LRC 滚动器 + Vue.js
LRC 滚动展示VueJS
cnblogs @ Orcim
最 近一直在学习尤大大的这个前端框架。Vue 无疑是一款极易上手的前端框架，因为官方的文档就是中文的，十分“本土化”，中文文档会比较快最先更新。除此之外，官方网站上的 Vue 教学非常适合像我这样的新手，教学文档很详尽，在这里给 Vue 的维护团队点个赞。
自己这几天边看文档，边动手跟着练习，然后今天花了一些时间，模仿手机音乐播放器实现了一个状态栏歌词滚动器，又在此之上添加了一个切换歌词语言的功能：点击左边的音符图标即可切换到歌词翻译，点击这里，在我的 CodePen 中查看这个 demo。
demo 大概就长这样，点击左侧 icon 即可切换翻译。
思路 & 逻辑
1. 对LRC文件字符串格式，进行解析。
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[ti:]
[ar:]
[al:]
[by:]
[00:00.05]
[00:01.09]Never knowing where our own futures lie,
[00:04.39]And easily we start simplifying all our planning,
这里要注意的是lrc文件每行，开头的“时间戳”的时间格式，普遍的格式有三种：①[min:sec.ms]②[min:sec]③其他，这里只对前两种情况做了兼容，因为这两种现在见得最多；还有要注意的就是ms（毫秒）的位数可能是一位、两位、三位。
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/**
* @method lrcHandler 返回指定 type 的歌词 json 对象
* @param { String } type lrc（原） 或 tlrc（译）
* @param { Object } lns_obj info&main
*/
function lrcHandler (type) {
var refer = {
"lrc": "lyric",
"tlrc": "translateLyric"
};
var lns_obj = {
"lrc-info": [],
"lrc-main": []
};
var lns = lrc[refer[type]].split("\n");
// lrc 文件字符串的每行所组成的 JSON
for(var i=0, len=lns.length; i<len; i++){
var m = lns[i];
var info = m.replace(/\[(.*)\](.*)/, "$1");
var lys = m.replace(/\[(.*)\](.*)/, "$2");
var mth = info.match(/([0-9]+)\:([0-9]+)\.([0-9]+)/);
var pad_0 = function(num_str){return (num_str + (new Array(4-num_str.length)).join("0"))};
if(mth){
var milis = mth[1]*1*60*1000 + mth[2]*1*1000 + pad_0(mth[3])*1;
var ln = {"time": milis, "lyric": lys};
lns_obj["lrc-main"].push(ln)
}else{
var inf = {};
inf[info.replace(/(.*)\:(.*)/, "$1")] = info.replace(/(.*)\:(.*)/, "$2");
lns_obj["lrc-info"].push(inf);
};
};
return lns_obj;
};
2. 对 ***.lrc 文件利用如上方法进行解析后，返回一个对象，对象包括歌词的附属信息（lrc-info）：by、ti、ar等头信息，歌词的主要部分（lrc-main）数组类型，其每项包含时间戳转换的毫秒总数，以及对应时间戳点（time）的歌词字符串（lyric）。之后要做的就是批量注册定时器，在 Vue 生命周期函数的 created 中注册这些定时器：
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"created": function(){
for(var j=0, len=$lrc["lrc-main"].length; j<len; j++){
var ti = that.displayLrc["lrc-main"][j]["time"];
var c = 0;
that.timers[j] = setTimeout(function(){
that.scroll_fn();
clearTimeout(that.transition_timer);
that.transition_timer = setTimeout(function(){
$lrc["lrc-main"][c-1] && that.setLnLrc(c-1, function(){
that.recover_fn();
console.log(that.displayLrc["lrc-main"][c-1]["time"], that.displayLrc["lrc-main"][c-1]["lyric"]);
});
clearTimeout(that.transition_timer);
}, 200)
nowLine = c++;
clearTimeout(that.timers[j]);
}, ti);
}
}
部分代码逻辑如上，完整代码可见文章开头处的 CodePen 链接。
3. 注册和创建 Vue 组件，这个部分就不多说了，直接贴代码，看看吧。
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<html>
<head>
<meta charset="utf-8">
<link rel="stylesheet" href="main.css">
<script src="../../vuejs_2.6.10.js"></script>
</head>
<body>
<div id="main">
<lrc-scroller
:offset-class="sim"
:lrc_top="tlrc"
:lrc_bt="blrc"
:swl="switchLang"
></lrc-scroller>
</div>
</body>
<script src="498286345" type="text/javascript"></script>
<!-- 引入 lrc 文件，为基于网易云音乐的歌词文件 @param { JSON } lrc -->
<script src="main.js" type="text/javascript"></script>
</html>
核心逻辑代码 main.js 如下：
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113
Vue.component("lrc-scroller", {
"template":
"<div class='container'>\
<div class='box'>\
<div class='box-outer' v-bind:class='offsetClass'>\
<div class='box1'><span>{{ lrc_top }}</span></div>\
<div class='box2'><span>{{ lrc_bt }}</span></div>\
</div>\
<div class='switchBtn' title='switch language' v-on:click='swl'></div>\
</div>\
</div>",
"props":["offsetClass", "lrc_top", "lrc_bt", "swl"]
});
var that = {};
var $lrc = lrcHandler("lrc");
var $tlrc = lrcHandler("tlrc");
var nowLine = 0;
var main = new Vue({
"el": "#main",
"data": {
"sim": {
"offset": false,
"transition": true
},
"tlrc": "",
"blrc": "",
"timers": [],
"transition_timer": null,
"displayLrc": window["$lrc"]
},
"methods": {
setLnLrc: function(line, fn){
that["tlrc"] = that.displayLrc["lrc-main"][line]["lyric"];
$lrc["lrc-main"][line+1] && (that["blrc"] = that.displayLrc["lrc-main"][line+1]["lyric"]);
fn && fn();
},
recover_fn: function(){
that.sim["transition-none"] = true;
that.sim["transition"] = false;
that.sim["offset"] = false;
},
scroll_fn: function(){
that.sim["offset"] = true;
that.sim["transition"] = true;
that.sim["transition-none"] = false;
},
switchLang: function(){
that.displayLrc = (that.displayLrc === window["$tlrc"] ? window["$lrc"] : window["$tlrc"]);
}
},
"watch": {
"displayLrc": function(){
that.setLnLrc(nowLine);
}
},
"beforeCreate": function(){
that = this;
},
"created": function(){
for(var j=0, len=$lrc["lrc-main"].length; j<len; j++){
var ti = that.displayLrc["lrc-main"][j]["time"];
var c = 0;
that.timers[j] = setTimeout(function(){
that.scroll_fn();
clearTimeout(that.transition_timer);
that.transition_timer = setTimeout(function(){
$lrc["lrc-main"][c-1] && that.setLnLrc(c-1, function(){
that.recover_fn();
console.log(that.displayLrc["lrc-main"][c-1]["time"], that.displayLrc["lrc-main"][c-1]["lyric"]);
});
clearTimeout(that.transition_timer);
}, 200)
nowLine = c++;
clearTimeout(that.timers[j]);
}, ti);
}
}
});
/**
* @method lrcHandler 返回指定 type 的歌词 json 对象
* @param { String } type lrc（原） 或 tlrc（译）
* @param { Object } lns_obj info&main
*/
function lrcHandler (type) {
var refer = {
"lrc": "lyric",
"tlrc": "translateLyric"
};
var lns_obj = {
"lrc-info": [],
"lrc-main": []
};
var lns = lrc[refer[type]].split("\n");
// lrc 文件字符串的每行所组成的 JSON
for(var i=0, len=lns.length; i<len; i++){
var m = lns[i];
var info = m.replace(/\[(.*)\](.*)/, "$1");
var lys = m.replace(/\[(.*)\](.*)/, "$2");
var mth = info.match(/([0-9]+)\:([0-9]+)\.([0-9]+)/);
var pad_0 = function(num_str){return (num_str + (new Array(4-num_str.length)).join("0"))};
if(mth){
var milis = mth[1]*1*60*1000 + mth[2]*1*1000 + pad_0(mth[3])*1;
var ln = {"time": milis, "lyric": lys};
lns_obj["lrc-main"].push(ln)
}else{
var inf = {};
inf[info.replace(/(.*)\:(.*)/, "$1")] = info.replace(/(.*)\:(.*)/, "$2");
lns_obj["lrc-info"].push(inf);
};
};
return lns_obj;
};
console.log(lrcHandler("tlrc"));
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body{padding: 0; margin: 0; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif; letter-spacing: .5px; font-size: 18px;}
.container{position: relative; width: 100%; height: 36px; background-color: #eee;}
.box{height: 32px; width: calc(100% - 36px); position: absolute; top: 0; left: 0; padding: 2px 0 2px 36px; overflow: hidden;}
.box::before{display: block; content: ""; width: 36px; height: 36px; position: absolute; top: 0; left: 0; background: url(data:image/svg+xml;base64,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) no-repeat center; background-size: 24px;}
.switchBtn{position: absolute; top: 0; left: 0; width: 36px; height: 36px; cursor: pointer;}
.switchBtn::before{display: block; content: ""; position: absolute; left: 0; top: 0; width: 100%; height: 100%; background-color: grey; border-radius: 50%; opacity: 0; transform: scale(0); transition: all 200ms linear}
.switchBtn:hover::before{transform: scale(1.5); opacity: .25;}
.box-outer{height: 64px; display: felx; flex-direction: column; transition: all 200ms;}
.box-outer.offset{transform: translateY(-32px);}
.box-outer.transition{transition: transform 200ms ease-in-out;}
.box-outer.transition-none{transition-duration: 0ms;}
.box1{height: 32px; display: flex; justify-content: flex-start; align-items: center; background-color: none; white-space: nowrap;}
.box2{height: 32px; display: flex; justify-content: flex-start; align-items: center; background-color: none; white-space: nowrap;}
结束语
Vue确实方便学习和使用，如果接触过微信小程序的话，基本上看看官网上的文档几乎就可以直接拿来用了，框架设计十分友好和人性化，除此外 Vue 式的组件化和模块化让代码变得简洁和明了易于维护，数据绑定等降低 DOM 渲染成本也恰到好处，是个很不错的前端框架。
其他
VueJS 版本：2.6.10，2019/07
更新
今天又花了一些时间完善了这个歌词滚动器，点击这里来查看demo，在我的CodePen中查看源代码。主要是修正了一些错误，适配了所有格式的LRC文件，添加了窄屏下歌词可以左右以较为合理的速度滚动的功能，优化了细节。2019/07/17
