图片往往在加载前端项目中占大头，如何既不损失图片质量，又提升加载速度呢？
根据显示设备pixelRatio和元素宽高来显示合适图片 略微压缩图片质量 使用webp注册全局自定义指令
Vue.directive('img-condense', {
bind: (el, binding, vnode) => {
let src = el.getAttribute('src')
let newSrc = compressImg(src, el)
el.setAttribute('src', newSrc)
}
})
获取元素宽高和显示设备pixelRatio
let compressImg = (imgUrl, el) => {
// 获取显示设备 pixelRatio
let pixelRatio = window.devicePixelRatio
let elWidth = elStyle.width * pixelRatio
let elHeight = elStyle.height * pixelRatio
let resize = '/resize'
if (elWidth) {
resize += `,w_${elWidth}`
}
if (elHeight) {
resize += `,h_${elHeight}`
}
})
判断webp
let canUseWebp = document.createElement('canvas').toDataURL('image/webp').indexOf('data:image/webp') == 0
let webp = ''
if (canUseWebp) {
webp = '/format,webp'
}
质量降低至80%
let ossParam?x-oss-process=image${resize}/auto-orient,1/quality,Q_80/bright,-1${webp}
完整版
<img v-img-condense alt="Vue logo" src="../assets/logo.png">
Vue.directive('img-condense', {
bind: (el, binding, vnode) => {
let src = el.getAttribute('src')
let newSrc = compressImg(src, el)
el.setAttribute('src', newSrc)
}
})
let compressImg = (imgUrl, el) => {
// 如果不是oss 或者已经压缩过的图片直接返回
if (imgUrl.includes('aliyuncs.com') || imgUrl.indexOf('blob') === 0 || imgUrl.includes('x-oss-process=')){
return imgUrl
}
// 获取显示设备 pixelRatio
let pixelRatio = window.devicePixelRatio
let elWidth = el.width * pixelRatio
let elHeight = el.height * pixelRatio
let resize = '/resize'
if (elWidth) {
resize += `,w_${elWidth}`
}
if (elHeight) {
resize += `,h_${elHeight}`
}
if (!elWidth && !elHeight) {
resize = ''
}
// 判断webp
let canUseWebp = document.createElement('canvas').toDataURL('image/webp').indexOf('data:image/webp') == 0
let webp = ''
if (canUseWebp) {
webp = '/format,webp'
}
return `${imgUrl}?x-oss-process=image${resize}/auto-orient,1/quality,Q_80/bright,-1${webp}`
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
