Javascript 图像不';t使用onLoad()中的代码在JS画布上渲染;
我试图用JS编写一个简单的游戏,主角是鱼的形象。但是,无论我尝试什么,我都无法加载图像。我查阅了一些教程,但没有一本是有效的。我读到我需要将图像代码放入Javascript 图像不';t使用onLoad()中的代码在JS画布上渲染;,javascript,html,canvas,Javascript,Html,Canvas,我试图用JS编写一个简单的游戏,主角是鱼的形象。但是,无论我尝试什么,我都无法加载图像。我查阅了一些教程,但没有一本是有效的。我读到我需要将图像代码放入onload()中所以 是片段中缺少的canvasContext方法 var-fishX=400; var fishY=300; var-fishSpeed=10; var-fishSize=80; window.onload=函数(){ var framesPerSecond=60; log(“页面加载!”); canvas=documen
onload()中代码>所以
是片段中缺少的canvasContext
方法
var-fishX=400;
var fishY=300;
var-fishSpeed=10;
var-fishSize=80;
window.onload=函数(){
var framesPerSecond=60;
log(“页面加载!”);
canvas=document.getElementById('canvas');
canvasContext=canvas.getContext('2d');
setInterval(函数img(){},1000/framesPerSecond);
canvasContext.drawImage(img,10,10);
}
var img=document.getElementById(“fish”);
document.onkeydown=checkKey;
功能检查键(e){
e=e | | window.event;
如果(e.keyCode==“38”| |“87”){
//向上箭头
鱼腥味=鱼腥味+鱼腥味速度;
}else if(e.keyCode==“40”| |“83”){
//向下箭头
鱼腥味=鱼腥味+鱼腥味速度;
}else if(e.keyCode==“37”| |“65”){
//左箭头
fishX=fishX+fishSpeed;
}else if(e.keyCode==“39”| |“68”){
//右箭头
fishX=fishX+fishSpeed;
}
}
setInterval(函数img(){},1000/framesPerSecond)
这每秒不执行任何操作60次canvasContext=canvas.getContext('2d');不定义canvasContext?是,但方法不会作为canvasContext.drawImage…
<!DOCTYPE html>
<html>
<head>
<title>Fish Game</title>
<style>
</style>
</head>
<canvas id="canvas" width="800" height="600" style="border:1px solid #000000; background: blue"></canvas>
<script>
var fishX = 400;
var fishY = 300;
var fishSpeed = 10;
var fishSize = 80;
window.onload = function() {
var framesPerSecond = 60;
console.log("Page Loaded!");
canvas = document.getElementById('canvas');
canvasContext = canvas.getContext('2d');
setInterval(function img() {
}, 1000/framesPerSecond);
drawImage(img, 10, 10);
}
var img = document.getElementById("fish");
document.onkeydown = checkKey;
function checkKey(e) {
e = e || window.event;
if (e.keyCode == '38' || '87') {
// up arrow
fishY = fishY + fishSpeed;
}
else if (e.keyCode == '40' || '83') {
// down arrow
fishY = fishY + fishSpeed;
}
else if (e.keyCode == '37' || '65') {
// left arrow
fishX = fishX + fishSpeed;
}
else if (e.keyCode == '39' || '68') {
// right arrow
fishX = fishX + fishSpeed;
}
}
</script>
<body>
<img src="fish.png" id="fish" width="80px" >
</body>
</html>