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Method for Providing Subfont Caching in Hidden Refresh Buffer Space

IP.com Disclosure Number: IPCOM000039258D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Baker, DC: AUTHOR [+2]

Abstract

In raster displays, one is often penalized (in terms of performance) for not using the invisible or hidden portions of the refresh buffer as the source for character raster mosaics when writing characters. On some local terminal support components, font sets are very large, often comprising more than 550 unique symbols which cover the gamut of requirements for most of the Latin alphabet languages of the world, mathematical symbols and line art symbols. In the typical case, most users rarely utilize the entire set of symbols in a font in any given document, let alone any screen representing a piece of a document. It is not uncommon to have multiple fonts in a document. Display management thus has the requirement to supply a small subset of many different fonts for a given screen.

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Method for Providing Subfont Caching in Hidden Refresh Buffer Space

In raster displays, one is often penalized (in terms of performance) for not using the invisible or hidden portions of the refresh buffer as the source for character raster mosaics when writing characters. On some local terminal support components, font sets are very large, often comprising more than 550 unique symbols which cover the gamut of requirements for most of the Latin alphabet languages of the world, mathematical symbols and line art symbols. In the typical case, most users rarely utilize the entire set of symbols in a font in any given document, let alone any screen representing a piece of a document. It is not uncommon to have multiple fonts in a document. Display management thus has the requirement to supply a small subset of many different fonts for a given screen. In the light of the performance penalties associated with not having characters in the hidden space and in the light of the fact that the hidden space is usually too small to store more than one or two complete font sets, one would like to find a way to partition the hidden space allocation. The new method involves a direct solution to this problem, similar in principle to caching as used in processor storage hierarchies. The idea here is that font sets would be broken into subsets of character mosaics. Generally they would be broken into fixed storage-size pieces, not a fixed number of characters. The hidden space would ...