X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/06ad863606966ceee6e7eea537f8d427f0d891a9..037267e1560a48434bd4e553389c679283500f1c:/docs/latex/wx/stream.tex?ds=sidebyside diff --git a/docs/latex/wx/stream.tex b/docs/latex/wx/stream.tex index 81d2144201..20cf2e72d2 100644 --- a/docs/latex/wx/stream.tex +++ b/docs/latex/wx/stream.tex @@ -1,9 +1,13 @@ -\section{\class{wxStreamBuffer}}\label{wxstreambuf} +\section{\class{wxStreamBuffer}}\label{wxstreambuffer} \wxheading{Derived from} None +\wxheading{Include files} + + + \wxheading{See also} \helpref{wxStreamBase}{wxstreambase} @@ -16,87 +20,150 @@ None % ----------- % ctor & dtor % ----------- -\membersection{wxStreamBuffer::wxStreamBuffer} +\membersection{wxStreamBuffer::wxStreamBuffer}\label{wxstreambufconst} \func{}{wxStreamBuffer}{\param{wxStreamBase\&}{ stream}, \param{BufMode}{ mode}} Constructor, creates a new stream buffer using \it{stream} as a parent stream and \it{mode} as the IO mode. \it{mode} can be: wxStreamBuffer::read, wxStreamBuffer::write, wxStreamBuffer::read\_write. +One stream can have many stream buffers but only one is used internally to +pass IO call (e.g. wxInputStream::Read() -> wxStreamBuffer::Read()). But you +can call directly wxStreamBuffer::Read without any problems. -\membersection{wxStreamBuffer::wxStreamBuffer} +\wxheading{Warning} + +All errors and messages linked to the stream are stored in the stream object. +\begin{verbatim} + streambuffer.Read(...); + streambuffer2.Read(...); /* This one erases previous error messages set by + ``streambuffer'' */ +\end{verbatim} \func{}{wxStreamBuffer}{\param{BufMode}{ mode}} -Constructor, creates a new empty stream buffer which won't flush any datas -to a stream. \it{mode} specifies the type of the buffer (read, write, read\_write). +Constructor, creates a new empty stream buffer which won't flush any data +to a stream. \it{mode} specifies the type of the buffer (read, write, read\_write). This stream buffer has the advantage to be stream independent and to +work only on memory buffers but it is still compatible with the rest of the +wxStream classes. You can write, read to this special stream and it will +grow (if it is allowed by the user) its internal buffer. Briefly, it has all +functionality of a ``normal'' stream. + +\wxheading{Warning} + +The "read\_write" mode may not work: it isn't completely finished. +You can create "memory" streams by this way: + +\begin{verbatim} + wxStreamBuffer *sb = new wxStreamBuffer(wxStreamBuffer::read) + wxInputStream *input = new wxInputStream(sb); + + sb->Fixed(FALSE); // It can change the size of the buffer. -\membersection{wxStreamBuffer::wxStreamBuffer} + // input is now a read-only memory stream. +\end{verbatim} -\func{}{wxStreamBuffer}{\param{const wxStreamBase\&}{ buffer}} +But you should take care when destroying the stream buffer yourself. + +\func{}{wxStreamBuffer}{\param{const wxStreamBuffer\&}{buffer}} + +Constructor. It initializes the stream buffer with the data of the specified +stream buffer. The new stream buffer is nearly exactly the same as the +original: it has the same attributes, the same size, the same position, shares +the same internal buffer. The interresting point is that they can differ +in the future but the root is the same. + +\wxheading{Warning} + +The fact that the two stream buffers shared the same buffer could generate +segmentation violation if the parent is destroyed and the children continues +operating. It is advised to use this feature only in very local area of the +program. + +\wxheading{See also} -Constructor, creates a new stream buffer from the specified stream \it{buffer}. +\helpref{wxStreamBuffer:SetBufferIO}{wxstreambuffersetbufferio} \membersection{wxStreamBuffer::\destruct{wxStreamBuffer}} -\func{}{\destruct{wxStreamBuffer}} +\func{}{wxStreamBuffer}{\destruct{wxStreamBuffer}} -Destructor, destroys the stream buffer. +Destructor. It finalizes all IO calls and frees all internal buffers if +necessary. In the case of a children stream buffer, the internal buffer isn't +freed, this is the job of the parent. +The "Write-Back" buffer is freed. % ----------- % Filtered IO % ----------- -\membersection{wxStreamBuffer::Read}\label{wxstreambufread} +\membersection{wxStreamBuffer::Read}\label{wxstreambufferread} \func{size\_t}{Read}{\param{void *}{buffer}, \param{size\_t }{size}} Reads a block of the specified \it{size} and stores datas in \it{buffer}. +This function uses also the "Write-Back" buffer: in the case there are datas +waiting in this buffer, they are used before anything else. After that, if there +are still datas to be read, the stream is read and the stream buffer position +is incremented. \wxheading{Return value} It returns the real read size. If returned size is different of the specified \it{size}, an error occured and should be tested using -\helpref{GetError}{wxstreambasegeterror}. +\helpref{LastError}{wxstreambaselasterror}. -\membersection{wxStreamBuffer::Read}\label{wxstreambufreadbuf} +\wxheading{See also} + +\helpref{wxStreamBuffer::WriteBack}{wxstreambufferwriteback} \func{size\_t}{Read}{\param{wxStreamBuffer *}{buffer}} Reads a \it{buffer}. The function returns when \it{buffer} is full or when there aren't datas anymore in the current buffer. -\membersection{wxStreamBuffer::Write} +\membersection{wxStreamBuffer::Write}\label{wxstreambufferwrite} \func{size\_t}{Write}{\param{const void *}{buffer}, \param{size\_t }{size}} -Writes a block of the specified \it{size} using datas of \it{buffer}. - -\membersection{wxStreamBuffer::Write} +Writes a block of the specified \it{size} using datas of \it{buffer}. The datas +are cached in a buffer before being sent in one block to the stream. \func{size\_t}{Write}{\param{wxStreamBuffer *}{buffer}} -See \helpref{Read}{wxstreambufreadbuf} +See \helpref{Read}{wxstreambufferread}. -\membersection{wxStreamBuffer::WriteBack} +\membersection{wxStreamBuffer::WriteBack}\label{wxstreambufferwriteback} \func{size\_t}{WriteBack}{\param{const char*}{ buffer}, \param{size\_t}{ size}} -This function is only useful in ``read'' mode. It puts the specified \it{buffer} -in the input queue of the stream buf. By this way, the next -\helpref{Read}{wxstreambufread} call will first use these datas. +This function is only useful in \it{read} mode. It is the manager of the "Write-Back" +buffer. This buffer acts like a temporary buffer where datas which has to be +read during the next read IO call are put. This is useful when you get a big +block of data which you didn't want to read: you can replace them at the top +of the input queue by this way. -\membersection{wxStreamBuffer::WriteBack} +\wxheading{Return value} + +Returns the amount of bytes saved in the Write-Back buffer. \func{size\_t}{WriteBack}{\param{char }{c}} -As for the previous function, it puts the specified byte in the input queue of the -stream buffer. +This function acts like the previous one except that it takes only one +character: it is sometimes shorter to use than the generic function. \membersection{wxStreamBuffer::GetChar} \func{char}{GetChar}{\void} -Gets a single char from the stream buffer. +Gets a single char from the stream buffer. It acts like the Read call. + +\wxheading{Problem} + +You aren't directly notified if an error occured during the IO call. + +\wxheading{See also} + +\helpref{wxStreamBuffer::Read}{wxstreambufferread} \membersection{wxStreamBuffer::PutChar} @@ -104,17 +171,47 @@ Gets a single char from the stream buffer. Puts a single char to the stream buffer. +\wxheading{Problem} + +You aren't directly notified if an error occured during the IO call. + +\wxheading{See also} + +\helpref{wxStreamBuffer::Read}{wxstreambufferwrite} + \membersection{wxStreamBuffer::Tell} \constfunc{off\_t}{Tell}{\void} -Gets the current position in the \it{stream}. +Gets the current position in the stream. This position is calculated from +the \it{real} position in the stream and from the internal buffer position: so +it gives you the position in the \it{real} stream counted from the start of +the stream. + +\wxheading{Return value} -\membersection{wxStreamBuffer::Seek} +Returns the current position in the stream if possible, wxInvalidOffset in the +other case. + +\membersection{wxStreamBuffer::Seek}\label{wxstreambufferseek} \func{off\_t}{Seek}{\param{off\_t }{pos}, \param{wxSeekMode }{mode}} -Changes the current position. (TODO) +Changes the current position. + +\it{mode} may be one of the following: + +\twocolwidtha{5cm} +\begin{twocollist}\itemsep=0pt +\twocolitem{{\bf wxFromStart}}{The position is counted from the start of the stream.} +\twocolitem{{\bf wxFromCurrent}}{The position is counted from the current position of the stream.} +\twocolitem{{\bf wxFromEnd}}{The position is counted from the end of the stream.} +\end{twocollist} + +\wxheading{Return value} + +Upon successful completion, it returns the new offset as measured in bytes from +the beginning of the stream. Otherwise, it returns wxInvalidOffset. % -------------- % Buffer control @@ -123,20 +220,47 @@ Changes the current position. (TODO) \func{void}{ResetBuffer}{\void} -Frees all internal buffers and resets to initial state all variables. +Resets to the initial state variables concerning the buffer. -\membersection{wxStreamBuffer::SetBufferIO} +\membersection{wxStreamBuffer::SetBufferIO}\label{wxstreambuffersetbufferio} \func{void}{SetBufferIO}{\param{char*}{ buffer\_start}, \param{char*}{ buffer\_end}} Specifies which pointers to use for stream buffering. You need to pass a pointer on the -start of the buffer end and another on the end. +start of the buffer end and another on the end. The object will use this buffer +to cache stream data. It may be used also as a source/destination buffer when +you create an empty stream buffer (See \helpref{wxStreamBuffer::wxStreamBuffer}{wxstreambufconst}). + +\wxheading{Remarks} + +When you use this function, you'll have to destroy the IO buffers yourself +after the stream buffer is destroyed or don't use it anymore. +In the case you use it with an empty buffer, the stream buffer will not grow +it when it is full. + +\wxheading{See also} -\membersection{wxStreamBuffer::SetBufferIO} +\helpref{wxStreamBuffer constructor}{wxstreambufconst}\\ +\helpref{wxStreamBuffer::Fixed}{wxstreambufferfixed}\\ +\helpref{wxStreamBuffer::Flushable}{wxstreambufferflushable} \func{void}{SetBufferIO}{\param{size\_t}{ bufsize}} -Changes the size of the current IO buffer. +Destroys or invalidates the previous IO buffer and allocates a new one of the +specified size. + +\wxheading{Warning} + +All previous pointers aren't valid anymore. + +\wxheading{Remark} + +The created IO buffer is growable by the object. + +\wxheading{See also} + +\helpref{wxStreamBuffer::Fixed}{wxstreambufferfixed}\\ +\helpref{wxStreamBuffer::Flushable}{wxstreambufferflushable} \membersection{wxStreamBuffer::GetBufferStart} @@ -160,13 +284,18 @@ Returns a pointer on the current position of the stream buffer. \constfunc{off\_t}{GetIntPosition}{\void} -Returns the current position in the stream buffer. +Returns the current position (counted in bytes) in the stream buffer. \membersection{wxStreamBuffer::SetIntPosition} \func{void}{SetIntPosition}{\void} -Sets the current position in the stream buffer. +Sets the current position (in bytes) in the stream buffer. + +\wxheading{Warning} + +Since it is a very low-level function, there is no check on the position: +specify an invalid position can induce unexpected results. \membersection{wxStreamBuffer::GetLastAccess} @@ -174,15 +303,19 @@ Sets the current position in the stream buffer. Returns the amount of bytes read during the last IO call to the parent stream. -\membersection{wxStreamBuffer::Fixed} +\membersection{wxStreamBuffer::Fixed}\label{wxstreambufferfixed} \func{void}{Fixed}{\param{bool}{ fixed}} Toggles the fixed flag. Usually this flag is toggled at the same time as -\it{flushable}. This flag allows (when it is FALSE) or forbids (when it is TRUE) -the stream buffer to resize dynamically the IO buffer. +\it{flushable}. This flag allows (when it has the FALSE value) or forbids +(when it has the TRUE value) the stream buffer to resize dynamically the IO buffer. + +\wxheading{See also} + +\helpref{wxStreamBuffer::SetBufferIO}{wxstreambuffersetbufferio} -\membersection{wxStreamBuffer::Flushable} +\membersection{wxStreamBuffer::Flushable}\label{wxstreambufferflushable} \func{void}{Flushable}{\param{bool}{ flushable}} @@ -214,5 +347,5 @@ Returns the amount of available datas in the buffer. \func{wxStreamBase*}{Stream}{\void} -Returns the stream parent of the stream buffer. +Returns the parent stream of the stream buffer.