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Display
special file
Display
display a document
[file] Display(in mediaType contents
[in title docName]);
DESCRIPTION
The
Display request causes the handler to display (present or manifest)
a document to the user.
For example, an audio manipulation utility would be said to
``display'' audio documents when it plays them.
The handler must decide issues such as:
When the display operation can be deemed completed
What user gesture signals the completion of the display
What the handling tool should do with itself after replying
The
contents argument
is the contents of the document.
If this argument is unset
(in other words, has a value of
(char *)0), then the contents of the document are in
the file named in the message's
file attribute.
The data type
(mediaType) of the
contents argument should be
string, unless nulls are valid in the given media type,
in which case the data type must be
bytes.
The
docName argument contains the name of the document.
If the
docName argument is absent and the
file attribute is set,
the file name is considered to be the title of the document.
This string would be suitable for display in a window title bar, for example.
APPLICATION USAGE
The
&cdeman.ttmedia.ptype.declare; function can be used to register for,
and help process, this message.
This message can be sent with the
&cdeman.ttmedia.load; function.
When the document to be displayed
is read-only or unlikely to be modified
the
Display message is frequently used instead of the
Edit message.
EXAMPLES
To display a PostScript document, the application can send a
Display request with a first argument whose vtype is
PostScript, and whose value is a vector of bytes such as:
%!\n/inch {72 mul} def...
The
\n in the example represents the newline character.
The notation is the same as in the &str-Z3;.
To display a PostScript document contained in a file,
the application can send a
Display request with the
file attribute set to that file
and with an unset first argument whose vtype is
PostScript.
ERRORS
The ToolTalk service may return one of the following errors
in processing the
Display request:
TT_DESKTOP_ENOENT
The file that was alleged to contain the document does not exist.
TT_DESKTOP_ENODATA
The in-mode
contents argument had no value and the
file attribute
of the message was not set.
TT_MEDIA_ERR_FORMAT
The document is not a valid instance of the media type.
SEE ALSO
&cdeman.ttmedia.ptype.declare;, &cdeman.ttmedia.load;; Intro, Deposit, Edit, Status requests.