如何解决我在 HTML 中制作的可玩结构变得扁平，并且 common 属性没有帮助

我正在尝试同时使用 Java 在 HTML 中制作游戏，但我不知道如何为 <canvas>元素。到目前为止，我的游戏是这样的：

<!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;
var myObstacles = [];
var myscore;

function startGame() {
    myGamePiece = new component(30,30,"red",10,120);
    myGamePiece.gravity = 0.05;
    myscore = new component("30px","Consolas","black",280,40,"text");
    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,this.canvas.width,this.canvas.height);
    }
}

function component(width,height,color,x,y,type) {
    this.type = type;
    this.score = 0;
    this.width = width;
    this.height = height;
    this.speedX = 0;
    this.speedY = 0;    
    this.x = x;
    this.y = y;
    this.gravity = 0;
    this.gravitySpeed = 0;
    this.update = function() {
        ctx = myGameArea.context;
        if (this.type == "text") {
            ctx.font = this.width + " " + this.height;
            ctx.fillStyle = color;
            ctx.fillText(this.text,this.x,this.y);
        } else {
            ctx.fillStyle = color;
            ctx.fillRect(this.x,this.y,this.width,this.height);
        }
    }
    this.newPos = function() {
        this.gravitySpeed += this.gravity;
        this.x += this.speedX;
        this.y += this.speedY + this.gravitySpeed;
        this.hitBottom();
    }
    this.hitBottom = function() {
        var rockbottom = myGameArea.canvas.height - this.height;
        if (this.y > rockbottom) {
            this.y = rockbottom;
            this.gravitySpeed = 0;
        }
    }
    this.crashWith = function(otherobj) {
        var myleft = this.x;
        var myright = this.x + (this.width);
        var mytop = this.y;
        var mybottom = this.y + (this.height);
        var otherleft = otherobj.x;
        var otherright = otherobj.x + (otherobj.width);
        var othertop = otherobj.y;
        var otherbottom = otherobj.y + (otherobj.height);
        var crash = true;
        if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
            crash = false;
        }
        return crash;
    }
}

function updateGameArea() {
    var x,gap,minHeight,maxHeight,minGap,maxGap;
    for (i = 0; i < myObstacles.length; i += 1) {
        if (myGamePiece.crashWith(myObstacles[i])) {
            return;
        } 
    }
    myGameArea.clear();
    myGameArea.frameNo += 1;
    if (myGameArea.frameNo == 1 || everyinterval(150)) {
        x = myGameArea.canvas.width;
        minHeight = 20;
        maxHeight = 200;
        height = Math.floor(Math.random()*(maxHeight-minHeight+1)+minHeight);
        minGap = 50;
        maxGap = 200;
        gap = Math.floor(Math.random()*(maxGap-minGap+1)+minGap);
        myObstacles.push(new component(10,"green",0));
        myObstacles.push(new component(10,x - height - gap,height + gap));
    }
    for (i = 0; i < myObstacles.length; i += 1) {
        myObstacles[i].x += -1;
        myObstacles[i].update();
    }
    myscore.text="score: " + myGameArea.frameNo;
    myscore.update();
    myGamePiece.newPos();
    myGamePiece.update();
}

function everyinterval(n) {
    if ((myGameArea.frameNo / n) % 1 == 0) {return true;}
    return false;
}

function accelerate(n) {
    myGamePiece.gravity = n;
}
</script>
<br>
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATE</button>
<p>Use the ACCELERATE button to stay in the air</p>
<p>How long can you stay alive?</p>
</body>

为什么要给画布上色

我想给画布上色的原因是我想添加一个背景，因为这将是一个公开的非官方游戏。你可以清楚地看到流行的游戏：“Doodle Jump”（无点击诱饵）有一个不错的背景颜色。

我想在游戏中发挥创意，而不是懒惰。

总而言之，<canvas> 是最好的元素吗？如果是这样，我如何使用 CSS 更改背景颜色？

解决方法

我用你的代码做了一个 fiddle。在小提琴中，我将背景颜色更改为黄色并且可以正常工作。

您还可以通过在画布上绘制一个与画布元素具有相同宽度和高度的彩色矩形来使画布的背景颜色不同。在绘制其他任何东西之前，请务必先绘制此矩形。这是我的意思的一个例子：

 // specify color
this.context.fillStyle = "red";
// draw a rectangle with the same width and height as canvas
this.context.fillRect(0,this.canvas.width,this.canvas.height);