实现逻辑是这样:
1,添加事件监听,比如说,鼠标按下 做什么,滑动 做什么,d起做什么.一般鼠标事件都是判断d起的位置
2,判断有效坐标,在事件中判断坐标位置是否在图片位置,也就是图片在canvas的位置.
ex:
//some code...
canvas.width=400
canvas.height=400
var context2d = canvas.getContext("2d")
var img =new Image()
img.src="xxx/xxx.png"
img.onload=function(){
context2d.drawImage(img,X,Y,WIDTH,HEIGTH)
//X=0,Y=0,W=50,H=50
canvas.addEventListener("mouseup", keyUp, false)
}
function keyUp(evt){
Event_UpX = evt.offsetX
Event_UpY = evt.offsetY
if(Event_UpX>=绘制坐标X&&Event_UpX<=图片宽度){
if(Event_UpY>=绘制坐标Y&&Event_UpY<=图片高度){
//do something
}
}
}
<!DOCTYPE html><html>
<head>
<meta charset="GB2312">
<title></title>
<script type="text/javascript">
window.onload=function()
{
var aDiv = document.getElementsByTagName('div')
for (var i=0 i<aDiv.length i++)
{
aDiv[i].onmouseover=function()
{
alert(this.innerHTML)//d出鼠标滑过区域
}
}
}
</script>
</head>
<body>
<div>111</div>
<div>222</div>
<div>333</div>
</body>
</html>
暴力方法：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<input type="text" id='input' />
<div id='main' style="min-height: 100pxword-break: break-all"></div>
<hr />
<button>断开监听</button>
<script>
document.addEventListener('DOMContentLoaded', () =>{
const input = document.querySelector('input')
const main = document.querySelector('#main')
const button = document.querySelector('button')
input.addEventListener('input', e =>{
main.innerHTML += e.target.value
})
const mutationObs = new MutationObserver(mutations =>{
for (const mutation of mutations) {
if (mutation.type === 'childList') {
console.log('你改变了main里的内容')
}
}
})
mutationObs.observe(main, { childList: true })
button.addEventListener('click', () =>{
mutationObs.disconnect()
})
})
</script>
</body>
</html>
参考
欢迎分享，转载请注明来源：内存溢出
微信扫一扫
支付宝扫一扫
评论列表（0条）