Graphics - CurveTo

Code

var stage = new Stage("canvas", 420, 500, 30);
var shape;

//simple curve
shape = new Shape();
shape.x = 20;
shape.y = 20;
shape.graphics.lineStyle(10, 0xFF0000);
shape.graphics.moveTo(0, 0);
shape.graphics.curveTo(100, 50, 0, 100);
stage.addChild(shape);

//try to draw a circle
//http://board.flashkit.com/board/archive/index.php/t-369672.html
var r = 50;
shape = new Shape();
shape.x = 170;
shape.y = 70;
shape.graphics.lineStyle(10, 0x0000FF);
shape.graphics.moveTo(r, 0); 
shape.graphics.curveTo(r, -0.4142 * r, 0.7071 * r, -0.7071 * r);
shape.graphics.curveTo(0.4142 * r, -r, 0, -r);
shape.graphics.curveTo(-0.4142 * r, -r, -0.7071 * r, -0.7071 * r);
shape.graphics.curveTo(-r, -0.4142 * r, -r, 0);
shape.graphics.curveTo(-r, 0.4142 * r, -0.7071 * r, 0.7071 * r);
shape.graphics.curveTo(-0.4142 * r, r, 0, r);
shape.graphics.curveTo(0.4142 * r, r, 0.7071 * r, 0.7071 * r) ;
shape.graphics.curveTo(r, 0.4142 * r, r, 0);
stage.addChild(shape);

//round rect
var w = 100;
var h = 100;
shape = new Shape();
shape.x = 260;
shape.y = 20;
shape.graphics.lineStyle(10, 0x00FF00);
shape.graphics.moveTo(10, 0);
shape.graphics.lineTo(w - 10, 0);
shape.graphics.curveTo(w, 0, w, 10);
shape.graphics.lineTo(w, h - 10);
shape.graphics.curveTo(w, h, w - 10, h);
shape.graphics.lineTo(10, h);
shape.graphics.curveTo(0, h, 0, h - 10);
shape.graphics.lineTo(0, 10);
shape.graphics.curveTo(0, 0, 10, 0);
stage.addChild(shape);

Canvas

Output