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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><HEAD> <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9"> <TITLE>GTK v1.2 Tutorial: Advanced Event and Signal Handling</TITLE> <LINK HREF="gtk_tut-19.html" REL=next> <LINK HREF="gtk_tut-17.html" REL=previous> <LINK HREF="gtk_tut.html#toc18" REL=contents></HEAD><BODY BGCOLOR="#FFFFFF"><A HREF="gtk_tut-19.html">Next</A><A HREF="gtk_tut-17.html">Previous</A><A HREF="gtk_tut.html#toc18">Contents</A><HR NOSHADE><H2><A NAME="sec_Adv_Events_and_Signals"></A> <A NAME="s18">18. Advanced Event and Signal Handling</A></H2><H2><A NAME="ss18.1">18.1 Signal Functions</A></H2><H3>Connecting and Disconnecting Signal Handlers</H3><P><P><BLOCKQUOTE><CODE><PRE>guint gtk_signal_connect( GtkObject *object, const gchar *name, GtkSignalFunc func, gpointer func_data );guint gtk_signal_connect_after( GtkObject *object, const gchar *name, GtkSignalFunc func, gpointer func_data );guint gtk_signal_connect_object( GtkObject *object, const gchar *name, GtkSignalFunc func, GtkObject *slot_object );guint gtk_signal_connect_object_after( GtkObject *object, const gchar *name, GtkSignalFunc func, GtkObject *slot_object );guint gtk_signal_connect_full( GtkObject *object, const gchar *name, GtkSignalFunc func, GtkCallbackMarshal marshal, gpointer data, GtkDestroyNotify destroy_func, gint object_signal, gint after );guint gtk_signal_connect_interp( GtkObject *object, const gchar *name, GtkCallbackMarshal func, gpointer data, GtkDestroyNotify destroy_func, gint after );void gtk_signal_connect_object_while_alive( GtkObject *object, const gchar *signal, GtkSignalFunc func, GtkObject *alive_object );void gtk_signal_connect_while_alive( GtkObject *object, const gchar *signal, GtkSignalFunc func, gpointer func_data, GtkObject *alive_object );void gtk_signal_disconnect( GtkObject *object, guint handler_id );void gtk_signal_disconnect_by_func( GtkObject *object, GtkSignalFunc func, gpointer data );</PRE></CODE></BLOCKQUOTE><P><H3>Blocking and Unblocking Signal Handlers</H3><P><BLOCKQUOTE><CODE><PRE>void gtk_signal_handler_block( GtkObject *object, guint handler_id);void gtk_signal_handler_block_by_func( GtkObject *object, GtkSignalFunc func, gpointer data );void gtk_signal_handler_block_by_data( GtkObject *object, gpointer data );void gtk_signal_handler_unblock( GtkObject *object, guint handler_id );void gtk_signal_handler_unblock_by_func( GtkObject *object, GtkSignalFunc func, gpointer data );void gtk_signal_handler_unblock_by_data( GtkObject *object, gpointer data );</PRE></CODE></BLOCKQUOTE><P><H3>Emitting and Stopping Signals</H3><P><BLOCKQUOTE><CODE><PRE>void gtk_signal_emit( GtkObject *object, guint signal_id, ... );void gtk_signal_emit_by_name( GtkObject *object, const gchar *name, ... );void gtk_signal_emitv( GtkObject *object, guint signal_id, GtkArg *params );void gtk_signal_emitv_by_name( GtkObject *object, const gchar *name, GtkArg *params );guint gtk_signal_n_emissions( GtkObject *object, guint signal_id );guint gtk_signal_n_emissions_by_name( GtkObject *object, const gchar *name );void gtk_signal_emit_stop( GtkObject *object, guint signal_id );void gtk_signal_emit_stop_by_name( GtkObject *object, const gchar *name );</PRE></CODE></BLOCKQUOTE><P><H2><A NAME="ss18.2">18.2 Signal Emission and Propagation</A></H2><P>Signal emission is the process wherby GTK runs all handlers for aspecific object and signal.<P>First, note that the return value from a signal emission is the returnvalue of the <EM>last</EM> handler executed. Since event signals areall of type GTK_RUN_LAST, this will be the default (GTK supplied)default handler, unless you connect with gtk_signal_connect_after().<P>The way an event (say GTK_BUTTON_PRESS) is handled, is:<UL><LI>Start with the widget where the event occured.</LI><LI>Emit the generic "event" signal. If that signal handler returnsa value of TRUE, stop all processing.</LI><LI>Otherwise, emit a specific, "button_press_event" signal. If thatreturns TRUE, stop all processing.</LI><LI>Otherwise, go to the widget's parent, and repeat the above steps.</LI><LI>Contimue until some signal handler returns TRUE, or until thetop-level widget is reached.</LI></UL><P>Some consequences of the above are:<UL><LI>Your handler's return value will have no effect if there is adefault handler, unless you connect with gtk_signal_connect_after().</LI><LI>To prevent the default handler from being run, you need toconnect with gtk_signal_connect() and usegtk_signal_emit_stop_by_name() - the return value only affects whetherthe signal is propagated, not the current emission.</LI></UL><P><HR NOSHADE><A HREF="gtk_tut-19.html">Next</A><A HREF="gtk_tut-17.html">Previous</A><A HREF="gtk_tut.html#toc18">Contents</A></BODY></HTML>⌨️ 快捷键说明
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