io::compress::rawdeflate.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

.PP
If the \f(CW$output\fR parameter is any other type, \f(CW\*(C`IO::Compress::RawDeflate\*(C'\fR::new will
return undef.
.Sh "Constructor Options"
.IX Subsection "Constructor Options"
\&\f(CW\*(C`OPTS\*(C'\fR is any combination of the following options:
.ie n .IP """AutoClose => 0|1""" 5
.el .IP "\f(CWAutoClose => 0|1\fR" 5
.IX Item "AutoClose => 0|1"
This option is only valid when the \f(CW$output\fR parameter is a filehandle. If
specified, and the value is true, it will result in the \f(CW$output\fR being
closed once either the \f(CW\*(C`close\*(C'\fR method is called or the \f(CW\*(C`IO::Compress::RawDeflate\*(C'\fR
object is destroyed.
.Sp
This parameter defaults to 0.
.ie n .IP """Append => 0|1""" 5
.el .IP "\f(CWAppend => 0|1\fR" 5
.IX Item "Append => 0|1"
Opens \f(CW$output\fR in append mode.
.Sp
The behaviour of this option is dependent on the type of \f(CW$output\fR.
.RS 5
.IP "\(bu" 5
A Buffer
.Sp
If \f(CW$output\fR is a buffer and \f(CW\*(C`Append\*(C'\fR is enabled, all compressed data
will be append to the end if \f(CW$output\fR. Otherwise \f(CW$output\fR will be
cleared before any data is written to it.
.IP "\(bu" 5
A Filename
.Sp
If \f(CW$output\fR is a filename and \f(CW\*(C`Append\*(C'\fR is enabled, the file will be
opened in append mode. Otherwise the contents of the file, if any, will be
truncated before any compressed data is written to it.
.IP "\(bu" 5
A Filehandle
.Sp
If \f(CW$output\fR is a filehandle, the file pointer will be positioned to the
end of the file via a call to \f(CW\*(C`seek\*(C'\fR before any compressed data is written
to it.  Otherwise the file pointer will not be moved.
.RE
.RS 5
.Sp
This parameter defaults to 0.
.RE
.ie n .IP """Merge => 0|1""" 5
.el .IP "\f(CWMerge => 0|1\fR" 5
.IX Item "Merge => 0|1"
This option is used to compress input data and append it to an existing
compressed data stream in \f(CW$output\fR. The end result is a single compressed
data stream stored in \f(CW$output\fR.
.Sp
It is a fatal error to attempt to use this option when \f(CW$output\fR is not an
\&\s-1RFC\s0 1951 data stream.
.Sp
There are a number of other limitations with the \f(CW\*(C`Merge\*(C'\fR option:
.RS 5
.IP "1." 5
This module needs to have been built with zlib 1.2.1 or better to work. A
fatal error will be thrown if \f(CW\*(C`Merge\*(C'\fR is used with an older version of
zlib.
.IP "2." 5
If \f(CW$output\fR is a file or a filehandle, it must be seekable.
.RE
.RS 5
.Sp
This parameter defaults to 0.
.RE
.IP "\-Level" 5
.IX Item "-Level"
Defines the compression level used by zlib. The value should either be
a number between 0 and 9 (0 means no compression and 9 is maximum
compression), or one of the symbolic constants defined below.
.Sp
.Vb 4
\&   Z_NO_COMPRESSION
\&   Z_BEST_SPEED
\&   Z_BEST_COMPRESSION
\&   Z_DEFAULT_COMPRESSION
.Ve
.Sp
The default is Z_DEFAULT_COMPRESSION.
.Sp
Note, these constants are not imported by \f(CW\*(C`IO::Compress::RawDeflate\*(C'\fR by default.
.Sp
.Vb 3
\&    use IO::Compress::RawDeflate qw(:strategy);
\&    use IO::Compress::RawDeflate qw(:constants);
\&    use IO::Compress::RawDeflate qw(:all);
.Ve
.IP "\-Strategy" 5
.IX Item "-Strategy"
Defines the strategy used to tune the compression. Use one of the symbolic
constants defined below.
.Sp
.Vb 5
\&   Z_FILTERED
\&   Z_HUFFMAN_ONLY
\&   Z_RLE
\&   Z_FIXED
\&   Z_DEFAULT_STRATEGY
.Ve
.Sp
The default is Z_DEFAULT_STRATEGY.
.ie n .IP """Strict => 0|1""" 5
.el .IP "\f(CWStrict => 0|1\fR" 5
.IX Item "Strict => 0|1"
This is a placeholder option.
.Sh "Examples"
.IX Subsection "Examples"
\&\s-1TODO\s0
.SH "Methods"
.IX Header "Methods"
.Sh "print"
.IX Subsection "print"
Usage is
.PP
.Vb 2
\&    $z\->print($data)
\&    print $z $data
.Ve
.PP
Compresses and outputs the contents of the \f(CW$data\fR parameter. This
has the same behaviour as the \f(CW\*(C`print\*(C'\fR built-in.
.PP
Returns true if successful.
.Sh "printf"
.IX Subsection "printf"
Usage is
.PP
.Vb 2
\&    $z\->printf($format, $data)
\&    printf $z $format, $data
.Ve
.PP
Compresses and outputs the contents of the \f(CW$data\fR parameter.
.PP
Returns true if successful.
.Sh "syswrite"
.IX Subsection "syswrite"
Usage is
.PP
.Vb 3
\&    $z\->syswrite $data
\&    $z\->syswrite $data, $length
\&    $z\->syswrite $data, $length, $offset
.Ve
.PP
Compresses and outputs the contents of the \f(CW$data\fR parameter.
.PP
Returns the number of uncompressed bytes written, or \f(CW\*(C`undef\*(C'\fR if
unsuccessful.
.Sh "write"
.IX Subsection "write"
Usage is
.PP
.Vb 3
\&    $z\->write $data
\&    $z\->write $data, $length
\&    $z\->write $data, $length, $offset
.Ve
.PP
Compresses and outputs the contents of the \f(CW$data\fR parameter.
.PP
Returns the number of uncompressed bytes written, or \f(CW\*(C`undef\*(C'\fR if
unsuccessful.
.Sh "flush"
.IX Subsection "flush"
Usage is
.PP
.Vb 2
\&    $z\->flush;
\&    $z\->flush($flush_type);
.Ve
.PP
Flushes any pending compressed data to the output file/buffer.
.PP
This method takes an optional parameter, \f(CW$flush_type\fR, that controls
how the flushing will be carried out. By default the \f(CW$flush_type\fR
used is \f(CW\*(C`Z_FINISH\*(C'\fR. Other valid values for \f(CW$flush_type\fR are
\&\f(CW\*(C`Z_NO_FLUSH\*(C'\fR, \f(CW\*(C`Z_SYNC_FLUSH\*(C'\fR, \f(CW\*(C`Z_FULL_FLUSH\*(C'\fR and \f(CW\*(C`Z_BLOCK\*(C'\fR. It is
strongly recommended that you only set the \f(CW\*(C`flush_type\*(C'\fR parameter if
you fully understand the implications of what it does \- overuse of \f(CW\*(C`flush\*(C'\fR
can seriously degrade the level of compression achieved. See the \f(CW\*(C`zlib\*(C'\fR
documentation for details.
.PP
Returns true on success.
.Sh "tell"
.IX Subsection "tell"
Usage is
.PP
.Vb 2
\&    $z\->tell()
\&    tell $z
.Ve
.PP
Returns the uncompressed file offset.
.Sh "eof"
.IX Subsection "eof"
Usage is
.PP
.Vb 2
\&    $z\->eof();
\&    eof($z);
.Ve
.PP
Returns true if the \f(CW\*(C`close\*(C'\fR method has been called.
.Sh "seek"
.IX Subsection "seek"
.Vb 2
\&    $z\->seek($position, $whence);
\&    seek($z, $position, $whence);
.Ve
.PP
Provides a sub-set of the \f(CW\*(C`seek\*(C'\fR functionality, with the restriction
that it is only legal to seek forward in the output file/buffer.
It is a fatal error to attempt to seek backward.
.PP
Empty parts of the file/buffer will have \s-1NULL\s0 (0x00) bytes written to them.
.PP
The \f(CW$whence\fR parameter takes one the usual values, namely \s-1SEEK_SET\s0,
\&\s-1SEEK_CUR\s0 or \s-1SEEK_END\s0.
.PP
Returns 1 on success, 0 on failure.
.Sh "binmode"
.IX Subsection "binmode"
Usage is
.PP
.Vb 2
\&    $z\->binmode
\&    binmode $z ;
.Ve
.PP
This is a noop provided for completeness.
.Sh "opened"
.IX Subsection "opened"
.Vb 1
\&    $z\->opened()
.Ve
.PP
Returns true if the object currently refers to a opened file/buffer.
.Sh "autoflush"
.IX Subsection "autoflush"
.Vb 2
\&    my $prev = $z\->autoflush()
\&    my $prev = $z\->autoflush(EXPR)
.Ve
.PP
If the \f(CW$z\fR object is associated with a file or a filehandle, this method
returns the current autoflush setting for the underlying filehandle. If
\&\f(CW\*(C`EXPR\*(C'\fR is present, and is non-zero, it will enable flushing after every
write/print operation.
.PP
If \f(CW$z\fR is associated with a buffer, this method has no effect and always
returns \f(CW\*(C`undef\*(C'\fR.
.PP
\&\fBNote\fR that the special variable \f(CW$|\fR \fBcannot\fR be used to set or
retrieve the autoflush setting.
.Sh "input_line_number"
.IX Subsection "input_line_number"
.Vb 2
\&    $z\->input_line_number()
\&    $z\->input_line_number(EXPR)
.Ve
.PP
This method always returns \f(CW\*(C`undef\*(C'\fR when compressing.
.Sh "fileno"
.IX Subsection "fileno"
.Vb 2
\&    $z\->fileno()
\&    fileno($z)
.Ve
.PP
If the \f(CW$z\fR object is associated with a file or a filehandle, this method
will return the underlying file descriptor.
.PP
If the \f(CW$z\fR object is is associated with a buffer, this method will
return undef.
.Sh "close"
.IX Subsection "close"
.Vb 2
\&    $z\->close() ;
\&    close $z ;
.Ve
.PP
Flushes any pending compressed data and then closes the output file/buffer.
.PP
For most versions of Perl this method will be automatically invoked if
the IO::Compress::RawDeflate object is destroyed (either explicitly or by the
variable with the reference to the object going out of scope). The
exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
these cases, the \f(CW\*(C`close\*(C'\fR method will be called automatically, but
not until global destruction of all live objects when the program is
terminating.
.PP
Therefore, if you want your scripts to be able to run on all versions
of Perl, you should call \f(CW\*(C`close\*(C'\fR explicitly and not rely on automatic
closing.
.PP
Returns true on success, otherwise 0.
.PP
If the \f(CW\*(C`AutoClose\*(C'\fR option has been enabled when the IO::Compress::RawDeflate
object was created, and the object is associated with a file, the
underlying file will also be closed.
.Sh "newStream([\s-1OPTS\s0])"
.IX Subsection "newStream([OPTS])"
Usage is
.PP
.Vb 1
\&    $z\->newStream( [OPTS] )
.Ve
.PP
Closes the current compressed data stream and starts a new one.
.PP
\&\s-1OPTS\s0 consists of any of the the options that are available when creating
the \f(CW$z\fR object.
.PP
See the \*(L"Constructor Options\*(R" section for more details.
.Sh "deflateParams"
.IX Subsection "deflateParams"
Usage is
.PP
.Vb 1
\&    $z\->deflateParams
.Ve
.PP
\&\s-1TODO\s0
.SH "Importing"
.IX Header "Importing"
A number of symbolic constants are required by some methods in 
\&\f(CW\*(C`IO::Compress::RawDeflate\*(C'\fR. None are imported by default.
.IP ":all" 5
.IX Item ":all"
Imports \f(CW\*(C`rawdeflate\*(C'\fR, \f(CW$RawDeflateError\fR and all symbolic
constants that can be used by \f(CW\*(C`IO::Compress::RawDeflate\*(C'\fR. Same as doing this
.Sp
.Vb 1
\&    use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError :constants) ;
.Ve
.IP ":constants" 5
.IX Item ":constants"
Import all symbolic constants. Same as doing this
.Sp
.Vb 1
\&    use IO::Compress::RawDeflate qw(:flush :level :strategy) ;
.Ve
.IP ":flush" 5
.IX Item ":flush"
These symbolic constants are used by the \f(CW\*(C`flush\*(C'\fR method.
.Sp
.Vb 6
\&    Z_NO_FLUSH
\&    Z_PARTIAL_FLUSH
\&    Z_SYNC_FLUSH
\&    Z_FULL_FLUSH
\&    Z_FINISH
\&    Z_BLOCK
.Ve
.IP ":level" 5
.IX Item ":level"
These symbolic constants are used by the \f(CW\*(C`Level\*(C'\fR option in the constructor.
.Sp
.Vb 4
\&    Z_NO_COMPRESSION
\&    Z_BEST_SPEED
\&    Z_BEST_COMPRESSION
\&    Z_DEFAULT_COMPRESSION
.Ve
.IP ":strategy" 5
.IX Item ":strategy"
These symbolic constants are used by the \f(CW\*(C`Strategy\*(C'\fR option in the constructor.
.Sp
.Vb 5
\&    Z_FILTERED
\&    Z_HUFFMAN_ONLY
\&    Z_RLE
\&    Z_FIXED
\&    Z_DEFAULT_STRATEGY
.Ve
.PP
For
.SH "EXAMPLES"
.IX Header "EXAMPLES"
\&\s-1TODO\s0
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate, IO::Uncompress::Inflate, IO::Uncompress::RawInflate, IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzop, IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress
.PP
Compress::Zlib::FAQ
.PP
File::GlobMapper, Archive::Zip,
Archive::Tar,
IO::Zlib
.PP
For \s-1RFC\s0 1950, 1951 and 1952 see 
\&\fIhttp://www.faqs.org/rfcs/rfc1950.html\fR,
\&\fIhttp://www.faqs.org/rfcs/rfc1951.html\fR and
\&\fIhttp://www.faqs.org/rfcs/rfc1952.html\fR
.PP
The \fIzlib\fR compression library was written by Jean-loup Gailly
\&\[e-mail]\fR and Mark Adler \[e-mail]\fR.
.PP
The primary site for the \fIzlib\fR compression library is
\&\fIhttp://www.zlib.org\fR.
.PP
The primary site for gzip is \fIhttp://www.gzip.org\fR.
.SH "AUTHOR"
.IX Header "AUTHOR"
This module was written by Paul Marquess, \[e-mail]\fR.
.SH "MODIFICATION HISTORY"
.IX Header "MODIFICATION HISTORY"
See the Changes file.
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright (c) 2005\-2007 Paul Marquess. All rights reserved.
.PP
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.