@芥末的糖------一像素的实现

1.styl里一像素线的实现

border($border-width = 1px, $border-color = #ccc, $border-style = solid, $radius = 0)
  // 为边框位置提供定位参考
  position: relative;

  if $border-width == null
    $border-width: 0;

  border-radius: $radius;

  &::after
    // 用以解决边框layer遮盖内容
    pointer-events: none;
    position: absolute;
    z-index: 999;
    top: 0;
    left: 0;
    // fix当元素宽度出现小数时，边框可能显示不全的问题
    // overflow: hidden;
    content: "\0020";
    border-color: $border-color;
    border-style: $border-style;
    border-width: $border-width;
    
    // 适配dpr进行缩放
    @media (max--moz-device-pixel-ratio: 1.49), (-webkit-max-device-pixel-ratio: 1.49), (max-device-pixel-ratio: 1.49), (max-resolution: 143dpi), (max-resolution: 1.49dppx)
      width: 100%;
      height: 100%;
      if $radius != null {
        border-radius: $radius;
      }
    
    @media (min--moz-device-pixel-ratio: 1.5) and (max--moz-device-pixel-ratio: 2.49), (-webkit-min-device-pixel-ratio: 1.5) and (-webkit-max-device-pixel-ratio: 2.49),(min-device-pixel-ratio: 1.5) and (max-device-pixel-ratio: 2.49),(min-resolution: 144dpi) and (max-resolution: 239dpi),(min-resolution: 1.5dppx) and (max-resolution: 2.49dppx)
      width: 200%;
      height: 200%;
      transform: scale(.5)
      if $radius != null {
        border-radius: $radius * 2;
      }
    
    @media (min--moz-device-pixel-ratio: 2.5), (-webkit-min-device-pixel-ratio: 2.5),(min-device-pixel-ratio: 2.5), (min-resolution: 240dpi),(min-resolution: 2.5dppx)
      width: 300%;
      height: 300%;
      transform: scale(.33333)
      if $radius != null {
        border-radius: $radius * 3;
      }

    transform-origin: 0 0;

2.styled-component

import styled from 'styled-components'

const border = ({
    component=null, 
    width='1px',
    style='solid',
    color='#ccc',
    radius=0
}) => {
  return styled(component) `
    position: relative;
    border-width: ${ width };
    border-radius: ${ radius + 'px' };
    &::after {
      pointer-events: none;
      position: absolute;
      z-index: 999;
      top: 0;
      left: 0;
      content: "";
      border-color: ${ color };
      border-style: ${ style };
      border-width: ${ width };

      @media
        (max--moz-device-pixel-ratio: 1.49), 
        (-webkit-max-device-pixel-ratio: 1.49), 
        (max-device-pixel-ratio: 1.49), 
        (max-resolution: 143dpi), 
        (max-resolution: 1.49dppx) {
          width: 100%;
          height: 100%;
          border-radius: ${ radius + 'px' };
        };
      
      @media 
        (min--moz-device-pixel-ratio: 1.5) and (max--moz-device-pixel-ratio: 2.49), 
        (-webkit-min-device-pixel-ratio: 1.5) and (-webkit-max-device-pixel-ratio: 2.49),
        (min-device-pixel-ratio: 1.5) and (max-device-pixel-ratio: 2.49),
        (min-resolution: 144dpi) and (max-resolution: 239dpi),
        (min-resolution: 1.5dppx) and (max-resolution: 2.49dppx) {
          width: 200%;
          height: 200%;
          transform: scale(.5);
          border-radius: ${ radius * 2 + 'px'};
        };
      
      @media 
        (min--moz-device-pixel-ratio: 2.5), 
        (-webkit-min-device-pixel-ratio: 2.5),
        (min-device-pixel-ratio: 2.5), 
        (min-resolution: 240dpi),
        (min-resolution: 2.5dppx) {
          width: 300%;
          height: 300%;
          transform: scale(.33333);
          border-radius: ${ radius * 3 + 'px' }
        };

        transform-origin: 0 0;
    };
  `
}

export default border