Patent ID: 6512847
Filing Date: 2003-01-28
Classification: G06T

Abstract:
A method for framing a graphic object whose contour is described by cubic Bezier curves by producing an approximately parallel, cubic Bezier frame curve having checkpoints Q0, Q1, Q2, Q3 for each given cubic Bezier curve of the contour having checkpoints P0, P1, P2, P3, comprising the steps of:defining the checkpoint Q0 proceeding from the checkpoint P0 perpendicular to a line P0-P1 at a spacing of a frame width; defining the checkpoint Q3 proceeding from the checkpoint P3 perpendicular to a line P2-P3 at the spacing of the frame width; placing the checkpoint Q1 onto a first parallel that proceeds through the checkpoint Q0 parallel to the line P0-P1; placing the checkpoint Q2 onto a second parallel that proceeds through the checkpoint Q3 parallel to the line P2-P3; constructing a mid-point PM for the given Bezier curve from the checkpoints P0, P1, P2, P3; determining a mid-point QM for the Bezier frame curve to be produced proceeding from the mid-point PM perpendicular to the given Bezier curve at the spacing of the frame width; and calculating a position of the checkpoint Q1 on the first parallel and the checkpoint Q2 on the second parallel from a condition that the mid-point QM can be constructed in the same way from the checkpoints Q0, Q1, Q2, Q3 as the mid-point PM is constructed from the checkpoints P0, P1, P2, P3.