Core Printing-Related Objects
QuickDraw GX uses objects to represent printing-related data in the same way it uses objects in its other major components, graphics and typography. The core QuickDraw GX printing-related objects are job objects, format objects, and paper-type objects. There are other printing-related objects that provide additional information in support of the core objects or represent printers and files.Because printing-related objects are interrelated, this section briefly describes how these objects work together to provide a complete specification for printing a document. For a more detailed description of each object, including those that support the core printing-related objects, see "About QuickDraw GX Printing-Related Objects" on page 1-16. The other chapters in this book provide a complete description of the printing-related objects and show how to use them.
In QuickDraw GX printing, a job object specifies everything QuickDraw GX needs to render a document. The most important specifications include the following ones; however, there are many others:
The pages to print and the printer on which to print them are typically straightforward specifications. The formatting specification can be more involved, however, because QuickDraw GX provides these formatting features:
- which pages to print
- which printer is to receive the output
- how to format the document; for example, for a particular page size and orientation, such as 8.5-by-11 inches and landscape
To support the first feature, the job object retains the formatting information for the formatting printer separately from the formatting information for the output printer. This allows a print job to be associated with two printers at the same time. The formatting printer specifies the document's format. The output printer is the printer to which the document is sent to be printed. The document retains the format specified by the formatting printer even though the output printer may affect the appearance of the printed document. This feature is useful, for example, if you have formatted a long document for a typesetter but want to make a final check of a page or two on a StyleWriter printer.
- You can print to a printer other than the one the document is formatted for; in other words, you can print without automatically reformatting the document.
- You can specify a different format for each page of a document.
To support the second feature, QuickDraw GX provides a format object. A format object can be specified for each page as it is printed. All pages can use the same format object, or selected pages can use different format objects. If desired, each page could use a different format object. You might also print the same page several times, each time specifying a different format object.
Associated with a format is a paper-type object. A paper-type object specifies the characteristics of the paper on which a page is printed. A paper-type object is separate from a format object because several format objects can share the same paper-type object.
Collection objects contain additional but less frequently used information about the job, formats, and paper types. The printer object represents a printer, and the print file object represents the spooled document or a portable digital document. Figure 1-2 shows the relationship between the core printing-related objects, the collection objects that support them, and the printer and print file objects.
Figure 1-2 QuickDraw GX printing-related objects
For more information about each object, see "About QuickDraw GX Printing-Related Objects" on page 1-16.
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