QuickTime 4 Reference

About QuickTime Vectors

QuickTime vectors are mathematical descriptions of images. Images described using QuickTime vectors can be scaled without loss of quality. In addition, the description of these images can be much smaller than equivalent images represented with bitmaps, even when the bitmaps are compressed.

Data for a QuickTime vector is stored in a QT atom container. The contents are a stream of atoms. Each atom contains one of the following:

a specification of a path
a style specification for the path, such as the stroke width of the pen used to draw the path
an atom that identifies the end of the data stream

In the current implementation, each path can include up to 32767 contours, and each contour can include up to 32767 points that define it.

An atom that contains a style specification determines the style of any paths in the stream that follow it unless or until it is replaced by another atom of the same type. If there is no atom for a particular style at any point the data stream, a default value is used for that style. The default value is replaced if and when an atom for the style appears in the data stream.

QuickTime Vectors and QuickDraw GX