]> git.saurik.com Git - wxWidgets.git/blob - docs/latex/wx/bufferdc.tex
interface headers reviewed
[wxWidgets.git] / 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 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, using the
17 associated wxDC, only once, when this object is destroyed. wxBufferedDC itself
18 is typically associated with \helpref{wxClientDC}{wxclientdc}, if you want to
19 use it in your \texttt{EVT\_PAINT} handler, you should look at
20 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} instead.
21
22 When used like this, a valid \arg{dc} must be specified in the constructor
23 while the \arg{buffer} bitmap doesn't have to be explicitly provided, by
24 default this class will allocate the bitmap of required size itself. However
25 using a dedicated bitmap can speed up the redrawing process by eliminating the
26 repeated creation and destruction of a possibly big bitmap. Otherwise,
27 wxBufferedDC can be used in the same way as any other device context.
28
29 There is another possible use for wxBufferedDC is to use it to maintain a
30 backing store for the window contents. In this case, the associated \arg{dc}
31 may be \NULL but a valid backing store bitmap should be specified.
32
33 Finally, please note that GTK+ 2.0 as well as OS X provide double buffering
34 themselves natively. You can either use \helpref{wxWindow::IsDoubleBuffered}{wxwindowisdoublebuffered}
35 to determine whether you need to use buffering or not, or use
36 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc} to avoid needless double
37 buffering on the systems which already do it automatically.
38
39 \wxheading{Derived from}
40
41 \helpref{wxMemoryDC}{wxmemorydc}\\
42 \helpref{wxDC}{wxdc}\\
43 \helpref{wxObject}{wxobject}
44
45 \wxheading{Include files}
46
47 <wx/dcbuffer.h>
48
49 \wxheading{Library}
50
51 \helpref{wxCore}{librarieslist}
52
53 \wxheading{See also}
54
55 \helpref{wxDC}{wxdc},\rtfsp
56 \helpref{wxMemoryDC}{wxmemorydc},\rtfsp
57 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc},\rtfsp
58 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
59
60
61 \latexignore{\rtfignore{\wxheading{Members}}}
62
63 \membersection{wxBufferedDC::wxBufferedDC}\label{wxbuffereddcctor}
64
65 \func{}{wxBufferedDC}{\void}
66
67 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
68
69 \func{}{wxBufferedDC}{\param{wxDC *}{dc}, \param{wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
70
71 If you use the first, default, constructor, you must call one of the
72 \helpref{Init}{wxbuffereddcinit} methods later in order to use the object.
73
74 The other constructors initialize the object immediately and \texttt{Init()}
75 must not be called after using them.
76
77 \wxheading{Parameters}
78
79 \docparam{dc}{The underlying DC: everything drawn to this object will be
80 flushed to this DC when this object is destroyed. You may pass NULL
81 in order to just initialize the buffer, and not flush it.}
82
83 \docparam{area}{The size of the bitmap to be used for buffering (this bitmap is
84 created internally when it is not given explicitly).}
85
86 \docparam{buffer}{Explicitly provided bitmap to be used for buffering: this is
87 the most efficient solution as the bitmap doesn't have to be recreated each
88 time but it also requires more memory as the bitmap is never freed. The bitmap
89 should have appropriate size, anything drawn outside of its bounds is clipped.}
90
91 \docparam{style}{wxBUFFER\_CLIENT\_AREA to indicate that just the client area of
92 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
93 covers the virtual area (in which case PrepareDC is automatically called for the actual window
94 device context).}
95
96 \membersection{wxBufferedDC::Init}\label{wxbuffereddcinit}
97
98 \func{void}{Init}{\param{wxDC *}{dc}, \param{const wxSize\& }{area}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
99
100 \func{void}{Init}{\param{wxDC *}{dc}, \param{wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
101
102 These functions initialize the object created using the default constructor.
103 Please see \helpref{constructors documentation}{wxbuffereddcctor} for details.
104
105
106 % VZ: UnMask() intentionally not documented, we might want to make it private
107
108
109 \membersection{wxBufferedDC::\destruct{wxBufferedDC}}\label{wxbuffereddcdtor}
110
111 Copies everything drawn on the DC so far to the underlying DC associated with
112 this object, if any.
113
114
115 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
116
117 \section{\class{wxBufferedPaintDC}}\label{wxbufferedpaintdc}
118
119 This is a subclass of \helpref{wxBufferedDC}{wxbuffereddc} which can be used
120 inside of an \texttt{OnPaint()} event handler. Just create an object of this class instead
121 of \helpref{wxPaintDC}{wxpaintdc} and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle}
122 is called with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all
123 you have to do to (mostly) avoid flicker. The only thing to watch out for is that if you are
124 using this class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably
125 do \textbf{not} want to call \helpref{PrepareDC}{wxscrolledwindowpreparedc} on it as it
126 already does this internally for the real underlying wxPaintDC.
127
128 \wxheading{Derived from}
129
130 \helpref{wxBufferedDC}{wxbuffereddc}\\
131 \helpref{wxMemoryDC}{wxmemorydc}\\
132 \helpref{wxDC}{wxdc}\\
133 \helpref{wxObject}{wxobject}
134
135 \wxheading{Include files}
136
137 <wx/dcbuffer.h>
138
139 \wxheading{Library}
140
141 \helpref{wxCore}{librarieslist}
142
143 \wxheading{See also}
144
145 \helpref{wxDC}{wxdc},\rtfsp
146 \helpref{wxBufferedDC}{wxbuffereddc},\rtfsp
147 \helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc}
148
149
150 \latexignore{\rtfignore{\wxheading{Members}}}
151
152 \membersection{wxBufferedPaintDC::wxBufferedPaintDC}\label{wxbufferedpaintdcctor}
153
154 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{wxBitmap\& }{buffer}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
155
156 \func{}{wxBufferedPaintDC}{\param{wxWindow *}{window}, \param{int }{style = wxBUFFER\_CLIENT\_AREA}}
157
158 As with \helpref{wxBufferedDC}{wxbuffereddcctor}, you may either provide the
159 bitmap to be used for buffering or let this object create one internally (in
160 the latter case, the size of the client part of the window is used).
161
162 Pass wxBUFFER\_CLIENT\_AREA for the {\it style} parameter to indicate that just the client area of
163 the window is buffered, or wxBUFFER\_VIRTUAL\_AREA to indicate that the buffer bitmap
164 covers the virtual area (in which case PrepareDC is automatically called for the actual window
165 device context).
166
167 \membersection{wxBufferedPaintDC::\destruct{wxBufferedPaintDC}}\label{wxbufferedpaintdcdtor}
168
169 Copies everything drawn on the DC so far to the window associated with this
170 object, using a \helpref{wxPaintDC}{wxpaintdc}.
171
172
173 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
174
175 \section{\class{wxAutoBufferedPaintDC}}\label{wxautobufferedpaintdc}
176
177 This wxDC derivative can be used inside of an \texttt{OnPaint()} event handler to achieve
178 double-buffered drawing. Just create an object of this class instead of \helpref{wxPaintDC}{wxpaintdc}
179 and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} is called
180 with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all you have
181 to do to (mostly) avoid flicker.
182
183 The difference between \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} and this class,
184 is the lightweigthness - on platforms which have native double-buffering, wxAutoBufferedPaintDC is simply
185 a typedef of wxPaintDC. Otherwise, it is a typedef of wxBufferedPaintDC.
186
187
188 \wxheading{Derived from}
189
190 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}\\
191 \helpref{wxBufferedDC}{wxbuffereddc}\\
192 \helpref{wxMemoryDC}{wxmemorydc}\\
193 \helpref{wxDC}{wxdc}\\
194 \helpref{wxObject}{wxobject}
195
196 \wxheading{Include files}
197
198 <wx/dcbuffer.h>
199
200 \wxheading{See also}
201
202 \helpref{wxDC}{wxdc},\rtfsp
203 \helpref{wxBufferedPaintDC}{wxbufferedpaintdc}
204
205
206 \latexignore{\rtfignore{\wxheading{Members}}}
207
208 \membersection{wxAutoBufferedPaintDC::wxAutoBufferedPaintDC}\label{wxautobufferedpaintdcctor}
209
210 \func{}{wxAutoBufferedPaintDC}{\param{wxWindow *}{window}}
211
212 Constructor. Pass a pointer to the window on which you wish to paint.
213