Abstract: Character style information is stored in an array, in parallel with character information stored within another data structure. The style information array has more memory allocated to it than would be required to store the style information. This surplus memory is employed to form a "gap" in the array at a location corresponding to the point at which characters are being modified. The gap permits rapid revisions to character style information, while the array storage mechanism permits rapid random access to the style information of any character. Character style information may be mapped to corresponding characters using a run--array mechanism which associates a style with characters through use of an offset which indicates a starting character to which the style applies and a run length which indicates the number of characters to which the style applies.

Abstract: An object-oriented text layout engine that implements an efficient two-pass text placement procedure. The interface allows the text layout engine to receive parameters that define the document space into which text is to be placed. The interface also allows the text layout engine to receive parameters that define one or more constraints around which the text is to be placed. The text layout engine then places the around the constraint within the document space and returns the text layout to the client program. The text layout engine may be configured in three components, a Fill Constrained Display Rectangle (FCDR) module, a Format Line module, and a Compute Unobstructed Spans (CUS) module. The FCDR module controls the operation of the text layout engine, interacts with the client program, and calls the Format Line and CUS modules as necessary. The CUS module receives a set of parameters that define a candidate rectangle and a constraint that may intersect the candidate rectangle.