docs/latex/wx/gzstream.tex

   1 %
   2 % automatically generated by HelpGen $Revision$ from
   3 % gzstream.h at 20/Aug/03 18:41:55
   4 %
   5
   6 %
   7 % wxGzipInputStream
   8 %
   9
  10 \section{\class{wxGzipInputStream}}\label{wxgzipinputstream}
  11
  12 A stream filter to decompress gzipped data. The gzip format is specified in
  13 RFC-1952.
  14
  15 A gzip stream can contain the original filename and timestamp of the
  16 compressed data. These fields can be obtained using the
  17  \helpref{GetName()}{wxgzipinputstreamgetname} and
  18  \helpref{GetDateTime()}{wxgzipinputstreamgetdatetime} accessors.
  19
  20 If the stream turns out not to be a gzip stream (i.e. the signature bytes
  21 0x1f, 0x8b are not found), then the constructor unreads the bytes read and
  22 sets the stream state to {\it wxSTREAM\_EOF}.
  23
  24 So given a possibly gzipped stream '{\it maybe\_gzipped}' you can construct
  25 a decompressed stream '{\it decompressed}' with something like:
  26
  27 \begin{verbatim}
  28 wxGzipInputStream gzip(maybe_gzipped);
  29 wxInputStream *decompressed = &gzip;
  30 if (gzip.Eof())
  31     decompressed = &maybe_gzipped;
  32
  33 \end{verbatim}
  34 The stream will not read past the end of the gzip data, therefore you
  35 can read another gzip entry concatenated by creating another
  36  {\it wxGzipInputStream} on the same underlying stream.
  37
  38 The stream is not seekable, \helpref{SeekI()}{wxinputstreamseeki} returns
  39  {\it wxInvalidOffset}.  Also \helpref{GetSize()}{wxstreambasegetsize} is
  40 not supported, it always returns $0$.
  41
  42 \wxheading{Derived from}
  43
  44 \helpref{wxFilterInputStream}{wxfilterinputstream}
  45
  46 \wxheading{Include files}
  47
  48 <wx/gzstream.h>
  49
  50 \wxheading{See also}
  51
  52 \helpref{wxGzipOutputStream}{wxgzipoutputstream},
  53  \helpref{wxZlibInputStream}{wxzlibinputstream},
  54  \helpref{wxInputStream}{wxinputstream}.
  55
  56 \latexignore{\rtfignore{\wxheading{Members}}}
  57
  58
  59 \membersection{wxGzipInputStream::wxGzipInputStream}\label{wxgzipinputstreamwxgzipinputstream}
  60
  61 \func{}{wxGzipInputStream}{\param{wxInputStream\& }{stream}, \param{wxMBConv\& }{conv = wxConvFile}}
  62
  63 Constructs an object to decompress a gzipped stream.
  64
  65 The constructor reads the gzip header. If the original file name and timestamp
  66 are present, then they can be obtained through the
  67  \helpref{GetName()}{wxgzipinputstreamgetname} and
  68  \helpref{GetDateTime()}{wxgzipinputstreamgetdatetime} accessors.
  69
  70 The filename in the header is stored using an 8-bit character set. In a
  71 Unicode build {\it conv} is used to translate the filename into Unicode (it
  72 has no effect on the stream data). RFC-1952 specifies that the character set
  73 should be ISO-8859-1, however the default here is to use {\it wxConvFile}
  74  which more closely matches the behaviour of the gzip program. In
  75 a non-Unicode build {\it conv} is ignored.
  76
  77 If the first two bytes are not the gzip signature, then the data is not
  78 gzipped after all. The stream state is set to {\it wxSTREAM\_EOF}, and the
  79 two bytes are unread so that the underlying stream can be read directly.
  80
  81
  82 \membersection{wxGzipInputStream::\destruct{wxGzipInputStream}}\label{wxgzipinputstreamdtor}
  83
  84 \func{}{\destruct{wxGzipInputStream}}{\void}
  85
  86 Destructor.
  87
  88
  89 \membersection{wxGzipInputStream::GetDateTime}\label{wxgzipinputstreamgetdatetime}
  90
  91 \constfunc{wxDateTime}{GetDateTime}{\void}
  92
  93 Returns the original modification time of gzipped data, as obtained from the
  94 gzip header.
  95
  96
  97 \membersection{wxGzipInputStream::GetName}\label{wxgzipinputstreamgetname}
  98
  99 \constfunc{wxString}{GetName}{\void}
 100
 101 Returns the original filename of gzipped data, with any directory components
 102 removed.
 103
 104
 105 %
 106 % wxGzipOutputStream
 107 %
 108
 109 \section{\class{wxGzipOutputStream}}\label{wxgzipoutputstream}
 110
 111 A stream filter to compress gzipped data. The gzip format is specified in
 112 RFC-1952.
 113
 114 The stream is not seekable, \helpref{SeekO()}{wxoutputstreamseeko} returns
 115  {\it wxInvalidOffset}.
 116
 117
 118 \wxheading{Derived from}
 119
 120 \helpref{wxFilterOutputStream}{wxfilteroutputstream}
 121
 122 \wxheading{Include files}
 123
 124 <wx/gzstream.h>
 125
 126 \wxheading{See also}
 127
 128 \helpref{wxGzipInputStream}{wxgzipinputstream},
 129  \helpref{wxZlibOutputStream}{wxzliboutputstream},
 130  \helpref{wxOutputStream}{wxoutputstream}.
 131
 132 \latexignore{\rtfignore{\wxheading{Members}}}
 133
 134
 135 \membersection{wxGzipOutputStream::wxGzipOutputStream}\label{wxgzipoutputstreamwxgzipoutputstream}
 136
 137 \func{}{wxGzipOutputStream}{\param{wxOutputStream\& }{stream}, \param{const wxString\& }{originalName = wxEmptyString}, \param{int }{level = -1}, \param{wxMBConv\& }{conv = wxConvFile}}
 138
 139 If the {\it originalName} is given, then it is written to the gzip header
 140 with any directory components removed. On a Unicode build it is first
 141 converted to an 8-bit encoding using {\it conv}. RFC-1952 specifies that
 142 the character set should be ISO-8859-1, however the default here is to
 143 use {\it wxConvFile} which more closely matches the behaviour of the gzip
 144 program. In a non-Unicode build {\it conv} is ignored. {\it conv} has no
 145 effect on the stream data.
 146
 147 If {\it originalName} specifies a file that exists then it's current
 148 modification time is also written to the gzip header as the timestamp.
 149 Otherwise the current time is used for the timestamp.
 150
 151 {\it level} is the compression level. It can be an integer between $0$ (no
 152 compression) and $9$ (most compression). $-1$ specifies that the default
 153 compression should be used, and is currently equivalent to $6$.
 154
 155 You can also use the following constants from <wx/zstream.h>:
 156
 157 \begin{verbatim}
 158 // Compression level
 159 enum {
 160     wxZ_DEFAULT_COMPRESSION = -1,
 161     wxZ_NO_COMPRESSION = 0,
 162     wxZ_BEST_SPEED = 1,
 163     wxZ_BEST_COMPRESSION = 9
 164 }
 165 \end{verbatim}
 166
 167
 168 \membersection{wxGzipOutputStream::\destruct{wxGzipOutputStream}}\label{wxgzipoutputstreamdtor}
 169
 170 \func{}{\destruct{wxGzipOutputStream}}{\void}
 171
 172 Destructor.
 173