octave-doc 4.2.2-1ubuntu1 / usr / share / doc / octave / octave.html / Callbacks.html

This file is indexed.

/usr/share/doc/octave/octave.html/Callbacks.html is in octave-doc 4.2.2-1ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below. 

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Callbacks (GNU Octave)</title>

<meta name="description" content="Callbacks (GNU Octave)">
<meta name="keywords" content="Callbacks (GNU Octave)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<link href="index.html#Top" rel="start" title="Top">
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Advanced-Plotting.html#Advanced-Plotting" rel="up" title="Advanced Plotting">
<link href="Application_002ddefined-Data.html#Application_002ddefined-Data" rel="next" title="Application-defined Data">
<link href="Marker-Styles.html#Marker-Styles" rel="prev" title="Marker Styles">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>
<link rel="stylesheet" type="text/css" href="octave.css">


</head>

<body lang="en">
<a name="Callbacks"></a>
<div class="header">
<p>
Next: <a href="Application_002ddefined-Data.html#Application_002ddefined-Data" accesskey="n" rel="next">Application-defined Data</a>, Previous: <a href="Marker-Styles.html#Marker-Styles" accesskey="p" rel="prev">Marker Styles</a>, Up: <a href="Advanced-Plotting.html#Advanced-Plotting" accesskey="u" rel="up">Advanced Plotting</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Callbacks-1"></a>
<h4 class="subsection">15.4.4 Callbacks</h4>
<a name="index-callbacks"></a>

<p>Callback functions can be associated with graphics objects and triggered
after certain events occur.  The basic structure of all callback function
is
</p>
<div class="example">
<pre class="example">function mycallback (hsrc, evt)
&hellip;
endfunction
</pre></div>

<p>where <code>hsrc</code> is a handle to the source of the callback, and <code>evt</code> 
gives some event specific data.  
</p>
<p>The function can be provided as a function handle to a plain Octave function, 
as an anonymous function or as a string representing an Octvae command. The 
latter syntax is not recommended since syntax errors will only occur when the 
string is evaluated.  
See <a href="Function-Handles-Anonymous-Functions-Inline-Functions.html#Function-Handles-Anonymous-Functions-Inline-Functions">Function Handles section</a>.
</p>
<p>This can then be associated
with an object either at the objects creation or later with the
<code>set</code> function.  For example,
</p>
<div class="example">
<pre class="example">plot (x, &quot;DeleteFcn&quot;, @(h, e) disp (&quot;Window Deleted&quot;))
</pre></div>

<p>where at the moment that the plot is deleted, the message &quot;Window
Deleted&quot; will be displayed.
</p>
<p>Additional user arguments can be passed to callback functions, and will
be passed after the 2 default arguments.  For example:
</p>
<div class="example">
<pre class="example">plot (x, &quot;DeleteFcn&quot;, {@mycallback, &quot;1&quot;})
&hellip;
function mycallback (h, e, a1)
  fprintf (&quot;Closing plot %d\n&quot;, a1);
endfunction
</pre></div>

<p>The basic callback functions that are available for all graphics objects
are
</p>
<ul>
<li> CreateFcn: 
called at the moment of the objects creation.  It is not called if the object is altered in any way, and so it only makes sense to define this callback in the function call that defines the object.  Callbacks that are added to <code>CreateFcn</code> later with the <code>set</code> function will never be executed.

</li><li> DeleteFcn: 
called at the moment an object is deleted.

</li><li> ButtonDownFcn: 
called if a mouse button is pressed while the pointer is over this object.  Note, that the gnuplot interface does not respect this callback.
</li></ul>

<p><strong>Caution:</strong> the second <code>evt</code> argument in callback functions is only 
loosely implemented in the Qt graphics toolkit:
</p>
<ul>
<li> Mouse click events:
<code>evt</code> is a class <code>double</code> value, 1 for left, 2 for middle and 3 
for right click.

</li><li> Key press events:
<code>evt</code> is a structure with fields <code>Key</code> (string), <code>Character</code> 
(string) and <code>Modifier</code> (cell array of strings).

</li><li> Other events:
<code>evt</code> is a class <code>double</code> empty matrix.
</li></ul>


<p>The object and figure that the event occurred in that resulted in the
callback being called can be found with the <code>gcbo</code> and <code>gcbf</code>
functions.
</p>
<a name="XREFgcbo"></a><dl>
<dt><a name="index-gcbo"></a>: <em><var>h</var> =</em> <strong>gcbo</strong> <em>()</em></dt>
<dt><a name="index-gcbo-1"></a>: <em>[<var>h</var>, <var>fig</var>] =</em> <strong>gcbo</strong> <em>()</em></dt>
<dd><p>Return a handle to the object whose callback is currently executing.
</p>
<p>If no callback is executing, this function returns the empty matrix.  This
handle is obtained from the root object property <code>&quot;CallbackObject&quot;</code>.
</p>
<p>When called with a second output argument, return the handle of the figure
containing the object whose callback is currently executing.  If no callback
is executing the second output is also set to the empty matrix.
</p>

<p><strong>See also:</strong> <a href="#XREFgcbf">gcbf</a>, <a href="Graphics-Objects.html#XREFgco">gco</a>, <a href="Graphics-Objects.html#XREFgca">gca</a>, <a href="Graphics-Objects.html#XREFgcf">gcf</a>, <a href="Graphics-Objects.html#XREFget">get</a>, <a href="Graphics-Objects.html#XREFset">set</a>.
</p></dd></dl>


<a name="XREFgcbf"></a><dl>
<dt><a name="index-gcbf"></a>: <em><var>fig</var> =</em> <strong>gcbf</strong> <em>()</em></dt>
<dd><p>Return a handle to the figure containing the object whose callback is
currently executing.
</p>
<p>If no callback is executing, this function returns the empty matrix.  The
handle returned by this function is the same as the second output argument
of <code>gcbo</code>.
</p>

<p><strong>See also:</strong> <a href="#XREFgcbo">gcbo</a>, <a href="Graphics-Objects.html#XREFgcf">gcf</a>, <a href="Graphics-Objects.html#XREFgco">gco</a>, <a href="Graphics-Objects.html#XREFgca">gca</a>, <a href="Graphics-Objects.html#XREFget">get</a>, <a href="Graphics-Objects.html#XREFset">set</a>.
</p></dd></dl>


<p>Callbacks can equally be added to properties with the <code>addlistener</code>
function described below.
</p>
<hr>
<div class="header">
<p>
Next: <a href="Application_002ddefined-Data.html#Application_002ddefined-Data" accesskey="n" rel="next">Application-defined Data</a>, Previous: <a href="Marker-Styles.html#Marker-Styles" accesskey="p" rel="prev">Marker Styles</a>, Up: <a href="Advanced-Plotting.html#Advanced-Plotting" accesskey="u" rel="up">Advanced Plotting</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>



</body>
</html>

APT Browse - Built by Thomas Orozco.