说说vue-cli中使用flexible和px2rem-loader

摘要：下载或在项目中引入一般情况在中引入设置标签视情况而定安装或在中配置，在项目文件中找到，将添加到中，，下的根据设计稿而定具体如下编译新加由于设计稿是添加到里面省略项目中使用假设设计稿和分别是，具体代码

1.下载lib-flexible

npm i lib-flexible --save
或
yarn add lib-flexible

2.在项目中引入lib-flexible 一般情况在(main.js中引入lib-flexible)

import "lib-flexible/flexible"

3.设置meta标签(视情况而定)

4.安装px2rem-loader

npm install px2rem-loader   --save
或
yarn add px2rem-loader

5.在webpack中配置px2rem-loader

1，在项目build文件中找到util.js，将px2rem-loader添加到cssLoaders中，
2，px2rem-loader 下的 remUnit 根据设计稿而定
具体如下：

exports.cssLoaders = function (options) {
  options = options || {}

  const cssLoader = {
    loader: "css-loader",
    options: {
      minimize: process.env.NODE_ENV === "production",
      sourceMap: options.sourceMap
    }
  }
  //rem编译（新加px2）
  const px2remLoader = {
    loader: "px2rem-loader",
    options: {
      remUnit: 75 // 由于设计稿是750
    }
  }

  function generateLoaders (loader, loaderOptions) {
    var loaders = [cssLoader,px2remLoader]//添加到loader里面
    省略.....
  }
}

6.项目中使用

假设设计稿width和font-size分别是200px，50px
具体代码：(按照设计稿写即可)

.demo{
    width: 200px;
    font-size: 50px;
}

7.多带带使用flexible可直接添加一个rem.js文件，具体如下：

1，配合less，sass和stylus来做px转换rem
2，具体可参看css编译

/*
** 移动端自适应方案  FROM 手淘
*/
export const setViewport = (()=>{//此处是多带带使用
    const win = window
    const lib = window.lib || (window.lib = {})
//;(function(win, lib) {//此处是直接使用
    let doc = win.document;
    let docEl = doc.documentElement;
    let metaEl = doc.querySelector("meta[name="viewport"]");
    let flexibleEl = doc.querySelector("meta[name="flexible"]");
    let dpr = 0;
    let scale = 0;
    let tid;
    let flexible = lib.flexible || (lib.flexible = {});
    
    if (metaEl) {
        //console.warn("将根据已有的meta标签来设置缩放比例");
        let match = metaEl.getAttribute("content").match(/initial-scale=([d.]+)/);
        if (match) {
            scale = parseFloat(match[1]);
            dpr = parseInt(1 / scale);
        }
    } else if (flexibleEl) {
        let content = flexibleEl.getAttribute("content");
        if (content) {
            let initialDpr = content.match(/initial-dpr=([d.]+)/);
            let maximumDpr = content.match(/maximum-dpr=([d.]+)/);
            if (initialDpr) {
                dpr = parseFloat(initialDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));
            }
            if (maximumDpr) {
                dpr = parseFloat(maximumDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));
            }
        }
    }

    if (!dpr && !scale) {
        //let isAndroid = win.navigator.appVersion.match(/android/gi);
        let isIPhone = win.navigator.appVersion.match(/iphone/gi);
        let devicePixelRatio = win.devicePixelRatio;
        if (isIPhone) {
            // iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
            if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {                
                dpr = 3;
            } else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)){
                dpr = 2;
            } else {
                dpr = 1;
            }
        } else {
            // 其他设备下，仍旧使用1倍的方案
            dpr = 1;
        }
        scale = 1 / dpr;
    }

    docEl.setAttribute("data-dpr", dpr);
    if (!metaEl) {
        metaEl = doc.createElement("meta");
        metaEl.setAttribute("name", "viewport");
        metaEl.setAttribute("content", "initial-scale=" + scale + ", maximum-scale=" + scale + ", minimum-scale=" + scale + ", user-scalable=no");
        if (docEl.firstElementChild) {
            docEl.firstElementChild.appendChild(metaEl);
        } else {
            let wrap = doc.createElement("div");
            wrap.appendChild(metaEl);
            doc.write(wrap.innerHTML);
        }
    }

    function refreshRem(){
        let width = docEl.getBoundingClientRect().width;
        if (width / dpr > 540) {
            width = 540 * dpr;
        }
        let rem = width / 10;
        docEl.style.fontSize = rem + "px";
        flexible.rem = win.rem = rem;
    }

    win.addEventListener("resize", function() {
        clearTimeout(tid);
        tid = setTimeout(refreshRem, 300);
    }, false);
    win.addEventListener("pageshow", function(e) {
        if (e.persisted) {
            clearTimeout(tid);
            tid = setTimeout(refreshRem, 300);
        }
    }, false);

    if (doc.readyState === "complete") {
        doc.body.style.fontSize = 12 * dpr + "px";
    } else {
        doc.addEventListener("DOMContentLoaded", function() {
            doc.body.style.fontSize = 12 * dpr + "px";
        }, false);
    }

    refreshRem();

    flexible.dpr = win.dpr = dpr;
    flexible.refreshRem = refreshRem;
    flexible.rem2px = function(d) {
        let val = parseFloat(d) * this.rem;
        if (typeof d === "string" && d.match(/rem$/)) {
            val += "px";
        }
        return val;
    };
    flexible.px2rem = function(d) {
        let val = parseFloat(d) / this.rem;
        if (typeof d === "string" && d.match(/px$/)) {
            val += "rem";
        }
        return val;
    };

});
//})(window, window.lib || (window.lib = {}));