C++ VisiblePosition::isNull方法代码示例

VisiblePosition Frame::visiblePositionForPoint(const IntPoint& framePoint)
{
    HitTestResult result = eventHandler()->hitTestResultAtPoint(framePoint, true);
    Node* node = result.innerNonSharedNode();
    if (!node)
        return VisiblePosition();
    RenderObject* renderer = node->renderer();
    if (!renderer)
        return VisiblePosition();
    VisiblePosition visiblePos = renderer->positionForPoint(result.localPoint());
    if (visiblePos.isNull())
        visiblePos = firstPositionInOrBeforeNode(node);
    return visiblePos;
}

VisiblePosition AccessibilityObject::previousSentenceStartPosition(const VisiblePosition& visiblePos) const
{
    // FIXME: FO 2 IMPLEMENT (currently returns incorrect answer)
    // Related? <rdar://problem/3927736> Text selection broken in 8A336
    if (visiblePos.isNull())
        return VisiblePosition();

    // make sure we move off of a sentence start
    VisiblePosition previousVisiblePos = visiblePos.previous();
    if (previousVisiblePos.isNull())
        return VisiblePosition();

    // treat empty line as a separate sentence.
    VisiblePosition startPosition;
    
    String lineString = plainText(makeRange(startOfLine(previousVisiblePos), endOfLine(previousVisiblePos)).get());
    if (lineString.isEmpty())
        startPosition = previousVisiblePos;
    else
        startPosition = startOfSentence(previousVisiblePos);

    return startPosition;
}

RenderedPosition::RenderedPosition(const VisiblePosition& position)
    : m_layoutObject(nullptr)
    , m_inlineBox(nullptr)
    , m_offset(0)
    , m_prevLeafChild(uncachedInlineBox())
    , m_nextLeafChild(uncachedInlineBox())
{
    if (position.isNull())
        return;
    position.getInlineBoxAndOffset(m_inlineBox, m_offset);
    if (m_inlineBox)
        m_layoutObject = &m_inlineBox->layoutObject();
    else
        m_layoutObject = layoutObjectFromPosition(position.deepEquivalent());
}

VisiblePosition AccessibilityObject::previousLineStartPosition(const VisiblePosition& visiblePos) const
{
    if (visiblePos.isNull())
        return VisiblePosition();

    // make sure we move off of a line start
    VisiblePosition prevVisiblePos = visiblePos.previous();
    if (prevVisiblePos.isNull())
        return VisiblePosition();

    VisiblePosition startPosition = startOfLine(prevVisiblePos);

    // as long as the position hasn't reached the beginning of the doc,  keep searching for a valid line start position
    // There are cases like when the position is next to a floating object that'll return null for start of line. This code will avoid returning null.
    if (startPosition.isNull()) {
        while (startPosition.isNull() && prevVisiblePos.isNotNull()) {
            prevVisiblePos = prevVisiblePos.previous();
            startPosition = startOfLine(prevVisiblePos);
        }
    } else
        startPosition = updateAXLineStartForVisiblePosition(startPosition);

    return startPosition;
}

VisiblePosition endOfWord(const VisiblePosition &c, EWordSide side)
{
    VisiblePosition p = c;
    if (side == LeftWordIfOnBoundary) {
        if (isStartOfParagraph(c))
            return c;
            
        p = c.previous();
        if (p.isNull())
            return c;
    } else if (isEndOfParagraph(c))
        return c;
    
    return nextBoundary(p, endWordBoundary);
}

RenderedPosition::RenderedPosition(const VisiblePosition& position)
    : m_renderer(0)
    , m_inlineBox(0)
    , m_offset(0)
    , m_prevLeafChild(uncachedInlineBox())
    , m_nextLeafChild(uncachedInlineBox())
{
    if (position.isNull())
        return;
    position.getInlineBoxAndOffset(m_inlineBox, m_offset);
    if (m_inlineBox)
        m_renderer = m_inlineBox->renderer();
    else
        m_renderer = rendererFromPosition(position.deepEquivalent());
}

static VisiblePosition visiblePositionForPoint(Frame* frame, IntPoint outerPoint)
{
    ASSERT(frame);
    HitTestResult result = frame->eventHandler()->hitTestResultAtPoint(outerPoint, true);
    Node* node = result.innerNode();
    if (!node)
        return VisiblePosition();
    RenderObject* renderer = node->renderer();
    if (!renderer)
        return VisiblePosition();
    VisiblePosition visiblePos = renderer->positionForCoordinates(result.localPoint().x(), result.localPoint().y());
    if (visiblePos.isNull())
        visiblePos = VisiblePosition(Position(node, 0));
    return visiblePos;
}

VisiblePosition AccessibilityObject::nextSentenceEndPosition(const VisiblePosition& visiblePos) const
{
    // FIXME: FO 2 IMPLEMENT (currently returns incorrect answer)
    // Related? <rdar://problem/3927736> Text selection broken in 8A336
    if (visiblePos.isNull())
        return VisiblePosition();

    // make sure we move off of a sentence end
    VisiblePosition nextVisiblePos = visiblePos.next();
    if (nextVisiblePos.isNull())
        return VisiblePosition();

    // an empty line is considered a sentence. If it's skipped, then the sentence parser will not
    // see this empty line.  Instead, return the end position of the empty line.
    VisiblePosition endPosition;
    
    String lineString = plainText(makeRange(startOfLine(nextVisiblePos), endOfLine(nextVisiblePos)).get());
    if (lineString.isEmpty())
        endPosition = nextVisiblePos;
    else
        endPosition = endOfSentence(nextVisiblePos);

    return endPosition;
}

VisiblePosition startOfWord(const VisiblePosition &c, EWordSide side)
{
    // FIXME: This returns a null VP for c at the start of the document
    // and side == LeftWordIfOnBoundary
    VisiblePosition p = c;
    if (side == RightWordIfOnBoundary) {
        // at paragraph end, the startofWord is the current position
        if (isEndOfParagraph(c))
            return c;
        
        p = c.next();
        if (p.isNull())
            return c;
    }
    return previousBoundary(p, startWordBoundary);
}

static VisiblePosition endPositionForLine(const VisiblePosition& c)
{
    if (c.isNull())
        return VisiblePosition();

    RootInlineBox *rootBox = rootBoxForLine(c);
    if (!rootBox) {
        // There are VisiblePositions at offset 0 in blocks without
        // RootInlineBoxes, like empty editable blocks and bordered blocks.
        Position p = c.deepEquivalent();
        if (p.node()->renderer() && p.node()->renderer()->isRenderBlock() && p.deprecatedEditingOffset() == 0)
            return c;
        return VisiblePosition();
    }
    
    // Generated content (e.g. list markers and CSS :before and :after
    // pseudoelements) have no corresponding DOM element, and so cannot be
    // represented by a VisiblePosition.  Use whatever precedes instead.
    Node *endNode;
    InlineBox *endBox = rootBox->lastLeafChild();
    while (1) {
        if (!endBox)
            return VisiblePosition();

        RenderObject *endRenderer = endBox->renderer();
        if (!endRenderer)
            return VisiblePosition();

        endNode = endRenderer->node();
        if (endNode)
            break;
        
        endBox = endBox->prevLeafChild();
    }
    
    int endOffset = 1;
    if (endNode->hasTagName(brTag)) {
        endOffset = 0;
    } else if (endBox->isInlineTextBox()) {
        InlineTextBox *endTextBox = static_cast<InlineTextBox *>(endBox);
        endOffset = endTextBox->start();
        if (!endTextBox->isLineBreak())
            endOffset += endTextBox->len();
    }
    
    return VisiblePosition(endNode, endOffset, VP_UPSTREAM_IF_POSSIBLE);
}

RenderedPosition::RenderedPosition(const VisiblePosition& position)
    : m_layoutObject(nullptr)
    , m_inlineBox(nullptr)
    , m_offset(0)
    , m_prevLeafChild(uncachedInlineBox())
    , m_nextLeafChild(uncachedInlineBox())
{
    if (position.isNull())
        return;
    InlineBoxPosition boxPosition = computeInlineBoxPosition(position);
    m_inlineBox = boxPosition.inlineBox;
    m_offset = boxPosition.offsetInBox;
    if (m_inlineBox)
        m_layoutObject = &m_inlineBox->layoutObject();
    else
        m_layoutObject = layoutObjectFromPosition(position.deepEquivalent());
}

static VisiblePosition startPositionForLine(const VisiblePosition& c)
{
    if (c.isNull())
        return VisiblePosition();

    RootInlineBox *rootBox = rootBoxForLine(c);
    if (!rootBox) {
        // There are VisiblePositions at offset 0 in blocks without
        // RootInlineBoxes, like empty editable blocks and bordered blocks.
        Position p = c.deepEquivalent();
        if (p.node()->renderer() && p.node()->renderer()->isRenderBlock() && p.deprecatedEditingOffset() == 0)
            return positionAvoidingFirstPositionInTable(c);
        
        return VisiblePosition();
    }
    
    // Generated content (e.g. list markers and CSS :before and :after
    // pseudoelements) have no corresponding DOM element, and so cannot be
    // represented by a VisiblePosition.  Use whatever follows instead.
    InlineBox *startBox = rootBox->firstLeafChild();
    Node *startNode;
    while (1) {
        if (!startBox)
            return VisiblePosition();

        RenderObject *startRenderer = startBox->renderer();
        if (!startRenderer)
            return VisiblePosition();

        startNode = startRenderer->node();
        if (startNode)
            break;
        
        startBox = startBox->nextLeafChild();
    }
    
    int startOffset = 0;
    if (startBox->isInlineTextBox()) {
        InlineTextBox *startTextBox = static_cast<InlineTextBox *>(startBox);
        startOffset = startTextBox->start();
    }
  
    VisiblePosition visPos = VisiblePosition(startNode, startOffset, DOWNSTREAM);
    return positionAvoidingFirstPositionInTable(visPos);
}

// FIXME: indexForVisiblePosition and visiblePositionForIndex use TextIterators to convert between 
// VisiblePositions and indices. But TextIterator iteration using TextIteratorEmitsCharactersBetweenAllVisiblePositions 
// does not exactly match VisiblePosition iteration, so using them to preserve a selection during an editing 
// opertion is unreliable. TextIterator's TextIteratorEmitsCharactersBetweenAllVisiblePositions mode needs to be fixed, 
// or these functions need to be changed to iterate using actual VisiblePositions.
// FIXME: Deploy these functions everywhere that TextIterators are used to convert between VisiblePositions and indices.
int indexForVisiblePosition(const VisiblePosition& visiblePosition, RefPtr<ContainerNode>& scope)
{
    if (visiblePosition.isNull())
        return 0;

    Position p(visiblePosition.deepEquivalent());
    Document* document = p.anchorNode()->document();
    ShadowRoot* shadowRoot = p.anchorNode()->containingShadowRoot();

    if (shadowRoot)
        scope = shadowRoot;
    else
        scope = document->documentElement();

    RefPtr<Range> range = Range::create(document, firstPositionInNode(scope.get()), p.parentAnchoredEquivalent());

    return TextIterator::rangeLength(range.get(), true);
}

VisiblePosition endOfLine(const VisiblePosition& c)
{
    VisiblePosition visPos = endPositionForLine(c);
    
    // Make sure the end of line is at the same line as the given input position.  Else use the previous position to 
    // obtain end of line.  This condition happens when the input position is before the space character at the end 
    // of a soft-wrapped non-editable line. In this scenario, endPositionForLine would incorrectly hand back a position
    // in the next line instead. This fix is to account for the discrepancy between lines with webkit-line-break:after-white-space style
    // versus lines without that style, which would break before a space by default. 
    if (!inSameLine(c, visPos)) {
        visPos = c.previous();
        if (visPos.isNull())
            return VisiblePosition();
        visPos = endPositionForLine(visPos);
    }
    
    return c.honorEditableBoundaryAtOrBefore(visPos);
}

bool Editor::canDeleteRange(Range* range) const
{
    Node* startContainer = range->startContainer();
    Node* endContainer = range->endContainer();
    if (!startContainer || !endContainer)
        return false;

    if (!startContainer->hasEditableStyle() || !endContainer->hasEditableStyle())
        return false;

    if (range->collapsed()) {
        VisiblePosition start(range->startPosition(), DOWNSTREAM);
        VisiblePosition previous = start.previous();
        // FIXME: We sometimes allow deletions at the start of editable roots, like when the caret is in an empty list item.
        if (previous.isNull() || previous.deepEquivalent().deprecatedNode()->rootEditableElement() != startContainer->rootEditableElement())
            return false;
    }
    return true;
}