Abstract: Laying out a paragraph using a layout services library. An entire paragraph is defined as a single text run. The text run is laid out by substituting glyphs for the characters of the text run and then positioning the glyphs. After the text run is laid out, the length of the text run is compared to the line length. If the length of the text run exceeds the line length, then the text run is divided into a parent text run and a child text run. If justification is enabled, then the parent text run is justified. If a child text run is created, then the length of the child text run is compared to the line length. If the length of the child text run exceeds the line length, then the process is repeated until the length of the last child text run does not exceed the line length. A layout services library provides text processing functions which support the paragraph layout and the justification.

Abstract: Rendering glyphs using a layout services library. A layout services library provides a set of text-processing functions for use by a client program. The text-processing functions access font information stored in the font tables insulating the client program from the details of the font table formats. The layout services library may be used to identify glyph variants and to position glyphs along a base line for a run of text. To identify glyph variants, the layout services library scans the run of text to identify the locations of characters having alternative glyph forms. The layout services library creates a list of feature parameter structures, each of which contains a count of the number of glyph alternates that apply for each identified character. The client program assembles a list of identical characters which have different parameters and presents a list of all glyph variants to the user who chooses one of the alternatives.

Abstract: A system and method of rendering a curve using data look-up tables for rasterizing the curve. The curve is subdivided so that it is approximated by a series of straight line segments of approximately equal length, with no line segment exceeds two pixels in length. The system subdivides any line segment that crosses horizontal axis of two adjacent horizontal scan rows. If the line segment does not cross the horizontal axis of a scan row, the pixel does not require detailed analysis. If the line segment does cross the horizontal axis of a particular horizontal scan row, the system uses look-up tables to determine the distance from the center point of the pixel in which the line segment crosses the horizontal axis to the point at which the line segment crosses the horizontal axis. The system uses three indices as pointers to the data look-up table containing the desired data.