<!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, "red", 10, 120);
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.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
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 moveup() {
myGamePiece.speedY = -1;
}
function movedown() {
myGamePiece.speedY = 1;
}
function moveleft() {
myGamePiece.speedX = -1;
}
function moveright() {
myGamePiece.speedX = 1;
}
function clearmove() {
myGamePiece.speedX = 0;
myGamePiece.speedY = 0;
}
</script>
<div style="text-align:center;width:480px;">
<button onmousedown="moveup()" onmouseup="clearmove()" ontouchstart="moveup()">UP</button><br><br>
<button onmousedown="moveleft()" onmouseup="clearmove()" ontouchstart="moveleft()">LEFT</button>
<button onmousedown="moveright()" onmouseup="clearmove()" ontouchstart="moveright()">RIGHT</button><br><br>
<button onmousedown="movedown()" onmouseup="clearmove()" ontouchstart="movedown()">DOWN</button>
</div>
<p>如果您按下一个按钮，红色方块将开始移动。 当您释放该按钮，移动将停止。</ p><p>我们已经在按钮上添加了ontouchstart事件，以使此示例适用于触摸屏设备。</ p>
</body>
</html>
