移動端(手機端)頁面自適應解決方案—rem佈局
假設設計妹妹給我們的設計稿尺寸爲750 * 1340
淘寶做法(推薦做法,尤其是app內嵌頁面):
引入:頁面開頭處引入下面這段代碼,用於動態計算font-size,或者單獨放入一個文件,引入文件也可以
;
(function(win, lib) {
var doc = win.document;
var docEl = doc.documentElement;
var metaEl = doc.querySelector('meta[name="viewport"]');
var flexibleEl = doc.querySelector('meta[name="flexible"]');
var dpr = 0;
var scale = 0;
var tid;
var flexible = lib.flexible || (lib.flexible = {});
if (metaEl) {
var match = metaEl.getAttribute('content').match(/initial\-scale=([\d\.]+)/);
if (match) {
scale = parseFloat(match[1]);
dpr = parseInt(1 / scale);
}
} else if (flexibleEl) {
var content = flexibleEl.getAttribute('content');
if (content) {
var initialDpr = content.match(/initial\-dpr=([\d\.]+)/);
var 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) {
var isAndroid = win.navigator.appVersion.match(/android/gi);
var isIPhone = win.navigator.appVersion.match(/iphone/gi);
var devicePixelRatio = win.devicePixelRatio;
if (isIPhone) {
// iOS下,對於2和3的屏,用2倍的方案,其餘的用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 {
// 其他設備下,仍舊使用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 {
var wrap = doc.createElement('div');
wrap.appendChild(metaEl);
doc.write(wrap.innerHTML);
}
}
function refreshRem() {
var width = docEl.getBoundingClientRect().width;
// 適配平板
if (width / dpr > 540) {
width = 540 * dpr;
}
var 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(e) {
doc.body.style.fontSize = 12 * dpr + 'px';
}, false);
}
refreshRem();
flexible.dpr = win.dpr = dpr;
flexible.refreshRem = refreshRem;
flexible.rem2px = function(d) {
var val = parseFloat(d) * this.rem;
if (typeof d === 'string' && d.match(/rem$/)) {
val += 'px';
}
return val;
}
flexible.px2rem = function(d) {
var val = parseFloat(d) / this.rem;
if (typeof d === 'string' && d.match(/px$/)) {
val += 'rem';
}
return val;
}
})(window, window['lib'] || (window['lib'] = {}));
使用:
未引入前:
body {
width: 750px;
height: 640px;
}
引入後:
@font-size-base: 75;
body {
width: 750rem/@font-size-base;
height: 640rem/@font-size-base;
}
換算依據:
function refreshRem() {
var width = docEl.getBoundingClientRect().width;
// 適配平板
if (width / dpr > 540) {
width = 540 * dpr;
}
var rem = width / 10;
docEl.style.fontSize = rem + 'px';
flexible.rem = win.rem = rem;
}
這邊是用的less,如果您沒有用less,就需要手動計算,當然也可以轉化爲px : rem = 100 : 1。
如果想轉化爲px : rem = 100 : 1,可以修改上面的refreshRem函數:
function refreshRem() {
var width = docEl.getBoundingClientRect().width
// 適配平板
if (width / dpr > 750) {
width = 750 * dpr
}
var rem = 100 * (width / 750)
docEl.style.fontSize = rem + 'px'
flexible.rem = win.rem = rem;
}
使用:
未引入前:
body {
width: 750px;
height: 640px;
}
引入後:除以100並將px換成rem
body {
width: 7.5rem;
height: 6.4rem;
}
具體實現原理請參照:從網易與淘寶的font-size思考前端設計稿與工作流,寫的很不錯!