我想添加 <button>到 Canvas 上，我认为像这样添加它可能会起作用，但事实并非如此!如何添加<button>元素到 Canvas 内的innerHTML？
之前(如果这有帮助的话):
ctx = myGameArea.context;
<script>
stop : function() {
clearInterval(this.interval);
ctx.fillStyle="red";
ctx.font="80px Georgia";
ctx.fillText("You died",125,120);
//this next part doesn't work!!!
ctx.innerHTML = ("<button onclick='startGame()'>Restart</button>");
}
}
</script>
完整代码:
<!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 myObstacle;
var transitionBlock;
var blockTransition;
function startGame() {
myGamePiece = new component(40, 40, "#00ff00ff", 50, 140);
myObstacle = new component(80, 37, "#cf0000ff", 240, 0);
transitionBlock=new component(10, 80, "#f1f1f1ff", 590, 120);
blockTransition=new component(10, 80, "#f1f1f1ff", -40, 120);
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 560;
this.canvas.height = 320;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
window.addEventListener('keydown', function (e) {
myGameArea.key = e.keyCode;
})
window.addEventListener('keyup', function (e) {
myGameArea.key = false;
})
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
},
stop : function() {
clearInterval(this.interval);
ctx.fillStyle="red";
ctx.font="80px Georgia";
ctx.fillText("You died",125,120);
}
}
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.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() {
if (myGamePiece.crashWith(myObstacle)) {
myGameArea.stop();
} else {
myGamePiece.update();
myGameArea.clear();
myObstacle.update()
transitionBlock.update();
blockTransition.update();
myGamePiece.x += myGamePiece.speedX;
myGamePiece.y += myGamePiece.speedY;
}
if (myGameArea.key && myGameArea.key == 37||myGameArea.key && myGameArea.key == 65) {myGamePiece.speedX = -3; } else if (myGameArea.key && myGameArea.key == 39||myGameArea.key && myGameArea.key == 68) {myGamePiece.speedX = 3; } else if (myGameArea.key && myGameArea.key == 38||myGameArea.key && myGameArea.key == 87) {myGamePiece.speedY = -3; } else if (myGameArea.key && myGameArea.key == 40||myGameArea.key && myGameArea.key == 83) {myGamePiece.speedY = 3; } else {myGamePiece.speedX = 0; myGamePiece.speedY = 0;}
myGamePiece.update();
}
</script>
</body>
</html>
最佳答案
Canvas 内的 HTML 是不可能的，但是您可以做的是为按钮提供 Canvas 顶部的绝对位置。 这是一个小例子:
button{
position:absolute;
left:100px;
top:50px;
}<!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 myObstacle;
var transitionBlock;
var blockTransition;
function startGame() {
myGamePiece = new component(40, 40, "#00ff00ff", 50, 140);
myObstacle = new component(80, 37, "#cf0000ff", 240, 0);
transitionBlock=new component(10, 80, "#f1f1f1ff", 590, 120);
blockTransition=new component(10, 80, "#f1f1f1ff", -40, 120);
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 560;
this.canvas.height = 320;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
window.addEventListener('keydown', function (e) {
myGameArea.key = e.keyCode;
})
window.addEventListener('keyup', function (e) {
myGameArea.key = false;
})
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
},
stop : function() {
clearInterval(this.interval);
ctx.fillStyle="red";
ctx.font="80px Georgia";
ctx.fillText("You died",125,120);
}
}
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.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() {
if (myGamePiece.crashWith(myObstacle)) {
myGameArea.stop();
} else {
myGamePiece.update();
myGameArea.clear();
myObstacle.update()
transitionBlock.update();
blockTransition.update();
myGamePiece.x += myGamePiece.speedX;
myGamePiece.y += myGamePiece.speedY;
}
if (myGameArea.key && myGameArea.key == 37||myGameArea.key && myGameArea.key == 65) {myGamePiece.speedX = -3; } else if (myGameArea.key && myGameArea.key == 39||myGameArea.key && myGameArea.key == 68) {myGamePiece.speedX = 3; } else if (myGameArea.key && myGameArea.key == 38||myGameArea.key && myGameArea.key == 87) {myGamePiece.speedY = -3; } else if (myGameArea.key && myGameArea.key == 40||myGameArea.key && myGameArea.key == 83) {myGamePiece.speedY = 3; } else {myGamePiece.speedX = 0; myGamePiece.speedY = 0;}
myGamePiece.update();
}
</script>
<button>Hello I am a button floating on the top of the canvas</button>
</body>
</html>正如您在示例中看到的，按钮 float 在 Canvas 上方，但不在 Canvas 内部。
关于javascript - 如何将innerHTML添加到现有属性，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49660651/