US 9,286,703 B2 · Redrawing recent curve sections for real-time smoothing

Abstract

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.

Claims20

Dependent claims

An automated curve smoothing process performed by a machine which includes a computer-readable memory, the process comprising the following steps:

getting in the computer-readable memory a group G of one or more recent data points Pi for a curve, the data points in the group G being the most recent data points in a sequence S of data points for the curve, the group G not containing all of the data points in S, the curve having a curve rendering which corresponds to the sequence S;
redrawing only a most recent section of the curve rendering, which is delineated in the memory by a checkpoint and which corresponds to data points Pi in group G, without thereby changing the entire curve rendering, the redrawn most recent section including a rendered spline that includes a portion which is visually smooth through at least q data points of group G, where q is a whole number greater than zero;
wherein the process uses rendered splines to smooth the recent section of the curve rendering by redrawing a section of the curve in real-time as data points are added to the sequence S;
and
wherein a portion of a rendered spline is considered visually smooth when the portion has G1 continuity.

2 more elements

A computer-readable storage medium configured with data and with instructions that when executed by a machine having a computer-readable memory, a digital display, and at least one processor causes the machine to perform a technical process for redrawing a digital ink curve, the process comprising the steps of:

getting in the computer-readable memory a data point Pn for a digital ink curve, the data point Pn being the most recent data point in a sequence S of data points for the digital ink curve, the digital ink curve having on the digital display a curve rendering which corresponds to the sequence S;
redrawing only a most recent section of the curve rendering without thereby changing the entire curve rendering, the redrawn most recent section including a rendered spline that includes a portion which is visually smooth through at least two most recent data points;
getting in the computer-readable memory a data point Pn+1 for the digital ink curve, and repeating the redrawing step with Pn+1 taking the place of Pn;
wherein the process uses rendered splines to smooth the digital ink curve by redrawing the most recent section of the curve in real-time as the curve is being interactively rendered on the digital display for a user of the machine;
and
wherein a portion of a rendered spline is considered visually smooth when any two parts of the visually smooth portion which meet at a point share a common tangent direction at the point where those two parts meet.

3 more elements

A computer graphics system comprising:

at least one logical processor;
an instruction memory in operable communication with the logical processor;
a digital ink display having a frame buffer in operable communication with the logical processor;
a curve redrawing code which resides in the instruction memory and which upon execution by the logical processor(s) will perform a technical process for redrawing a digital ink curve, the process comprising the steps of:
getting a group G of data points for a digital ink curve, the data points of group G being the most recent data points in a sequence S of data points for a digital ink curve, the digital ink curve having on the digital ink display a curve rendering which corresponds to the sequence S;
redrawing only a most recent section of the curve rendering, which corresponds to data points Pi in group G, without thereby changing the entire curve rendering, the redrawn most recent section including a rendered spline that includes a portion which is visually smooth through at least q data points of group G, where q is a whole number greater than zero;
and
wherein the curve redrawing code uses rendered splines to smooth the digital ink curve by redrawing the most recent section of the curve in real-time as the curve is being interactively rendered on the digital ink display;
and
wherein a portion of a rendered spline is considered visually smooth when any two parts of the visually smooth portion which meet at a point share a common tangent direction at the point where those two parts meet.

7 more elements

Dependencies are inferred from the claim text.

Redrawing recent curve sections for real-time smoothing

Life of this patent

Redrawing recent curve sections for real-time smoothing

Life of this patent

Abstract

Claims20