C++ RenderObject::caretMinOffset方法代码示例

bool Position::inRenderedContent() const
{
    if (isNull())
        return false;
        
    RenderObject *renderer = node()->renderer();
    if (!renderer)
        return false;
    
    if (renderer->style()->visibility() != VISIBLE)
        return false;

    // FIXME: This check returns false for a <br> at the end of a line!
    if (renderer->isBR() && static_cast<RenderText *>(renderer)->firstTextBox()) {
        return offset() == 0;
    }
    else if (renderer->isText()) {
        RenderText *textRenderer = static_cast<RenderText *>(renderer);
        for (InlineTextBox *box = textRenderer->firstTextBox(); box; box = box->nextTextBox()) {
            if (offset() >= box->m_start && offset() <= box->m_start + box->m_len) {
                return true;
            }
            else if (offset() < box->m_start) {
                // The offset we're looking for is before this node
                // this means the offset must be in content that is
                // not rendered. Return false.
                return false;
            }
        }
    }
    else if (offset() >= renderer->caretMinOffset() && offset() <= renderer->caretMaxOffset()) {
        // return true for replaced elements, for inline flows if they have a line box
        // and for blocks if they are empty
        if (renderer->isReplaced() ||
            (renderer->isInlineFlow() && static_cast<RenderFlow *>(renderer)->firstLineBox()) ||
            (renderer->isBlockFlow() && !renderer->firstChild() && renderer->height()))
            return true;
    }
    
    return false;
}

int caretMinOffset(const Node* n)
{
    RenderObject* r = n->renderer();
    ASSERT(!n->isCharacterDataNode() || !r || r->isText()); // FIXME: This was a runtime check that seemingly couldn't fail; changed it to an assertion for now.
    return r ? r->caretMinOffset() : 0;
}

Position Position::downstream(EStayInBlock stayInBlock) const
{
    Position start = equivalentDeepPosition();
    NodeImpl *startNode = start.node();
    if (!startNode)
        return Position();

    NodeImpl *block = startNode->enclosingBlockFlowOrTableElement();
    Position lastVisible;
    
    PositionIterator it(start);            
    for (; !it.atEnd(); it.next()) {   
        NodeImpl *currentNode = it.current().node();

        if (stayInBlock) {
            NodeImpl *currentBlock = currentNode->enclosingBlockFlowOrTableElement();
            if (block != currentBlock)
                return it.previous();
        }

        RenderObject *renderer = currentNode->renderer();
        if (!renderer)
            continue;

        if (renderer->style()->visibility() != VISIBLE)
            continue;

        lastVisible = it.current();

        if (currentNode != startNode && renderer->isBlockFlow()) {
            if (it.current().offset() == 0) {
                // If no first child, or first visible child is a not a block, return; otherwise continue.
                if (!currentNode->firstChild())
                    return Position(currentNode, 0);
                for (NodeImpl *child = currentNode->firstChild(); child; child = child->nextSibling()) {
                    RenderObject *r = child->renderer();
                    if (r && r->style()->visibility() == VISIBLE) {
                         if (r->isBlockFlow())
                            break; // break causes continue code below to run.
                         else
                            return Position(child, 0);
                    }
                }
                continue;
            }
        }

        if (renderer->isReplaced() || renderer->isBR()) {
            if (it.current().offset() <= renderer->caretMinOffset())
                return Position(currentNode, renderer->caretMinOffset());
            else
                continue;
        }

        if (renderer->isText() && static_cast<RenderText *>(renderer)->firstTextBox()) {
            if (currentNode != start.node())
                return Position(currentNode, renderer->caretMinOffset());

            if (it.current().offset() < 0)
                continue;
            uint textOffset = it.current().offset();

            RenderText *textRenderer = static_cast<RenderText *>(renderer);
            for (InlineTextBox *box = textRenderer->firstTextBox(); box; box = box->nextTextBox()) {
                if (textOffset >= box->start() && textOffset <= box->end())
                    return it.current();
                else if (box != textRenderer->lastTextBox() && 
                         !box->nextOnLine() && 
                         textOffset == box->start() + box->len())
                    return it.current();
            }
        }
    }
    
    return lastVisible.isNotNull() ? lastVisible : *this;
}

// P.downstream() returns the end of the range of positions that map to the same VisiblePosition as P.
Position Position::downstream() const
{
    Node* startNode = node();
    if (!startNode)
        return Position();

    // iterate forward from there, looking for a qualified position
    Node* block = enclosingBlock(startNode);
    PositionIterator lastVisible = *this;
    PositionIterator currentPos = lastVisible;
    Node* originalRoot = node()->rootEditableElement();
    for (; !currentPos.atEnd(); currentPos.increment()) {   
        Node* currentNode = currentPos.node();
        
        if (currentNode->rootEditableElement() != originalRoot)
            break;

        // stop before going above the body, up into the head
        // return the last visible streamer position
        if (currentNode->hasTagName(bodyTag) && currentPos.atEndOfNode())
            break;
            
        // Do not enter a new enclosing block flow or table element, and don't leave the original one.
        if (block != enclosingBlock(currentNode))
            return lastVisible;

        // skip position in unrendered or invisible node
        RenderObject* renderer = currentNode->renderer();
        if (!renderer || renderer->style()->visibility() != VISIBLE)
            continue;
            
        // track last visible streamer position
        if (isStreamer(currentPos))
            lastVisible = currentPos;

        // Return position before brs, tables, and nodes which have content that can be ignored.
        if (editingIgnoresContent(currentNode) || renderer->isBR() || isTableElement(currentNode)) {
            if (currentPos.offsetInLeafNode() <= renderer->caretMinOffset())
                return Position(currentNode, renderer->caretMinOffset());
            continue;
        }

        // return current position if it is in rendered text
        if (renderer->isText() && static_cast<RenderText*>(renderer)->firstTextBox()) {
            if (currentNode != startNode) {
                ASSERT(currentPos.atStartOfNode());
                return Position(currentNode, renderer->caretMinOffset());
            }

            unsigned textOffset = currentPos.offsetInLeafNode();

            RenderText* textRenderer = static_cast<RenderText*>(renderer);
            for (InlineTextBox* box = textRenderer->firstTextBox(); box; box = box->nextTextBox()) {
                if (textOffset >= box->start() && textOffset <= box->end())
                    return currentPos;
                
                if (box != textRenderer->lastTextBox() && 
                     !box->nextOnLine() &&
                     textOffset == box->start() + box->len()) {
                    return currentPos;
                }
            }
        }
    }
    
    return lastVisible;
}