path: root/docs/reference/pygtk-gtktreesortable.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
    "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">

<refentry id="class-gtktreesortable">
  <refnamediv>
    <refname>gtk.TreeSortable</refname>
    <refpurpose>an interface for sorting a <link
linkend="class-gtktreemodel"><classname>gtk.TreeModel</classname></link></refpurpose>
  </refnamediv>

  <refsect1>
    <title>Synopsis</title>

    <classsynopsis language="python">
      <ooclass><classname>gtk.TreeSortable</classname></ooclass>
      <ooclass><classname>gobject.GInterface</classname></ooclass>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--sort-column-changed">sort_column_changed</link></methodname>
	<methodparam></methodparam>  </methodsynopsis>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--get-sort-column-id">get_sort_column_id</link></methodname>
	<methodparam></methodparam>
      </methodsynopsis>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--set-sort-column-id">set_sort_column_id</link></methodname>
	<methodparam><parameter
		       role="keyword">sort_column_id</parameter></methodparam>
	<methodparam><parameter
		       role="keyword">order</parameter></methodparam>
      </methodsynopsis>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--set-sort-func">set_sort_func</link></methodname>
	<methodparam><parameter>sort_column_id</parameter></methodparam>
	<methodparam><parameter>sort_func</parameter></methodparam>
	<methodparam><parameter>user_data</parameter>
	  <initializer>None</initializer></methodparam>
      </methodsynopsis>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--set-default-sort-func">set_default_sort_func</link></methodname>
	<methodparam><parameter>sort_func</parameter></methodparam>
	<methodparam><parameter>user_data</parameter>
	  <initializer>None</initializer></methodparam>
      </methodsynopsis>
      <methodsynopsis language="python">
	<methodname><link
linkend="method-gtktreesortable--has-default-sort-func">has_default_sort_func</link></methodname>
	<methodparam></methodparam>  </methodsynopsis>
    </classsynopsis>

  </refsect1>

  <refsect1 id="signal-prototypes-gtktreesortable">
    <title>gtk.TreeSortable Signal Prototypes</title>

    <variablelist>
      <varlistentry>
        <term>"<link
linkend="signal-gtktreesortable--sort-column-changed">sort-column-changed</link>"</term>
        <listitem>
          <methodsynopsis
	    language="python"><methodname>callback</methodname>
            <methodparam><parameter>treesortable</parameter></methodparam>
            <methodparam><parameter>user_param1</parameter></methodparam>
            <methodparam><parameter>...</parameter></methodparam>
          </methodsynopsis>
        </listitem>
      </varlistentry>
    </variablelist>

  </refsect1>

  <refsect1>
    <title>Description</title>

    <para>The <link
linkend="class-gtktreesortable"><classname>gtk.TreeSortable</classname></link>
interface provide the common methods for a <link
linkend="class-gtktreemodel"><classname>gtk.TreeModel</classname></link> to
implement a sorted model for a <link
linkend="class-gtktreeview"><classname>gtk.TreeView</classname></link>. See
the <link
linkend="class-gtktreemodelsort"><classname>gtk.TreeModelSort</classname></link>
for an example of a treemodel that implements the <link
linkend="class-gtktreesortable"><classname>gtk.TreeSortable</classname></link>
interface. The key element of the interface is a "sort column ID" which is
an arbitrary integer value referring to a sort function and associated user
data. A sort column ID must be greater than or equal to zero. A usable sort
column ID is created by using the <link
linkend="method-gtktreesortable--set-sort-func"><methodname>set_sort_func</methodname>()</link>
method. The sort column ID can then be used for sorting a <link
linkend="class-gtkliststore"><classname>gtk.ListStore</classname></link> or
<link
linkend="class-gtktreestore"><classname>gtk.TreeStore</classname></link>
using the <link
linkend="method-gtktreesortable--set-sort-column-id"><methodname>set_sort_column_id</methodname>()</link>
method.</para>

    <para>The <link
linkend="class-gtkliststore"><classname>gtk.ListStore</classname></link> and
<link
linkend="class-gtktreestore"><classname>gtk.TreeStore</classname></link>
objects automatically setup sort column IDs corresponding to the columns in
the store. These sort column IDs are associated with an internal comparison
function that handles the fundamental types:</para>

    <itemizedlist>
      <listitem>
        <simpara>gboolean</simpara>
      </listitem>
      <listitem>
        <simpara>str</simpara>
      </listitem>
      <listitem>
        <simpara>int</simpara>
      </listitem>
      <listitem>
        <simpara>long</simpara>
      </listitem>
      <listitem>
        <simpara>float</simpara>
      </listitem>
    </itemizedlist>

    <note>
      <para>Once a sort column ID has been set on a <link
linkend="class-gtktreemodel"><classname>gtk.TreeModel</classname></link>
implementing the <link
linkend="class-gtktreesortable"><classname>gtk.TreeSortable</classname></link>
interface it cannot be returned to the original unsorted state. You can
change the sort function or use a default sort function but you cannot set
the <link
linkend="class-gtktreemodel"><classname>gtk.TreeModel</classname></link> to
have no sort function.</para>
    </note>

  </refsect1>

  <refsect1>
    <title>Methods</title>

    <refsect2 id="method-gtktreesortable--sort-column-changed">
      <title>gtk.TreeSortable.sort_column_changed</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>sort_column_changed</methodname>
	  <methodparam></methodparam>  </methodsynopsis></programlisting>

      <para>The <methodname>sort_column_changed</methodname>() method emits
the "sort_column_changed" signal on the treesortable object.</para>

    </refsect2>

    <refsect2 id="method-gtktreesortable--get-sort-column-id">
      <title>gtk.TreeSortable.get_sort_column_id</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>get_sort_column_id</methodname>
	  <methodparam></methodparam>
	</methodsynopsis></programlisting>
      <variablelist>
	<varlistentry>
	  <term><emphasis>Returns</emphasis>&nbsp;:</term>
	  <listitem><simpara>a tuple containing the sort column id and the
sort type: <literal>gtk.SORT_ASCENDING</literal> or
<literal>gtk.SORT_DESCENDING</literal></simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The <methodname>get_sort_column_id</methodname>() method returns
a tuple containing the current sort column ID and the sort type (either
<literal>gtk.SORT_ASCENDING</literal> or
<literal>gtk.SORT_DESCENDING</literal>), if applicable. If the sort column
ID is not set, then the tuple <literal>(-2, 0)</literal> is returned. If the
sort column ID is set to -1 indicating the default sort function is to be
used this method returns (<literal>None</literal>,
<literal>None</literal>)</para>

    </refsect2>

    <refsect2 id="method-gtktreesortable--set-sort-column-id">
      <title>gtk.TreeSortable.set_sort_column_id</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>set_sort_column_id</methodname>
	  <methodparam><parameter
			 role="keyword">sort_column_id</parameter></methodparam>
	  <methodparam><parameter
			 role="keyword">order</parameter></methodparam>
	</methodsynopsis></programlisting>
      <variablelist>
	<varlistentry>
	  <term><parameter
role="keyword">sort_column_id</parameter>&nbsp;:</term>
	  <listitem><simpara>the sort column id to set</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter role="keyword">order</parameter>&nbsp;:</term>
	  <listitem><simpara>the sort order:
	  <literal>gtk.SORT_ASCENDING</literal> or
	  <literal>gtk.SORT_DESCENDING</literal></simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The <methodname>set_sort_column_id</methodname>() method sets
the current sort comparison function to that associated with the sort column
ID specified by <parameter>sort_column_id</parameter> with the sort order
type specified by <parameter>order</parameter>. The value of order must be
either: <literal>gtk.SORT_ASCENDING</literal> or
<literal>gtk.SORT_DESCENDING</literal>. The treesortable will resort itself
to reflect this change, after emitting a "sort_column_changed" signal.</para>

      <para>If <parameter>sort_column_id</parameter> is -1, then the default
sort function will be used, if it is set. If a default sort function is not
set then the sort column ID is not changed.</para>

    </refsect2>

    <refsect2 id="method-gtktreesortable--set-sort-func">
      <title>gtk.TreeSortable.set_sort_func</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>set_sort_func</methodname>
	  <methodparam><parameter>sort_column_id</parameter></methodparam>
	  <methodparam><parameter>sort_func</parameter></methodparam>
	  <methodparam><parameter>user_data</parameter>
	    <initializer>None</initializer></methodparam>
	</methodsynopsis></programlisting>
      <variablelist>
	<varlistentry>
	  <term><parameter>sort_column_id</parameter>&nbsp;:</term>
	  <listitem><simpara>the sort column id to set the function
for</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter>sort_func</parameter>&nbsp;:</term>
	  <listitem><simpara>The sorting function</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter>user_data</parameter>&nbsp;:</term>
	  <listitem><simpara>the user data to pass to the sort func, or
<literal>None</literal></simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The <methodname>set_sort_func</methodname>() method sets the
comparison function (or method) used when sorting on the sort column ID
specified by <parameter>column_id</parameter> to the value specified by
<parameter>sort_func</parameter>. If the current sort column id of the
treesortable is the same as <parameter>sort_column_id</parameter>, the model
will be resorted. The signature of the comparison function (or method)
is:</para>

      <programlisting>
<methodsynopsis language="python">
	  <methodname>comparefunction</methodname>
	  <methodparam><parameter>treemodel</parameter></methodparam>
	  <methodparam><parameter>iter1</parameter></methodparam>
	  <methodparam><parameter>iter2</parameter></methodparam>
	  <methodparam><parameter>user_data</parameter></methodparam>
	</methodsynopsis>
<methodsynopsis language="python">
	  <methodname>comparemethod</methodname>
	  <methodparam><parameter>self</parameter></methodparam>
	  <methodparam><parameter>treemodel</parameter></methodparam>
	  <methodparam><parameter>iter1</parameter></methodparam>
	  <methodparam><parameter>iter2</parameter></methodparam>
	  <methodparam><parameter>user_data</parameter></methodparam>
	</methodsynopsis>
</programlisting>

      <para>where <parameter>treemodel</parameter> is the tree model
implementing the <link
linkend="class-gtktreesortable"><classname>gtk.TreeSortable</classname></link>
interface, <parameter>iter1</parameter> and <parameter>iter2</parameter>
point at the rows to compare and <parameter>user_data</parameter> is the
user data specified in <methodname>set_sort_func</methodname>() or
<parameter>None</parameter>. If <parameter>sort_func</parameter> is a method
then <parameter>self</parameter> is the object associated with the
method.</para>

      <para>The comparison callback should return -1 if the
<parameter>iter1</parameter> row should come before the
<parameter>iter2</parameter> row, 0 if the rows are equal, or 1 if the
<parameter>iter1</parameter> row should come after the
<parameter>iter2</parameter> row.</para>

    </refsect2>

    <refsect2 id="method-gtktreesortable--set-default-sort-func">
      <title>gtk.TreeSortable.set_default_sort_func</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>set_default_sort_func</methodname>
	  <methodparam><parameter>sort_func</parameter></methodparam>
	  <methodparam><parameter>user_data</parameter>
	    <initializer>None</initializer></methodparam>
	</methodsynopsis></programlisting>
      <variablelist>
	<varlistentry>
	  <term><parameter>sort_func</parameter>&nbsp;:</term>
	  <listitem><simpara>the sorting function</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter>user_data</parameter>&nbsp;:</term>
	  <listitem><simpara>the user data to pass to
<parameter>sort_func</parameter>, or
<literal>None</literal></simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The <methodname>set_default_sort_func</methodname>() method sets
the default comparison function (or method) to the value of
<parameter>sort_func</parameter>. If the current sort column id of the
treesortable is -1 (the <link
linkend="method-gtktreesortable--get-sort-column-id"><methodname>get_sort_column_id</methodname>()</link>
method returns (None, None)), then the model will be resorted using the
<parameter>sort_func</parameter>. See the <link
linkend="method-gtktreesortable--set-sort-func"><methodname>set_sort_func</methodname>()</link>
method for more details on the signature of the comparison function.</para>

<para>In Pygtk 2.10, <parameter>sort_func</parameter> can be
<literal>None</literal> to have no default comparison function. This means
that once the model has been sorted, it can't go back to the default
state. In this case, when the current sort column id of sortable is -1, the
model will be unsorted.</para>

    </refsect2>

    <refsect2 id="method-gtktreesortable--has-default-sort-func">
      <title>gtk.TreeSortable.has_default_sort_func</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>has_default_sort_func</methodname>
	  <methodparam></methodparam>  </methodsynopsis></programlisting>
      <variablelist>
	<varlistentry>
	  <term><emphasis>Returns</emphasis>&nbsp;:</term>
	  <listitem><simpara><literal>True</literal>, if the model has a
default sort function</simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The <methodname>has_default_sort_func</methodname>() method
returns <literal>True</literal> if the model has a default sort function.
This is used primarily by <link
linkend="class-gtktreeviewcolumn"><classname>gtk.TreeViewColumn</classname></link> 
to determine if a model can go back to the default state, or not.</para>

    </refsect2>

  </refsect1>

  <refsect1>
    <title>Signals</title>

    <refsect2 id="signal-gtktreesortable--sort-column-changed">
      <title>The "sort-column-changed" gtk.TreeSortable Signal</title>

      <programlisting><methodsynopsis language="python">
	  <methodname>callback</methodname>
	  <methodparam><parameter>treesortable</parameter></methodparam>
	  <methodparam><parameter>user_param1</parameter></methodparam>
	  <methodparam><parameter>...</parameter></methodparam>
	</methodsynopsis></programlisting>

      <variablelist>
	<varlistentry>
	  <term><parameter>treesortable</parameter>&nbsp;:</term>
	  <listitem><simpara>the treesortable that received the
signal</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter>user_param1</parameter>&nbsp;:</term>
          <listitem><simpara>the first user parameter (if any) specified
with the <link
linkend="method-gobject--connect"><methodname>connect</methodname>()</link>
method</simpara></listitem>
	</varlistentry>
	<varlistentry>
	  <term><parameter>...</parameter>&nbsp;:</term>
	  <listitem><simpara>additional user parameters (if
any)</simpara></listitem>
	</varlistentry>
      </variablelist>

      <para>The "sort-column-changed" signal is emitted when the <link
linkend="method-gtktreesortable--sort-column-changed"><methodname>sort_column_changed</methodname>()</link> 
method is called or the sort column is changed using the <link
linkend="method-gtktreesortable--set-sort-column-id"><methodname>set_sort_column_id</methodname>()</link> 
method.</para>

    </refsect2>

  </refsect1>

</refentry>