js使用Canvas将多张图片合并成一张的实现代码

解决方案

function mergeImgs(list) {
const imgDom = document.createElement('img')
document.body.appendChild(imgDom)

const canvas = document.createElement('canvas')
canvas.width = 500
canvas.height = 500 * list.length
const context = canvas.getContext('2d')

list.map((item, index) => {
const img = new Image()
img.src = item
// 跨域
img.crossOrigin = 'Anonymous'

img.onload = () => {
 context.drawImage(img, 0, 500 * index, 500, 500)
 const base64 = canvas.toDataURL('image/png')
 imgDom.setAttribute('src', base64)
 // console.log(baseList)
}
})
}

const urlList = ['./img/timg％20(1).jpg', './img/timg.jpg']
mergeImgs(urlList )

代码稍微优化一下，改成公共方法

/**
* 合并多张图片，返回新的图片
* @param {Array} list 图片url数组
* @param {Number} cwith 画布宽度 默认500
* @param {Number} cheight 画布高度 默认500
*/
function mergeImgs(list, cwith = 500, cheight = 500) {
return new Promise((resolve, reject) => {
const baseList = []

const canvas = document.createElement('canvas')
canvas.width = cwith
canvas.height = cheight * list.length
const context = canvas.getContext('2d')

list.map((item, index) => {
 const img = new Image()
 img.src = item
 // 跨域
 img.crossOrigin = 'Anonymous'

img.onload = () => {
 context.drawImage(img, 0, cheight * index, cwith, cheight)
 const base64 = canvas.toDataURL('image/png')
 baseList.push(base64)

if (baseList[list.length - 1]) {
  console.log(baseList)
  // 返回新的图片
  resolve(baseList[list.length - 1])
 }
 }
})
})
}

const urlList = ['./img/timg％20(1).jpg', './img/timg.jpg']
mergeImgs(urlList ).then(base64 => {
const imgDom = document.createElement('img')
imgDom.src = base64
document.body.appendChild(imgDom)
})

效果

来源：https://blog.csdn.net/weixin_45337170/article/details/115318940