canvas绘制视频封面--摘抄

一、需求：上传视频，同时截取视频某一帧作为视频的封面。二、实现思路：利用canvas绘制图像的功能，绘制图像某一帧，这里绘制了第一帧，很简单就实现了。三、代码：

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>capture screen</title>
    <style type="text/css">
        video,#container{ 300px;height: 200px;}
        #container>img{ 100%;}
    </style>
</head>
<body>
    <video id="video" controls="controls">
        <source src="video/video_test.mp4">
    </video>
    <div id="container"></div>
    <script type="text/javascript">
        (function() {
            var video, container;
            var scale = 0.8;
            var initialize = function() {
                container = document.getElementById("container");
                video = document.getElementById("video");
                video.addEventListener('loadeddata', captureImage);
            };
            var captureImage = function() {
                var canvas = document.createElement("canvas");
                canvas.width = video.videoWidth * scale;
                canvas.height = video.videoHeight * scale;
            canvas.getContext('2d').drawImage(video, 0, 0, canvas.width, canvas.height);
                var img = document.createElement("img");
                img.src = canvas.toDataURL("image/png");//转换成base64图片，地址拿出来就可以直接使用
                container.appendChild(img);
            };
            initialize();
        })();
    </script>
</body>
</html>

Canvas