NodeJS 获取拼图验证码滑动距离

import jimp from 'jimp'
import axios from 'axios'

interface TGetDistanceOptions {
  catpchaUrl: string
  catpchaWitdh: number
  catpchaHeight: number
  slideTop: number
  slideHeight: number
}

async function getDistance({
  catpchaUrl,
  catpchaWitdh,
  catpchaHeight,
  slideTop,
  slideHeight,
}: TGetDistanceOptions) {
  const bgImage = await axios
    .get(catpchaUrl, { responseType: 'arraybuffer' })
    .then(res => Buffer.from(res.data, 'binary'))

  const image = await jimp.read(bgImage)

  image.grayscale() // 灰度去颜色
  image.contrast(1) // 对比值拉高
  // image.write('./catpcha.jpg') // 生成处理后的图片（查看该图片你就知道原理是啥了）
  image.resize(catpchaWitdh, catpchaHeight)

  const { width, height } = image.bitmap

  const xList: number[] = []
  image.scan(0, 0, width, height, (x, y) => {
    if (y >= slideTop && y <= slideTop + slideHeight) {
      const color = image.getPixelColor(x, y)
      if (color === 255) { // 黑色
        const _color = image.getPixelColor(x - 2, y)
        if (_color === 4294967295) xList.push(x) // 白色
      }
    }
  })

  return Number(getRepeatMost(xList))
}

function getRepeatMost(arr: number[]) {
  const count: Record<string, number> = {}
  for (let i = 0; i < arr.length; i++) {
    if (count[arr[i]]) {
      count[arr[i]]++
    } else {
      count[arr[i]] = 1
    }
  }

  let max = 0
  let result: string | undefined
  for (let num in count) {
    if (count[num] > max) {
      max = count[num]
      result = num
    }
  }

  return result
}

getDistance({
  catpchaUrl: 'https://p9-catpcha.byteimg.com/tos-cn-i-188rlo5p4y/e2216ce13cec46fdb4e7ee9dc4d77e73~tplv-188rlo5p4y-2.jpeg',
  catpchaWitdh: 340,
  catpchaHeight: 212,
  slideTop: 82,
  slideHeight: 68,
})

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