Connected-run dropout-free center point fill method for displaying

Abstract

An improved method of displaying a character on a raster device using a modified center point fill method is described, beginning by defining the character by an outline of a series of edges in a path, scaling the character to a pixel grid of columns and scan lines in display space, identifying as a cross each point where an edge of the character intersects a horizontal midline of a scan line and storing a list of the crosses pairwise along each scan line as cross pairs. For each one of the cross pairs, all pixels having centers that are located between the crosses of the cross pair are selected and the range of the selected pixels is stored as a run for the cross pair. For each cross pair between two adjacent pixel centers, the pixel containing the horizontal midpoint of the cross pair is stored as a run for the cross pair. Adjacent cross pairs are identified and the run for each cross pair is tested against the run displaying each adjacent cross pair to see if the runs are properly connected. If they are not then at least one pixel is selected and an existing run is extended to include the selected pixel, if possible. Otherwise, a pseudocross pair is created as needed to properly connect the runs. Narrow horizontal features are also identified and connected to the character using similar methods.