src/utils/cues.js

import { fixLineBreaks } from './vttparser';
 
export function newCue (track, startTime, endTime, captionScreen) {
  let row;
  let cue;
  let indenting;
  let indent;
  let text;
  let VTTCue = window.VTTCue || window.TextTrackCue;
 
  for (let r = 0; r < captionScreen.rows.length; r++) {
    row = captionScreen.rows[r];
    indenting = true;
    indent = 0;
    text = '';
 
    if (!row.isEmpty()) {
      for (let c = 0; c < row.chars.length; c++) {
        if (row.chars[c].uchar.match(/\s/) && indenting) {
          indent++;
        } else {
          text += row.chars[c].uchar;
          indenting = false;
        }
      }
      // To be used for cleaning-up orphaned roll-up captions
      row.cueStartTime = startTime;
 
      // Give a slight bump to the endTime if it's equal to startTime to avoid a SyntaxError in IE
      if (startTime === endTime)
        endTime += 0.0001;
 
      cue = new VTTCue(startTime, endTime, fixLineBreaks(text.trim()));
 
      if (indent >= 16)
        indent--;
      else
        indent++;
 
      // VTTCue.line get's flakey when using controls, so let's now include line 13&14
      // also, drop line 1 since it's to close to the top
      if (navigator.userAgent.match(/Firefox\//))
        cue.line = r + 1;
      else
        cue.line = (r > 7 ? r - 2 : r + 1);
 
      cue.align = 'left';
      // Clamp the position between 0 and 100 - if out of these bounds, Firefox throws an exception and captions break
      cue.position = Math.max(0, Math.min(100, 100 * (indent / 32) + (navigator.userAgent.match(/Firefox\//) ? 50 : 0)));
      track.addCue(cue);
    }
  }
}