C++ VisibleSelection::isBaseFirst方法代码示例

static Position focusPosition(const VisibleSelection& selection) {
    Position focus =
        selection.isBaseFirst() ? selection.end() : selection.start();
    return focus.parentAnchoredEquivalent();
}

static Position focusPosition(const VisibleSelection& selection)
{
    Position focus = selection.isBaseFirst() ? selection.end() : selection.start();
    return rangeCompliantEquivalent(focus);
}

bool SelectionModifier::modify(EAlteration alter,
                               SelectionDirection direction,
                               TextGranularity granularity) {
  DCHECK(!frame()->document()->needsLayoutTreeUpdate());
  DocumentLifecycle::DisallowTransitionScope disallowTransition(
      frame()->document()->lifecycle());

  willBeModified(alter, direction);

  bool wasRange = m_selection.isRange();
  VisiblePosition originalStartPosition = m_selection.visibleStart();
  VisiblePosition position;
  switch (direction) {
    case DirectionRight:
      if (alter == FrameSelection::AlterationMove)
        position = modifyMovingRight(granularity);
      else
        position = modifyExtendingRight(granularity);
      break;
    case DirectionForward:
      if (alter == FrameSelection::AlterationExtend)
        position = modifyExtendingForward(granularity);
      else
        position = modifyMovingForward(granularity);
      break;
    case DirectionLeft:
      if (alter == FrameSelection::AlterationMove)
        position = modifyMovingLeft(granularity);
      else
        position = modifyExtendingLeft(granularity);
      break;
    case DirectionBackward:
      if (alter == FrameSelection::AlterationExtend)
        position = modifyExtendingBackward(granularity);
      else
        position = modifyMovingBackward(granularity);
      break;
  }

  if (position.isNull())
    return false;

  if (isSpatialNavigationEnabled(frame())) {
    if (!wasRange && alter == FrameSelection::AlterationMove &&
        position.deepEquivalent() == originalStartPosition.deepEquivalent())
      return false;
  }

  // Some of the above operations set an xPosForVerticalArrowNavigation.
  // Setting a selection will clear it, so save it to possibly restore later.
  // Note: the START position type is arbitrary because it is unused, it would
  // be the requested position type if there were no
  // xPosForVerticalArrowNavigation set.
  LayoutUnit x = lineDirectionPointForBlockDirectionNavigation(START);
  m_selection.setIsDirectional(shouldAlwaysUseDirectionalSelection(frame()) ||
                               alter == FrameSelection::AlterationExtend);

  switch (alter) {
    case FrameSelection::AlterationMove:
      m_selection = createVisibleSelection(
          SelectionInDOMTree::Builder()
              .collapse(position.toPositionWithAffinity())
              .setIsDirectional(m_selection.isDirectional())
              .build());
      break;
    case FrameSelection::AlterationExtend:

      if (!m_selection.isCaret() && (granularity == WordGranularity ||
                                     granularity == ParagraphGranularity ||
                                     granularity == LineGranularity) &&
          frame() &&
          !frame()
               ->editor()
               .behavior()
               .shouldExtendSelectionByWordOrLineAcrossCaret()) {
        // Don't let the selection go across the base position directly. Needed
        // to match mac behavior when, for instance, word-selecting backwards
        // starting with the caret in the middle of a word and then
        // word-selecting forward, leaving the caret in the same place where it
        // was, instead of directly selecting to the end of the word.
        VisibleSelection newSelection = m_selection;
        newSelection.setExtent(position);
        if (m_selection.isBaseFirst() != newSelection.isBaseFirst())
          position = m_selection.visibleBase();
      }

      // Standard Mac behavior when extending to a boundary is grow the
      // selection rather than leaving the base in place and moving the
      // extent. Matches NSTextView.
      if (!frame() ||
          !frame()
               ->editor()
               .behavior()
               .shouldAlwaysGrowSelectionWhenExtendingToBoundary() ||
          m_selection.isCaret() || !isBoundary(granularity)) {
        m_selection.setExtent(position);
      } else {
        TextDirection textDirection = directionOfEnclosingBlock();
        if (direction == DirectionForward ||
            (textDirection == LTR && direction == DirectionRight) ||
//.........这里部分代码省略.........

static Position anchorPosition(const VisibleSelection& selection)
{
    Position anchor = selection.isBaseFirst() ? selection.start() : selection.end();
    return rangeCompliantEquivalent(anchor);
}

bool SelectionEditor::modify(EAlteration alter, SelectionDirection direction, TextGranularity granularity, EUserTriggered userTriggered)
{
    if (userTriggered == UserTriggered) {
        OwnPtrWillBeRawPtr<FrameSelection> trialFrameSelection = FrameSelection::create();
        trialFrameSelection->setSelection(m_selection);
        trialFrameSelection->modify(alter, direction, granularity, NotUserTriggered);

        if (trialFrameSelection->selection().isRange() && m_selection.isCaret() && !dispatchSelectStart())
            return false;
    }

    willBeModified(alter, direction);

    bool wasRange = m_selection.isRange();
    VisiblePosition originalStartPosition = m_selection.visibleStart();
    VisiblePosition position;
    switch (direction) {
    case DirectionRight:
        if (alter == FrameSelection::AlterationMove)
            position = modifyMovingRight(granularity);
        else
            position = modifyExtendingRight(granularity);
        break;
    case DirectionForward:
        if (alter == FrameSelection::AlterationExtend)
            position = modifyExtendingForward(granularity);
        else
            position = modifyMovingForward(granularity);
        break;
    case DirectionLeft:
        if (alter == FrameSelection::AlterationMove)
            position = modifyMovingLeft(granularity);
        else
            position = modifyExtendingLeft(granularity);
        break;
    case DirectionBackward:
        if (alter == FrameSelection::AlterationExtend)
            position = modifyExtendingBackward(granularity);
        else
            position = modifyMovingBackward(granularity);
        break;
    }

    if (position.isNull())
        return false;

    if (isSpatialNavigationEnabled(frame())) {
        if (!wasRange && alter == FrameSelection::AlterationMove && position.deepEquivalent() == originalStartPosition.deepEquivalent())
            return false;
    }

    // Some of the above operations set an xPosForVerticalArrowNavigation.
    // Setting a selection will clear it, so save it to possibly restore later.
    // Note: the START position type is arbitrary because it is unused, it would be
    // the requested position type if there were no xPosForVerticalArrowNavigation set.
    LayoutUnit x = lineDirectionPointForBlockDirectionNavigation(START);
    m_selection.setIsDirectional(shouldAlwaysUseDirectionalSelection(frame()) || alter == FrameSelection::AlterationExtend);

    switch (alter) {
    case FrameSelection::AlterationMove:
        m_frameSelection->moveTo(position, userTriggered);
        break;
    case FrameSelection::AlterationExtend:

        if (!m_selection.isCaret()
            && (granularity == WordGranularity || granularity == ParagraphGranularity || granularity == LineGranularity)
            && frame() && !frame()->editor().behavior().shouldExtendSelectionByWordOrLineAcrossCaret()) {
            // Don't let the selection go across the base position directly. Needed to match mac
            // behavior when, for instance, word-selecting backwards starting with the caret in
            // the middle of a word and then word-selecting forward, leaving the caret in the
            // same place where it was, instead of directly selecting to the end of the word.
            VisibleSelection newSelection = m_selection;
            newSelection.setExtent(position);
            if (m_selection.isBaseFirst() != newSelection.isBaseFirst())
                position = m_selection.visibleBase();
        }

        // Standard Mac behavior when extending to a boundary is grow the
        // selection rather than leaving the base in place and moving the
        // extent. Matches NSTextView.
        if (!frame() || !frame()->editor().behavior().shouldAlwaysGrowSelectionWhenExtendingToBoundary()
            || m_selection.isCaret()
            || !isBoundary(granularity)) {
            m_frameSelection->setExtent(position, userTriggered);
        } else {
            TextDirection textDirection = directionOfEnclosingBlock();
            if (direction == DirectionForward || (textDirection == LTR && direction == DirectionRight) || (textDirection == RTL && direction == DirectionLeft))
                m_frameSelection->setEnd(position, userTriggered);
            else
                m_frameSelection->setStart(position, userTriggered);
        }
        break;
    }

    if (granularity == LineGranularity || granularity == ParagraphGranularity)
        m_xPosForVerticalArrowNavigation = x;

    return true;
}