我正在尝试在画布上绘图,但我越向右,我的绘图就越偏移。
有人知道为什么吗?
我在下面包含了相关代码:
CSS
html,body {
width:100%;
height:100%;
background:rgba(0,0,0,.2);
}
#container {
position:relative;
width:700px;
height:450px;
background:#fff;
overflow:hidden;
}
* {
-webkit-user-select: none;
}
canvas {
position: absolute;
top: 0;
left: 0;
background: #ccc;
width: 500px;
height: 200px;
}
HTML
<div id='adContainer'>
<canvas></canvas>
</div>
Javascript
var ctx;
var can = $('canvas');
$(document).ready(function() {
ctx = can[0].getContext('2d');
ctx.strokeStyle = "rgba(255,0,0,1)";
ctx.lineWidth = 5;
ctx.lineCap = 'round';
can.on("touchstart", function(event) {
event.preventDefault();
var e = event.originalEvent;
if(e.touches.length == 1) {
var posX = e.touches[0].pageX;
var posY = e.touches[0].pageY;
ctx.moveTo(posX, posY);
}
});
can.on("touchmove", function(event) {
event.preventDefault();
var e = event.originalEvent;
if(e.touches.length == 1) {
var posX = e.touches[0].pageX;
var posY = e.touches[0].pageY;
ctx.lineTo(posX, posY);
ctx.stroke();
}
});
});
演示:http: //jsfiddle.net/8Wtf8/