Canvas Palette line drawing

by Jim_Y

HTML

<div id="container">
    <canvas id="palette" width="400" height="400">Your browser does not support the HTML5 canvas tag.</canvas>
</div>

CSS

#container {
    width: 500px;
    height: 500px;
    margin: auto;
}
#palette {
    border: 1px solid #c3c3c3;
}

JavaScript

function Palette(canvas, context, game) {
    this.game = game;

    this.X = 100;
    this.Y = 100;
    this.self = canvas;
    this.context = context;
}

Palette.prototype.leftArrowPressed = function () {
    this.X = this.X - this.game.speed;
    this.context.lineTo(this.X, this.Y);
    this.context.stroke();
}

Palette.prototype.rightArrowPressed = function () {
    this.X = this.X + this.game.speed;
    this.context.lineTo(this.X, this.Y);
    this.context.stroke();
}

Palette.prototype.topArrowPressed = function () {
    this.Y = this.Y - this.game.speed;
    this.context.lineTo(this.X, this.Y);
    this.context.stroke();
}

Palette.prototype.bottomArrowPressed = function () {
    this.Y = this.Y + this.game.speed;
    this.context.lineTo(this.X, this.Y);
    this.context.stroke();
}

function Game(speed) {
    this.speed = speed;
}

$(document).ready(function () {
    var game = new Game(5);
    var canvas = document.getElementById("palette");
    var palette = new Palette(canvas, canvas.getContext("2d"), game);
    palette.context.moveTo(palette.X, palette.Y);
    palette.context.lineWidth = 1;
    palette.context.beginPath();

    $(document).keydown(function (e) {
        if (e.keyCode == 37) {
            // leftArrowPressed
            palette.leftArrowPressed();
        } else if (e.keyCode == 38) {
            // 	topArrowPressed
            palette.topArrowPressed();
        } else if (e.keyCode == 39) {
            // rightArrowPressed
            palette.rightArrowPressed();
        } else if (e.keyCode == 40) {
            // bottomArrowPressed
            palette.bottomArrowPressed();
        }

        return false;
    });
});