86e58bc0d8
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@8651 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
130 lines
3.4 KiB
Plaintext
130 lines
3.4 KiB
Plaintext
/**
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\page advanced Advanced FLTK
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This chapter explains advanced programming and design topics
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that will help you to get the most out of FLTK.
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\section advanced_multithreading Multithreading
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FLTK supports multithreaded applications using a locking mechanism
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based on "pthreads". We do not provide a threading interface as part of
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the library. However a simple example how threads can be implemented
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for all supported platforms can be found in \p test/threads.h
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and \p test/threads.cxx.
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To use the locking mechanism, FLTK must be compiled with
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\p --enable-threads set during the \p configure
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process. IDE-based versions of FLTK are automatically compiled with
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locking enabled if possible.
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In \p main(), call
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Fl::lock() before
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Fl::run() or
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Fl::wait() to start the runtime
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multithreading support for your program. All callbacks and derived
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functions like \p handle() and \p draw() will now be properly
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locked:
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\code
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int main() {
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Fl::lock();
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/* run thread */
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while (Fl::wait() > 0) {
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if (Fl::thread_message()) {
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/* process your data */
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}
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}
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}
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\endcode
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You can now start as many threads as you like. From within
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a thread (other than the main thread) FLTK calls must be wrapped
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with calls to Fl::lock() and Fl::unlock():
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\code
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Fl::lock(); // avoid conflicting calls
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... // your code here
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Fl::unlock(); // allow other threads to access FLTK again
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\endcode
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You can send messages from child threads to the main thread
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using Fl::awake(void* message):
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\code
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void *msg; // "msg" is a pointer to your message
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Fl::awake(msg); // send "msg" to main thread
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\endcode
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A message can be anything you like. The main thread can retrieve
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the message by calling Fl::thread_message(). See example above.
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You can also tell the main thread to call a function for you
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as soon as possible by using
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Fl::awake(Fl_Awake_Handler cb, void* userdata):
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\code
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void do_something(void *userdata) {
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// running with the main thread
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}
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// running in another thread
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void *data; // "data" is a pointer to your user data
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Fl::awake(do_something, data); // call something in main thread
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\endcode
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FLTK supports multiple platforms, some of which allow only the
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main thread to handle system events and open or close windows.
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The safe thing to do is to adhere to the following rules for
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threads on all operating systems:
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\li Don't \p show() or \p hide() anything that contains
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widgets derived from Fl_Window, including dialogs, file
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choosers, subwindows or those using Fl_Gl_Window.
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\li Don't call Fl::wait(), Fl::flush() or any
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related methods that will handle system messages
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\li Don't start or cancel timers
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\li Don't change window decorations or titles
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\li The \p make_current() method may or may not work well for
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regular windows, but should always work for a Fl_Gl_Window
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to allow for high speed rendering on graphics cards with multiple
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pipelines
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See also:
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Fl::awake(void* message),
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Fl::lock(),
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Fl::thread_message(),
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Fl::unlock().
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\htmlonly
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<hr>
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<table summary="navigation bar" width="100%" border="0">
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<tr>
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<td width="45%" align="LEFT">
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<a class="el" href="fluid.html">
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[Prev]
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Programming with FLUID
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</a>
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</td>
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<td width="10%" align="CENTER">
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<a class="el" href="index.html">[Index]</a>
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</td>
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<td width="45%" align="RIGHT">
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<a class="el" href="unicode.html">
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Unicode and utf-8 Support
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[Next]
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</a>
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</td>
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</tr>
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</table>
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\endhtmlonly
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*/
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