8
December 15, 1997
X Print Service Extension Library
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X Print Service Extension Library
Release 6.4
X Version 11
2.2.1 Creating and Managing Print Contexts
Use
XpCreateContext to create and initialize a new print context.
XPContext XpCreateContext (display, printer_name)
Display *display;
char *printer_name;
display
Specifies a pointer to the Display structure; returned from XOpenDisplay.
printer_name
The name of a printer on display. String encoded as COMPOUND_TEXT.
XpCreateContext creates a new print context that is initialized with the default printer attributes and other
information available for printer_name on display. A print context maintains the printer name, print
attributes, font capabilities, print (rendering) state and results, and is the object upon which the Xp calls act.
If the library fails to generate a new print context-id, a value of
None is returned, otherwise a print context-id
is always returned. If printer_name is invalid, a
BadMatch is generated later by the X Print Server.
A call to
XpGetPrinterList will return a valid list of values for printer_name. All printer name values in the X
Print Service are encoded as COMPOUND_TEXT (of which the ISO-8859-1 code-set is a proper subset).
As soon as a print context is created, the print attributes in it can be accessed and modified by calling
XpGetAttributes and XpSetAttributes, and the event selections in it can be modified by calling XpSelectInput and
XpInputSelected. Other Xp calls that explicitly take a print context-id as a parameter will operate directly on
that print context. All Xp and X calls without a print context-id parameter (for example, all rendering ori-
ented calls like
XpStartJob and XDrawLine) require that a print context be set on the display connection (see
XpSetContext). Failure to set a print context prior to calling a print-context-dependent call will result in the
generation of an
XPBadContext error.
The XPContext returned by
XpCreateContext is an XID, and can be used to set the print context on display
connections by calling
XpSetContext. The XPContext id can be shared between processes and display con-
nections. It is the responsibility of the clients sharing a print context to coordinate their usage of the context;
for example they must ensure that in-use print contexts are not prematurely destroyed.
The context_id remains valid for all clients until 1) the client creating the print context closes its display con-
nection, or 2) any client calls
XpDestroyContext. The context_id can be kept valid after the creating client's
display connection closes if
XSetCloseDownMode is called on display with RetainPermanent or RetainTempo-
rary.
After creating a print context, and possibly modifying the
XPDocAttr attribute document-format using a value
from the list of available formats shown in the
XPPrinterAttr attribute document-formats-supported, the applica-
tion must query the X Print Server via
XpGetScreenOfContext for the screen that has been associated with the
print context, and then create all server resources that will be used in the print job on that screen. Failure to
do so will result in undefined behavior.
When
XpCreateContext is called, the client's locale (see XpSetLocaleHinter) is included in the request as a
"hint" to the X Print Server. If supported by the implementation, the X Print Server will use the hint to ini-
tialize the attribute pools with any localized attribute values (for example, the human readable
XPPrinterAttr
attribute "descriptor" may be available in several different languages, and the hint will be used to select one).
If the X Print Server cannot understand the hint, the X Print Server chooses a default value.
This function can generate a
BadMatch error if the specified printer_name does not exist on display, or if the
print server could not interpret the code set specified in printer_name.
Use
XpSetContext to set or unset a print context with the specified display connection to the X Print Server.
void XpSetContext (display, print_context)
Display *display;