369 lines
11 KiB
XML
369 lines
11 KiB
XML
<sect1 id="Ascii_Source_Object_and_Multi_Source_Object">
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<title>Ascii Source Object and Multi Source Object</title>
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<para>
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<!-- .LP -->
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<!-- .XS -->
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<!-- AsciiSrc Object -->
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<!-- .XE -->
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<!-- .IN "AsciiSrc object" "" "@DEF@" -->
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</para>
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<para>
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<!-- .LP -->
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<literallayout class="monospaced">
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<!-- .TA 2.0i -->
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<!-- .ta 2.0i -->
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Application Header file <X11/Xaw/AsciiSrc.h> or <X11/Xaw/MultiSrc.h>
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<!-- .IN "AsciiSrc.h" "" -->
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Class Header file <X11/Xaw/AsciiSrcP.h> or <X11/Xaw/MultiSrcP.h>
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<!-- .IN "AsciiSrcP.h" "" -->
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Class asciiSrcObjectClass or multiSrcObjectClass
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<!-- .IN "asciiSrcObjectClass" "" -->
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Class Name AsciiSrc or MultiSrc
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<!-- .IN "AsciiSrc object" "class name" -->
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Superclass TextSource
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</literallayout>
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</para>
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<para>
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<!-- .LP -->
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The AsciiSrc or MultiSrc object is used by a text widget to read the text from a
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file or string in memory. Depending on its <function>international</function> resource, an
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AsciiText widget will create one or the other of these when the AsciiText
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itself is created. Both types are nearly identical; the following discussion
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applies to both, with MultiSrc differences noted only as they occur.
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</para>
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<para>
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<!-- .LP -->
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The AsciiSrc understands all Latin1 characters plus Tab
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and Carriage Return. \fIThe MultiSrc understands any set of character sets that
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the underlying X implementation's internationalization handles.\fP
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</para>
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<para>
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<!-- .LP -->
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The AsciiSrc can be either of two types: <function>XawAsciiFile</function>
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or <function>XawAsciiString</function>.
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</para>
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<para>
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<!-- .LP -->
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AsciiSrc objects of type <function>XawAsciiFile</function> read the text from a file and
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store it
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into an internal buffer. This buffer may then be modified, provided the
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text widget is in the correct edit mode, just as if it were a source of
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type <function>XawAsciiString</function>. Unlike R3 and earlier versions of the AsciiSrc,
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it is now possible to specify an editable disk source. The file is not
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updated, however, until a call to <function>XawAsciiSave</function> is made. When the
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source is in this mode the <function>useStringInPlace</function> resource is ignored.
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</para>
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<para>
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<!-- .LP -->
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AsciiSrc objects of type <function>XawAsciiString</function> have the text buffer
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implemented as a string.
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\fIMultiSrc objects of type <function>XawAsciiString</function> have the text buffer
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implemented as a wide character string.\fP
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The string owner is responsible for allocating and managing storage for the
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string.
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</para>
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<para>
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<!-- .LP -->
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In the default case for AsciiSrc objects of type <function>XawAsciiString</function>,
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the resource <function>useStringInPlace</function> is false,
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and the widget owns the string. The initial value of the
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string resource, and any update made by the application
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programmer to the string resource with <function>XtSetValues</function>, is copied
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into memory private to the widget, and managed internally by the widget.
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The application writer
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does not need to worry about running out of buffer space
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(subject to the total memory available to the application).
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The performance does not decay linearly as the buffer grows
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large, as is necessarily the case when the text buffer is used
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in place. The application writer must use <function>XtGetValues</function> to
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determine the contents of the text buffer, which will return
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a copy of the widget's text buffer as
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it existed at the time of the <function>XtGetValues</function> call. This copy
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is not affected by subsequent updates to the text buffer, i.e.,
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it is not updated as the user types input into the text buffer.
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This copy is freed upon the next call to XtGetValues to
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retrieve the string resource; however, to conserve memory,
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there is a convenience routine, <function>XawAsciiSourceFreeString</function>, allowing the
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application programmer to direct the widget to free the copy.
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</para>
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<para>
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<!-- .LP -->
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When the resource <function>useStringInPlace</function> is true and the AsciiSrc object
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is of type <function>XawAsciiString</function>, the application
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is the string owner. The widget will take the value
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of the string resource as its own text buffer, and the <function>length</function>
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resource indicates the buffer size. In this case
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the buffer contents change as the user types at the widget;
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it is not necessary to call <function>XtGetValues</function> on the string
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resource to determine the contents of the buffer-it will
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simply return the address of the application's implementation
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of the text buffer.
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</para>
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<sect2 id="asciisource_resources">
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<title>Resources</title>
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<para>
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<!-- .LP -->
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When creating an AsciiSrc object instance, the following resources are
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retrieved from the argument list or from the resource database:
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</para>
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<para>
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<!-- .LP -->
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<!-- .IN "AsciiSrc object" "resources" -->
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<informaltable>
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<tgroup cols='5' align='center'>
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<colspec colname='c1'/>
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<colspec colname='c2'/>
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<colspec colname='c3'/>
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<colspec colname='c4'/>
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<colspec colname='c5'/>
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<thead>
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<row>
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<entry>Name</entry>
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<entry>Class</entry>
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<entry>Type</entry>
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<entry>Notes</entry>
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<entry>Default Value</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>callback</entry>
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<entry>Callback</entry>
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<entry>XtCallbackList</entry>
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<entry></entry>
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<entry>NULL</entry>
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</row>
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<row>
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<entry>dataCompression</entry>
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<entry>DataCompression</entry>
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<entry>Boolean</entry>
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<entry></entry>
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<entry>True</entry>
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</row>
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<row>
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<entry>destroyCallback</entry>
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<entry>Callback</entry>
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<entry>Callback</entry>
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<entry></entry>
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<entry>NULL</entry>
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</row>
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<row>
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<entry>editType</entry>
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<entry>EditType</entry>
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<entry>EditMode</entry>
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<entry></entry>
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<entry>XawtextRead</entry>
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</row>
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<row>
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<entry>length</entry>
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<entry>Length</entry>
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<entry>Int</entry>
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<entry>A</entry>
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<entry>length of <function>string</function></entry>
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</row>
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<row>
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<entry>pieceSize</entry>
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<entry>PieceSize</entry>
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<entry>Int</entry>
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<entry></entry>
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<entry>BUFSIZ</entry>
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</row>
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<row>
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<entry>string</entry>
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<entry>String</entry>
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<entry>String</entry>
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<entry></entry>
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<entry>NULL</entry>
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</row>
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<row>
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<entry>type</entry>
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<entry>Type</entry>
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<entry>AsciiType</entry>
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<entry></entry>
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<entry>XawAsciiString</entry>
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</row>
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<row>
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<entry>useStringInPlace</entry>
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<entry>UseStringInPlace</entry>
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<entry>Boolean</entry>
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<entry></entry>
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<entry>False</entry>
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</row>
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<row>
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<entry>_</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<!-- .Oc Bold -->
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<!-- .Dc -->
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<!-- .Od Bold -->
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<!-- .Oe -->
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<!-- .Ol Bold -->
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<!-- .Op Bold -->
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<!-- .Os Bold -->
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<!-- .Ot Bold -->
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<!-- .Ou Bold -->
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</para>
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</sect2>
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<sect2 id="asciisource_convenience_routines">
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<title>Convenience Routines</title>
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<para>
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<!-- .LP -->
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The AsciiSrc has a few convenience routines that allow the
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application programmer quicker or easier access to some of the
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commonly used functionality of the AsciiSrc.
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</para>
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<sect3 id="Conserving_Memory">
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<title>Conserving Memory</title>
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<para>
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<!-- .LP -->
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When the AsciiSrc widget is not in <function>useStringInPlace</function> mode
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space must be allocated whenever the file is saved, or the string is
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requested with a call to <function>XtGetValues</function>. This memory is allocated on the
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fly, and remains valid until the next time a string needs to be allocated.
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You may save memory by freeing this string as soon as you are done
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with it by calling <function>XawAsciiSourceFreeString</function>.
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<funcsynopsis>
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<funcprototype>
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<funcdef>void<function> XawAsciiSourceFreeString</function></funcdef>
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<paramdef>Widget<parameter> w</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<!-- .FN -->
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>w</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the AsciiSrc object.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<!-- .LP -->
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This function will free the memory that contains the string pointer returned
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by <function>XtGetValues</function>. This will normally happen automatically when
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the next call to <function>XtGetValues</function> occurs, or when the widget is destroyed.
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</para>
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</sect3>
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<sect3 id="Saving_Files">
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<title>Saving Files</title>
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<para>
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<!-- .LP -->
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To save the changes made in the current text source into a file use
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<function>XawAsciiSave</function>.
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<funcsynopsis>
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<funcprototype>
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<funcdef>Boolean<function> XawAsciiSave</function></funcdef>
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<paramdef>Widget<parameter> w</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<!-- .FN -->
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>w</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the AsciiSrc object.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<!-- .LP -->
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<function>XawAsciiSave</function> returns <function>True</function> if the save was successful.
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It will update the file named in the <function>string</function> resource.
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If the buffer has not been changed, no action will be taken. This function
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only works on an AsciiSrc of type <function>XawAsciiFile</function>.
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</para>
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<para>
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<!-- .LP -->
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<!-- .sp 1 -->
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To save the contents of the current text buffer into a named file use
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<function>XawAsciiSaveAsFile</function>.
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<funcsynopsis>
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<funcprototype>
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<funcdef>Boolean<function> XawAsciiSaveAsFile</function></funcdef>
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<paramdef>Widget<parameter> w</parameter></paramdef>
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<paramdef>String<parameter> name</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<!-- .FN -->
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>w</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the AsciiSrc object.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>name</emphasis>
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</term>
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<listitem>
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<para>
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The name of the file to save the current buffer into.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<!-- .LP -->
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This function returns <function>True</function> if the save was successful.
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<function>XawAsciiSaveAsFile</function> will work with a buffer of either type
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<function>XawAsciiString</function> or type <function>XawAsciiFile</function>.
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</para>
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</sect3>
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<sect3 id="Seeing_if_the_Source_has_Changed">
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<title>Seeing if the Source has Changed</title>
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<para>
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<!-- .LP -->
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To find out if the text buffer in an AsciiSrc object has changed
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since the last time it was saved with <function>XawAsciiSave</function> or queried
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<!-- .IN "XawAsciiSave" "" -->
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use <function>XawAsciiSourceChanged</function>.
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<funcsynopsis>
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<funcprototype>
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<funcdef>Boolean<function> XawAsciiSourceChanged</function></funcdef>
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<paramdef>Widget<parameter> w</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<!-- .FN -->
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>w</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the AsciiSrc object.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<!-- .LP -->
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This function will return <function>True</function> if the source has changed since
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the last time it was saved or queried. The internal change flag is
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reset whenever the string is queried via <function>XtGetValues</function> or the
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buffer is saved via <function>XawAsciiSave</function>.
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</para>
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</sect3>
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</sect2>
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</sect1>
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