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Danmaku is a JavaScript library to display flying comments on HTML media elements (video and audio). It can also display comments to your container in real time without timeline.
npm install danmaku// Full version
import Danmaku from 'danmaku';
// DOM engine only
import Danmaku from 'danmaku/dist/esm/danmaku.dom.js';
// Canvas engine only
import Danmaku from 'danmaku/dist/esm/danmaku.canvas.js';<div id="my-video-container" style="width:640px;height:360px;position:relative;">
<video id="my-video" src="./example.mp4" style="position:absolute;"></video>
</div>
<div id="my-audio-container" style="width:640px;height:360px;position:relative;"></div>
<audio id="my-audio" src="./example.mp3"></audio>
<script src="path/to/danmaku.min.js"></script>
<script>
var danmaku1 = new Danmaku({
container: document.getElementById('my-video-container'),
media: document.getElementById('my-video'),
comments: []
});
var danmaku2 = new Danmaku({
container: document.getElementById('my-audio-container'),
media: document.getElementById('my-audio'),
comments: []
});
</script>To display comments in real time, you need to set up server and use something like Socket.IO. Danmaku is just receiving comments data and display them to container.
Here is a simple example using with Socket.IO and Node.js.
Server:
const app = require('http').createServer(handler);
const io = require('socket.io')(app);
app.listen(80);
function handler(req, res) {
// your handler...
}
io.on('connection', socket => {
socket.on('danmaku', comment => {
socket.broadcast.emit('danmaku', comment);
});
});Client:
<div id="my-container" style="width:640px;height:360px;"></div>
<button id="send-button">Send</button>
<script src="path/to/socket.io.js"></script>
<script src="path/to/danmaku.min.js"></script>
<script>
var danmaku = new Danmaku({
container: document.getElementById('my-container')
});
var socket = io();
socket.on('danmaku', function(comment) {
danmaku.emit(comment)
});
var btn = document.getElementById('send-button');
btn.addEventListener('click', function() {
var comment = {
text: 'bla bla',
style: {
fontSize: '20px',
color: '#ffffff'
},
};
danmaku.emit(comment);
socket.emit('danmaku', comment);
});
</script>var danmaku = new Danmaku({
// REQUIRED. The stage to display comments will be appended to container.
container: document.getElementById('my-container'),
// media can be <video> or <audio> element,
// if it's not provided, Danmaku will be in live mode
media: document.getElementById('my-media'),
// Array of comment, used in media mode,
// you can find its format in `danmaku.emit` API.
comments: [],
// You can use DOM engine or canvas engine to render comments.
// 'DOM' by default in full version.
engine: 'canvas',
// You can also set speed by using `danmaku.speed` API.
speed: 144
});danmaku.emit({
text: 'example',
// 'rtl'(right to left) by default, available mode: 'ltr', 'rtl', 'top', 'bottom'.
mode: 'rtl',
// Specified in seconds, if not provided when using with media,
// it will be set to `media.currentTime`. Not required in live mode.
time: 233.3,
// When using DOM engine, Danmaku will create a <div> node for each comment,
// the style object will be set to `node.style` directly, just write with CSS rules.
// For example:
style: {
fontSize: '20px',
color: '#ffffff',
border: '1px solid #337ab7',
textShadow: '-1px -1px #000, -1px 1px #000, 1px -1px #000, 1px 1px #000'
},
// When using canvas engine, Danmaku will create a <canvas> object for each comment,
// you should pass in a CanvasRenderingContext2D object.
// For example:
style: {
font: '10px sans-serif',
textAlign: 'start',
// Note that 'bottom' is the default
textBaseline: 'bottom',
direction: 'inherit',
fillStyle: '#000',
strokeStyle: '#000',
lineWidth: 1.0,
// ...
},
// A custom render to draw comment.
// when `render` exist, `text` and `style` will be ignored.
// When using DOM engine, you should return an HTMLElement.
render: function() {
var $div = document.createElement('div');
var $img = document.createElement('img');
$img.src = '/path/to/xxx.png';
$div.appendChild($img);
return $div;
},
// When using canvas engine, you should return an HTMLCanvasElement.
render: function() {
var canvas = document.createElement('canvas');
canvas.width = 320;
canvas.height = 180;
var ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.arc(75, 75, 50, 0, 2 * Math.PI);
ctx.stroke();
return canvas;
}
});More details about CanvasRenderingContext2D.
Tips:
- With DOM engine, you may want to change line spacing by set
line-heightto each comment, a better way is setline-heightto the container. - With canvas engine, line height is
1.2by default, you can set it withstyle.font. - With canvas engine,
style.fontuses the same syntax as the CSS font specifier. However you can only usepx,%,em,remunits, I'm sure you don't need others. - There is a hitbox for each comment, which height is determined by its line height. With canvas engine, when
style.textBaselineistoporhanging, the baseline is set to top of the hitbox; when it'smiddle, baseline is middle of the hitbox; otherwise baseline is bottom of the hitbox. So if you setstyle.textBaselinetoalphabeticorhanging, the comment's head or foot may out of the hitbox and be invisible. - With canvas engine,
style.filteris supported in Chrome 52 and Firefox 49.
Do it when you resize container.
danmaku.resize();danmaku.show();If you set display: none; to the container directly when using DOM engine, you should also do danmaku.hide() otherwise the typesetting will be broken when it's showed.
danmaku.hide();Clear current stage.
danmaku.clear();There is a property duration for all comments, which means how long will a comment be shown to the stage. duration is calculated by stage.width / danmaku.speed, and danmaku.speed is a standard for all comments, because the actually speed for each comment is then calculated by (comment.width + stage.width) / duration. The default value is 144.
danmaku.speed = 144;Destroy danmaku instance and release memory.
danmaku.destroy();