JS阅读笔记
myweb3.html
<video id="video" width="400" height="300" autoplay></video>
<button id="capture-btn">拍摄图片</button>
<canvas id="canvas" width="400" height="300"></canvas>
<img id="photo" src="" alt="拍摄的图片">
<script> const video = document.getElementById('video');const captureBtn = document.getElementById('capture-btn');const canvas = document.getElementById('canvas');const photo = document.getElementById('photo');// 获取用户媒体设备权限navigator.mediaDevices.getUserMedia({ video: true }).then(stream => {video.srcObject = stream;}).catch(error => {console.error('Error accessing media devices:', error);});// 拍摄图片captureBtn.addEventListener('click', () => {canvas.getContext('2d').drawImage(video, 0, 0, canvas.width, canvas.height);const imgDataUrl = canvas.toDataURL();photo.src = imgDataUrl;});
</script>
- canvas.getContext(‘2d’)：获取二维图像
- canvas.toDataURL：save canvas image to url
- drawImage(video,x,y,width,height)：
- video的属性：video/mp4/ogg/webm，simple implement：见菜鸟教程link
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(runoob.com)</title>
</head>
<body> <div style="text-align:center"> <button onclick="playPause()">播放/暂停</button> <button onclick="makeBig()">放大</button><button onclick="makeSmall()">缩小</button><button onclick="makeNormal()">普通</button><br> <video id="video1" width="420"><source src="mov_bbb.mp4" type="video/mp4"><source src="mov_bbb.ogg" type="video/ogg">您的浏览器不支持 HTML5 video 标签。</video>
</div> <script>
var myVideo=document.getElementById("video1"); function playPause()
{ if (myVideo.paused) myVideo.play(); else myVideo.pause();
} function makeBig()
{ myVideo.width=560;
} function makeSmall()
{ myVideo.width=320;
} function makeNormal()
{ myVideo.width=420;
}
</script>
</body>
</html>
修改tomcat 默认打开页面
在web.xml中
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
try it，it’s found the former,
convey xml protocal in http connection
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
function loadXMLDoc()
{var xmlhttp=new XMLHttpRequest();xmlhttp.onreadystatechange=function(){if (xmlhttp.readyState==4 && xmlhttp.status==200){document.getElementById("myDiv").innerHTML=xmlhttp.responseText;}}xmlhttp.open("GET","/try/ajax/ajax_info.txt",true);xmlhttp.send();
}
</script>
</head>
<body><div id="myDiv"><h2>使用 AJAX 修改该文本内容</h2></div>
<button type="button" onclick="loadXMLDoc()">修改内容</button></body>
</html>
HTML 如何显示 图片
- key words：base64 code
- 为了统一为file格式，传到后端
- link maybe helpful
https://blog.csdn.net/qq_43886365/article/details/126729188
js FileReader
https://juejin.cn/post/7028590772333051918
创建隐藏元素
- 作用：实现中间数据在不同函数间的共享、导出
const downloadPhoto = () => {const link = document.createElement('a');link.download = '你的帅照.png';link.href = canvas.toDataURL();link.click();
}