Move VTT functionality from TextTrackCue.* to VTTCue.*

Source/core/html/track/vtt/VTTCue.cpp

 /*
  * Copyright (c) 2013, Opera Software ASA. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 12 matching lines @@
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/html/track/vtt/VTTCue.h"
 
+#include "CSSPropertyNames.h"
+#include "CSSValueKeywords.h"
+#include "RuntimeEnabledFeatures.h"
+#include "bindings/v8/ExceptionMessages.h"
+#include "bindings/v8/ExceptionStatePlaceholder.h"
+#include "core/dom/DocumentFragment.h"
+#include "core/dom/NodeTraversal.h"
+#include "core/events/Event.h"
+#include "core/html/HTMLDivElement.h"
+#include "core/html/track/TextTrack.h"
+#include "core/html/track/TextTrackCueList.h"
+#include "core/html/track/vtt/VTTElement.h"
+#include "core/html/track/vtt/VTTParser.h"
+#include "core/html/track/vtt/VTTRegionList.h"
+#include "core/rendering/RenderVTTCue.h"
+#include "wtf/MathExtras.h"
+#include "wtf/text/StringBuilder.h"
+
 namespace WebCore {
 
+static const int undefinedPosition = -1;
+
+static const CSSValueID displayWritingModeMap[] = {
+    CSSValueHorizontalTb, CSSValueVerticalRl, CSSValueVerticalLr
+};
+COMPILE_ASSERT(WTF_ARRAY_LENGTH(displayWritingModeMap) == VTTCue::NumberOfWritingDirections,
+    displayWritingModeMap_has_wrong_size);
+
+static const CSSValueID displayAlignmentMap[] = {
+    CSSValueStart, CSSValueCenter, CSSValueEnd, CSSValueLeft, CSSValueRight
+};
+COMPILE_ASSERT(WTF_ARRAY_LENGTH(displayAlignmentMap) == VTTCue::NumberOfAlignments,
+    displayAlignmentMap_has_wrong_size);
+
+static const String& startKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, start, ("start"));
+    return start;
+}
+
+static const String& middleKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, middle, ("middle"));
+    return middle;
+}
+
+static const String& endKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, end, ("end"));
+    return end;
+}
+
+static const String& leftKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, left, ("left"));
+    return left;
+}
+
+static const String& rightKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, right, ("right"));
+    return right;
+}
+
+static const String& horizontalKeyword()
+{
+    return emptyString();
+}
+
+static const String& verticalGrowingLeftKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, verticalrl, ("rl"));
+    return verticalrl;
+}
+
+static const String& verticalGrowingRightKeyword()
+{
+    DEFINE_STATIC_LOCAL(const String, verticallr, ("lr"));
+    return verticallr;
+}
+
+static bool isInvalidPercentage(double value, const char* method, ExceptionState& exceptionState)
+{
+    if (TextTrackCue::isInfiniteOrNonNumber(value, method, exceptionState))
+        return true;
+    if (value < 0 || value > 100) {
+        exceptionState.throwDOMException(IndexSizeError, ExceptionMessages::failedToSet(method, "TextTrackCue", "The value provided (" + String::number(value) + ") is not between 0 and 100."));
+        return true;
+    }
+    return false;
+}
+
+// ----------------------------
+
+VTTCueBox::VTTCueBox(Document& document, VTTCue* cue)
+    : TextTrackCueBox(document)
+    , m_cue(cue)
+{
+    setPart(textTrackCueBoxShadowPseudoId());
+}
+
+void VTTCueBox::applyCSSProperties(const IntSize&)
+{
+    // FIXME: Apply all the initial CSS positioning properties. http://wkb.ug/79916
+    if (!m_cue->regionId().isEmpty()) {
+        setInlineStyleProperty(CSSPropertyPosition, CSSValueRelative);
+        return;
+    }
+
+    // 3.5.1 On the (root) List of WebVTT Node Objects:
+
+    // the 'position' property must be set to 'absolute'
+    setInlineStyleProperty(CSSPropertyPosition, CSSValueAbsolute);
+
+    //  the 'unicode-bidi' property must be set to 'plaintext'
+    setInlineStyleProperty(CSSPropertyUnicodeBidi, CSSValueWebkitPlaintext);
+
+    // the 'direction' property must be set to direction
+    setInlineStyleProperty(CSSPropertyDirection, m_cue->getCSSWritingDirection());
+
+    // the 'writing-mode' property must be set to writing-mode
+    setInlineStyleProperty(CSSPropertyWebkitWritingMode, m_cue->getCSSWritingMode());
+
+    std::pair<float, float> position = m_cue->getCSSPosition();
+
+    // the 'top' property must be set to top,
+    setInlineStyleProperty(CSSPropertyTop, position.second, CSSPrimitiveValue::CSS_PERCENTAGE);
+
+    // the 'left' property must be set to left
+    setInlineStyleProperty(CSSPropertyLeft, position.first, CSSPrimitiveValue::CSS_PERCENTAGE);
+
+    // the 'width' property must be set to width, and the 'height' property  must be set to height
+    if (m_cue->vertical() == horizontalKeyword()) {
+        setInlineStyleProperty(CSSPropertyWidth, static_cast<double>(m_cue->getCSSSize()), CSSPrimitiveValue::CSS_PERCENTAGE);
+        setInlineStyleProperty(CSSPropertyHeight, CSSValueAuto);
+    } else {
+        setInlineStyleProperty(CSSPropertyWidth, CSSValueAuto);
+        setInlineStyleProperty(CSSPropertyHeight, static_cast<double>(m_cue->getCSSSize()),  CSSPrimitiveValue::CSS_PERCENTAGE);
+    }
+
+    // The 'text-align' property on the (root) List of WebVTT Node Objects must
+    // be set to the value in the second cell of the row of the table below
+    // whose first cell is the value of the corresponding cue's text track cue
+    // alignment:
+    setInlineStyleProperty(CSSPropertyTextAlign, m_cue->getCSSAlignment());
+
+    if (!m_cue->snapToLines()) {
+        // 10.13.1 Set up x and y:
+        // Note: x and y are set through the CSS left and top above.
+
+        // 10.13.2 Position the boxes in boxes such that the point x% along the
+        // width of the bounding box of the boxes in boxes is x% of the way
+        // across the width of the video's rendering area, and the point y%
+        // along the height of the bounding box of the boxes in boxes is y%
+        // of the way across the height of the video's rendering area, while
+        // maintaining the relative positions of the boxes in boxes to each
+        // other.
+        setInlineStyleProperty(CSSPropertyWebkitTransform,
+            String::format("translate(-%.2f%%, -%.2f%%)", position.first, position.second));
+
+        setInlineStyleProperty(CSSPropertyWhiteSpace, CSSValuePre);
+    }
+}
+
+RenderObject* VTTCueBox::createRenderer(RenderStyle*)
+{
+    return new RenderVTTCue(this);
+}
+
+// ----------------------------
+
 VTTCue::VTTCue(Document& document, double startTime, double endTime, const String& text)
-    : TextTrackCue(document, startTime, endTime, text)
+    : TextTrackCue(startTime, endTime)
+    , m_text(text)
+    , m_linePosition(undefinedPosition)
+    , m_computedLinePosition(undefinedPosition)
+    , m_textPosition(50)
+    , m_cueSize(100)
+    , m_writingDirection(Horizontal)
+    , m_cueAlignment(Middle)
+    , m_vttNodeTree(0)
+    , m_snapToLines(true)
+    , m_cueBackgroundBox(HTMLDivElement::create(document))
+    , m_displayTreeShouldChange(true)
+    , m_displayDirection(CSSValueLtr)
+    , m_notifyRegion(true)
 {
     ScriptWrappable::init(this);
 }
 
-PassRefPtr<VTTCue> VTTCue::create(Document& document, double startTime, double endTime, const String& text)
-{
-    return adoptRef(new VTTCue(document, startTime, endTime, text));
+VTTCue::~VTTCue()
+{
+    displayTreeInternal()->remove(ASSERT_NO_EXCEPTION);
+}
+
+String VTTCue::toString() const
+{
+    return String::format("%p id=%s interval=%f-->%f cue=%s)", this, id().utf8().data(), startTime(), endTime(), text().utf8().data());
+}
+
+PassRefPtr<VTTCueBox> VTTCue::displayTreeInternal()
+{
+    if (!m_displayTree)
+        m_displayTree = VTTCueBox::create(document(), this);
+    return m_displayTree;
+}
+
+void VTTCue::cueDidChange()
+{
+    TextTrackCue::cueDidChange();
+    m_displayTreeShouldChange = true;
+}
+
+const String& VTTCue::vertical() const
+{
+    switch (m_writingDirection) {
+    case Horizontal:
+        return horizontalKeyword();
+    case VerticalGrowingLeft:
+        return verticalGrowingLeftKeyword();
+    case VerticalGrowingRight:
+        return verticalGrowingRightKeyword();
+    default:
+        ASSERT_NOT_REACHED();
+        return emptyString();
+    }
+}
+
+void VTTCue::setVertical(const String& value, ExceptionState& exceptionState)
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#dom-texttrackcue-vertical
+    // On setting, the text track cue writing direction must be set to the value given
+    // in the first cell of the row in the table above whose second cell is a
+    // case-sensitive match for the new value, if any. If none of the values match, then
+    // the user agent must instead throw a SyntaxError exception.
+
+    WritingDirection direction = m_writingDirection;
+    if (value == horizontalKeyword())
+        direction = Horizontal;
+    else if (value == verticalGrowingLeftKeyword())
+        direction = VerticalGrowingLeft;
+    else if (value == verticalGrowingRightKeyword())
+        direction = VerticalGrowingRight;
+    else
+        exceptionState.throwDOMException(SyntaxError, ExceptionMessages::failedToSet("vertical", "TextTrackCue", "The value provided ('" + value + "') is invalid. Only 'rl', 'lr', and the empty string are accepted."));
+
+    if (direction == m_writingDirection)
+        return;
+
+    cueWillChange();
+    m_writingDirection = direction;
+    cueDidChange();
+}
+
+void VTTCue::setSnapToLines(bool value)
+{
+    if (m_snapToLines == value)
+        return;
+
+    cueWillChange();
+    m_snapToLines = value;
+    cueDidChange();
+}
+
+void VTTCue::setLine(int position, ExceptionState& exceptionState)
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#dom-texttrackcue-line
+    // On setting, if the text track cue snap-to-lines flag is not set, and the new
+    // value is negative or greater than 100, then throw an IndexSizeError exception.
+    if (!m_snapToLines && (position < 0 || position > 100)) {
+        exceptionState.throwDOMException(IndexSizeError, ExceptionMessages::failedToSet("line", "TextTrackCue", "The snap-to-lines flag is not set, and the value provided (" + String::number(position) + ") is not between 0 and 100."));
+        return;
+    }
+
+    // Otherwise, set the text track cue line position to the new value.
+    if (m_linePosition == position)
+        return;
+
+    cueWillChange();
+    m_linePosition = position;
+    m_computedLinePosition = calculateComputedLinePosition();
+    cueDidChange();
+}
+
+void VTTCue::setPosition(int position, ExceptionState& exceptionState)
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#dom-texttrackcue-position
+    // On setting, if the new value is negative or greater than 100, then throw an IndexSizeError exception.
+    // Otherwise, set the text track cue text position to the new value.
+    if (isInvalidPercentage(position, "line", exceptionState))
+        return;
+
+    // Otherwise, set the text track cue line position to the new value.
+    if (m_textPosition == position)
+        return;
+
+    cueWillChange();
+    m_textPosition = position;
+    cueDidChange();
+}
+
+void VTTCue::setSize(int size, ExceptionState& exceptionState)
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#dom-texttrackcue-size
+    // On setting, if the new value is negative or greater than 100, then throw an IndexSizeError
+    // exception. Otherwise, set the text track cue size to the new value.
+    if (isInvalidPercentage(size, "line", exceptionState))
+        return;
+
+    // Otherwise, set the text track cue line position to the new value.
+    if (m_cueSize == size)
+        return;
+
+    cueWillChange();
+    m_cueSize = size;
+    cueDidChange();
+}
+
+const String& VTTCue::align() const
+{
+    switch (m_cueAlignment) {
+    case Start:
+        return startKeyword();
+    case Middle:
+        return middleKeyword();
+    case End:
+        return endKeyword();
+    case Left:
+        return leftKeyword();
+    case Right:
+        return rightKeyword();
+    default:
+        ASSERT_NOT_REACHED();
+        return emptyString();
+    }
+}
+
+void VTTCue::setAlign(const String& value, ExceptionState& exceptionState)
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#dom-texttrackcue-align
+    // On setting, the text track cue alignment must be set to the value given in the
+    // first cell of the row in the table above whose second cell is a case-sensitive
+    // match for the new value, if any. If none of the values match, then the user
+    // agent must instead throw a SyntaxError exception.
+
+    CueAlignment alignment = m_cueAlignment;
+    if (value == startKeyword())
+        alignment = Start;
+    else if (value == middleKeyword())
+        alignment = Middle;
+    else if (value == endKeyword())
+        alignment = End;
+    else if (value == leftKeyword())
+        alignment = Left;
+    else if (value == rightKeyword())
+        alignment = Right;
+    else
+        exceptionState.throwDOMException(SyntaxError, ExceptionMessages::failedToSet("align", "TextTrackCue", "The value provided ('" + value + "') is invalid. Only 'start', 'middle', 'end', 'left', and 'right' are accepted."));
+
+    if (alignment == m_cueAlignment)
+        return;
+
+    cueWillChange();
+    m_cueAlignment = alignment;
+    cueDidChange();
+}
+
+void VTTCue::setText(const String& text)
+{
+    if (m_text == text)
+        return;
+
+    cueWillChange();
+    // Clear the document fragment but don't bother to create it again just yet as we can do that
+    // when it is requested.
+    m_vttNodeTree = 0;
+    m_text = text;
+    cueDidChange();
+}
+
+void VTTCue::createVTTNodeTree()
+{
+    if (!m_vttNodeTree)
+        m_vttNodeTree = VTTParser::createDocumentFragmentFromCueText(document(), m_text);
+}
+
+void VTTCue::copyVTTNodeToDOMTree(ContainerNode* vttNode, ContainerNode* parent)
+{
+    for (Node* node = vttNode->firstChild(); node; node = node->nextSibling()) {
+        RefPtr<Node> clonedNode;
+        if (node->isVTTElement())
+            clonedNode = toVTTElement(node)->createEquivalentHTMLElement(document());
+        else
+            clonedNode = node->cloneNode(false);
+        parent->appendChild(clonedNode);
+        if (node->isContainerNode())
+            copyVTTNodeToDOMTree(toContainerNode(node), toContainerNode(clonedNode));
+    }
+}
+
+PassRefPtr<DocumentFragment> VTTCue::getCueAsHTML()
+{
+    createVTTNodeTree();
+    RefPtr<DocumentFragment> clonedFragment = DocumentFragment::create(document());
+    copyVTTNodeToDOMTree(m_vttNodeTree.get(), clonedFragment.get());
+    return clonedFragment.release();
+}
+
+PassRefPtr<DocumentFragment> VTTCue::createCueRenderingTree()
+{
+    RefPtr<DocumentFragment> clonedFragment;
+    createVTTNodeTree();
+    clonedFragment = DocumentFragment::create(document());
+    m_vttNodeTree->cloneChildNodes(clonedFragment.get());
+    return clonedFragment.release();
+}
+
+void VTTCue::setRegionId(const String& regionId)
+{
+    if (m_regionId == regionId)
+        return;
+
+    cueWillChange();
+    m_regionId = regionId;
+    cueDidChange();
+}
+
+void VTTCue::notifyRegionWhenRemovingDisplayTree(bool notifyRegion)
+{
+    m_notifyRegion = notifyRegion;
+}
+
+int VTTCue::calculateComputedLinePosition()
+{
+    // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#text-track-cue-computed-line-position
+
+    // If the text track cue line position is numeric, then that is the text
+    // track cue computed line position.
+    if (m_linePosition != undefinedPosition)
+        return m_linePosition;
+
+    // If the text track cue snap-to-lines flag of the text track cue is not
+    // set, the text track cue computed line position is the value 100;
+    if (!m_snapToLines)
+        return 100;
+
+    // Otherwise, it is the value returned by the following algorithm:
+
+    // If cue is not associated with a text track, return -1 and abort these
+    // steps.
+    if (!track())
+        return -1;
+
+    // Let n be the number of text tracks whose text track mode is showing or
+    // showing by default and that are in the media element's list of text
+    // tracks before track.
+    int n = track()->trackIndexRelativeToRenderedTracks();
+
+    // Increment n by one.
+    n++;
+
+    // Negate n.
+    n = -n;
+
+    return n;
+}
+
+static bool isCueParagraphSeparator(UChar character)
+{
+    // Within a cue, paragraph boundaries are only denoted by Type B characters,
+    // such as U+000A LINE FEED (LF), U+0085 NEXT LINE (NEL), and U+2029 PARAGRAPH SEPARATOR.
+    return WTF::Unicode::category(character) & WTF::Unicode::Separator_Paragraph;
+}
+
+void VTTCue::determineTextDirection()
+{
+    DEFINE_STATIC_LOCAL(const String, rtTag, ("rt"));
+    createVTTNodeTree();
+
+    // Apply the Unicode Bidirectional Algorithm's Paragraph Level steps to the
+    // concatenation of the values of each WebVTT Text Object in nodes, in a
+    // pre-order, depth-first traversal, excluding WebVTT Ruby Text Objects and
+    // their descendants.
+    StringBuilder paragraphBuilder;
+    for (Node* node = m_vttNodeTree->firstChild(); node; node = NodeTraversal::next(*node, m_vttNodeTree.get())) {
+        if (!node->isTextNode() || node->localName() == rtTag)
+            continue;
+
+        paragraphBuilder.append(node->nodeValue());
+    }
+
+    String paragraph = paragraphBuilder.toString();
+    if (!paragraph.length())
+        return;
+
+    for (size_t i = 0; i < paragraph.length(); ++i) {
+        UChar current = paragraph[i];
+        if (!current || isCueParagraphSeparator(current))
+            return;
+
+        if (UChar current = paragraph[i]) {
+            WTF::Unicode::Direction charDirection = WTF::Unicode::direction(current);
+            if (charDirection == WTF::Unicode::LeftToRight) {
+                m_displayDirection = CSSValueLtr;
+                return;
+            }
+            if (charDirection == WTF::Unicode::RightToLeft
+                || charDirection == WTF::Unicode::RightToLeftArabic) {
+                m_displayDirection = CSSValueRtl;
+                return;
+            }
+        }
+    }
+}
+
+void VTTCue::calculateDisplayParameters()
+{
+    // Steps 10.2, 10.3
+    determineTextDirection();
+
+    // 10.4 If the text track cue writing direction is horizontal, then let
+    // block-flow be 'tb'. Otherwise, if the text track cue writing direction is
+    // vertical growing left, then let block-flow be 'lr'. Otherwise, the text
+    // track cue writing direction is vertical growing right; let block-flow be
+    // 'rl'.
+
+    // The above step is done through the writing direction static map.
+
+    // 10.5 Determine the value of maximum size for cue as per the appropriate
+    // rules from the following list:
+    int maximumSize = m_textPosition;
+    if ((m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueLtr)
+        || (m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueRtl)
+        || (m_writingDirection == Horizontal && m_cueAlignment == Left)
+        || (m_writingDirection == VerticalGrowingLeft && (m_cueAlignment == Start || m_cueAlignment == Left))
+        || (m_writingDirection == VerticalGrowingRight && (m_cueAlignment == Start || m_cueAlignment == Left))) {
+        maximumSize = 100 - m_textPosition;
+    } else if ((m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueLtr)
+        || (m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueRtl)
+        || (m_writingDirection == Horizontal && m_cueAlignment == Right)
+        || (m_writingDirection == VerticalGrowingLeft && (m_cueAlignment == End || m_cueAlignment == Right))
+        || (m_writingDirection == VerticalGrowingRight && (m_cueAlignment == End || m_cueAlignment == Right))) {
+        maximumSize = m_textPosition;
+    } else if (m_cueAlignment == Middle) {
+        maximumSize = m_textPosition <= 50 ? m_textPosition : (100 - m_textPosition);
+        maximumSize = maximumSize * 2;
+    } else {
+        ASSERT_NOT_REACHED();
+    }
+
+    // 10.6 If the text track cue size is less than maximum size, then let size
+    // be text track cue size. Otherwise, let size be maximum size.
+    m_displaySize = std::min(m_cueSize, maximumSize);
+
+    // FIXME: Understand why step 10.7 is missing (just a copy/paste error?)
+    // Could be done within a spec implementation check - http://crbug.com/301580
+
+    // 10.8 Determine the value of x-position or y-position for cue as per the
+    // appropriate rules from the following list:
+    if (m_writingDirection == Horizontal) {
+        switch (m_cueAlignment) {
+        case Start:
+            if (m_displayDirection == CSSValueLtr)
+                m_displayPosition.first = m_textPosition;
+            else
+                m_displayPosition.first = 100 - m_textPosition - m_displaySize;
+            break;
+        case End:
+            if (m_displayDirection == CSSValueRtl)
+                m_displayPosition.first = 100 - m_textPosition;
+            else
+                m_displayPosition.first = m_textPosition - m_displaySize;
+            break;
+        case Left:
+            if (m_displayDirection == CSSValueLtr)
+                m_displayPosition.first = m_textPosition;
+            else
+                m_displayPosition.first = 100 - m_textPosition;
+            break;
+        case Right:
+            if (m_displayDirection == CSSValueLtr)
+                m_displayPosition.first = m_textPosition - m_displaySize;
+            else
+                m_displayPosition.first = 100 - m_textPosition - m_displaySize;
+            break;
+        case Middle:
+            if (m_displayDirection == CSSValueLtr)
+                m_displayPosition.first = m_textPosition - m_displaySize / 2;
+            else
+                m_displayPosition.first = 100 - m_textPosition - m_displaySize / 2;
+            break;
+        case NumberOfAlignments:
+            ASSERT_NOT_REACHED();
+        }
+    } else {
+        // Cases for m_writingDirection being VerticalGrowing{Left|Right}
+        switch (m_cueAlignment) {
+        case Start:
+        case Left:
+            m_displayPosition.second = m_textPosition;
+            break;
+        case End:
+        case Right:
+            m_displayPosition.second = m_textPosition - m_displaySize;
+            break;
+        case Middle:
+            m_displayPosition.second = m_textPosition - m_displaySize / 2;
+            break;
+        case NumberOfAlignments:
+            ASSERT_NOT_REACHED();
+        }
+    }
+
+    // A text track cue has a text track cue computed line position whose value
+    // is defined in terms of the other aspects of the cue.
+    m_computedLinePosition = calculateComputedLinePosition();
+
+    // 10.9 Determine the value of whichever of x-position or y-position is not
+    // yet calculated for cue as per the appropriate rules from the following
+    // list:
+    if (m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
+        m_displayPosition.second = 0;
+
+    if (!m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
+        m_displayPosition.second = m_computedLinePosition;
+
+    if (m_snapToLines && m_displayPosition.first == undefinedPosition
+        && (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
+        m_displayPosition.first = 0;
+
+    if (!m_snapToLines && (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
+        m_displayPosition.first = m_computedLinePosition;
+}
+
+void VTTCue::markFutureAndPastNodes(ContainerNode* root, double previousTimestamp, double movieTime)
+{
+    DEFINE_STATIC_LOCAL(const String, timestampTag, ("timestamp"));
+
+    bool isPastNode = true;
+    double currentTimestamp = previousTimestamp;
+    if (currentTimestamp > movieTime)
+        isPastNode = false;
+
+    for (Node* child = root->firstChild(); child; child = NodeTraversal::next(*child, root)) {
+        if (child->nodeName() == timestampTag) {
+            unsigned position = 0;
+            String timestamp = child->nodeValue();
+            double currentTimestamp = VTTParser::collectTimeStamp(timestamp, &position);
+            ASSERT(currentTimestamp != -1);
+
+            if (currentTimestamp > movieTime)
+                isPastNode = false;
+        }
+
+        if (child->isVTTElement()) {
+            toVTTElement(child)->setIsPastNode(isPastNode);
+            // Make an elemenet id match a cue id for style matching purposes.
+            if (!id().isEmpty())
+                toElement(child)->setIdAttribute(id());
+        }
+    }
+}
+
+void VTTCue::updateDisplayTree(double movieTime)
+{
+    // The display tree may contain WebVTT timestamp objects representing
+    // timestamps (processing instructions), along with displayable nodes.
+
+    if (!track()->isRendered())
+        return;
+
+    // Clear the contents of the set.
+    m_cueBackgroundBox->removeChildren();
+
+    // Update the two sets containing past and future WebVTT objects.
+    RefPtr<DocumentFragment> referenceTree = createCueRenderingTree();
+    markFutureAndPastNodes(referenceTree.get(), startTime(), movieTime);
+    m_cueBackgroundBox->appendChild(referenceTree, ASSERT_NO_EXCEPTION);
+}
+
+PassRefPtr<TextTrackCueBox> VTTCue::getDisplayTree(const IntSize& videoSize)
+{
+    RefPtr<VTTCueBox> displayTree = displayTreeInternal();
+    if (!m_displayTreeShouldChange || !track()->isRendered())
+        return displayTree;
+
+    // 10.1 - 10.10
+    calculateDisplayParameters();
+
+    // 10.11. Apply the terms of the CSS specifications to nodes within the
+    // following constraints, thus obtaining a set of CSS boxes positioned
+    // relative to an initial containing block:
+    displayTree->removeChildren();
+
+    // The document tree is the tree of WebVTT Node Objects rooted at nodes.
+
+    // The children of the nodes must be wrapped in an anonymous box whose
+    // 'display' property has the value 'inline'. This is the WebVTT cue
+    // background box.
+
+    // Note: This is contained by default in m_cueBackgroundBox.
+    m_cueBackgroundBox->setPart(cueShadowPseudoId());
+    displayTree->appendChild(m_cueBackgroundBox);
+
+    // FIXME(BUG 79916): Runs of children of WebVTT Ruby Objects that are not
+    // WebVTT Ruby Text Objects must be wrapped in anonymous boxes whose
+    // 'display' property has the value 'ruby-base'.
+
+    // FIXME(BUG 79916): Text runs must be wrapped according to the CSS
+    // line-wrapping rules, except that additionally, regardless of the value of
+    // the 'white-space' property, lines must be wrapped at the edge of their
+    // containing blocks, even if doing so requires splitting a word where there
+    // is no line breaking opportunity. (Thus, normally text wraps as needed,
+    // but if there is a particularly long word, it does not overflow as it
+    // normally would in CSS, it is instead forcibly wrapped at the box's edge.)
+    displayTree->applyCSSProperties(videoSize);
+
+    m_displayTreeShouldChange = false;
+
+    // 10.15. Let cue's text track cue display state have the CSS boxes in
+    // boxes.
+    return displayTree;
+}
+
+void VTTCue::removeDisplayTree()
+{
+    if (m_notifyRegion && track()->regions()) {
+        // The region needs to be informed about the cue removal.
+        VTTRegion* region = track()->regions()->getRegionById(m_regionId);
+        if (region)
+            region->willRemoveTextTrackCueBox(m_displayTree.get());
+    }
+
+    displayTreeInternal()->remove(ASSERT_NO_EXCEPTION);
+}
+
+void VTTCue::updateDisplay(const IntSize& videoSize, HTMLDivElement& container)
+{
+    RefPtr<TextTrackCueBox> displayBox = getDisplayTree(videoSize);
+    VTTRegion* region = 0;
+    if (track()->regions())
+        region = track()->regions()->getRegionById(regionId());
+
+    if (!region) {
+        // If cue has an empty text track cue region identifier or there is no
+        // WebVTT region whose region identifier is identical to cue's text
+        // track cue region identifier, run the following substeps:
+        if (displayBox->hasChildNodes() && !container.contains(displayBox.get())) {
+            // Note: the display tree of a cue is removed when the active flag of the cue is unset.
+            container.appendChild(displayBox);
+        }
+    } else {
+        // Let region be the WebVTT region whose region identifier
+        // matches the text track cue region identifier of cue.
+        RefPtr<HTMLDivElement> regionNode = region->getDisplayTree(document());
+
+        // Append the region to the viewport, if it was not already.
+        if (!container.contains(regionNode.get()))
+            container.appendChild(regionNode);
+
+        region->appendTextTrackCueBox(displayBox);
+    }
+}
+
+std::pair<double, double> VTTCue::getPositionCoordinates() const
+{
+    // This method is used for setting x and y when snap to lines is not set.
+    std::pair<double, double> coordinates;
+
+    if (m_writingDirection == Horizontal && m_displayDirection == CSSValueLtr) {
+        coordinates.first = m_textPosition;
+        coordinates.second = m_computedLinePosition;
+
+        return coordinates;
+    }
+
+    if (m_writingDirection == Horizontal && m_displayDirection == CSSValueRtl) {
+        coordinates.first = 100 - m_textPosition;
+        coordinates.second = m_computedLinePosition;
+
+        return coordinates;
+    }
+
+    if (m_writingDirection == VerticalGrowingLeft) {
+        coordinates.first = 100 - m_computedLinePosition;
+        coordinates.second = m_textPosition;
+
+        return coordinates;
+    }
+
+    if (m_writingDirection == VerticalGrowingRight) {
+        coordinates.first = m_computedLinePosition;
+        coordinates.second = m_textPosition;
+
+        return coordinates;
+    }
+
+    ASSERT_NOT_REACHED();
+
+    return coordinates;
+}
+
+VTTCue::CueSetting VTTCue::settingName(const String& name)
+{
+    DEFINE_STATIC_LOCAL(const String, verticalKeyword, ("vertical"));
+    DEFINE_STATIC_LOCAL(const String, lineKeyword, ("line"));
+    DEFINE_STATIC_LOCAL(const String, positionKeyword, ("position"));
+    DEFINE_STATIC_LOCAL(const String, sizeKeyword, ("size"));
+    DEFINE_STATIC_LOCAL(const String, alignKeyword, ("align"));
+    DEFINE_STATIC_LOCAL(const String, regionIdKeyword, ("region"));
+
+    if (name == verticalKeyword)
+        return Vertical;
+    if (name == lineKeyword)
+        return Line;
+    if (name == positionKeyword)
+        return Position;
+    if (name == sizeKeyword)
+        return Size;
+    if (name == alignKeyword)
+        return Align;
+    if (RuntimeEnabledFeatures::webVTTRegionsEnabled() && name == regionIdKeyword)
+        return RegionId;
+
+    return None;
+}
+
+void VTTCue::parseSettings(const String& input)
+{
+    unsigned position = 0;
+
+    while (position < input.length()) {
+
+        // The WebVTT cue settings part of a WebVTT cue consists of zero or more of the following components, in any order,
+        // separated from each other by one or more U+0020 SPACE characters or U+0009 CHARACTER TABULATION (tab) characters.
+        while (position < input.length() && VTTParser::isValidSettingDelimiter(input[position]))
+            position++;
+        if (position >= input.length())
+            break;
+
+        // When the user agent is to parse the WebVTT settings given by a string input for a text track cue cue,
+        // the user agent must run the following steps:
+        // 1. Let settings be the result of splitting input on spaces.
+        // 2. For each token setting in the list settings, run the following substeps:
+        //    1. If setting does not contain a U+003A COLON character (:), or if the first U+003A COLON character (:)
+        //       in setting is either the first or last character of setting, then jump to the step labeled next setting.
+        unsigned endOfSetting = position;
+        String setting = VTTParser::collectWord(input, &endOfSetting);
+        CueSetting name;
+        size_t colonOffset = setting.find(':', 1);
+        if (colonOffset == kNotFound || !colonOffset || colonOffset == setting.length() - 1)
+            goto NextSetting;
+
+        // 2. Let name be the leading substring of setting up to and excluding the first U+003A COLON character (:) in that string.
+        name = settingName(setting.substring(0, colonOffset));
+
+        // 3. Let value be the trailing substring of setting starting from the character immediately after the first U+003A COLON character (:) in that string.
+        position += colonOffset + 1;
+        if (position >= input.length())
+            break;
+
+        // 4. Run the appropriate substeps that apply for the value of name, as follows:
+        switch (name) {
+        case Vertical:
+            {
+            // If name is a case-sensitive match for "vertical"
+            // 1. If value is a case-sensitive match for the string "rl", then let cue's text track cue writing direction
+            //    be vertical growing left.
+            String writingDirection = VTTParser::collectWord(input, &position);
+            if (writingDirection == verticalGrowingLeftKeyword())
+                m_writingDirection = VerticalGrowingLeft;
+
+            // 2. Otherwise, if value is a case-sensitive match for the string "lr", then let cue's text track cue writing
+            //    direction be vertical growing right.
+            else if (writingDirection == verticalGrowingRightKeyword())
+                m_writingDirection = VerticalGrowingRight;
+            }
+            break;
+        case Line:
+            {
+            // 1-2 - Collect chars that are either '-', '%', or a digit.
+            // 1. If value contains any characters other than U+002D HYPHEN-MINUS characters (-), U+0025 PERCENT SIGN
+            //    characters (%), and characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then jump
+            //    to the step labeled next setting.
+            StringBuilder linePositionBuilder;
+            while (position < input.length() && (input[position] == '-' || input[position] == '%' || isASCIIDigit(input[position])))
+                linePositionBuilder.append(input[position++]);
+            if (position < input.length() && !VTTParser::isValidSettingDelimiter(input[position]))
+                break;
+
+            // 2. If value does not contain at least one character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+            //    NINE (9), then jump to the step labeled next setting.
+            // 3. If any character in value other than the first character is a U+002D HYPHEN-MINUS character (-), then
+            //    jump to the step labeled next setting.
+            // 4. If any character in value other than the last character is a U+0025 PERCENT SIGN character (%), then
+            //    jump to the step labeled next setting.
+            String linePosition = linePositionBuilder.toString();
+            if (linePosition.find('-', 1) != kNotFound || linePosition.reverseFind("%", linePosition.length() - 2) != kNotFound)
+                break;
+
+            // 5. If the first character in value is a U+002D HYPHEN-MINUS character (-) and the last character in value is a
+            //    U+0025 PERCENT SIGN character (%), then jump to the step labeled next setting.
+            if (linePosition[0] == '-' && linePosition[linePosition.length() - 1] == '%')
+                break;
+
+            // 6. Ignoring the trailing percent sign, if any, interpret value as a (potentially signed) integer, and
+            //    let number be that number.
+            // NOTE: toInt ignores trailing non-digit characters, such as '%'.
+            bool validNumber;
+            int number = linePosition.toInt(&validNumber);
+            if (!validNumber)
+                break;
+
+            // 7. If the last character in value is a U+0025 PERCENT SIGN character (%), but number is not in the range
+            //    0 ≤ number ≤ 100, then jump to the step labeled next setting.
+            // 8. Let cue's text track cue line position be number.
+            // 9. If the last character in value is a U+0025 PERCENT SIGN character (%), then let cue's text track cue
+            //    snap-to-lines flag be false. Otherwise, let it be true.
+            if (linePosition[linePosition.length() - 1] == '%') {
+                if (number < 0 || number > 100)
+                    break;
+
+                // 10 - If '%' then set snap-to-lines flag to false.
+                m_snapToLines = false;
+            }
+
+            m_linePosition = number;
+            }
+            break;
+        case Position:
+            {
+            // 1. If value contains any characters other than U+0025 PERCENT SIGN characters (%) and characters in the range
+            //    U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then jump to the step labeled next setting.
+            // 2. If value does not contain at least one character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9),
+            //    then jump to the step labeled next setting.
+            String textPosition = VTTParser::collectDigits(input, &position);
+            if (textPosition.isEmpty())
+                break;
+            if (position >= input.length())
+                break;
+
+            // 3. If any character in value other than the last character is a U+0025 PERCENT SIGN character (%), then jump
+            //    to the step labeled next setting.
+            // 4. If the last character in value is not a U+0025 PERCENT SIGN character (%), then jump to the step labeled
+            //    next setting.
+            if (input[position++] != '%')
+                break;
+            if (position < input.length() && !VTTParser::isValidSettingDelimiter(input[position]))
+                break;
+
+            // 5. Ignoring the trailing percent sign, interpret value as an integer, and let number be that number.
+            // 6. If number is not in the range 0 ≤ number ≤ 100, then jump to the step labeled next setting.
+            // NOTE: toInt ignores trailing non-digit characters, such as '%'.
+            bool validNumber;
+            int number = textPosition.toInt(&validNumber);
+            if (!validNumber)
+                break;
+            if (number < 0 || number > 100)
+                break;
+
+            // 7. Let cue's text track cue text position be number.
+            m_textPosition = number;
+            }
+            break;
+        case Size:
+            {
+            // 1. If value contains any characters other than U+0025 PERCENT SIGN characters (%) and characters in the
+            //    range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then jump to the step labeled next setting.
+            // 2. If value does not contain at least one character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
+            //    NINE (9), then jump to the step labeled next setting.
+            String cueSize = VTTParser::collectDigits(input, &position);
+            if (cueSize.isEmpty())
+                break;
+            if (position >= input.length())
+                break;
+
+            // 3. If any character in value other than the last character is a U+0025 PERCENT SIGN character (%),
+            //    then jump to the step labeled next setting.
+            // 4. If the last character in value is not a U+0025 PERCENT SIGN character (%), then jump to the step
+            //    labeled next setting.
+            if (input[position++] != '%')
+                break;
+            if (position < input.length() && !VTTParser::isValidSettingDelimiter(input[position]))
+                break;
+
+            // 5. Ignoring the trailing percent sign, interpret value as an integer, and let number be that number.
+            // 6. If number is not in the range 0 ≤ number ≤ 100, then jump to the step labeled next setting.
+            bool validNumber;
+            int number = cueSize.toInt(&validNumber);
+            if (!validNumber)
+                break;
+            if (number < 0 || number > 100)
+                break;
+
+            // 7. Let cue's text track cue size be number.
+            m_cueSize = number;
+            }
+            break;
+        case Align:
+            {
+            String cueAlignment = VTTParser::collectWord(input, &position);
+
+            // 1. If value is a case-sensitive match for the string "start", then let cue's text track cue alignment be start alignment.
+            if (cueAlignment == startKeyword())
+                m_cueAlignment = Start;
+
+            // 2. If value is a case-sensitive match for the string "middle", then let cue's text track cue alignment be middle alignment.
+            else if (cueAlignment == middleKeyword())
+                m_cueAlignment = Middle;
+
+            // 3. If value is a case-sensitive match for the string "end", then let cue's text track cue alignment be end alignment.
+            else if (cueAlignment == endKeyword())
+                m_cueAlignment = End;
+
+            // 4. If value is a case-sensitive match for the string "left", then let cue's text track cue alignment be left alignment.
+            else if (cueAlignment == leftKeyword())
+                m_cueAlignment = Left;
+
+            // 5. If value is a case-sensitive match for the string "right", then let cue's text track cue alignment be right alignment.
+            else if (cueAlignment == rightKeyword())
+                m_cueAlignment = Right;
+            }
+            break;
+        case RegionId:
+            m_regionId = VTTParser::collectWord(input, &position);
+            break;
+        case None:
+            break;
+        }
+
+NextSetting:
+        position = endOfSetting;
+    }
+
+    // If cue's line position is not auto or cue's size is not 100 or cue's
+    // writing direction is not horizontal, but cue's region identifier is not
+    // the empty string, let cue's region identifier be the empty string.
+    if (m_regionId.isEmpty())
+        return;
+
+    if (m_linePosition != undefinedPosition || m_cueSize != 100 || m_writingDirection != Horizontal)
+        m_regionId = emptyString();
+}
+
+CSSValueID VTTCue::getCSSAlignment() const
+{
+    return displayAlignmentMap[m_cueAlignment];
+}
+
+CSSValueID VTTCue::getCSSWritingDirection() const
+{
+    return m_displayDirection;
+}
+
+CSSValueID VTTCue::getCSSWritingMode() const
+{
+    return displayWritingModeMap[m_writingDirection];
+}
+
+int VTTCue::getCSSSize() const
+{
+    return m_displaySize;
+}
+
+std::pair<double, double> VTTCue::getCSSPosition() const
+{
+    if (!m_snapToLines)
+        return getPositionCoordinates();
+
+    return m_displayPosition;
+}
+
+ExecutionContext* VTTCue::executionContext() const
+{
+    ASSERT(m_cueBackgroundBox);
+    return m_cueBackgroundBox->executionContext();
+}
+
+Document& VTTCue::document() const
+{
+    ASSERT(m_cueBackgroundBox);
+    return m_cueBackgroundBox->document();
 }
 
 } // namespace WebCore