Patent ID: 7439980

Claim:
A method for drawing a line having a prescribed width on the basis of a start-point coordinate of the line, an end-point coordinate of the line, and the prescribed width of the line on a screen of a display apparatus by using data regarding dots aligned on scanning lines displayed on the screen, said method comprising the steps of: calculating a drawing range in a vertical direction of the screen required for drawing the line having the prescribed width to be drawn on the basis of the start-point coordinate of the line, the end-point coordinate of the line and the prescribed width of the line, a terminal of the line to be drawn being formed of a perpendicular line which is perpendicular to a direction of the line to be drawn, wherein the drawing of the line is not performed outside of the drawing range in the vertical direction; calculating coordinates of intersections between the scanning lines and boundaries of the line to be drawn; selecting dots constituting the line to be drawn on scanning lines on the basis of the calculated coordinates of the intersections: writing data regarding the selected dots on the scanning lines into a line buffer; and displaying the line to be drawn having the prescribed width and the terminal on the screen by using the data written into the line buffer.