Importance

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Abstract

A method of drawing a straight or curved line of predetermined thickness on a raster device having a display or printed page consisting of a rectangular array of pels. Initially, a spine list is generated which comprises a digitization of a spine that can be swept by a preselected pen of thickness 2t centered on the spine to draw the line or 'stroke.' The next step is to generate penleft and penright lists representing the X and Y coordinate values of the left and right sides of the pen. Thereafter, left and right lists representing a pair of boundaries of the stroke are generated by starting at a first end of the spine list and sequentially moving toward a second end of the spine list. For each position in the spine list, the X, Y coordinate values thereof are added to the X and Y coordinate values in the penleft list. The left list is updated when any of the resulting sums yield an X value less than the current X value for the corresponding Y value in the left list. The right list is similarly updated for each position in the spine list when any of the resulting sums yield an X value more than the current X value for the corresponding Y value in the right list. Finally, the stroke is drawn by filling in between the left and right lists.

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First Claim