procedure ArcTo(X1, Y1, X2, Y2, X3, Y3, X4, Y4: Integer); virtual; abstract;
virtual void __fastcall ArcTo(int X1, int Y1, int X2, int Y2, int X3, int Y3, int X4, int Y4) = 0 ;
Draws an arc on the image along the perimeter of the ellipse bounded by the specified rectangle.
Override the ArcTo method (or just use Arcto from descendant classes) to implement drawing of an elliptically curved line with the current Pen. The arc traverses the perimeter of an ellipse that is bounded by the points (X1,Y1) and (X2,Y2). The arc is drawn following the perimeter of the ellipse, counterclockwise, from the starting point to the ending point. The starting point is defined by the intersection of the ellipse and a line defined by the center of the ellipse and (X3,Y3). The ending point is defined by the intersection of the ellipse and a line defined by the center of the ellipse and (X4, Y4).
This procedure draws lines by using the current pen and updates the value of PenPos to the value of the last endpoint.