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{const wxDateTime\& }{originalTime = wxDateTime::Now()}, \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 originalTime} is given then it is also written to the gzip header
 148 as the timestamp. If omitted the current time is used.
 149
 150 {\it level} is the compression level. It can be an integer between $0$ (no
 151 compression) and $9$ (most compression). $-1$ specifies that the default
 152 compression should be used, and is currently equivalent to $6$.
 153
 154 You can also use the following constants from <wx/zstream.h>:
 155
 156 \begin{verbatim}
 157 // Compression level
 158 enum {
 159     wxZ_DEFAULT_COMPRESSION = -1,
 160     wxZ_NO_COMPRESSION = 0,
 161     wxZ_BEST_SPEED = 1,
 162     wxZ_BEST_COMPRESSION = 9
 163 }
 164 \end{verbatim}
 165
 166
 167 \membersection{wxGzipOutputStream::\destruct{wxGzipOutputStream}}\label{wxgzipoutputstreamdtor}
 168
 169 \func{}{\destruct{wxGzipOutputStream}}{\void}
 170
 171 Destructor.
 172