docs/reference/gio/html/GSeekable.html

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  24 <a href="#GSeekable.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#GSeekable.description" class="shortcut">Description</a>
  27                    |
  28                   <a href="#GSeekable.object-hierarchy" class="shortcut">Object Hierarchy</a>
  29                    |
  30                   <a href="#GSeekable.prerequisites" class="shortcut">Prerequisites</a>
  31                    |
  32                   <a href="#GSeekable.implementations" class="shortcut">Known Implementations</a>
  33 </td></tr>
  34 </table>
  35 <div class="refentry">
  36 <a name="GSeekable"></a><div class="titlepage"></div>
  37 <div class="refnamediv"><table width="100%"><tr>
  38 <td valign="top">
  39 <h2><span class="refentrytitle"><a name="GSeekable.top_of_page"></a>GSeekable</span></h2>
  40 <p>GSeekable — Stream seeking interface</p>
  41 </td>
  42 <td valign="top" align="right"></td>
  43 </tr></table></div>
  44 <div class="refsynopsisdiv">
  45 <a name="GSeekable.synopsis"></a><h2>Synopsis</h2>
  46 <pre class="synopsis">
  47 #include &lt;gio/gio.h&gt;
  48
  49                     <a class="link" href="GSeekable.html#GSeekable-struct" title="GSeekable">GSeekable</a>;
  50 struct              <a class="link" href="GSeekable.html#GSeekableIface" title="struct GSeekableIface">GSeekableIface</a>;
  51 <a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="returnvalue">goffset</span></a>             <a class="link" href="GSeekable.html#g-seekable-tell" title="g_seekable_tell ()">g_seekable_tell</a>                     (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);
  52 <a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GSeekable.html#g-seekable-can-seek" title="g_seekable_can_seek ()">g_seekable_can_seek</a>                 (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);
  53 <a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GSeekable.html#g-seekable-seek" title="g_seekable_seek ()">g_seekable_seek</a>                     (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>,
  54                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a> offset</code></em>,
  55                                                          <em class="parameter"><code><a href="./../glib/glib/glib-IO-Channels.html#GSeekType"><span class="type">GSeekType</span></a> type</code></em>,
  56                                                          <em class="parameter"><code><a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> *cancellable</code></em>,
  57                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> **error</code></em>);
  58 <a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GSeekable.html#g-seekable-can-truncate" title="g_seekable_can_truncate ()">g_seekable_can_truncate</a>             (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);
  59 <a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GSeekable.html#g-seekable-truncate" title="g_seekable_truncate ()">g_seekable_truncate</a>                 (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>,
  60                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a> offset</code></em>,
  61                                                          <em class="parameter"><code><a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> *cancellable</code></em>,
  62                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> **error</code></em>);
  63 </pre>
  64 </div>
  65 <div class="refsect1">
  66 <a name="GSeekable.object-hierarchy"></a><h2>Object Hierarchy</h2>
  67 <pre class="synopsis">
  68   GInterface
  69    +----GSeekable
  70 </pre>
  71 </div>
  72 <div class="refsect1">
  73 <a name="GSeekable.prerequisites"></a><h2>Prerequisites</h2>
  74 <p>
  75 GSeekable requires
  76  <a href="./../gobject/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a>.</p>
  77 </div>
  78 <div class="refsect1">
  79 <a name="GSeekable.implementations"></a><h2>Known Implementations</h2>
  80 <p>
  81 GSeekable is implemented by
  82  <a class="link" href="GFileIOStream.html" title="GFileIOStream">GFileIOStream</a>,  <a class="link" href="GFileInputStream.html" title="GFileInputStream">GFileInputStream</a>,  <a class="link" href="GFileOutputStream.html" title="GFileOutputStream">GFileOutputStream</a>,  <a class="link" href="GMemoryInputStream.html" title="GMemoryInputStream">GMemoryInputStream</a> and  <a class="link" href="GMemoryOutputStream.html" title="GMemoryOutputStream">GMemoryOutputStream</a>.</p>
  83 </div>
  84 <div class="refsect1">
  85 <a name="GSeekable.description"></a><h2>Description</h2>
  86 <p>
  87 <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> is implemented by streams (implementations of
  88 <a class="link" href="GInputStream.html" title="GInputStream"><span class="type">GInputStream</span></a> or <a class="link" href="GOutputStream.html" title="GOutputStream"><span class="type">GOutputStream</span></a>) that support seeking.
  89 </p>
  90 </div>
  91 <div class="refsect1">
  92 <a name="GSeekable.details"></a><h2>Details</h2>
  93 <div class="refsect2">
  94 <a name="GSeekable-struct"></a><h3>GSeekable</h3>
  95 <pre class="programlisting">typedef struct _GSeekable GSeekable;</pre>
  96 <p>
  97 Seek object for streaming operations.
  98 </p>
  99 </div>
 100 <hr>
 101 <div class="refsect2">
 102 <a name="GSeekableIface"></a><h3>struct GSeekableIface</h3>
 103 <pre class="programlisting">struct GSeekableIface {
 104   GTypeInterface g_iface;
 105
 106   /* Virtual Table */
 107
 108   goffset     (* tell)           (GSeekable    *seekable);
 109
 110   gboolean    (* can_seek)       (GSeekable    *seekable);
 111   gboolean    (* seek)           (GSeekable    *seekable,
 112                                   goffset       offset,
 113                                   GSeekType     type,
 114                                   GCancellable *cancellable,
 115                                   GError      **error);
 116
 117   gboolean    (* can_truncate)   (GSeekable    *seekable);
 118   gboolean    (* truncate_fn)    (GSeekable    *seekable,
 119                                   goffset       offset,
 120                                   GCancellable *cancellable,
 121                                   GError       **error);
 122
 123   /* TODO: Async seek/truncate */
 124 };
 125 </pre>
 126 <p>
 127 Provides an interface for implementing seekable functionality on I/O Streams.
 128 </p>
 129 <div class="variablelist"><table border="0">
 130 <col align="left" valign="top">
 131 <tbody>
 132 <tr>
 133 <td><p><span class="term"><a href="./../gobject/gobject/gobject-Type-Information.html#GTypeInterface"><span class="type">GTypeInterface</span></a> <em class="structfield"><code><a name="GSeekableIface.g-iface"></a>g_iface</code></em>;</span></p></td>
 134 <td>The parent interface.</td>
 135 </tr>
 136 <tr>
 137 <td><p><span class="term"><em class="structfield"><code><a name="GSeekableIface.tell"></a>tell</code></em> ()</span></p></td>
 138 <td>Tells the current location within a stream.</td>
 139 </tr>
 140 <tr>
 141 <td><p><span class="term"><em class="structfield"><code><a name="GSeekableIface.can-seek"></a>can_seek</code></em> ()</span></p></td>
 142 <td>Checks if seeking is supported by the stream.</td>
 143 </tr>
 144 <tr>
 145 <td><p><span class="term"><em class="structfield"><code><a name="GSeekableIface.seek"></a>seek</code></em> ()</span></p></td>
 146 <td>Seeks to a location within a stream.</td>
 147 </tr>
 148 <tr>
 149 <td><p><span class="term"><em class="structfield"><code><a name="GSeekableIface.can-truncate"></a>can_truncate</code></em> ()</span></p></td>
 150 <td>Checks if truncation is supported by the stream.</td>
 151 </tr>
 152 <tr>
 153 <td><p><span class="term"><em class="structfield"><code><a name="GSeekableIface.truncate-fn"></a>truncate_fn</code></em> ()</span></p></td>
 154 <td>Truncates a stream.</td>
 155 </tr>
 156 </tbody>
 157 </table></div>
 158 </div>
 159 <hr>
 160 <div class="refsect2">
 161 <a name="g-seekable-tell"></a><h3>g_seekable_tell ()</h3>
 162 <pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="returnvalue">goffset</span></a>             g_seekable_tell                     (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);</pre>
 163 <p>
 164 Tells the current position within the stream.
 165 </p>
 166 <div class="variablelist"><table border="0">
 167 <col align="left" valign="top">
 168 <tbody>
 169 <tr>
 170 <td><p><span class="term"><em class="parameter"><code>seekable</code></em> :</span></p></td>
 171 <td>a <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a>.</td>
 172 </tr>
 173 <tr>
 174 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 175 <td>the offset from the beginning of the buffer.</td>
 176 </tr>
 177 </tbody>
 178 </table></div>
 179 </div>
 180 <hr>
 181 <div class="refsect2">
 182 <a name="g-seekable-can-seek"></a><h3>g_seekable_can_seek ()</h3>
 183 <pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            g_seekable_can_seek                 (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);</pre>
 184 <p>
 185 Tests if the stream supports the <a class="link" href="GSeekable.html#GSeekableIface" title="struct GSeekableIface"><span class="type">GSeekableIface</span></a>.
 186 </p>
 187 <div class="variablelist"><table border="0">
 188 <col align="left" valign="top">
 189 <tbody>
 190 <tr>
 191 <td><p><span class="term"><em class="parameter"><code>seekable</code></em> :</span></p></td>
 192 <td>a <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a>.</td>
 193 </tr>
 194 <tr>
 195 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 196 <td>
 197 <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if <em class="parameter"><code>seekable</code></em> can be seeked. <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> otherwise.</td>
 198 </tr>
 199 </tbody>
 200 </table></div>
 201 </div>
 202 <hr>
 203 <div class="refsect2">
 204 <a name="g-seekable-seek"></a><h3>g_seekable_seek ()</h3>
 205 <pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            g_seekable_seek                     (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>,
 206                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a> offset</code></em>,
 207                                                          <em class="parameter"><code><a href="./../glib/glib/glib-IO-Channels.html#GSeekType"><span class="type">GSeekType</span></a> type</code></em>,
 208                                                          <em class="parameter"><code><a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> *cancellable</code></em>,
 209                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> **error</code></em>);</pre>
 210 <p>
 211 Seeks in the stream by the given <em class="parameter"><code>offset</code></em>, modified by <em class="parameter"><code>type</code></em>.
 212 </p>
 213 <p>
 214 If <em class="parameter"><code>cancellable</code></em> is not <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, then the operation can be cancelled by
 215 triggering the cancellable object from another thread. If the operation
 216 was cancelled, the error <a class="link" href="gio-GIOError.html#G-IO-ERROR-CANCELLED:CAPS"><code class="literal">G_IO_ERROR_CANCELLED</code></a> will be returned.
 217 </p>
 218 <div class="variablelist"><table border="0">
 219 <col align="left" valign="top">
 220 <tbody>
 221 <tr>
 222 <td><p><span class="term"><em class="parameter"><code>seekable</code></em> :</span></p></td>
 223 <td>a <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a>.</td>
 224 </tr>
 225 <tr>
 226 <td><p><span class="term"><em class="parameter"><code>offset</code></em> :</span></p></td>
 227 <td>a <a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a>.</td>
 228 </tr>
 229 <tr>
 230 <td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
 231 <td>a <a href="./../glib/glib/glib-IO-Channels.html#GSeekType"><span class="type">GSeekType</span></a>.</td>
 232 </tr>
 233 <tr>
 234 <td><p><span class="term"><em class="parameter"><code>cancellable</code></em> :</span></p></td>
 235 <td>optional <a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> object, <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to ignore. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 236 </td>
 237 </tr>
 238 <tr>
 239 <td><p><span class="term"><em class="parameter"><code>error</code></em> :</span></p></td>
 240 <td>a <a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> location to store the error occurring, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to
 241 ignore.</td>
 242 </tr>
 243 <tr>
 244 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 245 <td>
 246 <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if successful. If an error
 247 has occurred, this function will return <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> and set <em class="parameter"><code>error</code></em>
 248 appropriately if present.</td>
 249 </tr>
 250 </tbody>
 251 </table></div>
 252 </div>
 253 <hr>
 254 <div class="refsect2">
 255 <a name="g-seekable-can-truncate"></a><h3>g_seekable_can_truncate ()</h3>
 256 <pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            g_seekable_can_truncate             (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>);</pre>
 257 <p>
 258 Tests if the stream can be truncated.
 259 </p>
 260 <div class="variablelist"><table border="0">
 261 <col align="left" valign="top">
 262 <tbody>
 263 <tr>
 264 <td><p><span class="term"><em class="parameter"><code>seekable</code></em> :</span></p></td>
 265 <td>a <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a>.</td>
 266 </tr>
 267 <tr>
 268 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 269 <td>
 270 <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the stream can be truncated, <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> otherwise.</td>
 271 </tr>
 272 </tbody>
 273 </table></div>
 274 </div>
 275 <hr>
 276 <div class="refsect2">
 277 <a name="g-seekable-truncate"></a><h3>g_seekable_truncate ()</h3>
 278 <pre class="programlisting"><a href="./../glib/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            g_seekable_truncate                 (<em class="parameter"><code><a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a> *seekable</code></em>,
 279                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a> offset</code></em>,
 280                                                          <em class="parameter"><code><a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> *cancellable</code></em>,
 281                                                          <em class="parameter"><code><a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> **error</code></em>);</pre>
 282 <p>
 283 Truncates a stream with a given <span class="type">offset</span>.
 284 </p>
 285 <p>
 286 If <em class="parameter"><code>cancellable</code></em> is not <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, then the operation can be cancelled by
 287 triggering the cancellable object from another thread. If the operation
 288 was cancelled, the error <a class="link" href="gio-GIOError.html#G-IO-ERROR-CANCELLED:CAPS"><code class="literal">G_IO_ERROR_CANCELLED</code></a> will be returned. If an
 289 operation was partially finished when the operation was cancelled the
 290 partial result will be returned, without an error.
 291 </p>
 292 <p>
 293 Virtual: truncate_fn
 294 </p>
 295 <div class="variablelist"><table border="0">
 296 <col align="left" valign="top">
 297 <tbody>
 298 <tr>
 299 <td><p><span class="term"><em class="parameter"><code>seekable</code></em> :</span></p></td>
 300 <td>a <a class="link" href="GSeekable.html" title="GSeekable"><span class="type">GSeekable</span></a>.</td>
 301 </tr>
 302 <tr>
 303 <td><p><span class="term"><em class="parameter"><code>offset</code></em> :</span></p></td>
 304 <td>a <a href="./../glib/glib/glib-Basic-Types.html#goffset"><span class="type">goffset</span></a>.</td>
 305 </tr>
 306 <tr>
 307 <td><p><span class="term"><em class="parameter"><code>cancellable</code></em> :</span></p></td>
 308 <td>optional <a class="link" href="GCancellable.html" title="GCancellable"><span class="type">GCancellable</span></a> object, <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to ignore. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 309 </td>
 310 </tr>
 311 <tr>
 312 <td><p><span class="term"><em class="parameter"><code>error</code></em> :</span></p></td>
 313 <td>a <a href="./../glib/glib/glib-Error-Reporting.html#GError"><span class="type">GError</span></a> location to store the error occurring, or <a href="./../glib/glib/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to
 314 ignore.</td>
 315 </tr>
 316 <tr>
 317 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 318 <td>
 319 <a href="./../glib/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if successful. If an error
 320 has occurred, this function will return <a href="./../glib/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> and set <em class="parameter"><code>error</code></em>
 321 appropriately if present.</td>
 322 </tr>
 323 </tbody>
 324 </table></div>
 325 </div>
 326 </div>
 327 <div class="refsect1">
 328 <a name="GSeekable.see-also"></a><h2>See Also</h2>
 329 <a class="link" href="GInputStream.html" title="GInputStream"><span class="type">GInputStream</span></a>, <a class="link" href="GOutputStream.html" title="GOutputStream"><span class="type">GOutputStream</span></a>
 330 </div>
 331 </div>
 332 <div class="footer">
 333 <hr>
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