main_tstream.htm

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   3 <title>KOL Help: TStream object (main frame)</title>
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   7 <body bgcolor="#FFFFEF" text="#000000" link="#008080" vlink="#008000" alink="#808000">
   8 <p><font face="Courier" color="#800080"><b>TStream( unit <a href=kol_pas.htm>KOL.pas</a> )
   9  <font face="Wingdings">ï</font> <a href=tobj.htm>TObj</a>
  10  <font face="Wingdings">ï</font> <a href=_tobj.htm>_TObj</a>
  11 </b></font></p>
  12 <p><b>
  13 TStream = object( <a href=tobj.htm target="_top">TObj</a> )
  14 </b></p>
  15 Simple stream object. Can be opened for file, or as memory stream (see
  16 <a href=kol_pas.htm#newreadfilestream target="_top">NewReadFileStream</a>, <a href=kol_pas.htm#newwritefilestream target="_top">NewWriteFileStream</a>, <a href=kol_pas.htm#newmemorystream target="_top">NewMemoryStream</a>, etc.). And, another
  17 type of streaming object can be derived (without inheriting new object
  18 type, just by writing another New...Stream method, which calls
  19 <a href=kol_pas.htm#_newstream target="_top">_NewStream</a> and pass methods record to it).
  20 <h3 align="center"><font color="#FF8080">TStream properties</font></h3>
  21 <a name="size"></a>
  22 <p>
  23 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Size</b></font>: <b>DWord</b>;</font>
  24 <br>
  25 Returns stream size. For some custom streams, can be slow
  26 operation, or even always return undefined value (-1 recommended).
  27 </p>
  28 <a name="position"></a>
  29 <p>
  30 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Position</b></font>: <b>DWord</b>;</font>
  31 <br>
  32 Current position.
  33 </p>
  34 <a name="memory"></a>
  35 <p>
  36 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Memory</b></font>: <b>Pointer</b>;</font>
  37 &nbsp;&nbsp;&nbsp;<font face="Webdings" size=7>&#209;</font>&nbsp;&nbsp;&nbsp;
  38 <br>
  39 Only for memory stream.
  40 </p>
  41 <a name="handle"></a>
  42 <p>
  43 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Handle</b></font>: THandle;</font>
  44 &nbsp;&nbsp;&nbsp;<font face="Webdings" size=7>&#209;</font>&nbsp;&nbsp;&nbsp;
  45 <br>
  46 Only for file stream. It is possible to check that Handle &lt;&gt;
  47 INVALID_HANDLE_VALUE to ensure that file stream is created OK.
  48 </p>
  49 <a name="methods"></a>
  50 <p>
  51 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Methods</b></font>: PStreamMethods;</font>
  52 &nbsp;&nbsp;&nbsp;<font face="Webdings" size=7>&#209;</font>&nbsp;&nbsp;&nbsp;
  53 <br>
  54 Pointer to TStreamMethods record. Useful to implement custom-defined
  55 streams, which can access its fCustom field, or even to change
  56 methods when necessary.
  57 </p>
  58 <a name="data"></a>
  59 <p>
  60 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Data</b></font>: TStreamData;</font>
  61 &nbsp;&nbsp;&nbsp;<font face="Webdings" size=7>&#209;</font>&nbsp;&nbsp;&nbsp;
  62 <br>
  63 Pointer to TStreamData record. Useful to implement custom-defined
  64 streams, which can access Data fields directly when implemented.
  65 </p>
  66 <a name="capacity"></a>
  67 <p>
  68 <font face="Courier" color="#800080"><b>property</b> <font color="#808000"><b>Capacity</b></font>: <b>DWORD</b>;</font>
  69 <br>
  70 Amound of memory allocated for data (MemoryStream).
  71 </p>
  72 <h4 align="center"><font color="black">Properties, inherited from <a href="tobj.htm" target="_top">TObj</a></font></h4>
  73 <h3 align="center"><font color="#FF8080">TStream methods</font></h3>
  74 <a name="read"></a>
  75 <p>
  76 <font face="Courier" color="#800080"><b>function</b> <b>Read</b>( <b>var</b> Buffer; Count: <b>DWord</b> ): <b>DWord</b>;</font>
  77 <br>
  78 Reads Count bytes from a stream. Returns number of bytes read.
  79 </p>
  80 <a name="seek"></a>
  81 <p>
  82 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>Seek</b></font>( MoveTo: <b>Integer</b>; MoveMethod: TMoveMethod ): <b>DWord</b>;</font>
  83 <br>
  84 Allows to change current position or to obtain it. Property
  85 <a href=#position target="main">Position</a> uses this method both for get and set position.
  86 </p>
  87 <a name="write"></a>
  88 <p>
  89 <font face="Courier" color="#800080"><b>function</b> <b>Write</b>( <b>var</b> Buffer; Count: <b>DWord</b> ): <b>DWord</b>;</font>
  90 <br>
  91 Writes Count bytes from Buffer, starting from current position
  92 in a stream. Returns how much bytes are written.
  93 </p>
  94 <a name="writestr"></a>
  95 <p>
  96 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>WriteStr</b></font>( S: <b>String</b> ): <b>DWORD</b>;</font>
  97 <br>
  98 Writes string to the stream, not including ending #0. Exactly
  99 Length( S ) characters are written.
 100 </p>
 101 <a name="writestrz"></a>
 102 <p>
 103 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>WriteStrZ</b></font>( S: <b>String</b> ): <b>DWORD</b>;</font>
 104 <br>
 105 Writes string, adding #0. Number of bytes written is returned.
 106 </p>
 107 <a name="readstrz"></a>
 108 <p>
 109 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>ReadStrZ</b></font>: <b>String</b>;</font>
 110 <br>
 111 Reads string, finished by #0. After reading, current position in
 112 the stream is set to the byte, follows #0.
 113 </p>
 114 <a name="readstr"></a>
 115 <p>
 116 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>ReadStr</b></font>: <b>String</b>;</font>
 117 <br>
 118 Reads string, finished by #13, #10 or #13#10 symbols. Terminating symbols
 119 #13 and/or #10 are not added to the end of returned string though
 120 stream positioned follow it.
 121 </p>
 122 <a name="writestrex"></a>
 123 <p>
 124 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>WriteStrEx</b></font>( S: <b>String</b> ): <b>DWord</b>;</font>
 125 <br>
 126 Writes string S to stream, also saving its size for future use by
 127 ReadStrEx* functions. Returns number of actually written characters.
 128 </p>
 129 <a name="readstrexvar"></a>
 130 <p>
 131 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>ReadStrExVar</b></font>( <b>var</b> S: <b>String</b> ): <b>DWord</b>;</font>
 132 <br>
 133 Reads string from stream and assigns it to S.
 134 Returns number of actually read characters.
 135 Note:
 136 String must be written by using <a href=#writestrex target="main">WriteStrEx</a> function.
 137 Return value is count of characters READ, not the length of string.
 138 </p>
 139 <a name="readstrex"></a>
 140 <p>
 141 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>ReadStrEx</b></font>: <b>String</b>;</font>
 142 <br>
 143 Reads string from stream and returns it.
 144 </p>
 145 <a name="writestrpas"></a>
 146 <p>
 147 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>WriteStrPas</b></font>( S: <b>String</b> ): <b>DWORD</b>;</font>
 148 <br>
 149 Writes a string in Pascal short string format - 1 byte length, then string
 150 itself without trailing #0 char. S parameter length should not exceed 255
 151 chars, rest chars are truncated while writing. Total amount of bytes
 152 written is returned.
 153 </p>
 154 <a name="readstrpas"></a>
 155 <p>
 156 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>ReadStrPas</b></font>: <b>String</b>;</font>
 157 <br>
 158 Reads 1 byte from a stream, then treat it as a length of following string
 159 which is read and returned. A purpose of this function is reading strings
 160 written using <a href=#writestrpas target="main">WriteStrPas</a>.
 161 </p>
 162 <a name="seekasync"></a>
 163 <p>
 164 <font face="Courier" color="#800080"><b>procedure</b> <font color="#808000"><b>SeekAsync</b></font>( MoveTo: <b>Integer</b>; MoveMethod: TMoveMethod );</font>
 165 <br>
 166 Changes current position asynchronously. To wait for finishing the
 167 operation, use method <a href=#wait target="main">Wait</a>.
 168 </p>
 169 <a name="readasync"></a>
 170 <p>
 171 <font face="Courier" color="#800080"><b>procedure</b> <font color="#808000"><b>ReadAsync</b></font>( <b>var</b> Buffer; Count: <b>DWord</b> );</font>
 172 <br>
 173 Reads Count bytes from a stream asynchronously. To wait finishing the
 174 operation, use method <a href=#wait target="main">Wait</a>.
 175 </p>
 176 <a name="writeasync"></a>
 177 <p>
 178 <font face="Courier" color="#800080"><b>procedure</b> <font color="#808000"><b>WriteAsync</b></font>( <b>var</b> Buffer; Count: <b>DWord</b> );</font>
 179 <br>
 180 Writes Count bytes from Buffer, starting from current position
 181 in a stream - asynchronously. To wait finishing the operation,
 182 use method <a href=#wait target="main">Wait</a>.
 183 </p>
 184 <a name="busy"></a>
 185 <p>
 186 <font face="Courier" color="#800080"><b>function</b> <font color="#808000"><b>Busy</b></font>: <b>Boolean</b>;</font>
 187 <br>
 188 Returns TRUE until finishing the last asynchronous operation
 189 started by calling <a href=#seekasync target="main">SeekAsync</a>, <a href=#readasync target="main">ReadAsync</a>, <a href=#writeasync target="main">WriteAsync</a> methods.
 190 </p>
 191 <a name="wait"></a>
 192 <p>
 193 <font face="Courier" color="#800080"><b>procedure</b> <font color="#808000"><b>Wait</b></font>;</font>
 194 <br>
 195 Waits for finishing the last asynchronous operation.
 196 </p>
 197 <h4 align="center"><font color="black">Methods, inherited from <a href="tobj.htm" target="_top">TObj</a></font></h4>
 198 <h3 align="center"><font color="#FF8080">TStream events</font></h3>
 199 <h4 align="center"><font color="black">Events, inherited from <a href="tobj.htm" target="_top">TObj</a></font></h4>
 200 <h3 align="center"><font color="#FF8080">TStream fields</font></h3>
 201 <h4 align="center"><font color="black">Fields, inherited from <a href="tobj.htm" target="_top">TObj</a></font></h4>
 202 <hr>
 203 <p align="center">[&nbsp;<a href=index.htm>Index</a>&nbsp;]</p>
 204 <p align="center"><font face="Comic Sans MS"><small>This help is generated 22-Sep-2005 by KOL Help generator, (C) 2000-2001 by Vladimir Kladov<br>Modified (C) 2003 by Alexander Bartov</small></font></p>
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