Draws a rounded rectangle using the current state of the canvas

roundRect.js

CanvasRenderingContext2D.prototype.roundRect =
/**
 * Draws a rounded rectangle using the current state of the canvas.
 * If you omit the last three params, it will draw a rectangle
 * outline with a 5 pixel border radius
 * @param {CanvasRenderingContext2D} ctx
 * @param {Number} x The top left x coordinate
 * @param {Number} y The top left y coordinate
 * @param {Number} width The width of the rectangle
 * @param {Number} height The height of the rectangle
 * @param {Number} radius The corner radius. Defaults to 5;
 * @param {Boolean} fill Whether to fill the rectangle. Defaults to false.
 * @param {Boolean} stroke Whether to stroke the rectangle. Defaults to true.
 */
function(x, y, width, height, radius, fill, stroke) {
    if (typeof stroke == "undefined") {
        stroke = true;
    }
    if (typeof radius === "undefined") {
        radius = 5;
    }
    this.beginPath();
    this.moveTo(x + radius, y);
    this.lineTo(x + width - radius, y);
    this.quadraticCurveTo(x + width, y, x + width, y + radius);
    this.lineTo(x + width, y + height - radius);
    this.quadraticCurveTo(x + width, y + height, x + width - radius, y + height);
    this.lineTo(x + radius, y + height);
    this.quadraticCurveTo(x, y + height, x, y + height - radius);
    this.lineTo(x, y + radius);
    this.quadraticCurveTo(x, y, x + radius, y);
    this.closePath();
    if (fill) {
        this.fill();
    }
    if (stroke) {
        this.stroke();
    }
};