移动端 web
开发遇到的问题:UI稿上要求设置边框为1px
,css设置border: 1px solid #eee;
以后,UI又说边框太粗了。css
这是由于devicePixelRatio
特性致使。css设置的1px
是css像素,而UI稿上指的是设备像素,它们之间存在一个比例关系,即,devicePixelRatio
。iPhone的devicePixelRatio == 2
,而border-width: 1px
描述的是css像素,因此,border
被放大到物理像素2px
显示,在iPhone
上就显得较粗。html
device pixel / physical pixel (设置像素、物理像素、硬件像素): 显示屏中最小的物理单元。 移动设备出厂时,不一样设备自带的不一样像素,每一个像素点根据操做系统的指示设置本身的颜色和亮度。web
density-independent pixel(DIP)(设备无关像素或密度无关像素):能够认为是计算机坐标系统中得一个点,这个点表明一个能够由程序使用的虚拟像素,而后由相关系统转换为物理像素。segmentfault
CSS pixel (css 像素):浏览器使用的抽象单元,用于精确地,一致地在网页上绘制内容。 一般,CSS 像素被称为与设备无关的像素(DIP)。浏览器
devicePixelRatio(设备像素比):物理像素和逻辑像素的比例关系,一般能够经过js
的 window.devicePixelRatio
来获取。app
devicePixelRatio能够用来区分视网膜设备仍是非视网膜设备。url
devicePixelRatio
值为 1 的屏幕称之为标准屏(也称,非视网膜屏);目前,大部分移动设备都是高清屏(也称,视网膜屏),即 devicePixelRatio
值大于 1 的屏幕,对于苹果设备来讲,咱们常常听到 Retina
屏(视网膜屏),其中 iPhone6/6s/7
的 devicePixelRatio
值为 2;而 iPhone6 plus/6s plus/7 plus
的 devicePixelRatio
值为 3。spa
优势:实现简单操作系统
缺点:retina
屏的浏览器可能不认识0.5px
的边框,将会把它解释成0px
,没有边框。包括 iOS 7
和以前版本,OS X Mavericks
及之前版本,还有 Android
设备。scala
//判断手机是否支持0.5px if (window.devicePixelRatio && devicePixelRatio >= 2) { var divElem = document.createElement('div') divElem.style.border = '.5px solid transparent' document.body.appendChild(divElem) if (divElem.offsetHeight == 1) { document.querySelector('html').classList.add('hairlines'); } document.body.removeChild(divElem); } //在html中,加上此样式 .hairlines { *:not(table tr td), *:not(.noHairlines) { border-width: 0.5px!important; } }
优势:能够设置圆角
缺点:颜色很差控制
.border-1px { box-shadow:0 1px 1px -1px rgba(0, 0, 0, 0.5); }
使用的图片是2px
高,上部的1px
颜色为透明,下部的1px
使用视觉规定的border
的颜色。
优势:
缺点:修改颜色麻烦,须要替换图片;圆角须要特殊处理,而且边缘会模糊。
.border-image-1px { border-width: 1px 0px; border-image: url("data:image/png;base64,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") 2 0 stretch; }
缺点:不能实现圆角。
.border-1px { background-image:linear-gradient(180deg, red, red 50%, transparent 50%), linear-gradient(270deg, red, red 50%, transparent 50%), linear-gradient(0deg, red, red 50%, transparent 50%), linear-gradient(90deg, red, red 50%, transparent 50%); background-size: 100% 1px,1px 100% ,100% 1px, 1px 100%; background-repeat: no-repeat; background-position: top, right top, bottom, left top; padding: 10px; }
/*height:1px,而后根据媒体查询设置transform: scaleY(0.5)*/ .border-1px { height:1px; background:#000; transform: scaleY(0.5); transform-origin:0 0; overflow: hidden; }
/*伪类::after和::befor,设置border-bottom:1px solid #000,而后在缩放transform: scaleY(0.5),能够实现两根边线的需求*/ .border-1px:after, .border-1px::after { content:''; width:100%; border-bottom:1px solid #000; transform: scaleY(0.5); }
/*伪类::after设置border:1px solid #000; width:200%; height:200%,而后再缩放scale(0.5); 优势能够实现圆角,缺点是按钮添加active比较麻烦。*/ .border-1px:after, .border-1px::after { content: ''; width: 200%; height: 200%; position: absolute; top: 0; left: 0; border: 1px solid #bfbfbf; border-radius: 4px; transform: scale(0.5,0.5); transform-origin: top left; }
优势:能够自适应已知的各种手机屏幕,且不存在其它方法存在的变颜色困难、圆角阴影失效问题。
缺点:样式必须用rem为单位
var viewport = document.querySelector("meta[name=viewport]"); //下面是根据设备像素设置viewport if (window.devicePixelRatio == 1) { viewport.setAttribute('content', 'width=device-width,initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no'); } if (window.devicePixelRatio == 2) { viewport.setAttribute('content', 'width=device-width,initial-scale=0.5, maximum-scale=0.5, minimum-scale=0.5, user-scalable=no'); } if (window.devicePixelRatio == 3) { viewport.setAttribute('content', 'width=device-width,initial-scale=0.3333333333333333, maximum-scale=0.3333333333333333, minimum-scale=0.3333333333333333, user-scalable=no'); } var docEl = document.documentElement; var fontsize = 10 * (docEl.clientWidth / 320) + 'px'; docEl.style.fontSize = fontsize;
缘由: 未肯定。可能与元素的高度、行高及像素的小点有关
解决方法:
position: absolute; top:50%
,能够尝试把改为 top: 51%
。display: inline-block
,改用display: block
。0.5px
改成0.7px
。line-height: normal
)。