Converting QuickDraw Graphics to Quartz

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Intaglio uses the graphics layer in Mac OS X called Quartz. Traditional Macintosh drawing programs such as ClarisDraw use the graphics layer in the classic Mac OS called QuickDraw. QuickDraw graphics can be stored in collections called pictures or PICT graphics and files. Vector PICT files retain the graphics geometry used to create them, while bitmap PICT files are much like other bitmap image formats. Occasionally you may want to import QuickDraw pictures into Intaglio or convert ClarisDraw files into Intaglio drawings.

Intaglio can treat vector QuickDraw pictures created in traditional Macintosh applications in three different ways. First they can be converted to bitmap images with QuickDraw, this will render them exactly as they originally appeared, but the resolution will be fixed and the graphics can't be edited. Second they can rendered with Quartz, this will maintain most of the original appearance and add some Quartz features such as anti-aliasing (i.e., it will remove the "jaggies"), but the pictures still can't be edited. Finally, QuickDraw pictures and ClarisDraw graphics can be converted to Quartz graphics allowing them to be edited, but this may introduce various artifacts due to the differences between QuickDraw and Quartz.

The following issues arise when converting pictures for editing due to various ways in which Quartz differs from QuickDraw.
Preference options allow some of these options to be customized.

  • QuickDraw strokes (i.e., outlines) graphics with a square pen that can differ in width and height. The thickness of a line varies depending on its angle. Converted lines can use the average pen size or attempt to compensate for these differences by setting the stroke width based on the line's angle, or by creating two graphics to represent the original fill and outline respectively.
    The line caps (i.e., the style of the end of a line) will also vary due to the ways QuickDraw and Quartz draw lines.

  • The QuickDraw transfer modes don't have an analog in Quartz and are ignored. Some of the transfer modes are copy, or, and (sometimes called bic), and xor (i.e., exclusive or). These modes change the appearance of a graphic based on what is behind it.
    In some cases, ignoring the transfer mode causes a graphic to change its appearance or even become visible where it was originally invisible.

  • The QuickDraw text style outline and shadow also have no analog in Quartz and are ignored. In Intaglio, outline text can be created by converting a text block to a path and setting the appropriate stroke and fill options. Text can be given the appearance of a shadow by creating a duplicate behind it, offset down and to the right.

  • QuickDraw and Quartz fill arcs differently. If an arc is both filled and stroked the visual appearance can be maintained by converting it to two separate paths for the fill and stroke respectively, or it can be combined as a single path that fills differently that the original.

  • QuickDraw patterns are sometimes used to simulate a solid color a computer monitor isn't capable of displaying, by combining colors the monitor can display. Intaglio can either maintain patterns as they are presented or convert them to solid colors.

  • When text is saved in a QuickDraw picture each separate line and style run within a line is saved as a separate text element. Intaglio attempts to reconstruct the original text block from these pieces but this process isn't perfect. Sometimes a single text element may be spread across multiple Intaglio text blocks or multiple text elements may be combined incorrectly.

  • Most ClarisDraw files can be converted to Intaglio drawings by simply opening them from the File menu or dropping the file on the Intaglio icon in the dock. A few files contain elements not supported by Intaglio, and because of this some files can't be converted. In this case you can save the file in PICT format within ClarisDraw, import that file and convert it for editing.



Mac OS, Macintosh, Quartz, QuickDraw, and ClarisDraw are trademarks of Apple Computer, Inc.