visible_units.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 APPLE COMPUTER, INC. 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 "visible_units.h"

#include "Document.h"
#include "Element.h"
#include "HTMLNames.h"
#include "RenderBlock.h"
#include "RenderLayer.h"
#include "TextBoundaries.h"
#include "TextBreakIterator.h"
#include "TextIterator.h"
#include "VisiblePosition.h"
#include "htmlediting.h"

namespace WebCore {

using namespace HTMLNames;

static VisiblePosition previousBoundary(const VisiblePosition &c, unsigned (*searchFunction)(const UChar *, unsigned))
{
    Position pos = c.deepEquivalent();
    Node *n = pos.node();
    if (!n)
        return VisiblePosition();
    Document *d = n->document();
    Node *de = d->documentElement();
    if (!de)
        return VisiblePosition();
    Node *boundary = n->enclosingBlockFlowElement();
    if (!boundary)
        return VisiblePosition();
    bool isContentEditable = boundary->isContentEditable();
    while (boundary && boundary != de && boundary->parentNode() && isContentEditable == boundary->parentNode()->isContentEditable())
        boundary = boundary->parentNode();

    Position start = rangeCompliantEquivalent(Position(boundary, 0));
    Position end = rangeCompliantEquivalent(pos);
    RefPtr<Range> searchRange = Range::create(d);
    
    int exception = 0;
    searchRange->setStart(start.node(), start.offset(), exception);
    searchRange->setEnd(end.node(), end.offset(), exception);
    
    ASSERT(!exception);
    if (exception)
        return VisiblePosition();
        
    SimplifiedBackwardsTextIterator it(searchRange.get());
    Vector<UChar, 1024> string;
    unsigned next = 0;
    bool inTextSecurityMode = start.node() && start.node()->renderer() && start.node()->renderer()->style()->textSecurity() != TSNONE;
    while (!it.atEnd()) {
        // iterate to get chunks until the searchFunction returns a non-zero value.
        if (!inTextSecurityMode) 
            string.prepend(it.characters(), it.length());
        else {
            // Treat bullets used in the text security mode as regular characters when looking for boundaries
            String iteratorString(it.characters(), it.length());
            iteratorString = iteratorString.impl()->secure('x');
            string.prepend(iteratorString.characters(), iteratorString.length());
        }
        
        next = searchFunction(string.data(), string.size());
        if (next != 0)
            break;
        it.advance();
    }
    
    if (it.atEnd() && next == 0) {
        pos = it.range()->startPosition();
    } else if (next != 0) {
        Node *node = it.range()->startContainer(exception);
        if (node->isTextNode() || (node->renderer() && node->renderer()->isBR()))
            // The next variable contains a usable index into a text node
            pos = Position(node, next);
        else {
            // Use the end of the found range, the start is not guaranteed to
            // be correct.
            Position end = it.range()->endPosition();
            VisiblePosition boundary(end);
            unsigned i = it.length() - next;
            while (i--)
                boundary = boundary.previous();
            return boundary;
        }
    }

    return VisiblePosition(pos, DOWNSTREAM);
}

static VisiblePosition nextBoundary(const VisiblePosition &c, unsigned (*searchFunction)(const UChar *, unsigned))
{
    Position pos = c.deepEquivalent();
    Node *n = pos.node();
    if (!n)
        return VisiblePosition();
    Document *d = n->document();
    Node *de = d->documentElement();
    if (!de)
        return VisiblePosition();
    Node *boundary = n->enclosingBlockFlowElement();
    if (!boundary)
        return VisiblePosition();
    bool isContentEditable = boundary->isContentEditable();
    while (boundary && boundary != de && boundary->parentNode() && isContentEditable == boundary->parentNode()->isContentEditable())
        boundary = boundary->parentNode();

    RefPtr<Range> searchRange(d->createRange());
    Position start(rangeCompliantEquivalent(pos));
    ExceptionCode ec = 0;
    searchRange->selectNodeContents(boundary, ec);
    searchRange->setStart(start.node(), start.offset(), ec);
    TextIterator it(searchRange.get(), true);
    Vector<UChar, 1024> string;
    unsigned next = 0;
    bool inTextSecurityMode = start.node() && start.node()->renderer() && start.node()->renderer()->style()->textSecurity() != TSNONE;
    while (!it.atEnd()) {
        // Keep asking the iterator for chunks until the search function
        // returns an end value not equal to the length of the string passed to it.
        if (!inTextSecurityMode)
            string.append(it.characters(), it.length());
        else {
            // Treat bullets used in the text security mode as regular characters when looking for boundaries
            String iteratorString(it.characters(), it.length());
            iteratorString = iteratorString.impl()->secure('x');
            string.append(iteratorString.characters(), iteratorString.length());
        }

        next = searchFunction(string.data(), string.size());
        if (next != string.size())
            break;
        it.advance();
    }
    
    if (it.atEnd() && next == string.size()) {
        pos = it.range()->startPosition();
    } else if (next != 0) {
        // Use the character iterator to translate the next value into a DOM position.
        CharacterIterator charIt(searchRange.get(), true);
        charIt.advance(next - 1);
        pos = charIt.range()->endPosition();
        
        // FIXME: workaround for collapsed range (where only start position is correct) emitted for some emitted newlines (see rdar://5192593)
        VisiblePosition visPos = VisiblePosition(pos);
        if (visPos == VisiblePosition(charIt.range()->startPosition()))
            pos = visPos.next(true).deepEquivalent();
    }

    // generate VisiblePosition, use UPSTREAM affinity if possible
    return VisiblePosition(pos, VP_UPSTREAM_IF_POSSIBLE);
}

// ---------

static unsigned startWordBoundary(const UChar* characters, unsigned length)
{
    int start, end;
    findWordBoundary(characters, length, length, &start, &end);
    return start;
}

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 unsigned endWordBoundary(const UChar* characters, unsigned length)
{
    int start, end;
    findWordBoundary(characters, length, 0, &start, &end);
    return end;
}

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);
}

static unsigned previousWordPositionBoundary(const UChar* characters, unsigned length)
{
    return findNextWordFromIndex(characters, length, length, false);
}

VisiblePosition previousWordPosition(const VisiblePosition &c)
{
    VisiblePosition prev = previousBoundary(c, previousWordPositionBoundary);
    return c.honorEditableBoundaryAtOrAfter(prev);
}

static unsigned nextWordPositionBoundary(const UChar* characters, unsigned length)
{
    return findNextWordFromIndex(characters, length, 0, true);
}

VisiblePosition nextWordPosition(const VisiblePosition &c)
{
    VisiblePosition next = nextBoundary(c, nextWordPositionBoundary);    
    return c.honorEditableBoundaryAtOrBefore(next);
}

// ---------

static RootInlineBox *rootBoxForLine(const VisiblePosition &c)
{
    Position p = c.deepEquivalent();
    Node *node = p.node();
    if (!node)
        return 0;

    RenderObject *renderer = node->renderer();
    if (!renderer)
        return 0;

    InlineBox* box;
    int offset;
    c.getInlineBoxAndOffset(box, offset);
    
    return box ? box->root() : 0;
}

static VisiblePosition positionAvoidingFirstPositionInTable(const VisiblePosition& c)
{
    // return table offset 0 instead of the first VisiblePosition inside the table
    VisiblePosition previous = c.previous();
    if (isLastPositionBeforeTable(previous))
        return previous;
    
    return c;
}

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.offset() == 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();
    }