danmaku
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Display danmaku (flying comments) on HTML5 video.
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# Danmaku
[](https://github.com/weizhenye/Danmaku/actions)
[](https://codecov.io/gh/weizhenye/Danmaku)
[](https://github.com/weizhenye/danmaku/blob/master/LICENSE)
[](https://bundlephobia.com/result?p=danmaku)
<span>・</span>
<a href="https://danmaku.js.org/">Online Demo</a>
<span>・</span>
<a href="https://github.com/weizhenye/Danmaku/wiki/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3">中文文档</a>
<span>・</span>
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.
## Installation
[](https://www.npmjs.com/package/danmaku)
[](https://www.jsdelivr.com/package/npm/danmaku)
[](https://unpkg.com/danmaku/)
```bash
npm install danmaku
```
```js
// 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';
```
## Usage
### Media mode
```html
<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>
```
### Live mode
To display comments in real time, you need to set up server and use something like [Socket.IO](http://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:
```js
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:
```html
<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>
```
## API
### Initialization
```js
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
});
```
### Emit a comment
```js
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](https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D).
Tips:
* With DOM engine, you may want to change line spacing by set `line-height` to each comment, a better way is set `line-height` to the container.
* With canvas engine, line height is `1.2` by default, you can set it with `style.font`.
* With canvas engine, `style.font` uses the same syntax as the [CSS font](https://developer.mozilla.org/en-US/docs/Web/CSS/font) specifier. However you can only use `px`, `%`, `em`, `rem` units, 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.textBaseline` is `top` or `hanging`, the baseline is set to top of the hitbox; when it's `middle`, baseline is middle of the hitbox; otherwise baseline is bottom of the hitbox. So if you set `style.textBaseline` to `alphabetic` or `hanging`, the comment's head or foot may out of the hitbox and be invisible.
* With canvas engine, [`style.filter`](https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/filter) is supported in Chrome 52 and Firefox 49.
### Resize
Do it when you resize container.
```js
danmaku.resize();
```
### Show
```js
danmaku.show();
```
### Hide
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.
```js
danmaku.hide();
```
### Clear
Clear current stage.
```js
danmaku.clear();
```
### Speed
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.
```js
danmaku.speed = 144;
```
### Destroy
Destroy `danmaku` instance and release memory.
```js
danmaku.destroy();
```