documentation/winedev-graphical.sgml

   1   <chapter>
   2     <title>Graphical modules</title>
   3     <sect1>
   4       <title>GDI Module</title>
   5
   6       <sect2>
   7         <title>X Windows System interface</title>
   8
   9         <para>
  10           The X libraries used to implement X clients (such as Wine)
  11           do not work properly if multiple threads access the same
  12           display concurrently. It is possible to compile the X
  13           libraries to perform their own synchronization (initiated
  14           by calling <function>XInitThreads()</function>). However,
  15           Wine does not use this approach. Instead Wine performs its
  16           own synchronization using the
  17           <function>wine_tsx11_lock()</function> / <function>wine_tsx11_unlock()</function>
  18           functions.  This locking protects library access
  19           with a critical section, and also arranges things so that
  20           X libraries compiled without <option>-D_REENTRANT</option>
  21           (eg. with global <varname>errno</varname> variable) will
  22           work with Wine.
  23         </para>
  24         <para>
  25           In the past, all calls to X used to go through a wrapper called
  26           <function>TSX...()</function> (for "Thread Safe X ...").
  27           While it is still being used in the code, it's inefficient
  28           as the lock is potentially aquired and released unnecessarily.
  29           New code should explicitly aquire the lock.
  30         </para>
  31       </sect2>
  32     </sect1>
  33   </chapter>
  34
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