xref: /xsrc/external/mit/libXaw/dist/specs/TextCustom.xml

<sect1 id="Customizing_the_Text_Widget">
<title>Customizing the Text Widget</title>
<para>
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<!-- .XS -->
<!-- 	Customizing the Text Widget -->
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<indexterm significance="preferred"><primary>Text widget</primary><secondary>customizing</secondary></indexterm>
</para>
<para>
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The remainder of this chapter will describe customizing the Text
widget.  The Text widget may be customized by subclassing, or by
creating new sources and sinks.  Subclassing is described in
detail in Chapter 7; this section will describe only those things that
are specific to the Text widget.  Attributes of the Text widget base
class and creating new sources and sinks will be discussed.
</para>
<para>
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The Text widget is made up of a number of different pieces, with the
Text widget as the base widget class.  It and the AsciiText widget are
the only true "widgets" in the Text widget family.  The other pieces
(sources and sinks) are X Toolkit objects and have no window
associated with them.  No source or sink is useful unless assigned to
a Text widget.
</para>
<para>
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Each of the following pieces of the Text widget has a specific purpose,
and will be, or has been, discussed in detail in this chapter:
<indexterm><primary>Text widget</primary></indexterm>
</para>
<para>
<variablelist>
  <varlistentry>
    <term><function>Text</function></term>
    <listitem>
      <para>
This is the glue that binds everything else together.  This widget reads
the text data from the source, and displays the information in the sink.
All translations and actions are handled in the Text widget itself.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>TextSink</function></term>
    <listitem>
      <para>
<indexterm><primary>TextSink object</primary></indexterm>
This object is responsible for displaying and clearing the drawing area.
It also reports the configuration of the window that contains the
drawing area.  The TextSink does not have its own window; instead it does
its drawing on the Text widget's window.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>TextSrc</function></term>
    <listitem>
      <para>
<indexterm><primary>TextSrc object</primary></indexterm>
This object is responsible for reading, editing and searching through the
text buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>AsciiSink</function></term>
    <listitem>
      <para>
<indexterm><primary>AsciiSink object</primary></indexterm>
This object is a subclass of the TextSink and knows how to display
ASCII text.  Support has been added to display any 8-bit character set, given
the font.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>MultiSink</function></term>
    <listitem>
      <para>
<indexterm><primary>MultiSink object</primary></indexterm>
This object is a subclass of the TextSink and knows how to display
font sets.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>AsciiSrc</function></term>
    <listitem>
      <para>
<indexterm><primary>AsciiSrc object</primary></indexterm>
This object is a subclass of the TextSrc and knows how to read strings
and files.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>MultiSrc</function></term>
    <listitem>
      <para>
<indexterm><primary>MultiSrc object</primary></indexterm>
This object is a subclass of the TextSrc and knows how to read strings
and multibyte files, converting them to wide characters based on locale.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>AsciiText</function></term>
    <listitem>
      <para>
<indexterm><primary>AsciiText widget</primary></indexterm>
This widget is a subclass of the Text widget.  When created, the AsciiText
automatically creates and attaches either an AsciiSrc and AsciiSink, or a
MultiSrc and MultiSink, to itself.  The AsciiText provides the simplest
interface to the Athena Text widgets.
      </para>
    </listitem>
  </varlistentry>
</variablelist>
</para>
</sect1>