网络字体原理

css 3 的兴起，从而让 前端这个逐渐火了起来，越来越多的人参与研究当中。由 Font-Awesome、ionicons 为代表的网络字体在 css 上火了起来。

以 Font-Awesome 为例：

@font-face {
  font-family: 'FontAwesome';
  src: url('../fonts/fontawesome-webfont.eot?v=4.4.0');
  src: url('../fonts/fontawesome-webfont.eot?#iefix&v=4.4.0') format('embedded-opentype'), url('../fonts/fontawesome-webfont.woff2?v=4.4.0') format('woff2'), url('../fonts/fontawesome-webfont.woff?v=4.4.0') format('woff'), url('../fonts/fontawesome-webfont.ttf?v=4.4.0') format('truetype'), url('../fonts/fontawesome-webfont.svg?v=4.4.0#fontawesomeregular') format('svg');
  font-weight: normal;
  font-style: normal;
}
.fa {
  display: inline-block;
  font: normal normal normal 14px/1 FontAwesome;
  font-size: inherit;
  text-rendering: auto;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
.fa-flag:before {
  content: "f024";
}

通过在页面上 <i class="fa fa-flag"></i>  就可以得到  这么个图标，感觉是不是很神奇，下面看以下里面的原理。

找到 fontawesome-webfont.ttf  这个文件，用 FontLab Studio 打开

原理原来这么简单。

一、TureTpe(.ttf)格式：

.ttf字体是Windows和Mac的最常见的字体，是一种RAW格式，因此他不为网站优化,支持这种字体的浏览器有【IE9+,Firefox3.5+,Chrome4+,Safari3+,Opera10+,iOS Mobile Safari4.2+】；

二、OpenType(.otf)格式：

.otf字体被认为是一种原始的字体格式，其内置在TureType的基础上，所以也提供了更多的功能,支持这种字体的浏览器有【Firefox3.5+,Chrome4.0+,Safari3.1+,Opera10.0+,iOS Mobile Safari4.2+】；

三、Web Open Font Format(.woff)格式：

.woff字体是Web字体中最佳格式，他是一个开放的TrueType/OpenType的压缩版本，同时也支持元数据包的分离,支持这种字体的浏览器有【IE9+,Firefox3.5+,Chrome6+,Safari3.6+,Opera11.1+】；

四、Embedded Open Type(.eot)格式：

.eot字体是IE专用字体，可以从TrueType创建此格式字体,支持这种字体的浏览器有【IE4+】；

五、SVG(.svg)格式：

.svg字体是基于SVG字体渲染的一种格式,支持这种字体的浏览器有【Chrome4+,Safari3.1+,Opera10.0+,iOS Mobile Safari3.2+】。

下面再看看 weui 里面的图标是怎么实现的 

@font-face {
    font-weight: 400;
    font-style: normal;
    font-family: weui;
    src: 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) format('truetype');
}

除了 src 其他都一样， 想要看这个字体文件，首先需要 下载下来，怎么下载呢？其实很简单

把这个请求的内容到浏览器请求以下，会自动下载一个 不带任何扩展名的文件， 通过它的 src 最后的 format 格式可以知道是 ttf 格式，我把它下载下来后保存为 1.ttf，然后用 FontLab Studio 打开