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<H2><A NAME="sec:5.5"><SPAN class="sec-nr">5.5</SPAN> <SPAN class="sec-title">Activating
graphicals using the mouse</SPAN></A></H2>
<A NAME="sec:recogniser"></A>
<P><A NAME="idx:eventprocessing:178"></A><A NAME="idx:sensitive:179"></A><A NAME="idx:movinggraphicals:180"></A><B>Recogniser</B>
objects enable detection of mouse- and keyboard activities. <font size=-1>XPCE</font>
defines both primitive and complex recognisers. The first (called <A class="" href="summary.html#class:handler">handler</A>)
processes a single event. The latter processes a <A class="" href="summary.html#class:gesture">gesture</A>:
sequence of events starting with a mouse-button-down up to the
corresponding mouse-button-up. The following example allows us to move
the icon by dragging with the middle mouse button:
<PRE class="code">
11 ?- send(@ic, recogniser, new(move_gesture)).
</PRE>
<P>The second example allows us to double-click on the icon. This is a
common way to `open'<A NAME="idx:openicon:181"></A> an icon. In the
example we will just print 'hello' in the Prolog window.
<PRE class="code">
12 ?- send(@ic, recogniser,
click_gesture(left, '', double,
message(@pce, write_ln, hello))).
</PRE>
<P>The predefined recogniser classes are summarised in
<A class="tab" href="recogniser.html#tab:recognisers">table 5</A>.
Besides the built-in recognisers, the <font size=-1>XPCE/P</font>rolog
library defines various additional ones. See also <A class="sec" href="dragdrop.html">section
11.8</A>.
<P>
<CENTER>
<TABLE BORDER=2 FRAME=box RULES=groups>
<TR VALIGN=top><TD><A class="" href="summary.html#class:handler">handler</A> </TD><TD>Binds
a single event to a <A class="" href="summary.html#class:message">message</A>. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:handler_group">handler_group</A> </TD><TD>Combines
multiple recognisers into a single. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:key_binding">key_binding</A> </TD><TD>Maps
keyboard sequences to commands. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:click_gesture">click_gesture</A> </TD><TD>Maps
a mouse-click to a message. Allows to specify modifiers (alt/meta,
control, shift), button and multi (single, double, triple). </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:connect_gesture">connect_gesture</A> </TD><TD>Connect
two graphicals dragging from the first to the second. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:move_gesture">move_gesture</A> </TD><TD>Move
graphical by dragging it. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:move_outline_gesture">move_outline_gesture</A> </TD><TD>Move
graphical by dragging an outline. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:resize_gesture">resize_gesture</A> </TD><TD>Resize
graphical by dragging a side or corner. </TD></TR>
<TBODY>
<TR VALIGN=top><TD><A class="" href="summary.html#class:resize_outline_gesture">resize_outline_gesture</A> </TD><TD>Resize
graphical by dragging a side or corner of the outline. </TD></TR>
</TABLE>
</CENTER>
<TABLE ALIGN=center WIDTH="75%"><TR><TD>
<B>Table 5 : </B>Recogniser classes</TABLE>
<A NAME="tab:recognisers"></A>
<P></BODY></HTML>
