41 lines
2.2 KiB
HTML
41 lines
2.2 KiB
HTML
<HTML><HEAD><TITLE>Tcl Built-In Commands - update manual page</TITLE></HEAD><BODY>
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<H3><A NAME="M2">NAME</A></H3>
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update - Process pending events and idle callbacks
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<H3><A NAME="M3">SYNOPSIS</A></H3>
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<B>update</B> ?<B>idletasks</B>?<BR>
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<H3><A NAME="M4">DESCRIPTION</A></H3>
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This command is used to bring the application ``up to date''
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by entering the event loop repeatedly until all pending events
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(including idle callbacks) have been processed.
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<P>
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If the <B>idletasks</B> keyword is specified as an argument to the
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command, then no new events or errors are processed; only idle
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callbacks are invoked.
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This causes operations that are normally deferred, such as display
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updates and window layout calculations, to be performed immediately.
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<P>
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The <B>update idletasks</B> command is useful in scripts where
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changes have been made to the application's state and you want those
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changes to appear on the display immediately, rather than waiting
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for the script to complete. Most display updates are performed as
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idle callbacks, so <B>update idletasks</B> will cause them to run.
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However, there are some kinds of updates that only happen in
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response to events, such as those triggered by window size changes;
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these updates will not occur in <B>update idletasks</B>.
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<P>
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The <B>update</B> command with no options is useful in scripts where
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you are performing a long-running computation but you still want
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the application to respond to events such as user interactions; if
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you occasionally call <B>update</B> then user input will be processed
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during the next call to <B>update</B>.
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<H3><A NAME="M5">SEE ALSO</A></H3>
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<B><A HREF="../TkCmd/after.htm">after</A></B>, <B><A HREF="../TkCmd/bgerror.htm">bgerror</A></B>
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<H3><A NAME="M6">KEYWORDS</A></H3>
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<A href="../Keywords/E.htm#event">event</A>, <A href="../Keywords/F.htm#flush">flush</A>, <A href="../Keywords/H.htm#handler">handler</A>, <A href="../Keywords/I.htm#idle">idle</A>, <A href="../Keywords/U.htm#update">update</A>
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<HR><PRE>
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<A HREF="../copyright.htm">Copyright</A> © 1990-1992 The Regents of the University of California.
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<A HREF="../copyright.htm">Copyright</A> © 1994-1996 Sun Microsystems, Inc.
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<A HREF="../copyright.htm">Copyright</A> © 1995-1997 Roger E. Critchlow Jr.</PRE>
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</BODY></HTML>
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