meyfa/atom-screenshot

'use babel'

import CaptureResult from './capture-result'
import mergeImages from 'merge-images'

const { nativeImage } = require('electron')

/**
 * Stitch the given array of capture regions together vertically.
 *
 * @param {CaptureResult[]} captures The captures.
 * @returns {Promise} Resolves to a capture result spanning the whole range.
 */
export default async function stitch (captures) {
  let width = 0
  let height = 0
  const images = []

  for (const capture of captures) {
    // convert capture to { src, x, y } objects
    images.push({
      src: capture.image.toDataURL(),
      x: 0,
      y: height
    })

    const size = capture.image.getSize()
    // width = max(width_1, width_2, ..., width_n)
    width = Math.max(width, size.width)
    // height = height_1 + height_2 + ... + height_n
    height += size.height
  }

  // perform merge
  const b64 = await mergeImages(images, { width, height })
  const img = nativeImage.createFromDataURL(b64)

  // new line range
  const first = captures[0].firstLine
  const last = captures[captures.length - 1].lastLine

  return new CaptureResult(img, first, last)
}