refactor(core): CORE-15 type subtitles and own request and track lifetimes

packages/artplayer/src/player/subtitleOffsetMix.ts

@@ -0,0 +1,29 @@
+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)
+    },
+  })
+}