<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Chapter 14. Adjustments</title> <link rel="stylesheet" type="text/css" href="style.css"> <meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> <link rel="home" href="index.html" title="Programming with gtkmm 3"> <link rel="up" href="index.html" title="Programming with gtkmm 3"> <link rel="prev" href="toolpalette-example.html" title="ToolPalette Example"> <link rel="next" href="sec-adjustments-easy.html" title="Using Adjustments the Easy Way"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr><th colspan="3" align="center">Chapter 14. Adjustments</th></tr> <tr> <td width="20%" align="left"> <a accesskey="p" href="toolpalette-example.html"><img src="icons/prev.png" alt="Prev"></a> </td> <th width="60%" align="center"> </th> <td width="20%" align="right"> <a accesskey="n" href="sec-adjustments-easy.html"><img src="icons/next.png" alt="Next"></a> </td> </tr> </table> <hr> </div> <div class="chapter"> <div class="titlepage"><div><div><h1 class="title"> <a name="chapter-adjustment"></a>Chapter 14. Adjustments</h1></div></div></div> <div class="toc"> <p><b>Table of Contents</b></p> <ul class="toc"> <li><span class="sect1"><a href="chapter-adjustment.html#sec-creating-adjustment">Creating an Adjustment</a></span></li> <li><span class="sect1"><a href="sec-adjustments-easy.html">Using Adjustments the Easy Way</a></span></li> <li><span class="sect1"><a href="sec-adjustment-internals.html">Adjustment Internals</a></span></li> </ul> </div> <p> <span class="application">gtkmm</span> has various widgets that can be visually adjusted using the mouse or the keyboard, such as the <code class="classname">Range</code> widgets (described in the <a class="link" href="chapter-range-widgets.html" title="Chapter 6. Range Widgets">Range Widgets</a> section). There are also a few widgets that display some adjustable part of a larger area, such as the <code class="classname">Viewport</code> widget. These widgets have <code class="classname">Gtk::Adjustment</code> objects that express this common part of their API. </p> <p> So that applications can react to changes, for instance when a user moves a scrollbar, <code class="classname">Gtk::Adjustment</code> has a <code class="literal">value_changed</code> signal. You can then use the <code class="methodname">get_value()</code> method to discover the new value. </p> <div class="sect1"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="sec-creating-adjustment"></a>Creating an Adjustment</h2></div></div></div> <p> The <code class="classname">Gtk::Adjustment</code> is created by its <code class="methodname">create()</code> method which is as follows: </p> <pre class="programlisting">Glib::RefPtr<Gtk::Adjustment> Gtk::Adjustment::create( double value, double lower, double upper, double step_increment = 1, double page_increment = 10, double page_size = 0);</pre> <p> The <em class="parameter"><code>value</code></em> argument is the initial value of the adjustment, usually corresponding to the topmost or leftmost position of an adjustable widget. The <em class="parameter"><code>lower</code></em> and <em class="parameter"><code>upper</code></em> arguments specify the possible range of values which the adjustment can hold. The <em class="parameter"><code>step_increment</code></em> argument specifies the smaller of the two increments by which the user can change the value, while the <em class="parameter"><code>page_increment</code></em> is the larger one. The <em class="parameter"><code>page_size</code></em> argument usually corresponds somehow to the visible area of a panning widget. The <em class="parameter"><code>upper</code></em> argument is used to represent the bottommost or rightmost coordinate in a panning widget's child. </p> </div> </div> <div class="navfooter"> <hr> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"> <a accesskey="p" href="toolpalette-example.html"><img src="icons/prev.png" alt="Prev"></a> </td> <td width="20%" align="center"> </td> <td width="40%" align="right"> <a accesskey="n" href="sec-adjustments-easy.html"><img src="icons/next.png" alt="Next"></a> </td> </tr> <tr> <td width="40%" align="left" valign="top">ToolPalette Example </td> <td width="20%" align="center"><a accesskey="h" href="index.html"><img src="icons/home.png" alt="Home"></a></td> <td width="40%" align="right" valign="top"> Using Adjustments the Easy Way</td> </tr> </table> </div> </body> </html>
