<!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()">上</button><br><br>
<button onmousedown="moveleft()" onmouseup="clearmove()" ontouchstart="moveleft()">左</button>
<button onmousedown="moveright()" onmouseup="clearmove()" ontouchstart="moveright()">右</button><br><br>
<button onmousedown="movedown()" onmouseup="clearmove()" ontouchstart="movedown()">下</button>
</div>
<p>如果您单击按钮，红色方块将开始移动。当您停止按下按钮时，运动将停止。</p>
<p>我们在按钮上添加了 ontouchstart 事件，以使此例适用于触摸设备。</p>
</body>
</html>