ArtPlayer/packages/artplayer/src/player/subtitleOffsetMix.ts

import type { SubtitleOffsetHost } from '../subtitle/types'
import { clamp, def } from '../utils'

export default function subtitleOffsetMix(art: SubtitleOffsetHost): void {
  const { notice, i18n, template } = art

  def(art, 'subtitleOffset', {
    get() {
      return template.$track?.offset || 0
    },
    set(value: number) {
      const { cues } = art.subtitle
      if (!template.$track || cues.length === 0)
        return
      const offset = clamp(value, -10, 10)
      template.$track.offset = offset
      for (let index = 0; index < cues.length; index++) {
        const cue = cues[index]!
        cue.originalStartTime = cue.originalStartTime ?? cue.startTime
        cue.originalEndTime = cue.originalEndTime ?? cue.endTime
        cue.startTime = clamp(cue.originalStartTime + offset, 0, art.duration)
        cue.endTime = clamp(cue.originalEndTime + offset, 0, art.duration)
      }
      art.subtitle.update()
      notice.show = `${i18n.get('Subtitle Offset')}: ${value}s`
      art.emit('subtitleOffset', value)
    },
  })
}