mirror of https://github.com/python/cpython.git
72 lines
2.4 KiB
TeX
72 lines
2.4 KiB
TeX
\section{\module{chunk} ---
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Helper for reading IFF chunks}
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\declaremodule{standard}{chunk}
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\sectionauthor{Moshe Zadka}{mzadka@geocities.com}
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\modulesynopsis{Helper class for reading from IFF-based file formats.}
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The \module{chunk} module defines a class for interfacing to ``IFF''
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chunk-based files, like TIFF or AIFF. This is used as a helper module
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for the \refmodule{aifc} and \refmodule{wave} modules.
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The \module{chunk} module defines the following class:
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\begin{classdesc}{Chunk}{file\optional{, align}}
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The chunk from \var{file} starting at \var{file}'s current
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position. The \var{align} argument, which defaults to true, determines
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whether to align chunk data on 2-byte boundaries.
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\exception{EOFError} is raised if \var{file} does not contain enough
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data to read the IFF header.
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\end{classdesc}
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The IFF header format is described in this table:
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\begin{tableiii}{c|c|l}{textrm}{Offset}{Length}{Contents}
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\lineiii{0}{4}{Chunk ID}
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\lineiii{4}{4}{Size of chunk in big-endian byte order, including the
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header}
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\end{tableiii}
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\subsection{Chunk Objects \label{iff-chunk-objects}}
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Chunk objects have the following methods:
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\begin{methoddesc}{getname}{}
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Return the ID of the chunk.
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\end{methoddesc}
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\begin{methoddesc}{close}{}
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Close the chunk, forwarding the file pointer to the end of the chunk.
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\end{methoddesc}
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\begin{methoddesc}{isatty}{}
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Returns false unless the chunk has been closed, in which case
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\exception{ValueError} is raised.
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\end{methoddesc}
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\begin{methoddesc}{seek}{offset\optional{, whence}}
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Seek to a position within the chunk. If file pointer is not seekable,
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or \var{offset} would point outside the chunk, an error is raised.
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\var{whence} is interpreted the same as for the \method{seek()} method
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on file objects; see section \ref{bltin-file-objects} for more
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information.
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\end{methoddesc}
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\begin{methoddesc}{tell}{}
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Return the current position within this chunk.
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\end{methoddesc}
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\begin{methoddesc}{read}{\optional{n}}
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Read at most \var{n} bytes from the chunk. If \var{n} is omitted
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or negative, read until the end of the chunk.
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\end{methoddesc}
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\begin{methoddesc}{skip}{}
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Skip to the end of the chunk. All further calls to \method{read()}
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for the chunk will return \code{''}. If you are not interested in the
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contents of the chunk, this method should be called so that the file
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points to the start of the next chunk.
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\end{methoddesc}
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