Question

所以我们几乎让这个程序工作得很好，我们只需要一点帮助，或者在正确的方向上指出我们如何开始和停止动画的好指针。我尝试了几种方法，但似乎都没有。我花了很多时间在线尝试寻求解决方案的帮助。我开始相信这个问题存在于告诉形状移动的线条中。感谢您提前提供任何帮助。

JS：

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; 
}

HTML：

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<script type="text/javascript" src="HallettBrocatoLab2.js"></script>

<style>
canvas {
    border:1px solid #d3d3d3;
    background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">

<div style="text-align:center;width:480px;">
  <button onclick="moveup()">UP</button><br><br>
  <button onclick="moveleft()">LEFT</button>
  <button onclick="moveright()">RIGHT</button><br><br>
  <button onclick="movedown()">DOWN</button><br><br>
  <button onclick="start()">Start</button>
  <button onclick="stop()">Stop</button>
</div>

<p>If you click a button the red square will start moving. Click the same button many times, and it will move faster and faster.</p>
</body>
</html>

Answer 1

clearInterval（）方法清除使用setInterval（）方法设置的计时器。 setInterval（）返回的ID值用作clearInterval（）方法的参数。

添加功能结束pauseGame()

function pauseGame(){
    clearInterval(this.interval);
}

更改updateGameArea功能

的定义

function updateGameArea() {
    if(condition_to_stop){
        myGameArea.pauseGame();
    }
    myGameArea.clear();
    myGamePiece.newPos();    
    myGamePiece.update();
}

使用JS启动和停止JS HTML动画

1 个答案: