Source: lib/text/ttml_text_parser.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.text.TtmlTextParser');
  9. goog.require('goog.asserts');
  10. goog.require('goog.Uri');
  11. goog.require('shaka.log');
  12. goog.require('shaka.text.Cue');
  13. goog.require('shaka.text.CueRegion');
  14. goog.require('shaka.text.TextEngine');
  15. goog.require('shaka.util.ArrayUtils');
  16. goog.require('shaka.util.Error');
  17. goog.require('shaka.util.StringUtils');
  18. goog.require('shaka.util.TXml');
  21. /**
  22.  * @implements {shaka.extern.TextParser}
  23.  * @export
  24.  */
  25. shaka.text.TtmlTextParser = class {
  26.   /**
  27.    * @override
  28.    * @export
  29.    */
  30.   parseInit(data) {
  31.     goog.asserts.assert(false, 'TTML does not have init segments');
  32.   }
  34.   /**
  35.    * @override
  36.    * @export
  37.    */
  38.   setSequenceMode(sequenceMode) {
  39.     // Unused.
  40.   }
  42.   /**
  43.    * @override
  44.    * @export
  45.    */
  46.   setManifestType(manifestType) {
  47.     // Unused.
  48.   }
  50.   /**
  51.    * @override
  52.    * @export
  53.    */
  54.   parseMedia(data, time, uri, images) {
  55.     const TtmlTextParser = shaka.text.TtmlTextParser;
  56.     const TXml = shaka.util.TXml;
  57.     const ttpNs = TtmlTextParser.parameterNs_;
  58.     const ttsNs = TtmlTextParser.styleNs_;
  59.     const str = shaka.util.StringUtils.fromUTF8(data);
  60.     const cues = [];
  62.     // dont try to parse empty string as
  63.     // DOMParser will not throw error but return an errored xml
  64.     if (str == '') {
  65.       return cues;
  66.     }
  68.     const tt = TXml.parseXmlString(str, 'tt');
  69.     if (!tt) {
  70.       throw new shaka.util.Error(
  71.           shaka.util.Error.Severity.CRITICAL,
  72.           shaka.util.Error.Category.TEXT,
  73.           shaka.util.Error.Code.INVALID_XML,
  74.           'Failed to parse TTML.');
  75.     }
  77.     const body = TXml.getElementsByTagName(tt, 'body')[0];
  78.     if (!body) {
  79.       return [];
  80.     }
  82.     // Get the framerate, subFrameRate and frameRateMultiplier if applicable.
  83.     const frameRate = TXml.getAttributeNSList(tt, ttpNs, 'frameRate');
  84.     const subFrameRate = TXml.getAttributeNSList(
  85.         tt, ttpNs, 'subFrameRate');
  86.     const frameRateMultiplier =
  87.         TXml.getAttributeNSList(tt, ttpNs, 'frameRateMultiplier');
  88.     const tickRate = TXml.getAttributeNSList(tt, ttpNs, 'tickRate');
  90.     const cellResolution = TXml.getAttributeNSList(
  91.         tt, ttpNs, 'cellResolution');
  92.     const spaceStyle = tt.attributes['xml:space'] || 'default';
  93.     const extent = TXml.getAttributeNSList(tt, ttsNs, 'extent');
  95.     if (spaceStyle != 'default' && spaceStyle != 'preserve') {
  96.       throw new shaka.util.Error(
  97.           shaka.util.Error.Severity.CRITICAL,
  98.           shaka.util.Error.Category.TEXT,
  99.           shaka.util.Error.Code.INVALID_XML,
  100.           'Invalid xml:space value: ' + spaceStyle);
  101.     }
  102.     const collapseMultipleSpaces = spaceStyle == 'default';
  104.     const rateInfo = new TtmlTextParser.RateInfo_(
  105.         frameRate, subFrameRate, frameRateMultiplier, tickRate);
  107.     const cellResolutionInfo =
  108.       TtmlTextParser.getCellResolution_(cellResolution);
  110.     const metadata = TXml.getElementsByTagName(tt, 'metadata')[0];
  111.     const metadataElements = metadata ? metadata.children : [];
  112.     const styles = TXml.getElementsByTagName(tt, 'style');
  113.     const regionElements = TXml.getElementsByTagName(tt, 'region');
  115.     const cueRegions = [];
  116.     for (const region of regionElements) {
  117.       const cueRegion =
  118.           TtmlTextParser.parseCueRegion_(region, styles, extent);
  119.       if (cueRegion) {
  120.         cueRegions.push(cueRegion);
  121.       }
  122.     }
  124.     // A <body> element should only contain <div> elements, not <p> or <span>
  125.     // elements.  We used to allow this, but it is non-compliant, and the
  126.     // loose nature of our previous parser made it difficult to implement TTML
  127.     // nesting more fully.
  128.     if (TXml.findChildren(body, 'p').length) {
  129.       throw new shaka.util.Error(
  130.           shaka.util.Error.Severity.CRITICAL,
  131.           shaka.util.Error.Category.TEXT,
  132.           shaka.util.Error.Code.INVALID_TEXT_CUE,
  133.           '<p> can only be inside <div> in TTML');
  134.     }
  136.     for (const div of TXml.findChildren(body, 'div')) {
  137.       // A <div> element should only contain <p>, not <span>.
  138.       if (TXml.findChildren(div, 'span').length) {
  139.         throw new shaka.util.Error(
  140.             shaka.util.Error.Severity.CRITICAL,
  141.             shaka.util.Error.Category.TEXT,
  142.             shaka.util.Error.Code.INVALID_TEXT_CUE,
  143.             '<span> can only be inside <p> in TTML');
  144.       }
  145.     }
  147.     const cue = TtmlTextParser.parseCue_(
  148.         body, time, rateInfo, metadataElements, styles,
  149.         regionElements, cueRegions, collapseMultipleSpaces,
  150.         cellResolutionInfo, /* parentCueElement= */ null,
  151.         /* isContent= */ false, uri, images);
  152.     if (cue) {
  153.       // According to the TTML spec, backgrounds default to transparent.
  154.       // So default the background of the top-level element to transparent.
  155.       // Nested elements may override that background color already.
  156.       if (!cue.backgroundColor) {
  157.         cue.backgroundColor = 'transparent';
  158.       }
  159.       cues.push(cue);
  160.     }
  162.     return cues;
  163.   }
  165.   /**
  166.    * Parses a TTML node into a Cue.
  167.    *
  168.    * @param {!shaka.extern.xml.Node} cueNode
  169.    * @param {shaka.extern.TextParser.TimeContext} timeContext
  170.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  171.    * @param {!Array.<!shaka.extern.xml.Node>} metadataElements
  172.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  173.    * @param {!Array.<!shaka.extern.xml.Node>} regionElements
  174.    * @param {!Array.<!shaka.text.CueRegion>} cueRegions
  175.    * @param {boolean} collapseMultipleSpaces
  176.    * @param {?{columns: number, rows: number}} cellResolution
  177.    * @param {?shaka.extern.xml.Node} parentCueElement
  178.    * @param {boolean} isContent
  179.    * @param {?(string|undefined)} uri
  180.    * @param {!Array.<string>} images
  181.    * @return {shaka.text.Cue}
  182.    * @private
  183.    */
  184.   static parseCue_(
  185.       cueNode, timeContext, rateInfo, metadataElements, styles, regionElements,
  186.       cueRegions, collapseMultipleSpaces, cellResolution, parentCueElement,
  187.       isContent, uri, images) {
  188.     const TXml = shaka.util.TXml;
  189.     const StringUtils = shaka.util.StringUtils;
  190.     /** @type {shaka.extern.xml.Node} */
  191.     let cueElement;
  192.     /** @type {?shaka.extern.xml.Node} */
  193.     let parentElement = parentCueElement;
  195.     if (TXml.isText(cueNode)) {
  196.       if (!isContent) {
  197.         // Ignore text elements outside the content. For example, whitespace
  198.         // on the same lexical level as the <p> elements, in a document with
  199.         // xml:space="preserve", should not be renderer.
  200.         return null;
  201.       }
  202.       // This should generate an "anonymous span" according to the TTML spec.
  203.       // So pretend the element was a <span>.  parentElement was set above, so
  204.       // we should still be able to correctly traverse up for timing
  205.       // information later.
  206.       /** @type {shaka.extern.xml.Node} */
  207.       const span = {
  208.         tagName: 'span',
  209.         children: [TXml.getTextContents(cueNode)],
  210.         attributes: {},
  211.         parent: null,
  212.       };
  213.       cueElement = span;
  214.     } else {
  215.       cueElement = cueNode;
  216.     }
  217.     goog.asserts.assert(cueElement, 'cueElement should be non-null!');
  219.     let imageElement = null;
  220.     for (const nameSpace of shaka.text.TtmlTextParser.smpteNsList_) {
  221.       imageElement = shaka.text.TtmlTextParser.getElementsFromCollection_(
  222.           cueElement, 'backgroundImage', metadataElements, '#',
  223.           nameSpace)[0];
  224.       if (imageElement) {
  225.         break;
  226.       }
  227.     }
  229.     let imageUri = null;
  230.     const backgroundImage = TXml.getAttributeNSList(
  231.         cueElement,
  232.         shaka.text.TtmlTextParser.smpteNsList_,
  233.         'backgroundImage');
  234.     const imsc1ImgUrnTester =
  235.         /^(urn:)(mpeg:[a-z0-9][a-z0-9-]{0,31}:)(subs:)([0-9]+)$/;
  236.     if (backgroundImage && imsc1ImgUrnTester.test(backgroundImage)) {
  237.       const index = parseInt(backgroundImage.split(':').pop(), 10) -1;
  238.       if (index >= images.length) {
  239.         return null;
  240.       }
  241.       imageUri = images[index];
  242.     } else if (uri && backgroundImage && !backgroundImage.startsWith('#')) {
  243.       const baseUri = new goog.Uri(uri);
  244.       const relativeUri = new goog.Uri(backgroundImage);
  245.       const newUri = baseUri.resolve(relativeUri).toString();
  246.       if (newUri) {
  247.         imageUri = newUri;
  248.       }
  249.     }
  251.     if (cueNode.tagName == 'p' || imageElement || imageUri) {
  252.       isContent = true;
  253.     }
  255.     const parentIsContent = isContent;
  257.     const spaceStyle = cueElement.attributes['xml:space'] ||
  258.         (collapseMultipleSpaces ? 'default' : 'preserve');
  260.     const localCollapseMultipleSpaces = spaceStyle == 'default';
  262.     // Parse any nested cues first.
  263.     const isLeafNode = cueElement.children.every(TXml.isText);
  264.     const nestedCues = [];
  265.     if (!isLeafNode) {
  266.       // Otherwise, recurse into the children.  Text nodes will convert into
  267.       // anonymous spans, which will then be leaf nodes.
  268.       for (const childNode of cueElement.children) {
  269.         const nestedCue = shaka.text.TtmlTextParser.parseCue_(
  270.             childNode,
  271.             timeContext,
  272.             rateInfo,
  273.             metadataElements,
  274.             styles,
  275.             regionElements,
  276.             cueRegions,
  277.             localCollapseMultipleSpaces,
  278.             cellResolution,
  279.             cueElement,
  280.             isContent,
  281.             uri,
  282.             images,
  283.         );
  285.         // This node may or may not generate a nested cue.
  286.         if (nestedCue) {
  287.           nestedCues.push(nestedCue);
  288.         }
  289.       }
  290.     }
  292.     const isNested = /** @type {boolean} */ (parentCueElement != null);
  294.     const textContent = TXml.getTextContents(cueElement);
  295.     // In this regex, "\S" means "non-whitespace character".
  296.     const hasTextContent = cueElement.children.length &&
  297.         textContent &&
  298.         /\S/.test(textContent);
  300.     const hasTimeAttributes =
  301.         cueElement.attributes['begin'] ||
  302.         cueElement.attributes['end'] ||
  303.         cueElement.attributes['dur'];
  305.     if (!hasTimeAttributes && !hasTextContent && cueElement.tagName != 'br' &&
  306.         nestedCues.length == 0) {
  307.       if (!isNested) {
  308.         // Disregards empty <p> elements without time attributes nor content.
  309.         // <p begin="..." smpte:backgroundImage="..." /> will go through,
  310.         // as some information could be held by its attributes.
  311.         // <p /> won't, as it would not be displayed.
  312.         return null;
  313.       } else if (localCollapseMultipleSpaces) {
  314.         // Disregards empty anonymous spans when (local) trim is true.
  315.         return null;
  316.       }
  317.     }
  319.     // Get local time attributes.
  320.     let {start, end} = shaka.text.TtmlTextParser.parseTime_(
  321.         cueElement, rateInfo);
  322.     // Resolve local time relative to parent elements.  Time elements can appear
  323.     // all the way up to 'body', but not 'tt'.
  324.     while (parentElement && TXml.isNode(parentElement) &&
  325.         parentElement.tagName != 'tt') {
  326.       ({start, end} = shaka.text.TtmlTextParser.resolveTime_(
  327.           parentElement, rateInfo, start, end));
  328.       parentElement =
  329.         /** @type {shaka.extern.xml.Node} */ (parentElement.parent);
  330.     }
  332.     if (start == null) {
  333.       start = 0;
  334.     }
  335.     start += timeContext.periodStart;
  337.     // If end is null, that means the duration is effectively infinite.
  338.     if (end == null) {
  339.       end = Infinity;
  340.     } else {
  341.       end += timeContext.periodStart;
  342.     }
  344.     // Clip times to segment boundaries.
  345.     // https://github.com/shaka-project/shaka-player/issues/4631
  346.     start = Math.max(start, timeContext.segmentStart);
  347.     end = Math.min(end, timeContext.segmentEnd);
  349.     if (!hasTimeAttributes && nestedCues.length > 0) {
  350.       // If no time is defined for this cue, base the timing information on
  351.       // the time of the nested cues. In the case of multiple nested cues with
  352.       // different start times, it is the text displayer's responsibility to
  353.       // make sure that only the appropriate nested cue is drawn at any given
  354.       // time.
  355.       start = Infinity;
  356.       end = 0;
  357.       for (const cue of nestedCues) {
  358.         start = Math.min(start, cue.startTime);
  359.         end = Math.max(end, cue.endTime);
  360.       }
  361.     }
  363.     if (cueElement.tagName == 'br') {
  364.       const cue = new shaka.text.Cue(start, end, '');
  365.       cue.lineBreak = true;
  366.       return cue;
  367.     }
  369.     let payload = '';
  370.     if (isLeafNode) {
  371.       // If the childNodes are all text, this is a leaf node.  Get the payload.
  372.       payload = StringUtils.htmlUnescape(
  373.           shaka.util.TXml.getTextContents(cueElement) || '');
  374.       if (localCollapseMultipleSpaces) {
  375.         // Collapse multiple spaces into one.
  376.         payload = payload.replace(/\s+/g, ' ');
  377.       }
  378.     }
  380.     const cue = new shaka.text.Cue(start, end, payload);
  381.     cue.nestedCues = nestedCues;
  383.     if (!isContent) {
  384.       // If this is not a <p> element or a <div> with images, and it has no
  385.       // parent that was a <p> element, then it's part of the outer containers
  386.       // (e.g. the <body> or a normal <div> element within it).
  387.       cue.isContainer = true;
  388.     }
  390.     if (cellResolution) {
  391.       cue.cellResolution = cellResolution;
  392.     }
  394.     // Get other properties if available.
  395.     const regionElement = shaka.text.TtmlTextParser.getElementsFromCollection_(
  396.         cueElement, 'region', regionElements, /* prefix= */ '')[0];
  397.     // Do not actually apply that region unless it is non-inherited, though.
  398.     // This makes it so that, if a parent element has a region, the children
  399.     // don't also all independently apply the positioning of that region.
  400.     if (cueElement.attributes['region']) {
  401.       if (regionElement && regionElement.attributes['xml:id']) {
  402.         const regionId = regionElement.attributes['xml:id'];
  403.         cue.region = cueRegions.filter((region) => region.id == regionId)[0];
  404.       }
  405.     }
  407.     let regionElementForStyle = regionElement;
  408.     if (parentCueElement && isNested && !cueElement.attributes['region'] &&
  409.       !cueElement.attributes['style']) {
  410.       regionElementForStyle =
  411.           shaka.text.TtmlTextParser.getElementsFromCollection_(
  412.               parentCueElement, 'region', regionElements, /* prefix= */ '')[0];
  413.     }
  415.     shaka.text.TtmlTextParser.addStyle_(
  416.         cue,
  417.         cueElement,
  418.         regionElementForStyle,
  419.         /** @type {!shaka.extern.xml.Node} */(imageElement),
  420.         imageUri,
  421.         styles,
  422.         /** isNested= */ parentIsContent, // "nested in a <div>" doesn't count.
  423.         /** isLeaf= */ (nestedCues.length == 0));
  425.     return cue;
  426.   }
  428.   /**
  429.    * Parses an Element into a TextTrackCue or VTTCue.
  430.    *
  431.    * @param {!shaka.extern.xml.Node} regionElement
  432.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  433.    * Defined in the top of tt element and used principally for images.
  434.    * @param {?string} globalExtent
  435.    * @return {shaka.text.CueRegion}
  436.    * @private
  437.    */
  438.   static parseCueRegion_(regionElement, styles, globalExtent) {
  439.     const TtmlTextParser = shaka.text.TtmlTextParser;
  440.     const region = new shaka.text.CueRegion();
  441.     const id = regionElement.attributes['xml:id'];
  442.     if (!id) {
  443.       shaka.log.warning('TtmlTextParser parser encountered a region with ' +
  444.                         'no id. Region will be ignored.');
  445.       return null;
  446.     }
  447.     region.id = id;
  449.     let globalResults = null;
  450.     if (globalExtent) {
  451.       globalResults = TtmlTextParser.percentValues_.exec(globalExtent) ||
  452.         TtmlTextParser.pixelValues_.exec(globalExtent);
  453.     }
  454.     const globalWidth = globalResults ? Number(globalResults[1]) : null;
  455.     const globalHeight = globalResults ? Number(globalResults[2]) : null;
  457.     let results = null;
  458.     let percentage = null;
  459.     const extent = TtmlTextParser.getStyleAttributeFromRegion_(
  460.         regionElement, styles, 'extent');
  461.     if (extent) {
  462.       percentage = TtmlTextParser.percentValues_.exec(extent);
  463.       results = percentage || TtmlTextParser.pixelValues_.exec(extent);
  464.       if (results != null) {
  465.         region.width = Number(results[1]);
  466.         region.height = Number(results[2]);
  468.         if (!percentage) {
  469.           if (globalWidth != null) {
  470.             region.width = region.width * 100 / globalWidth;
  471.           }
  472.           if (globalHeight != null) {
  473.             region.height = region.height * 100 / globalHeight;
  474.           }
  475.         }
  477.         region.widthUnits = percentage || globalWidth != null ?
  478.                            shaka.text.CueRegion.units.PERCENTAGE :
  479.                            shaka.text.CueRegion.units.PX;
  481.         region.heightUnits = percentage || globalHeight != null ?
  482.                            shaka.text.CueRegion.units.PERCENTAGE :
  483.                            shaka.text.CueRegion.units.PX;
  484.       }
  485.     }
  487.     const origin = TtmlTextParser.getStyleAttributeFromRegion_(
  488.         regionElement, styles, 'origin');
  489.     if (origin) {
  490.       percentage = TtmlTextParser.percentValues_.exec(origin);
  491.       results = percentage || TtmlTextParser.pixelValues_.exec(origin);
  492.       if (results != null) {
  493.         region.viewportAnchorX = Number(results[1]);
  494.         region.viewportAnchorY = Number(results[2]);
  496.         if (!percentage) {
  497.           if (globalHeight != null) {
  498.             region.viewportAnchorY = region.viewportAnchorY * 100 /
  499.               globalHeight;
  500.           }
  501.           if (globalWidth != null) {
  502.             region.viewportAnchorX = region.viewportAnchorX * 100 /
  503.               globalWidth;
  504.           }
  505.         } else if (!extent) {
  506.           region.width = 100 - region.viewportAnchorX;
  507.           region.widthUnits = shaka.text.CueRegion.units.PERCENTAGE;
  508.           region.height = 100 - region.viewportAnchorY;
  509.           region.heightUnits = shaka.text.CueRegion.units.PERCENTAGE;
  510.         }
  512.         region.viewportAnchorUnits = percentage || globalWidth != null ?
  513.                   shaka.text.CueRegion.units.PERCENTAGE :
  514.                   shaka.text.CueRegion.units.PX;
  515.       }
  516.     }
  518.     return region;
  519.   }
  521.   /**
  522.    * Adds applicable style properties to a cue.
  523.    *
  524.    * @param {!shaka.text.Cue} cue
  525.    * @param {!shaka.extern.xml.Node} cueElement
  526.    * @param {shaka.extern.xml.Node} region
  527.    * @param {shaka.extern.xml.Node} imageElement
  528.    * @param {?string} imageUri
  529.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  530.    * @param {boolean} isNested
  531.    * @param {boolean} isLeaf
  532.    * @private
  533.    */
  534.   static addStyle_(
  535.       cue, cueElement, region, imageElement, imageUri, styles,
  536.       isNested, isLeaf) {
  537.     const TtmlTextParser = shaka.text.TtmlTextParser;
  538.     const TXml = shaka.util.TXml;
  539.     const Cue = shaka.text.Cue;
  541.     // Styles should be inherited from regions, if a style property is not
  542.     // associated with a Content element (or an anonymous span).
  543.     const shouldInheritRegionStyles = isNested || isLeaf;
  545.     const direction = TtmlTextParser.getStyleAttribute_(
  546.         cueElement, region, styles, 'direction', shouldInheritRegionStyles);
  547.     if (direction == 'rtl') {
  548.       cue.direction = Cue.direction.HORIZONTAL_RIGHT_TO_LEFT;
  549.     }
  551.     // Direction attribute specifies one-dimentional writing direction
  552.     // (left to right or right to left). Writing mode specifies that
  553.     // plus whether text is vertical or horizontal.
  554.     // They should not contradict each other. If they do, we give
  555.     // preference to writing mode.
  556.     const writingMode = TtmlTextParser.getStyleAttribute_(
  557.         cueElement, region, styles, 'writingMode', shouldInheritRegionStyles);
  558.     // Set cue's direction if the text is horizontal, and cue's writingMode if
  559.     // it's vertical.
  560.     if (writingMode == 'tb' || writingMode == 'tblr') {
  561.       cue.writingMode = Cue.writingMode.VERTICAL_LEFT_TO_RIGHT;
  562.     } else if (writingMode == 'tbrl') {
  563.       cue.writingMode = Cue.writingMode.VERTICAL_RIGHT_TO_LEFT;
  564.     } else if (writingMode == 'rltb' || writingMode == 'rl') {
  565.       cue.direction = Cue.direction.HORIZONTAL_RIGHT_TO_LEFT;
  566.     } else if (writingMode) {
  567.       cue.direction = Cue.direction.HORIZONTAL_LEFT_TO_RIGHT;
  568.     }
  570.     const align = TtmlTextParser.getStyleAttribute_(
  571.         cueElement, region, styles, 'textAlign', true);
  572.     if (align) {
  573.       cue.positionAlign = TtmlTextParser.textAlignToPositionAlign_[align];
  574.       cue.lineAlign = TtmlTextParser.textAlignToLineAlign_[align];
  576.       goog.asserts.assert(align.toUpperCase() in Cue.textAlign,
  577.           align.toUpperCase() + ' Should be in Cue.textAlign values!');
  579.       cue.textAlign = Cue.textAlign[align.toUpperCase()];
  580.     } else {
  581.       // Default value is START in the TTML spec: https://bit.ly/32OGmvo
  582.       // But to make the subtitle render consitent with other players and the
  583.       // shaka.text.Cue we use CENTER
  584.       cue.textAlign = Cue.textAlign.CENTER;
  585.     }
  587.     const displayAlign = TtmlTextParser.getStyleAttribute_(
  588.         cueElement, region, styles, 'displayAlign', true);
  589.     if (displayAlign) {
  590.       goog.asserts.assert(displayAlign.toUpperCase() in Cue.displayAlign,
  591.           displayAlign.toUpperCase() +
  592.                           ' Should be in Cue.displayAlign values!');
  593.       cue.displayAlign = Cue.displayAlign[displayAlign.toUpperCase()];
  594.     }
  596.     const color = TtmlTextParser.getStyleAttribute_(
  597.         cueElement, region, styles, 'color', shouldInheritRegionStyles);
  598.     if (color) {
  599.       cue.color = color;
  600.     }
  602.     // Background color should not be set on a container.  If this is a nested
  603.     // cue, you can set the background.  If it's a top-level that happens to
  604.     // also be a leaf, you can set the background.
  605.     // See https://github.com/shaka-project/shaka-player/issues/2623
  606.     // This used to be handled in the displayer, but that is confusing.  The Cue
  607.     // structure should reflect what you want to happen in the displayer, and
  608.     // the displayer shouldn't have to know about TTML.
  609.     const backgroundColor = TtmlTextParser.getStyleAttribute_(
  610.         cueElement, region, styles, 'backgroundColor',
  611.         shouldInheritRegionStyles);
  612.     if (backgroundColor) {
  613.       cue.backgroundColor = backgroundColor;
  614.     }
  616.     const border = TtmlTextParser.getStyleAttribute_(
  617.         cueElement, region, styles, 'border', shouldInheritRegionStyles);
  618.     if (border) {
  619.       cue.border = border;
  620.     }
  622.     const fontFamily = TtmlTextParser.getStyleAttribute_(
  623.         cueElement, region, styles, 'fontFamily', shouldInheritRegionStyles);
  624.     // See https://github.com/sandflow/imscJS/blob/1.1.3/src/main/js/html.js#L1384
  625.     if (fontFamily) {
  626.       switch (fontFamily) {
  627.         case 'monospaceSerif':
  628.           cue.fontFamily = 'Courier New,Liberation Mono,Courier,monospace';
  629.           break;
  630.         case 'proportionalSansSerif':
  631.           cue.fontFamily = 'Arial,Helvetica,Liberation Sans,sans-serif';
  632.           break;
  633.         case 'sansSerif':
  634.           cue.fontFamily = 'sans-serif';
  635.           break;
  636.         case 'monospaceSansSerif':
  637.           cue.fontFamily = 'Consolas,monospace';
  638.           break;
  639.         case 'proportionalSerif':
  640.           cue.fontFamily = 'serif';
  641.           break;
  642.         default:
  643.           cue.fontFamily = fontFamily.split(',').filter((font) => {
  644.             return font != 'default';
  645.           }).join(',');
  646.           break;
  647.       }
  648.     }
  650.     const fontWeight = TtmlTextParser.getStyleAttribute_(
  651.         cueElement, region, styles, 'fontWeight', shouldInheritRegionStyles);
  652.     if (fontWeight && fontWeight == 'bold') {
  653.       cue.fontWeight = Cue.fontWeight.BOLD;
  654.     }
  656.     const wrapOption = TtmlTextParser.getStyleAttribute_(
  657.         cueElement, region, styles, 'wrapOption', shouldInheritRegionStyles);
  658.     if (wrapOption && wrapOption == 'noWrap') {
  659.       cue.wrapLine = false;
  660.     } else {
  661.       cue.wrapLine = true;
  662.     }
  664.     const lineHeight = TtmlTextParser.getStyleAttribute_(
  665.         cueElement, region, styles, 'lineHeight', shouldInheritRegionStyles);
  666.     if (lineHeight && lineHeight.match(TtmlTextParser.unitValues_)) {
  667.       cue.lineHeight = lineHeight;
  668.     }
  670.     const fontSize = TtmlTextParser.getStyleAttribute_(
  671.         cueElement, region, styles, 'fontSize', shouldInheritRegionStyles);
  672.     if (fontSize) {
  673.       const isValidFontSizeUnit =
  674.           fontSize.match(TtmlTextParser.unitValues_) ||
  675.           fontSize.match(TtmlTextParser.percentValue_);
  677.       if (isValidFontSizeUnit) {
  678.         cue.fontSize = fontSize;
  679.       }
  680.     }
  682.     const fontStyle = TtmlTextParser.getStyleAttribute_(
  683.         cueElement, region, styles, 'fontStyle', shouldInheritRegionStyles);
  684.     if (fontStyle) {
  685.       goog.asserts.assert(fontStyle.toUpperCase() in Cue.fontStyle,
  686.           fontStyle.toUpperCase() +
  687.                           ' Should be in Cue.fontStyle values!');
  688.       cue.fontStyle = Cue.fontStyle[fontStyle.toUpperCase()];
  689.     }
  691.     if (imageElement) {
  692.       // According to the spec, we should use imageType (camelCase), but
  693.       // historically we have checked for imagetype (lowercase).
  694.       // This was the case since background image support was first introduced
  695.       // in PR #1859, in April 2019, and first released in v2.5.0.
  696.       // Now we check for both, although only imageType (camelCase) is to spec.
  697.       const backgroundImageType =
  698.           imageElement.attributes['imageType'] ||
  699.           imageElement.attributes['imagetype'];
  700.       const backgroundImageEncoding = imageElement.attributes['encoding'];
  701.       const backgroundImageData = (TXml.getTextContents(imageElement)).trim();
  702.       if (backgroundImageType == 'PNG' &&
  703.           backgroundImageEncoding == 'Base64' &&
  704.           backgroundImageData) {
  705.         cue.backgroundImage = 'data:image/png;base64,' + backgroundImageData;
  706.       }
  707.     } else if (imageUri) {
  708.       cue.backgroundImage = imageUri;
  709.     }
  711.     const textOutline = TtmlTextParser.getStyleAttribute_(
  712.         cueElement, region, styles, 'textOutline', shouldInheritRegionStyles);
  713.     if (textOutline) {
  714.       // tts:textOutline isn't natively supported by browsers, but it can be
  715.       // mostly replicated using the non-standard -webkit-text-stroke-width and
  716.       // -webkit-text-stroke-color properties.
  717.       const split = textOutline.split(' ');
  718.       if (split[0].match(TtmlTextParser.unitValues_)) {
  719.         // There is no defined color, so default to the text color.
  720.         cue.textStrokeColor = cue.color;
  721.       } else {
  722.         cue.textStrokeColor = split[0];
  723.         split.shift();
  724.       }
  725.       if (split[0] && split[0].match(TtmlTextParser.unitValues_)) {
  726.         cue.textStrokeWidth = split[0];
  727.       } else {
  728.         // If there is no width, or the width is not a number, don't draw a
  729.         // border.
  730.         cue.textStrokeColor = '';
  731.       }
  732.       // There is an optional blur radius also, but we have no way of
  733.       // replicating that, so ignore it.
  734.     }
  736.     const letterSpacing = TtmlTextParser.getStyleAttribute_(
  737.         cueElement, region, styles, 'letterSpacing', shouldInheritRegionStyles);
  738.     if (letterSpacing && letterSpacing.match(TtmlTextParser.unitValues_)) {
  739.       cue.letterSpacing = letterSpacing;
  740.     }
  742.     const linePadding = TtmlTextParser.getStyleAttribute_(
  743.         cueElement, region, styles, 'linePadding', shouldInheritRegionStyles);
  744.     if (linePadding && linePadding.match(TtmlTextParser.unitValues_)) {
  745.       cue.linePadding = linePadding;
  746.     }
  748.     const opacity = TtmlTextParser.getStyleAttribute_(
  749.         cueElement, region, styles, 'opacity', shouldInheritRegionStyles);
  750.     if (opacity) {
  751.       cue.opacity = parseFloat(opacity);
  752.     }
  754.     // Text decoration is an array of values which can come both from the
  755.     // element's style or be inherited from elements' parent nodes. All of those
  756.     // values should be applied as long as they don't contradict each other. If
  757.     // they do, elements' own style gets preference.
  758.     const textDecorationRegion = TtmlTextParser.getStyleAttributeFromRegion_(
  759.         region, styles, 'textDecoration');
  760.     if (textDecorationRegion) {
  761.       TtmlTextParser.addTextDecoration_(cue, textDecorationRegion);
  762.     }
  764.     const textDecorationElement = TtmlTextParser.getStyleAttributeFromElement_(
  765.         cueElement, styles, 'textDecoration');
  766.     if (textDecorationElement) {
  767.       TtmlTextParser.addTextDecoration_(cue, textDecorationElement);
  768.     }
  770.     const textCombine = TtmlTextParser.getStyleAttribute_(
  771.         cueElement, region, styles, 'textCombine', shouldInheritRegionStyles);
  772.     if (textCombine) {
  773.       cue.textCombineUpright = textCombine;
  774.     }
  776.     const ruby = TtmlTextParser.getStyleAttribute_(
  777.         cueElement, region, styles, 'ruby', shouldInheritRegionStyles);
  778.     switch (ruby) {
  779.       case 'container':
  780.         cue.rubyTag = 'ruby';
  781.         break;
  782.       case 'text':
  783.         cue.rubyTag = 'rt';
  784.         break;
  785.     }
  786.   }
  788.   /**
  789.    * Parses text decoration values and adds/removes them to/from the cue.
  790.    *
  791.    * @param {!shaka.text.Cue} cue
  792.    * @param {string} decoration
  793.    * @private
  794.    */
  795.   static addTextDecoration_(cue, decoration) {
  796.     const Cue = shaka.text.Cue;
  797.     for (const value of decoration.split(' ')) {
  798.       switch (value) {
  799.         case 'underline':
  800.           if (!cue.textDecoration.includes(Cue.textDecoration.UNDERLINE)) {
  801.             cue.textDecoration.push(Cue.textDecoration.UNDERLINE);
  802.           }
  803.           break;
  804.         case 'noUnderline':
  805.           if (cue.textDecoration.includes(Cue.textDecoration.UNDERLINE)) {
  806.             shaka.util.ArrayUtils.remove(cue.textDecoration,
  807.                 Cue.textDecoration.UNDERLINE);
  808.           }
  809.           break;
  810.         case 'lineThrough':
  811.           if (!cue.textDecoration.includes(Cue.textDecoration.LINE_THROUGH)) {
  812.             cue.textDecoration.push(Cue.textDecoration.LINE_THROUGH);
  813.           }
  814.           break;
  815.         case 'noLineThrough':
  816.           if (cue.textDecoration.includes(Cue.textDecoration.LINE_THROUGH)) {
  817.             shaka.util.ArrayUtils.remove(cue.textDecoration,
  818.                 Cue.textDecoration.LINE_THROUGH);
  819.           }
  820.           break;
  821.         case 'overline':
  822.           if (!cue.textDecoration.includes(Cue.textDecoration.OVERLINE)) {
  823.             cue.textDecoration.push(Cue.textDecoration.OVERLINE);
  824.           }
  825.           break;
  826.         case 'noOverline':
  827.           if (cue.textDecoration.includes(Cue.textDecoration.OVERLINE)) {
  828.             shaka.util.ArrayUtils.remove(cue.textDecoration,
  829.                 Cue.textDecoration.OVERLINE);
  830.           }
  831.           break;
  832.       }
  833.     }
  834.   }
  836.   /**
  837.    * Finds a specified attribute on either the original cue element or its
  838.    * associated region and returns the value if the attribute was found.
  839.    *
  840.    * @param {!shaka.extern.xml.Node} cueElement
  841.    * @param {shaka.extern.xml.Node} region
  842.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  843.    * @param {string} attribute
  844.    * @param {boolean=} shouldInheritRegionStyles
  845.    * @return {?string}
  846.    * @private
  847.    */
  848.   static getStyleAttribute_(cueElement, region, styles, attribute,
  849.       shouldInheritRegionStyles=true) {
  850.     // An attribute can be specified on region level or in a styling block
  851.     // associated with the region or original element.
  852.     const TtmlTextParser = shaka.text.TtmlTextParser;
  853.     const attr = TtmlTextParser.getStyleAttributeFromElement_(
  854.         cueElement, styles, attribute);
  855.     if (attr) {
  856.       return attr;
  857.     }
  859.     if (shouldInheritRegionStyles) {
  860.       return TtmlTextParser.getStyleAttributeFromRegion_(
  861.           region, styles, attribute);
  862.     }
  863.     return null;
  864.   }
  866.   /**
  867.    * Finds a specified attribute on the element's associated region
  868.    * and returns the value if the attribute was found.
  869.    *
  870.    * @param {shaka.extern.xml.Node} region
  871.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  872.    * @param {string} attribute
  873.    * @return {?string}
  874.    * @private
  875.    */
  876.   static getStyleAttributeFromRegion_(region, styles, attribute) {
  877.     const TXml = shaka.util.TXml;
  878.     const ttsNs = shaka.text.TtmlTextParser.styleNs_;
  880.     if (!region) {
  881.       return null;
  882.     }
  884.     const attr = TXml.getAttributeNSList(region, ttsNs, attribute);
  885.     if (attr) {
  886.       return attr;
  887.     }
  889.     return shaka.text.TtmlTextParser.getInheritedStyleAttribute_(
  890.         region, styles, attribute);
  891.   }
  893.   /**
  894.    * Finds a specified attribute on the cue element and returns the value
  895.    * if the attribute was found.
  896.    *
  897.    * @param {!shaka.extern.xml.Node} cueElement
  898.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  899.    * @param {string} attribute
  900.    * @return {?string}
  901.    * @private
  902.    */
  903.   static getStyleAttributeFromElement_(cueElement, styles, attribute) {
  904.     const TXml = shaka.util.TXml;
  905.     const ttsNs = shaka.text.TtmlTextParser.styleNs_;
  907.     // Styling on elements should take precedence
  908.     // over the main styling attributes
  909.     const elementAttribute = TXml.getAttributeNSList(
  910.         cueElement,
  911.         ttsNs,
  912.         attribute);
  914.     if (elementAttribute) {
  915.       return elementAttribute;
  916.     }
  917.     return shaka.text.TtmlTextParser.getInheritedStyleAttribute_(
  918.         cueElement, styles, attribute);
  919.   }
  921.   /**
  922.    * Finds a specified attribute on an element's styles and the styles those
  923.    * styles inherit from.
  924.    *
  925.    * @param {!shaka.extern.xml.Node} element
  926.    * @param {!Array.<!shaka.extern.xml.Node>} styles
  927.    * @param {string} attribute
  928.    * @return {?string}
  929.    * @private
  930.    */
  931.   static getInheritedStyleAttribute_(element, styles, attribute) {
  932.     const TXml = shaka.util.TXml;
  933.     const ttsNs = shaka.text.TtmlTextParser.styleNs_;
  934.     const ebuttsNs = shaka.text.TtmlTextParser.styleEbuttsNs_;
  936.     const inheritedStyles =
  937.         shaka.text.TtmlTextParser.getElementsFromCollection_(
  938.             element, 'style', styles, /* prefix= */ '');
  940.     let styleValue = null;
  942.     // The last value in our styles stack takes the precedence over the others
  943.     for (let i = 0; i < inheritedStyles.length; i++) {
  944.       // Check ebu namespace first.
  945.       let styleAttributeValue = TXml.getAttributeNS(
  946.           inheritedStyles[i],
  947.           ebuttsNs,
  948.           attribute);
  950.       if (!styleAttributeValue) {
  951.         // Fall back to tts namespace.
  952.         styleAttributeValue = TXml.getAttributeNSList(
  953.             inheritedStyles[i],
  954.             ttsNs,
  955.             attribute);
  956.       }
  958.       if (!styleAttributeValue) {
  959.         // Next, check inheritance.
  960.         // Styles can inherit from other styles, so traverse up that chain.
  961.         styleAttributeValue =
  962.             shaka.text.TtmlTextParser.getStyleAttributeFromElement_(
  963.                 inheritedStyles[i], styles, attribute);
  964.       }
  966.       if (styleAttributeValue) {
  967.         styleValue = styleAttributeValue;
  968.       }
  969.     }
  971.     return styleValue;
  972.   }
  975.   /**
  976.    * Selects items from |collection| whose id matches |attributeName|
  977.    * from |element|.
  978.    *
  979.    * @param {shaka.extern.xml.Node} element
  980.    * @param {string} attributeName
  981.    * @param {!Array.<shaka.extern.xml.Node>} collection
  982.    * @param {string} prefixName
  983.    * @param {string=} nsName
  984.    * @return {!Array.<!shaka.extern.xml.Node>}
  985.    * @private
  986.    */
  987.   static getElementsFromCollection_(
  988.       element, attributeName, collection, prefixName, nsName) {
  989.     const items = [];
  991.     if (!element || collection.length < 1) {
  992.       return items;
  993.     }
  995.     const attributeValue = shaka.text.TtmlTextParser.getInheritedAttribute_(
  996.         element, attributeName, nsName);
  998.     if (attributeValue) {
  999.       // There could be multiple items in one attribute
  1000.       // <span style="style1 style2">A cue</span>
  1001.       const itemNames = attributeValue.split(' ');
  1003.       for (const name of itemNames) {
  1004.         for (const item of collection) {
  1005.           if ((prefixName + item.attributes['xml:id']) == name) {
  1006.             items.push(item);
  1007.             break;
  1008.           }
  1009.         }
  1010.       }
  1011.     }
  1013.     return items;
  1014.   }
  1017.   /**
  1018.    * Traverses upwards from a given node until a given attribute is found.
  1019.    *
  1020.    * @param {!shaka.extern.xml.Node} element
  1021.    * @param {string} attributeName
  1022.    * @param {string=} nsName
  1023.    * @return {?string}
  1024.    * @private
  1025.    */
  1026.   static getInheritedAttribute_(element, attributeName, nsName) {
  1027.     let ret = null;
  1028.     const TXml = shaka.util.TXml;
  1029.     while (!ret) {
  1030.       ret = nsName ?
  1031.           TXml.getAttributeNS(element, nsName, attributeName) :
  1032.           element.attributes[attributeName];
  1033.       if (ret) {
  1034.         break;
  1035.       }
  1037.       // Element.parentNode can lead to XMLDocument, which is not an Element and
  1038.       // has no getAttribute().
  1039.       const parentNode = element.parent;
  1040.       if (parentNode) {
  1041.         element = parentNode;
  1042.       } else {
  1043.         break;
  1044.       }
  1045.     }
  1046.     return ret;
  1047.   }
  1049.   /**
  1050.    * Factor parent/ancestor time attributes into the parsed time of a
  1051.    * child/descendent.
  1052.    *
  1053.    * @param {!shaka.extern.xml.Node} parentElement
  1054.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1055.    * @param {?number} start The child's start time
  1056.    * @param {?number} end The child's end time
  1057.    * @return {{start: ?number, end: ?number}}
  1058.    * @private
  1059.    */
  1060.   static resolveTime_(parentElement, rateInfo, start, end) {
  1061.     const parentTime = shaka.text.TtmlTextParser.parseTime_(
  1062.         parentElement, rateInfo);
  1064.     if (start == null) {
  1065.       // No start time of your own?  Inherit from the parent.
  1066.       start = parentTime.start;
  1067.     } else {
  1068.       // Otherwise, the start time is relative to the parent's start time.
  1069.       if (parentTime.start != null) {
  1070.         start += parentTime.start;
  1071.       }
  1072.     }
  1074.     if (end == null) {
  1075.       // No end time of your own?  Inherit from the parent.
  1076.       end = parentTime.end;
  1077.     } else {
  1078.       // Otherwise, the end time is relative to the parent's _start_ time.
  1079.       // This is not a typo.  Both times are relative to the parent's _start_.
  1080.       if (parentTime.start != null) {
  1081.         end += parentTime.start;
  1082.       }
  1083.     }
  1085.     return {start, end};
  1086.   }
  1088.   /**
  1089.    * Parse TTML time attributes from the given element.
  1090.    *
  1091.    * @param {!shaka.extern.xml.Node} element
  1092.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1093.    * @return {{start: ?number, end: ?number}}
  1094.    * @private
  1095.    */
  1096.   static parseTime_(element, rateInfo) {
  1097.     const start = shaka.text.TtmlTextParser.parseTimeAttribute_(
  1098.         element.attributes['begin'], rateInfo);
  1099.     let end = shaka.text.TtmlTextParser.parseTimeAttribute_(
  1100.         element.attributes['end'], rateInfo);
  1101.     const duration = shaka.text.TtmlTextParser.parseTimeAttribute_(
  1102.         element.attributes['dur'], rateInfo);
  1103.     if (end == null && duration != null) {
  1104.       end = start + duration;
  1105.     }
  1106.     return {start, end};
  1107.   }
  1109.   /**
  1110.    * Parses a TTML time from the given attribute text.
  1111.    *
  1112.    * @param {string} text
  1113.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1114.    * @return {?number}
  1115.    * @private
  1116.    */
  1117.   static parseTimeAttribute_(text, rateInfo) {
  1118.     let ret = null;
  1119.     const TtmlTextParser = shaka.text.TtmlTextParser;
  1121.     if (TtmlTextParser.timeColonFormatFrames_.test(text)) {
  1122.       ret = TtmlTextParser.parseColonTimeWithFrames_(rateInfo, text);
  1123.     } else if (TtmlTextParser.timeColonFormat_.test(text)) {
  1124.       ret = TtmlTextParser.parseTimeFromRegex_(
  1125.           TtmlTextParser.timeColonFormat_, text);
  1126.     } else if (TtmlTextParser.timeColonFormatMilliseconds_.test(text)) {
  1127.       ret = TtmlTextParser.parseTimeFromRegex_(
  1128.           TtmlTextParser.timeColonFormatMilliseconds_, text);
  1129.     } else if (TtmlTextParser.timeFramesFormat_.test(text)) {
  1130.       ret = TtmlTextParser.parseFramesTime_(rateInfo, text);
  1131.     } else if (TtmlTextParser.timeTickFormat_.test(text)) {
  1132.       ret = TtmlTextParser.parseTickTime_(rateInfo, text);
  1133.     } else if (TtmlTextParser.timeHMSFormat_.test(text)) {
  1134.       ret = TtmlTextParser.parseTimeFromRegex_(
  1135.           TtmlTextParser.timeHMSFormat_, text);
  1136.     } else if (text) {
  1137.       // It's not empty or null, but it doesn't match a known format.
  1138.       throw new shaka.util.Error(
  1139.           shaka.util.Error.Severity.CRITICAL,
  1140.           shaka.util.Error.Category.TEXT,
  1141.           shaka.util.Error.Code.INVALID_TEXT_CUE,
  1142.           'Could not parse cue time range in TTML');
  1143.     }
  1145.     return ret;
  1146.   }
  1148.   /**
  1149.    * Parses a TTML time in frame format.
  1150.    *
  1151.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1152.    * @param {string} text
  1153.    * @return {?number}
  1154.    * @private
  1155.    */
  1156.   static parseFramesTime_(rateInfo, text) {
  1157.     // 75f or 75.5f
  1158.     const results = shaka.text.TtmlTextParser.timeFramesFormat_.exec(text);
  1159.     const frames = Number(results[1]);
  1161.     return frames / rateInfo.frameRate;
  1162.   }
  1164.   /**
  1165.    * Parses a TTML time in tick format.
  1166.    *
  1167.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1168.    * @param {string} text
  1169.    * @return {?number}
  1170.    * @private
  1171.    */
  1172.   static parseTickTime_(rateInfo, text) {
  1173.     // 50t or 50.5t
  1174.     const results = shaka.text.TtmlTextParser.timeTickFormat_.exec(text);
  1175.     const ticks = Number(results[1]);
  1177.     return ticks / rateInfo.tickRate;
  1178.   }
  1180.   /**
  1181.    * Parses a TTML colon formatted time containing frames.
  1182.    *
  1183.    * @param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
  1184.    * @param {string} text
  1185.    * @return {?number}
  1186.    * @private
  1187.    */
  1188.   static parseColonTimeWithFrames_(rateInfo, text) {
  1189.     // 01:02:43:07 ('07' is frames) or 01:02:43:07.1 (subframes)
  1190.     const results = shaka.text.TtmlTextParser.timeColonFormatFrames_.exec(text);
  1192.     const hours = Number(results[1]);
  1193.     const minutes = Number(results[2]);
  1194.     let seconds = Number(results[3]);
  1195.     let frames = Number(results[4]);
  1196.     const subframes = Number(results[5]) || 0;
  1198.     frames += subframes / rateInfo.subFrameRate;
  1199.     seconds += frames / rateInfo.frameRate;
  1201.     return seconds + (minutes * 60) + (hours * 3600);
  1202.   }
  1204.   /**
  1205.    * Parses a TTML time with a given regex. Expects regex to be some
  1206.    * sort of a time-matcher to match hours, minutes, seconds and milliseconds
  1207.    *
  1208.    * @param {!RegExp} regex
  1209.    * @param {string} text
  1210.    * @return {?number}
  1211.    * @private
  1212.    */
  1213.   static parseTimeFromRegex_(regex, text) {
  1214.     const results = regex.exec(text);
  1215.     if (results == null || results[0] == '') {
  1216.       return null;
  1217.     }
  1218.     // This capture is optional, but will still be in the array as undefined,
  1219.     // in which case it is 0.
  1220.     const hours = Number(results[1]) || 0;
  1221.     const minutes = Number(results[2]) || 0;
  1222.     const seconds = Number(results[3]) || 0;
  1223.     const milliseconds = Number(results[4]) || 0;
  1225.     return (milliseconds / 1000) + seconds + (minutes * 60) + (hours * 3600);
  1226.   }
  1228.   /**
  1229.    * If ttp:cellResolution provided returns cell resolution info
  1230.    * with number of columns and rows into which the Root Container
  1231.    * Region area is divided
  1232.    *
  1233.    * @param {?string} cellResolution
  1234.    * @return {?{columns: number, rows: number}}
  1235.    * @private
  1236.    */
  1237.   static getCellResolution_(cellResolution) {
  1238.     if (!cellResolution) {
  1239.       return null;
  1240.     }
  1241.     const matches = /^(\d+) (\d+)$/.exec(cellResolution);
  1243.     if (!matches) {
  1244.       return null;
  1245.     }
  1247.     const columns = parseInt(matches[1], 10);
  1248.     const rows = parseInt(matches[2], 10);
  1250.     return {columns, rows};
  1251.   }
  1252. };
  1254. /**
  1255.  * @summary
  1256.  * Contains information about frame/subframe rate
  1257.  * and frame rate multiplier for time in frame format.
  1258.  *
  1259.  * @example 01:02:03:04(4 frames) or 01:02:03:04.1(4 frames, 1 subframe)
  1260.  * @private
  1261.  */
  1262. shaka.text.TtmlTextParser.RateInfo_ = class {
  1263.   /**
  1264.    * @param {?string} frameRate
  1265.    * @param {?string} subFrameRate
  1266.    * @param {?string} frameRateMultiplier
  1267.    * @param {?string} tickRate
  1268.    */
  1269.   constructor(frameRate, subFrameRate, frameRateMultiplier, tickRate) {
  1270.     /**
  1271.      * @type {number}
  1272.      */
  1273.     this.frameRate = Number(frameRate) || 30;
  1275.     /**
  1276.      * @type {number}
  1277.      */
  1278.     this.subFrameRate = Number(subFrameRate) || 1;
  1280.     /**
  1281.      * @type {number}
  1282.      */
  1283.     this.tickRate = Number(tickRate);
  1284.     if (this.tickRate == 0) {
  1285.       if (frameRate) {
  1286.         this.tickRate = this.frameRate * this.subFrameRate;
  1287.       } else {
  1288.         this.tickRate = 1;
  1289.       }
  1290.     }
  1292.     if (frameRateMultiplier) {
  1293.       const multiplierResults = /^(\d+) (\d+)$/g.exec(frameRateMultiplier);
  1294.       if (multiplierResults) {
  1295.         const numerator = Number(multiplierResults[1]);
  1296.         const denominator = Number(multiplierResults[2]);
  1297.         const multiplierNum = numerator / denominator;
  1298.         this.frameRate *= multiplierNum;
  1299.       }
  1300.     }
  1301.   }
  1302. };
  1304. /**
  1305.  * @const
  1306.  * @private {!RegExp}
  1307.  * @example 50.17% 10%
  1308.  */
  1309. shaka.text.TtmlTextParser.percentValues_ =
  1310.     /^(\d{1,2}(?:\.\d+)?|100(?:\.0+)?)% (\d{1,2}(?:\.\d+)?|100(?:\.0+)?)%$/;
  1312. /**
  1313.  * @const
  1314.  * @private {!RegExp}
  1315.  * @example 0.6% 90% 300% 1000%
  1316.  */
  1317. shaka.text.TtmlTextParser.percentValue_ = /^(\d{1,4}(?:\.\d+)?|100)%$/;
  1319. /**
  1320.  * @const
  1321.  * @private {!RegExp}
  1322.  * @example 100px, 8em, 0.80c
  1323.  */
  1324. shaka.text.TtmlTextParser.unitValues_ = /^(\d+px|\d+em|\d*\.?\d+c)$/;
  1326. /**
  1327.  * @const
  1328.  * @private {!RegExp}
  1329.  * @example 100px
  1330.  */
  1331. shaka.text.TtmlTextParser.pixelValues_ = /^(\d+)px (\d+)px$/;
  1333. /**
  1334.  * @const
  1335.  * @private {!RegExp}
  1336.  * @example 00:00:40:07 (7 frames) or 00:00:40:07.1 (7 frames, 1 subframe)
  1337.  */
  1338. shaka.text.TtmlTextParser.timeColonFormatFrames_ =
  1339.     /^(\d{2,}):(\d{2}):(\d{2}):(\d{2})\.?(\d+)?$/;
  1341. /**
  1342.  * @const
  1343.  * @private {!RegExp}
  1344.  * @example 00:00:40 or 00:40
  1345.  */
  1346. shaka.text.TtmlTextParser.timeColonFormat_ = /^(?:(\d{2,}):)?(\d{2}):(\d{2})$/;
  1348. /**
  1349.  * @const
  1350.  * @private {!RegExp}
  1351.  * @example 01:02:43.0345555 or 02:43.03 or 02:45.5
  1352.  */
  1353. shaka.text.TtmlTextParser.timeColonFormatMilliseconds_ =
  1354.     /^(?:(\d{2,}):)?(\d{2}):(\d{2}\.\d+)$/;
  1356. /**
  1357.  * @const
  1358.  * @private {!RegExp}
  1359.  * @example 75f or 75.5f
  1360.  */
  1361. shaka.text.TtmlTextParser.timeFramesFormat_ = /^(\d*(?:\.\d*)?)f$/;
  1363. /**
  1364.  * @const
  1365.  * @private {!RegExp}
  1366.  * @example 50t or 50.5t
  1367.  */
  1368. shaka.text.TtmlTextParser.timeTickFormat_ = /^(\d*(?:\.\d*)?)t$/;
  1370. /**
  1371.  * @const
  1372.  * @private {!RegExp}
  1373.  * @example 3.45h, 3m or 4.20s
  1374.  */
  1375. shaka.text.TtmlTextParser.timeHMSFormat_ =
  1376.     new RegExp(['^(?:(\\d*(?:\\.\\d*)?)h)?',
  1377.       '(?:(\\d*(?:\\.\\d*)?)m)?',
  1378.       '(?:(\\d*(?:\\.\\d*)?)s)?',
  1379.       '(?:(\\d*(?:\\.\\d*)?)ms)?$'].join(''));
  1381. /**
  1382.  * @const
  1383.  * @private {!Object.<string, shaka.text.Cue.lineAlign>}
  1384.  */
  1385. shaka.text.TtmlTextParser.textAlignToLineAlign_ = {
  1386.   'left': shaka.text.Cue.lineAlign.START,
  1387.   'center': shaka.text.Cue.lineAlign.CENTER,
  1388.   'right': shaka.text.Cue.lineAlign.END,
  1389.   'start': shaka.text.Cue.lineAlign.START,
  1390.   'end': shaka.text.Cue.lineAlign.END,
  1391. };
  1393. /**
  1394.  * @const
  1395.  * @private {!Object.<string, shaka.text.Cue.positionAlign>}
  1396.  */
  1397. shaka.text.TtmlTextParser.textAlignToPositionAlign_ = {
  1398.   'left': shaka.text.Cue.positionAlign.LEFT,
  1399.   'center': shaka.text.Cue.positionAlign.CENTER,
  1400.   'right': shaka.text.Cue.positionAlign.RIGHT,
  1401. };
  1403. /**
  1404.  * The namespace URL for TTML parameters.  Can be assigned any name in the TTML
  1405.  * document, not just "ttp:", so we use this with getAttributeNS() to ensure
  1406.  * that we support arbitrary namespace names.
  1407.  *
  1408.  * @const {!Array.<string>}
  1409.  * @private
  1410.  */
  1411. shaka.text.TtmlTextParser.parameterNs_ = [
  1412.   'http://www.w3.org/ns/ttml#parameter',
  1413.   'http://www.w3.org/2006/10/ttaf1#parameter',
  1414. ];
  1416. /**
  1417.  * The namespace URL for TTML styles.  Can be assigned any name in the TTML
  1418.  * document, not just "tts:", so we use this with getAttributeNS() to ensure
  1419.  * that we support arbitrary namespace names.
  1420.  *
  1421.  * @const {!Array.<string>}
  1422.  * @private
  1423.  */
  1424. shaka.text.TtmlTextParser.styleNs_ = [
  1425.   'http://www.w3.org/ns/ttml#styling',
  1426.   'http://www.w3.org/2006/10/ttaf1#styling',
  1427. ];
  1429. /**
  1430.  * The namespace URL for EBU TTML styles.  Can be assigned any name in the TTML
  1431.  * document, not just "ebutts:", so we use this with getAttributeNS() to ensure
  1432.  * that we support arbitrary namespace names.
  1433.  *
  1434.  * @const {string}
  1435.  * @private
  1436.  */
  1437. shaka.text.TtmlTextParser.styleEbuttsNs_ = 'urn:ebu:tt:style';
  1439. /**
  1440.  * The supported namespace URLs for SMPTE fields.
  1441.  * @const {!Array.<string>}
  1442.  * @private
  1443.  */
  1444. shaka.text.TtmlTextParser.smpteNsList_ = [
  1445.   'http://www.smpte-ra.org/schemas/2052-1/2010/smpte-tt',
  1446.   'http://www.smpte-ra.org/schemas/2052-1/2013/smpte-tt',
  1447. ];
  1449. shaka.text.TextEngine.registerParser(
  1450.     'application/ttml+xml', () => new shaka.text.TtmlTextParser());