Method for estimating the memory required for scan conversation of a glyph

摘要

An improved scan converter to support the efficient and accurate display of character outlines by pixel-oriented display devices. To conserve the finite resource of memory, the improved scan converter supports an efficient use of available memory workspace by accurately determining an upper bound for the amount of memory required to support scan conversion calculations. To achieve improvements in speed and character image quality, the improved scan converter renders the spline segments of a character outline by using a second order equation to calculate an implicit function based on the control points of each segment. The improved scan converter further addresses in a systematic manner the rendering of an endpoint located on a scan line to determine whether the pixel associated with the endpoint should be activated. This decision is based upon the direction of approach to and exit from this endpoint for the pair of segments connected to the endpoint. The improved scan converter also reduces the number of calculations requiring sub-pixel precision to support the selection of a pixel located nearest the contour, thereby providing an improved solution for dropout condition.