REDRAWING RECENT CURVE SECTIONS FOR REAL-TIME SMOOTHING

摘要

A recently rendered section of a curve is redrawn to smooth the curve on-the-fly while a user moves a stylus or other input device. On receiving data points for the curve, an old rendered section for prior data points is deleted by curve redrawing code, and a new spline that's visually smooth through the new data points and at least one prior data point is added. “Visually smooth” is defined using tangents. The rendered spline is a cardinal or other cubic Hermite spline. The curve is redrawn for display by overwriting frame buffer data. A single instruction multiple data processing architecture simultaneously calculates multiple data points for the new section of the curve rendering. A digital ink rendering uses a pen-tip shape or an arc shape, based on data point locations. The pen-tip shape simulates a square-tip pen, highlighter, pencil, charcoal, paintbrush, or liquid ink pen.

主权项

1. An automated digital ink curve smoothing method performed by a system which includes a computer-readable memory and also includes hardware that supports parallel processing, the method comprising:
getting in the computer-readable memory a group of data points for a digital ink curve, the digital ink curve having a displayed curve rendering; calculating in parallel multiple data points for a new section of the curve rendering, said calculating comprising using the hardware which supports parallel processing; and smoothing the digital ink curve using at least some of the calculated data points, thereby obtaining a smoothed digital ink curve which has a rendered spline that includes a portion that is visually smooth through at least two data points; wherein a portion of a rendered spline is considered visually smooth when the portion has G1 continuity.