\label{wxbufferedpaintdc}
 106
 107 This is a subclass of \helpref{wxBufferedDC}{wxbuffereddc} which can be used
 108 inside of an \texttt{OnPaint()} event handler. Just create an object of this class instead
 109 of \helpref{wxPaintDC}{wxpaintdc} and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle}
 110 is called with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all
 111 you have to do to (mostly) avoid flicker. The only thing to watch out for is that if you are
 112 using this class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably
 113 do \textbf{not} want to call \helpref{PrepareDC}{wxscrolledwindowpreparedc} on it as it
 114 already does this internally for the real underlying wxPaintDC.
 115
 116 \wxheading{Derived from}
 117
 118 \helpref{wxBufferedDC}{wxbuffereddc}\\
 119 \helpref{wxDC}{wxdc}\\
 120 \helpref{wxObject}{wxobject}
 121
 122 \wxheading{Include files}
 123
 124 <wx/dcbuffer.h>
 125
 126 \wxheading{See also}
 127
 128 \helpref{wxDC}{wxdc},\rtfsp
 129 \helpref{wxBufferedDC}{wxbuffereddc},\rtfsp
 130 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
 131
 132
 133 \latexignore{\rtfignore{\wxheading{Members}}}
 134
 135 \membersection{wxBufferedPaintDC::wxBufferedPaintDC}\label{wxbufferedpaintdcctor}
 136
 137 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{const wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 138
 139 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
 140
 141 As with \helpref{wxBufferedDC}{wxbuffereddcctor}, you may either provide the
 142 bitmap to be used for buffering or let this object create one internally (in
 143 the latter case, the size of the client part of the window is used).
 144
 145 Pass wxBUFFER\_CLIENT\_AREA for the {\it style} parameter to indicate that just the client area of
 146 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
 147 covers the virtual area (in which case PrepareDC is automatically called for the actual window
 148 device context).
 149
 150 \membersection{wxBufferedPaintDC::\destruct{wxBufferedPaintDC}}\label{wxbufferedpaintdcdtor}
 151
 152 Copies everything drawn on the DC so far to the window associated with this
 153 object, using a \helpref{wxPaintDC}{wxpaintdc}.
 154
 155
 156 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 157
 158 \section{\class{wxAutoBufferedPaintDC}}\label{wxautobufferedpaintdc}
 159
 160 This wxDC derivative can be used inside of an \texttt{OnPaint()} event handler to achieve
 161 double-buffered drawing. Just create an object of this class instead of \helpref{wxPaintDC}{wxpaintdc}
 162 and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} is called
 163 with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all you have
 164 to do to (mostly) avoid flicker.
 165
 166 The difference between \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} and this class,
 167 is the lightweigthness - on platforms which have native double-buffering, wxAutoBufferedPaintDC is simply
 168 a typedef of wxPaintDC. Otherwise, it is a typedef of wxBufferedPaintDC.
 169
 170
 171 \wxheading{Derived from}
 172
 173 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}\\
 174 \helpref{wxPaintDC}{wxpaintdc}\\
 175 \helpref{wxDC}{wxdc}\\
 176 \helpref{wxObject}{wxobject}
 177
 178 \wxheading{Include files}
 179
 180 <wx/dcbuffer.h>
 181
 182 \wxheading{See also}
 183
 184 \helpref{wxDC}{wxdc},\rtfsp
 185 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}
 186
 187
 188 \latexignore{\rtfignore{\wxheading{Members}}}
 189
 190 \membersection{wxAutoBufferedPaintDC::wxAutoBufferedPaintDC}\label{wxautobufferedpaintdcctor}
 191
 192 \func{}{wxAutoBufferedPaintDC}{\param{wxWindow *}{window}}
 193
 194 Constructor. Pass a pointer to the window on which you wish to paint.
 195