我尝试构建一个javascript代码,在画布上绘制图像,但我不知道哪里出错了.那是我的代码:
<body>
<canvas id = "my_canvas"></canvas>
<script>
function setup(){
var canvas = document.getElementById('my_canvas');
var ctx = canvas.getContext('2d');
canvas.width = 800;
canvas.height = 600;
var image = new Image();
image.src = 'a.png';
ctx.drawImage(image,5,5);
};
window.onload = setup;
setup();
</script>
问题是,如果我setup();在最后放一行代码然后图像正确绘制,我不知道为什么.
谢谢.