<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
function startGame() {
myGamePiece = new component(30, 30, "smiley.gif", 10, 120, "image");
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
},
stop : function() {
clearInterval(this.interval);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
if (type == "image") {
this.image = new Image();
this.image.src = color;
}
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
if (type == "image") {
ctx.drawImage(this.image,
this.x,
this.y,
this.width, this.height);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
}
}
function updateGameArea() {
myGameArea.clear();
myGamePiece.newPos();
myGamePiece.update();
}
function move(dir) {
myGamePiece.image.src = "angry.gif";
if (dir == "up") {myGamePiece.speedY = -1; }
if (dir == "down") {myGamePiece.speedY = 1; }
if (dir == "left") {myGamePiece.speedX = -1; }
if (dir == "right") {myGamePiece.speedX = 1; }
}
function clearmove() {
myGamePiece.image.src = "smiley.gif";
myGamePiece.speedX = 0;
myGamePiece.speedY = 0;
}
</script>
<div style="text-align:center;width:480px;">
<button onmousedown="move('up')" onmouseup="clearmove()" ontouchstart="move('up')">UP</button><br><br>
<button onmousedown="move('left')" onmouseup="clearmove()" ontouchstart="move('left')">LEFT</button>
<button onmousedown="move('right')" onmouseup="clearmove()" ontouchstart="move('right')">RIGHT</button><br><br>
<button onmousedown="move('down')" onmouseup="clearmove()" ontouchstart="move('down')">DOWN</button>
</div>
<p>See the image changes when you click on a button.</p>
</body>
</html>
