<sect1 id="TextSrc_Object">
<title>TextSrc Object</title>
<literallayout class="monospaced">
Application Header file &lt;X11/Xaw/TextSrc.h&gt;
Class Header file       &lt;X11/Xaw/TextSrcP.h&gt;
Class                   textSrcObjectClass
Class Name              TextSrc
Superclass              Object
</literallayout>

<para>
<!-- .LP -->
The TextSrc object is the root object for all text sources.  Any new text
source objects should be subclasses of the TextSrc Object.  The
TextSrc Class contains all methods the Text widget expects a text
source to export.
</para>

<para>
<!-- .LP -->
Since all text sources will have some resources in common the
TextSrc defines a few new resources.
</para>

<sect2 id="textsource_resources">
<title>Resources</title>
<para>
When creating an TextSrc object instance, the following resources are
retrieved from the argument list or from the resource database:
</para>

<informaltable>
  <tgroup cols='5' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <colspec colname='c3'/>
  <colspec colname='c4'/>
  <colspec colname='c5'/>
  <thead>
    <row>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Type</entry>
      <entry>Notes</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>destroyCallback</entry>
      <entry>Callback</entry>
      <entry>XtCallbackList</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>editType</entry>
      <entry>EditType</entry>
      <entry>EditMode</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>
</sect2>

<sect2 id="Subclassing_the_TextSrc">
<title>Subclassing the TextSrc</title>
<para>
The only purpose of the TextSrc Object is to be subclassed.  It contains
the minimum set of class methods that all text sources must have.  All
class methods of the TextSrc must be defined, as the Text widget uses
them all.  While all may be inherited, the direct descendant of TextSrc
<function>must</function> specify some of them as TextSrc does not contain enough
information to be a valid text source by itself.  Do not try to use the
TextSrc as a valid source for the Text widget; it is not intended to be
used as a source by itself and bad things will probably happen.
</para>

<informaltable>
  <tgroup cols='4' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <colspec colname='c3'/>
  <colspec colname='c4'/>
  <thead>
    <row>
      <entry>Function</entry>
      <entry>Inherit with</entry>
      <entry>Public Interface</entry>
      <entry>must specify</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>Read</entry>
      <entry>XtInheritRead</entry>
      <entry>XawTextSourceRead</entry>
      <entry>yes</entry>
    </row>
    <row>
      <entry>Replace</entry>
      <entry>XtInheritReplace</entry>
      <entry>XawTextSourceReplace</entry>
      <entry>no</entry>
    </row>
    <row>
      <entry>Scan</entry>
      <entry>XtInheritScan</entry>
      <entry>XawTextSourceScan</entry>
      <entry>yes</entry>
    </row>
    <row>
      <entry>Search</entry>
      <entry>XtInheritSearch</entry>
      <entry>XawTextSourceSearch</entry>
      <entry>no</entry>
    </row>
    <row>
      <entry>SetSelection</entry>
      <entry>XtInheritSetSelection</entry>
      <entry>XawTextSourceSetSelection</entry>
      <entry>no</entry>
    </row>
    <row>
      <entry>ConvertSelection</entry>
      <entry>XtInheritConvertSelection</entry>
      <entry>XawTextSourceConvertSelection</entry>
      <entry>no</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

<sect3 id="Reading_Text_">
<title>Reading Text.</title>
<para>
<!-- .LP -->
To read the text in a text source use the <function>Read</function> function:
<!-- .IN "TextSrc object" "Read" "@DEF@" -->
</para>
<funcsynopsis>
<funcprototype>
  <funcdef>XawTextPosition<function> Read</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XawTextPosition<parameter> pos</parameter></paramdef>
  <paramdef>XawTextBlock<parameter> *text_return</parameter></paramdef>
  <paramdef>int<parameter> length</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>pos</emphasis>
    </term>
    <listitem>
      <para>
Specifies the position of the first character to be read from the text buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>text</emphasis></term>
    <listitem>
      <para>
Returns the text read from the source.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>length</emphasis>
    </term>
    <listitem>
      <para>
Specifies the maximum number of characters the TextSrc should
return to the application in <emphasis remap='I'>text_return</emphasis>.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function returns the text position immediately after the
characters read from the
text buffer.  The function is not required to read <emphasis remap='I'>length</emphasis>
characters if that many characters are in the file, it may break at
any point that is convenient to the internal structure of the
source.  It may take several calls to <function>Read</function> before the desired
portion of the text buffer is fully retrieved.
</para>
</sect3>

<sect3 id="Replacing_Text_">
<title>Replacing Text.</title>
<para>
To replace or edit the text in a text buffer use the <function>Replace</function> function:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>XawTextPosition<function> Replace</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XawTextPositionstart,<parameter> end</parameter></paramdef>
  <paramdef>XawTextBlock<parameter> *text</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term><emphasis remap='I'>w</emphasis></term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>start</emphasis></term>
    <listitem>
      <para>
Specifies the position of the first character to be removed from the text
buffer.  This is also the location to begin inserting the new text.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>end</emphasis></term>
    <listitem>
      <para>
Specifies the position immediately after the last character to be
removed from the text buffer.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>text</emphasis></term>
    <listitem>
      <para>
Specifies the text to be added to the text source.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function can return any of the following values:
</para>

<variablelist>
  <varlistentry>
    <term><function>XawEditDone</function></term>
    <listitem>
      <para>
The text replacement was successful.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>XawPositionError</function></term>
    <listitem>
      <para>
<!-- .IN "XawPositionError" "" -->
The edit mode is <function>XawtextAppend</function> and <function>start</function> is not the last
character of the source.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><function>XawEditError</function></term>
    <listitem>
      <para>
<!-- .IN "XawEditError" "" -->
Either the Source was read-only or the range to be deleted is larger
than the length of the Source.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
<!-- .LP -->
The <function>Replace</function> arguments <function>start</function> and <function>end</function> represent the
text source character positions for the existing text that is to be
replaced by the text in the text block.  The characters from
<emphasis remap='I'>start</emphasis> up to but not including <emphasis remap='I'>end</emphasis> are deleted, and the
buffer specified by the text block is inserted in their
place.  If <emphasis remap='I'>start</emphasis> and <emphasis remap='I'>end</emphasis> are equal, no text is deleted and
the new text is inserted after <emphasis remap='I'>start</emphasis>.
</para>
</sect3>

<sect3 id="Scanning_the_TextSrc">
<title>Scanning the TextSrc</title>
<para>
To search the text source for one of the predefined boundary types use
the <function>Scan</function> function:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>XawTextPosition<function> Scan</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XawTextPosition<parameter> position</parameter></paramdef>
  <paramdef>XawTextScanType<parameter> type</parameter></paramdef>
  <paramdef>XawTextScanDirection<parameter> dir</parameter></paramdef>
  <paramdef>int<parameter> count</parameter></paramdef>
  <paramdef>Boolean<parameter> include</parameter></paramdef>
</funcprototype>
</funcsynopsis>


<variablelist>
  <varlistentry>
    <term><emphasis remap='I'>w</emphasis></term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>position</emphasis></term>
    <listitem>
      <para>
Specifies the position to begin scanning the source.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>type</emphasis></term>
    <listitem>
      <para>
Specifies the type of boundary to scan for, may be one of:
<function>XawstPosition</function>, <function>XawstWhiteSpace</function>, <function>XawstEOL</function>,
<function>XawstParagraph</function>, <function>XawstAll</function>.  The exact meaning of these
boundaries is left up to the individual text source.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>dir</emphasis></term>
    <listitem>
      <para>
Specifies the direction to scan, may be either <function>XawsdLeft</function> to search
<!-- .IN "XawsdLeft" "" -->
backward, or <function>XawsdRight</function> to search forward.
<!-- .IN "XawsdRight" "" -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>count</emphasis></term>
    <listitem>
      <para>
Specifies the number of boundaries to scan for.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>include</emphasis></term>
    <listitem>
      <para>
Specifies whether the boundary itself should be included in the scan.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
<!-- .LP -->
The <function>Scan</function> function returns the position in the text source of the desired
boundary.  It is expected to return a valid address for
all calls made to it, thus if a particular request is made that would take
the text widget beyond the end of the source it must return the
position of that end.
</para>
</sect3>

<sect3 id="Searching_through_a_TextSrc">
<title>Searching through a TextSrc</title>
<para>
To search for a particular string use the <function>Search</function> function.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>XawTextPosition<function> Search</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XawTextPosition<parameter> position</parameter></paramdef>
  <paramdef>XawTextScanDirection<parameter> dir</parameter></paramdef>
  <paramdef>XawTextBlock<parameter> *text</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term><emphasis remap='I'>w</emphasis></term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>position</emphasis></term>
    <listitem>
      <para>
Specifies the position to begin the search.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>dir</emphasis></term>
    <listitem>
      <para>
Specifies the direction to search, may be either <function>XawsdLeft</function> to search
<!-- .IN "XawsdLeft" "" -->
backward, or <function>XawsdRight</function> to search forward.
<!-- .IN "XawsdRight" "" -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>text</emphasis></term>
    <listitem>
      <para>
Specifies a text block containing the text to search for.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
This function will search through the text buffer attempting to find a
match for the string in the text block.  If a match is found in the
direction specified, then the character location of the first character
in the string is returned.  If no text was found then
<function>XawTextSearchError</function> is returned.
</para>

</sect3>

<sect3 id="Text_Selections">
<title>Text Selections</title>

<para>
<!-- .LP -->
While many selection types are handled by the Text widget, text sources
may have selection types unknown to the Text widget.  When a selection
conversion is requested by the X server the Text widget will first call
the <function>ConvertSelection</function> function, to attempt the selection
conversion.
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>Boolean<function> ConvertSelections</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>Atom*selection,*target,<parameter> *type</parameter></paramdef>
  <paramdef>caddr_t<parameter> *value_return</parameter></paramdef>
  <paramdef>unsignedlong<parameter> *length_return</parameter></paramdef>
  <paramdef>int<parameter> *format_return</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>selection</emphasis>
    </term>
    <listitem>
      <para>
Specifies the type of selection that was requested (e.g. <function>PRIMARY</function>).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>target</emphasis>
    </term>
    <listitem>
      <para>
Specifies the type of the selection that has been requested, which
indicates the desired information about the selection (e.g. Filename,
Text, Window).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>type</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the atom into which the property type of the converted
value of the selection is to be stored.  For instance, either file
name or text might have property type <function>XA_STRING</function>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>value_return</emphasis>
    </term>
    <listitem>
      <para>
Returns a pointer into which a pointer to the converted value of the
selection
is to be stored.  The selection owner is responsible for allocating
this storage.  The memory is considered owned by the toolkit, and is
freed by XtFree when the Intrinsics selection mechanism is done with it.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>length_return</emphasis>
    </term>
    <listitem>
      <para>
Returns a pointer into which the number of elements in value is to be stored.
The size of each element is determined by <emphasis remap='I'>format</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>format_return</emphasis>
    </term>
    <listitem>
      <para>
Returns a pointer into which the size in bits of the data elements of the
selection value is to be stored.
      </para>
    </listitem>
  </varlistentry>
</variablelist>

<para>
If this function returns <function>True</function> then the Text widget will assume
that the source has taken care of converting the selection, Otherwise the
Text widget will attempt to convert the selection itself.
</para>

<para>
If the source needs to know when the text selection is modified it
should define a <function>SetSelection</function> procedure:
</para>

<funcsynopsis>
<funcprototype>
  <funcdef>void<function> SetSelection</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>XawTextPositionstart,<parameter> end</parameter></paramdef>
  <paramdef>Atom<parameter> selection</parameter></paramdef>
</funcprototype>
</funcsynopsis>

<variablelist>
  <varlistentry>
    <term><emphasis remap='I'>w</emphasis></term>
    <listitem>
      <para>
Specifies the TextSrc object.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>start</emphasis></term>
    <listitem>
      <para>
Specifies the character position of the beginning of the new text selection.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>end</emphasis></term>
    <listitem>
      <para>
Specifies the character position of the end of the new text selection.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term><emphasis remap='I'>selection</emphasis></term>
    <listitem>
      <para>
Specifies the type of selection that was requested (e.g. <function>PRIMARY</function>).
      </para>
    </listitem>
  </varlistentry>
</variablelist>

</sect3>
</sect2>
</sect1>
