X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/265a3864bbbc7ac8af309c80321efbba8c0ca6e9..a43ec16b16cf61894294f071011ec984d8a3d673:/docs/latex/wx/bufferdc.tex diff --git a/docs/latex/wx/bufferdc.tex b/docs/latex/wx/bufferdc.tex index 0e903887ec..903c40d6b4 100644 --- a/docs/latex/wx/bufferdc.tex +++ b/docs/latex/wx/bufferdc.tex @@ -11,15 +11,30 @@ \section{\class{wxBufferedDC}}\label{wxbuffereddc} -This simple class provides a simple way to avoid flicker: when drawing on it, -everything is in fact first drawn on an in-memory buffer (a -\helpref{wxBitmap}{wxbitmap}) and then copied to the screen only once, when this -object is destroyed. - -It can be used in the same way as any other device context. wxBufferedDC itself -typically replaces \helpref{wxClientDC}{wxclientdc}, if you want to use it in -your \texttt{OnPaint()} handler, you should look at -\helpref{wxBufferedPaintDC}{wxbufferedpaintdc}. +This class provides a simple way to avoid flicker: when drawing on it, +everything is in fact first drawn on an in-memory buffer (a +\helpref{wxBitmap}{wxbitmap}) and then copied to the screen, using the +associated wxDC, only once, when this object is destroyed. wxBufferedDC itself +is typically associated with \helpref{wxClientDC}{wxclientdc}, if you want to +use it in your \texttt{EVT\_PAINT} handler, you should look at +\helpref{wxBufferedPaintDC}{wxbufferedpaintdc} instead. + +When used like this, a valid \arg{dc} must be specified in the constructor +while the \arg{buffer} bitmap doesn't have to be explicitly provided, by +default this class will allocate the bitmap of required size itself. However +using a dedicated bitmap can speed up the redrawing process by eliminating the +repeated creation and destruction of a possibly big bitmap. Otherwise, +wxBufferedDC can be used in the same way as any other device context. + +There is another possible use for wxBufferedDC is to use it to maintain a +backing store for the window contents. In this case, the associated \arg{dc} +may be \NULL but a valid backing store bitmap should be specified. + +Finally, please note that GTK+ 2.0 as well as OS X provide double buffering +themselves natively. You can either use \helpref{wxWindow::IsDoubleBuffered}{wxwindowisdoublebuffered} +to determine whether you need to use buffering or not, or use +\helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc} to avoid needless double +buffering on the systems which already do it automatically. \wxheading{Derived from} @@ -33,7 +48,10 @@ your \texttt{OnPaint()} handler, you should look at \wxheading{See also} -\helpref{wxDC}{wxdc} +\helpref{wxDC}{wxdc},\rtfsp +\helpref{wxMemoryDC}{wxmemorydc},\rtfsp +\helpref{wxBufferedPaintDC}{wxbufferedpaintdc},\rtfsp +\helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc} \latexignore{\rtfignore{\wxheading{Members}}} @@ -96,14 +114,16 @@ this object, if any. This is a subclass of \helpref{wxBufferedDC}{wxbuffereddc} which can be used inside of an \texttt{OnPaint()} event handler. Just create an object of this class instead -of \helpref{wxPaintDC}{wxpaintdc} and that's all you have to do to (mostly) -avoid flicker. The only thing to watch out for is that if you are using this -class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably +of \helpref{wxPaintDC}{wxpaintdc} and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} +is called with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all +you have to do to (mostly) avoid flicker. The only thing to watch out for is that if you are +using this class together with \helpref{wxScrolledWindow}{wxscrolledwindow}, you probably do \textbf{not} want to call \helpref{PrepareDC}{wxscrolledwindowpreparedc} on it as it already does this internally for the real underlying wxPaintDC. \wxheading{Derived from} +\helpref{wxBufferedDC}{wxbuffereddc}\\ \helpref{wxMemoryDC}{wxmemorydc}\\ \helpref{wxDC}{wxdc}\\ \helpref{wxObject}{wxobject} @@ -112,6 +132,12 @@ already does this internally for the real underlying wxPaintDC. +\wxheading{See also} + +\helpref{wxDC}{wxdc},\rtfsp +\helpref{wxBufferedDC}{wxbuffereddc},\rtfsp +\helpref{wxAutoBufferedPaintDC}{wxautobufferedpaintdc} + \latexignore{\rtfignore{\wxheading{Members}}} @@ -136,3 +162,43 @@ Copies everything drawn on the DC so far to the window associated with this object, using a \helpref{wxPaintDC}{wxpaintdc}. +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +\section{\class{wxAutoBufferedPaintDC}}\label{wxautobufferedpaintdc} + +This wxDC derivative can be used inside of an \texttt{OnPaint()} event handler to achieve +double-buffered drawing. Just create an object of this class instead of \helpref{wxPaintDC}{wxpaintdc} +and make sure \helpref{wxWindow::SetBackgroundStyle}{wxwindowgetbackgroundstyle} is called +with wxBG\_STYLE\_CUSTOM somewhere in the class initialization code, and that's all you have +to do to (mostly) avoid flicker. + +The difference between \helpref{wxBufferedPaintDC}{wxbufferedpaintdc} and this class, +is the lightweigthness - on platforms which have native double-buffering, wxAutoBufferedPaintDC is simply +a typedef of wxPaintDC. Otherwise, it is a typedef of wxBufferedPaintDC. + + +\wxheading{Derived from} + +\helpref{wxBufferedPaintDC}{wxbufferedpaintdc}\\ +\helpref{wxPaintDC}{wxpaintdc}\\ +\helpref{wxDC}{wxdc}\\ +\helpref{wxObject}{wxobject} + +\wxheading{Include files} + + + +\wxheading{See also} + +\helpref{wxDC}{wxdc},\rtfsp +\helpref{wxBufferedPaintDC}{wxbufferedpaintdc} + + +\latexignore{\rtfignore{\wxheading{Members}}} + +\membersection{wxAutoBufferedPaintDC::wxAutoBufferedPaintDC}\label{wxautobufferedpaintdcctor} + +\func{}{wxAutoBufferedPaintDC}{\param{wxWindow *}{window}} + +Constructor. Pass a pointer to the window on which you wish to paint. +