# Ascii Source Object and Multi Source Object

    Application Header file	<X11/Xaw/AsciiSrc.h> or <X11/Xaw/MultiSrc.h>

    Class Header file	<X11/Xaw/AsciiSrcP.h> or  <X11/Xaw/MultiSrcP.h>

    Class		asciiSrcObjectClass or multiSrcObjectClass

    Class Name	AsciiSrc or MultiSrc

    Superclass	TextSource

The AsciiSrc or MultiSrc object is used by a text widget to read the text from a file or string in memory. Depending on its `international` resource, an AsciiText widget will create one or the other of these when the AsciiText itself is created. Both types are nearly identical; the following discussion applies to both, with MultiSrc differences noted only as they occur.

The AsciiSrc understands all Latin1 characters plus Tab and Carriage Return. The MultiSrc understands any set of character sets that the underlying X implementation's internationalization handles.

The AsciiSrc can be either of two types: `XawAsciiFile` or `XawAsciiString`.

AsciiSrc objects of type `XawAsciiFile` read the text from a file and store it into an internal buffer. This buffer may then be modified, provided the text widget is in the correct edit mode, just as if it were a source of type `XawAsciiString`. Unlike R3 and earlier versions of the AsciiSrc, it is now possible to specify an editable disk source. The file is not updated, however, until a call to XawAsciiSave is made. When the source is in this mode the `useStringInPlace` resource is ignored.

AsciiSrc objects of type `XawAsciiString` have the text buffer implemented as a string. MultiSrc objects of type `XawAsciiString` have the text buffer implemented as a wide character string. The string owner is responsible for allocating and managing storage for the string.

In the default case for AsciiSrc objects of type `XawAsciiString`, the resource `useStringInPlace` is false, and the widget owns the string. The initial value of the string resource, and any update made by the application programmer to the string resource with XtSetValues, is copied into memory private to the widget, and managed internally by the widget. The application writer does not need to worry about running out of buffer space (subject to the total memory available to the application). The performance does not decay linearly as the buffer grows large, as is necessarily the case when the text buffer is used in place. The application writer must use XtGetValues to determine the contents of the text buffer, which will return a copy of the widget's text buffer as it existed at the time of the XtGetValues call. This copy is not affected by subsequent updates to the text buffer, i.e., it is not updated as the user types input into the text buffer. This copy is freed upon the next call to XtGetValues to retrieve the string resource; however, to conserve memory, there is a convenience routine, XawAsciiSourceFreeString, allowing the application programmer to direct the widget to free the copy.

When the resource `useStringInPlace` is true and the AsciiSrc object is of type `XawAsciiString`, the application is the string owner. The widget will take the value of the string resource as its own text buffer, and the `length` resource indicates the buffer size. In this case the buffer contents change as the user types at the widget; it is not necessary to call XtGetValues on the string resource to determine the contents of the buffer-it will simply return the address of the application's implementation of the text buffer.

## Resources

When creating an AsciiSrc object instance, the following resources are retrieved from the argument list or from the resource database:

Name | Class | Type | Notes | Default Value
callback | Callback | XtCallbackList |  | NULL
dataCompression | DataCompression | Boolean |  | True
destroyCallback | Callback | Callback |  | NULL
editType | EditType | EditMode |  | XawtextRead
length | Length | Int | A | length of `string`
pieceSize | PieceSize | Int |  | BUFSIZ
string | String | String |  | NULL
type | Type | AsciiType |  | XawAsciiString
useStringInPlace | UseStringInPlace | Boolean |  | False
_

## Convenience Routines

The AsciiSrc has a few convenience routines that allow the application programmer quicker or easier access to some of the commonly used functionality of the AsciiSrc.

### Conserving Memory

When the AsciiSrc widget is not in `useStringInPlace` mode space must be allocated whenever the file is saved, or the string is requested with a call to XtGetValues. This memory is allocated on the fly, and remains valid until the next time a string needs to be allocated. You may save memory by freeing this string as soon as you are done with it by calling XawAsciiSourceFreeString.

      void XawAsciiSourceFreeString
      Widget w

w

- Specifies the AsciiSrc object.

This function will free the memory that contains the string pointer returned by XtGetValues. This will normally happen automatically when the next call to XtGetValues occurs, or when the widget is destroyed.

### Saving Files

To save the changes made in the current text source into a file use XawAsciiSave.

      Boolean XawAsciiSave
      Widget w

w

- Specifies the AsciiSrc object.

XawAsciiSave returns `True` if the save was successful. It will update the file named in the `string` resource. If the buffer has not been changed, no action will be taken. This function only works on an AsciiSrc of type `XawAsciiFile`.

To save the contents of the current text buffer into a named file use XawAsciiSaveAsFile.

      Boolean XawAsciiSaveAsFile
      Widget w
      String name

w

- Specifies the AsciiSrc object.

name

- The name of the file to save the current buffer into.

This function returns `True` if the save was successful. XawAsciiSaveAsFile will work with a buffer of either type `XawAsciiString` or type `XawAsciiFile`.

### Seeing if the Source has Changed

To find out if the text buffer in an AsciiSrc object has changed since the last time it was saved with XawAsciiSave or queried
use XawAsciiSourceChanged.

      Boolean XawAsciiSourceChanged
      Widget w

w

- Specifies the AsciiSrc object.

This function will return `True` if the source has changed since the last time it was saved or queried. The internal change flag is reset whenever the string is queried via XtGetValues or the buffer is saved via XawAsciiSave.