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

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This source file includes following definitions.
startKeyword
middleKeyword
endKeyword
leftKeyword
rightKeyword
horizontalKeyword
verticalGrowingLeftKeyword
verticalGrowingRightKeyword
isInvalidPercentage
m_cue
applyCSSProperties
createRenderer
m_notifyRegion
toString
displayTreeInternal
cueDidChange
vertical
setVertical
setSnapToLines
setLine
setPosition
setSize
align
setAlign
setText
createVTTNodeTree
copyVTTNodeToDOMTree
getCueAsHTML
createCueRenderingTree
setRegionId
notifyRegionWhenRemovingDisplayTree
calculateComputedLinePosition
atParagraphSeparator
determineDirectionality
determineTextDirection
calculateDisplayParameters
markFutureAndPastNodes
updateDisplayTree
getDisplayTree
removeDisplayTree
updateDisplay
getPositionCoordinates
settingName
scanPercentage
parseSettings
getCSSAlignment
getCSSWritingDirection
getCSSWritingMode
getCSSSize
getCSSPosition
executionContext
document
/*
 * 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
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Opera Software ASA nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * 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/html/track/vtt/VTTScanner.h"
#include "core/rendering/RenderVTTCue.h"
#include "platform/text/BidiResolver.h"
#include "platform/text/TextRunIterator.h"
#include "wtf/MathExtras.h"
#include "wtf/text/StringBuilder.h"

namespace WebCore {

static const int undefinedPosition = -1;
static const int undefinedSize = -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, ExceptionState& exceptionState)
{
    if (TextTrackCue::isInfiniteOrNonNumber(value, exceptionState))
        return true;
    if (value < 0 || value > 100) {
        exceptionState.throwDOMException(IndexSizeError, ExceptionMessages::indexOutsideRange("value", value, 0.0, ExceptionMessages::InclusiveBound, 100.0, ExceptionMessages::InclusiveBound));
        return true;
    }
    return false;
}

VTTCueBox::VTTCueBox(Document& document, VTTCue* cue)
    : HTMLDivElement(document)
    , m_cue(cue)
{
    setShadowPseudoId(AtomicString("-webkit-media-text-track-display", AtomicString::ConstructFromLiteral));
}

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(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(nullptr)
    , m_cueBackgroundBox(HTMLDivElement::create(document))
    , m_displayDirection(CSSValueLtr)
    , m_displaySize(undefinedSize)
    , m_snapToLines(true)
    , m_displayTreeShouldChange(true)
    , m_notifyRegion(true)
{
    ScriptWrappable::init(this);
}

VTTCue::~VTTCue()
{
    displayTreeInternal()->remove(ASSERT_NO_EXCEPTION);
}

#ifndef NDEBUG
String VTTCue::toString() const
{
    return String::format("%p id=%s interval=%f-->%f cue=%s)", this, id().utf8().data(), startTime(), endTime(), text().utf8().data());
}
#endif

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, "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, "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, 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, 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, "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 = nullptr;
    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;
}

class VTTTextRunIterator : public TextRunIterator {
public:
    VTTTextRunIterator() { }
    VTTTextRunIterator(const TextRun* textRun, unsigned offset) : TextRunIterator(textRun, offset) { }

    bool atParagraphSeparator() const
    {
        // 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(current()) & WTF::Unicode::Separator_Paragraph;
    }
};

// Almost the same as determineDirectionality in core/html/HTMLElement.cpp, but
// that one uses a "plain" TextRunIterator (which only checks for '\n').
static TextDirection determineDirectionality(const String& value, bool& hasStrongDirectionality)
{
    TextRun run(value);
    BidiResolver<VTTTextRunIterator, BidiCharacterRun> bidiResolver;
    bidiResolver.setStatus(BidiStatus(LTR, false));
    bidiResolver.setPositionIgnoringNestedIsolates(VTTTextRunIterator(&run, 0));
    return bidiResolver.determineParagraphDirectionality(&hasStrongDirectionality);
}

static CSSValueID determineTextDirection(DocumentFragment* vttRoot)
{
    DEFINE_STATIC_LOCAL(const String, rtTag, ("rt"));
    ASSERT(vttRoot);

    // 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.
    TextDirection textDirection = LTR;
    for (Node* node = vttRoot->firstChild(); node; node = NodeTraversal::next(*node, vttRoot)) {
        if (!node->isTextNode() || node->localName() == rtTag)
            continue;

        bool hasStrongDirectionality;
        textDirection = determineDirectionality(node->nodeValue(), hasStrongDirectionality);
        if (hasStrongDirectionality)
            break;
    }
    return isLeftToRightDirection(textDirection) ? CSSValueLtr : CSSValueRtl;
}

void VTTCue::calculateDisplayParameters()
{
    createVTTNodeTree();

    // Steps 10.2, 10.3
    m_displayDirection = determineTextDirection(m_vttNodeTree.get());

    // 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) {
            double currentTimestamp;
            bool check = VTTParser::collectTimeStamp(child->nodeValue(), currentTimestamp);
            ASSERT_UNUSED(check, check);

            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<VTTCueBox> 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->setShadowPseudoId(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->willRemoveVTTCueBox(m_displayTree.get());
    }

    displayTreeInternal()->remove(ASSERT_NO_EXCEPTION);
}

void VTTCue::updateDisplay(const IntSize& videoSize, HTMLDivElement& container)
{
    RefPtr<VTTCueBox> 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->hasChildren() && !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->appendVTTCueBox(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(VTTScanner& input)
{
    CueSetting parsedSetting = None;
    if (input.scan("vertical"))
        parsedSetting = Vertical;
    else if (input.scan("line"))
        parsedSetting = Line;
    else if (input.scan("position"))
        parsedSetting = Position;
    else if (input.scan("size"))
        parsedSetting = Size;
    else if (input.scan("align"))
        parsedSetting = Align;
    else if (RuntimeEnabledFeatures::webVTTRegionsEnabled() && input.scan("region"))
        parsedSetting = RegionId;
    // Verify that a ':' follows.
    if (parsedSetting != None && input.scan(':'))
        return parsedSetting;
    return None;
}

// Used for 'position' and 'size'.
static bool scanPercentage(VTTScanner& input, const VTTScanner::Run& valueRun, int& number)
{
    // 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.
    if (!input.scanDigits(number))
        return false;

    // 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.scan('%') || !input.isAt(valueRun.end()))
        return false;

    // 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.
    return number >= 0 && number <= 100;
}

void VTTCue::parseSettings(const String& inputString)
{
    VTTScanner input(inputString);

    while (!input.isAtEnd()) {

        // 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.
        input.skipWhile<VTTParser::isValidSettingDelimiter>();

        if (input.isAtEnd())
            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.
        //    2. Let name be the leading substring of setting up to and excluding the first U+003A COLON character (:) in that string.
        CueSetting name = settingName(input);

        // 3. Let value be the trailing substring of setting starting from the character immediately after the first U+003A COLON character (:) in that string.
        VTTScanner::Run valueRun = input.collectUntil<VTTParser::isValidSettingDelimiter>();

        // 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.
            if (input.scanRun(valueRun, 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 (input.scanRun(valueRun, 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.
            bool isNegative = input.scan('-');
            int linePosition;
            unsigned numDigits = input.scanDigits(linePosition);
            bool isPercentage = input.scan('%');

            if (!input.isAt(valueRun.end()))
                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.

            // 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 (!numDigits || (isPercentage && isNegative))
                break;

            // 6. Ignoring the trailing percent sign, if any, interpret value as a (potentially signed) integer, and
            //    let number be that number.
            // 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 (isPercentage) {
                if (linePosition < 0 || linePosition > 100)
                    break;
                // 10 - If '%' then set snap-to-lines flag to false.
                m_snapToLines = false;
            } else {
                if (isNegative)
                    linePosition = -linePosition;
                m_snapToLines = true;
            }
            m_linePosition = linePosition;
            break;
        }
        case Position: {
            int number;
            // Steps 1 - 6.
            if (!scanPercentage(input, valueRun, number))
                break;

            // 7. Let cue's text track cue text position be number.
            m_textPosition = number;
            break;
        }
        case Size: {
            int number;
            // Steps 1 - 6.
            if (!scanPercentage(input, valueRun, number))
                break;

            // 7. Let cue's text track cue size be number.
            m_cueSize = number;
            break;
        }
        case Align: {
            // 1. If value is a case-sensitive match for the string "start", then let cue's text track cue alignment be start alignment.
            if (input.scanRun(valueRun, 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 (input.scanRun(valueRun, 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 (input.scanRun(valueRun, 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 (input.scanRun(valueRun, 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 (input.scanRun(valueRun, rightKeyword()))
                m_cueAlignment = Right;
            break;
        }
        case RegionId:
            m_regionId = input.extractString(valueRun);
            break;
        case None:
            break;
        }

        // Make sure the entire run is consumed.
        input.skipRun(valueRun);
    }

    // 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
{
    ASSERT(m_displaySize != undefinedSize);
    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
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root/Source/core/html/track/vtt/VTTCue.cpp

DEFINITIONS
