You want to draw an ellipse (oval) at runtime.
Create a custom MovieClip.drawEllipse( ) method using the Drawing API and invoke it on a movie clip.
You can create a method of the MovieClip class to draw an ellipse that is very similar to the drawCircle( ) method in Recipe 4.5. In fact, the drawCircle( ) method is merely a degenerate version of drawEllipse( ), in which the radii in the x and y directions are the same.
The custom drawEllipse( ) method accepts four parameters:
The radius of the ellipse in the x direction (major axis).
The radius of the ellipse in the y direction (minor axis).
The x coordinate of the center of the ellipse.
The y coordinate of the center of the ellipse.
Refer to Recipe 4.5 for those aspects of the drawEllipse( ) method that are not commented on here.
MovieClip.prototype.drawEllipse = function (xRadius, yRadius, x, y) { var angleDelta = Math.PI / 4; // While the circle has only one distance to the control point for each segment, // the ellipse has two distances: one that corresponds to xRadius and another that // corresponds to yRadius. var xCtrlDist = xRadius/Math.cos(angleDelta/2); var yCtrlDist = yRadius/Math.cos(angleDelta/2); var rx, ry, ax, ay; this.moveTo(x + xRadius, y); for (var i = 0; i < 8; i++) { angle += angleDelta; rx = x + Math.cos(angle-(angleDelta/2))*(xCtrlDist); ry = y + Math.sin(angle-(angleDelta/2))*(yCtrlDist); ax = x + Math.cos(angle)*xRadius; ay = y + Math.sin(angle)*yRadius; this.curveTo(rx, ry, ax, ay); } }
Once you have defined and included the drawEllipse( ) method in your Flash document, you can draw an ellipse rather easily. Use the drawEllipse( ) method the same way you used the drawCircle( ) method in Recipe 4.5 but provide both x and y radii instead of just a single radius. Remember that you still need to define the line style before you call the drawEllipse( ) method.
// Create an ellipse with minor and major axes of 100 and 200, respectively. this.createEmptyMovieClip("ellipse", 1); ellipse.lineStyle(1, 0x000000, 100); // Use a one-pixel, black, solid border ellipse.drawEllipse(100, 200);
Having defined drawEllipse( ), we can rewrite the drawCircle( ) method, as follows:
MovieClip.prototype.drawCircle = function (radius, x, y) { // Call drawEllipse( ) with the same radius for both x and y. this.drawEllipse (radius, radius, x, y); }
Recipe 4.5