selectioncontroller.cpp

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    switch (granularity) {
        case CharacterGranularity:
            if (isRange()) 
                pos = VisiblePosition(m_sel.start(), m_sel.affinity());
            else
                pos = VisiblePosition(m_sel.extent(), m_sel.affinity()).left(true);
            break;
        case WordGranularity:
        case SentenceGranularity:
        case LineGranularity:
        case ParagraphGranularity:
        case SentenceBoundary:
        case LineBoundary:
        case ParagraphBoundary:
        case DocumentBoundary:
            // FIXME: Implement all of the above.
            pos = modifyMovingBackward(granularity);
            break;
    }
    return pos;
}

VisiblePosition SelectionController::modifyMovingBackward(TextGranularity granularity)
{
    VisiblePosition pos;
    switch (granularity) {
        case CharacterGranularity:
            if (isRange()) 
                pos = VisiblePosition(m_sel.start(), m_sel.affinity());
            else
                pos = VisiblePosition(m_sel.extent(), m_sel.affinity()).previous(true);
            break;
        case WordGranularity:
            pos = previousWordPosition(VisiblePosition(m_sel.extent(), m_sel.affinity()));
            break;
        case SentenceGranularity:
            pos = previousSentencePosition(VisiblePosition(m_sel.extent(), m_sel.affinity()));
            break;
        case LineGranularity:
            pos = previousLinePosition(VisiblePosition(m_sel.start(), m_sel.affinity()), xPosForVerticalArrowNavigation(START));
            break;
        case ParagraphGranularity:
            pos = previousParagraphPosition(VisiblePosition(m_sel.start(), m_sel.affinity()), xPosForVerticalArrowNavigation(START));
            break;
        case SentenceBoundary:
            pos = startOfSentence(VisiblePosition(m_sel.start(), m_sel.affinity()));
            break;
        case LineBoundary:
            pos = startOfLine(VisiblePosition(m_sel.start(), m_sel.affinity()));
            break;
        case ParagraphBoundary:
            pos = startOfParagraph(VisiblePosition(m_sel.start(), m_sel.affinity()));
            break;
        case DocumentBoundary:
            pos = VisiblePosition(m_sel.start(), m_sel.affinity());
            if (isEditablePosition(pos.deepEquivalent()))
                pos = startOfEditableContent(pos);
            else 
                pos = startOfDocument(pos);
            break;
    }
    return pos;
}

bool SelectionController::modify(EAlteration alter, EDirection dir, TextGranularity granularity, bool userTriggered)
{
    if (userTriggered) {
        SelectionController trialSelectionController;
        trialSelectionController.setLastChangeWasHorizontalExtension(m_lastChangeWasHorizontalExtension);
        trialSelectionController.setSelection(m_sel);
        trialSelectionController.modify(alter, dir, granularity, false);

        bool change = m_frame->shouldChangeSelection(trialSelectionController.selection());
        if (!change)
            return false;
    }

    if (m_frame)
        m_frame->setSelectionGranularity(granularity);
    
    willBeModified(alter, dir);

    VisiblePosition pos;
    switch (dir) {
        case RIGHT:
            if (alter == MOVE)
                pos = modifyMovingRight(granularity);
            else
                pos = modifyExtendingRightForward(granularity);
            break;
        case FORWARD:
            if (alter == EXTEND)
                pos = modifyExtendingRightForward(granularity);
            else
                pos = modifyMovingForward(granularity);
            break;
        case LEFT:
            if (alter == MOVE)
                pos = modifyMovingLeft(granularity);
            else
                pos = modifyExtendingLeftBackward(granularity);
            break;
        case BACKWARD:
            if (alter == EXTEND)
                pos = modifyExtendingLeftBackward(granularity);
            else
                pos = modifyMovingBackward(granularity);
            break;
    }

    if (pos.isNull())
        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.
    int x = xPosForVerticalArrowNavigation(START);

    switch (alter) {
        case MOVE:
            moveTo(pos, userTriggered);
            break;
        case EXTEND:
            setExtent(pos, userTriggered);
            break;
    }
    
    if (granularity == LineGranularity || granularity == ParagraphGranularity)
        m_xPosForVerticalArrowNavigation = x;

    if (userTriggered) {
        // User modified selection change also sets the granularity back to character.
        // NOTE: The one exception is that we need to keep word granularity to
        // preserve smart delete behavior when extending by word (e.g. double-click),
        // then shift-option-right arrow, then delete needs to smart delete, per TextEdit.
        if (!(alter == EXTEND && granularity == WordGranularity && m_frame->selectionGranularity() == WordGranularity))
            m_frame->setSelectionGranularity(CharacterGranularity);
    }

    setNeedsLayout();

    return true;
}

// FIXME: Maybe baseline would be better?
static bool absoluteCaretY(const VisiblePosition &c, int &y)
{
    IntRect rect = c.absoluteCaretBounds();
    if (rect.isEmpty())
        return false;
    y = rect.y() + rect.height() / 2;
    return true;
}

bool SelectionController::modify(EAlteration alter, int verticalDistance, bool userTriggered)
{
    if (verticalDistance == 0)
        return false;

    if (userTriggered) {
        SelectionController trialSelectionController;
        trialSelectionController.setSelection(m_sel);
        trialSelectionController.modify(alter, verticalDistance, false);

        bool change = m_frame->shouldChangeSelection(trialSelectionController.selection());
        if (!change)
            return false;
    }

    bool up = verticalDistance < 0;
    if (up)
        verticalDistance = -verticalDistance;

    willBeModified(alter, up ? BACKWARD : FORWARD);

    VisiblePosition pos;
    int xPos = 0;
    switch (alter) {
        case MOVE:
            pos = VisiblePosition(up ? m_sel.start() : m_sel.end(), m_sel.affinity());
            xPos = xPosForVerticalArrowNavigation(up ? START : END);
            m_sel.setAffinity(up ? UPSTREAM : DOWNSTREAM);
            break;
        case EXTEND:
            pos = VisiblePosition(m_sel.extent(), m_sel.affinity());
            xPos = xPosForVerticalArrowNavigation(EXTENT);
            m_sel.setAffinity(DOWNSTREAM);
            break;
    }

    int startY;
    if (!absoluteCaretY(pos, startY))
        return false;
    if (up)
        startY = -startY;
    int lastY = startY;

    VisiblePosition result;
    VisiblePosition next;
    for (VisiblePosition p = pos; ; p = next) {
        next = (up ? previousLinePosition : nextLinePosition)(p, xPos);
        if (next.isNull() || next == p)
            break;
        int nextY;
        if (!absoluteCaretY(next, nextY))
            break;
        if (up)
            nextY = -nextY;
        if (nextY - startY > verticalDistance)
            break;
        if (nextY >= lastY) {
            lastY = nextY;
            result = next;
        }
    }

    if (result.isNull())
        return false;

    switch (alter) {
        case MOVE:
            moveTo(result, userTriggered);
            break;
        case EXTEND:
            setExtent(result, userTriggered);
            break;
    }

    if (userTriggered)
        m_frame->setSelectionGranularity(CharacterGranularity);

    return true;
}

bool SelectionController::expandUsingGranularity(TextGranularity granularity)
{
    if (isNone())
        return false;

    m_sel.expandUsingGranularity(granularity);
    m_needsLayout = true;
    return true;
}

int SelectionController::xPosForVerticalArrowNavigation(EPositionType type)
{
    int x = 0;

    if (isNone())
        return x;

    Position pos;
    switch (type) {
        case START:
            pos = m_sel.start();
            break;
        case END:
            pos = m_sel.end();
            break;
        case BASE:
            pos = m_sel.base();
            break;
        case EXTENT:
            pos = m_sel.extent();
            break;
    }

    Frame *frame = pos.node()->document()->frame();
    if (!frame)
        return x;
        
    if (m_xPosForVerticalArrowNavigation == NoXPosForVerticalArrowNavigation) {
        VisiblePosition visiblePosition(pos, m_sel.affinity());
        // VisiblePosition creation can fail here if a node containing the selection becomes visibility:hidden
        // after the selection is created and before this function is called.
        x = visiblePosition.isNotNull() ? visiblePosition.xOffsetForVerticalNavigation() : 0;
        m_xPosForVerticalArrowNavigation = x;
    }
    else
        x = m_xPosForVerticalArrowNavigation;
        
    return x;
}

void SelectionController::clear()
{
    setSelection(VisibleSelection());
}

void SelectionController::setBase(const VisiblePosition &pos, bool userTriggered)
{
    setSelection(VisibleSelection(pos.deepEquivalent(), m_sel.extent(), pos.affinity()), true, true, userTriggered);
}

void SelectionController::setExtent(const VisiblePosition &pos, bool userTriggered)
{
    setSelection(VisibleSelection(m_sel.base(), pos.deepEquivalent(), pos.affinity()), true, true, userTriggered);
}

void SelectionController::setBase(const Position &pos, EAffinity affinity, bool userTriggered)
{
    setSelection(VisibleSelection(pos, m_sel.extent(), affinity), true, true, userTriggered);
}

void SelectionController::setExtent(const Position &pos, EAffinity affinity, bool userTriggered)
{
    setSelection(VisibleSelection(m_sel.base(), pos, affinity), true, true, userTriggered);
}

void SelectionController::setNeedsLayout(bool flag)
{
    m_needsLayout = flag;
}

void SelectionController::layout()
{
    if (isNone() || !m_sel.start().node()->inDocument() || !m_sel.end().node()->inDocument()) {
        m_caretRect = IntRect();
        return;
    }

    m_sel.start().node()->document()->updateRendering();
    
    m_caretRect = IntRect();
        
    if (isCaret()) {
        VisiblePosition pos(m_sel.start(), m_sel.affinity());
        if (pos.isNotNull()) {
            ASSERT(pos.deepEquivalent().node()->renderer());
            
            // First compute a rect local to the renderer at the selection start
            RenderObject* renderer;
            IntRect localRect = pos.localCaretRect(renderer);

            // Get the renderer that will be responsible for painting the caret (which
            // is either the renderer we just found, or one of its containers)
            RenderObject* caretPainter = caretRenderer();

            // Compute an offset between the renderer and the caretPainter
            IntSize offsetFromPainter;
            bool unrooted = false;
            while (renderer != caretPainter) {
                RenderObject* containerObject = renderer->container();
                if (!containerObject) {
                    unrooted = true;
                    break;
                }
                offsetFromPainter += renderer->offsetFromContainer(containerObject);
                renderer = containerObject;
            }
            
            if (!unrooted) {
                // Move the caret rect to the coords of the painter
                localRect.move(offsetFromPainter);
                m_caretRect = localRect;
            }
            
            m_absCaretBoundsDirty = true;
        }
    }

    m_needsLayout = false;
}

RenderObject* SelectionController::caretRenderer() const
{
    Node* node = m_sel.start().node();
    if (!node)
        return 0;

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

    // if caretNode is a block and caret is inside it then caret should be painted by that block
    bool paintedByBlock = renderer->isBlockFlow() && caretRendersInsideNode(node);
    return paintedByBlock ? renderer : renderer->containingBlock();
}

IntRect SelectionController::localCaretRect() const
{
    if (m_needsLayout)
        const_cast<SelectionController *>(this)->layout();
    
    return m_caretRect;
}

IntRect SelectionController::absoluteCaretBounds()
{
    recomputeCaretRect();
    return m_absCaretBounds;
}

static IntRect repaintRectForCaret(IntRect caret)
{
    if (caret.isEmpty())
        return IntRect();
    // Ensure that the dirty rect intersects the block that paints the caret even in the case where
    // the caret itself is just outside the block. See <https://bugs.webkit.org/show_bug.cgi?id=19086>.
    caret.inflateX(1);
    return caret;
}

IntRect SelectionController::caretRepaintRect() const
{
    IntRect localRect = repaintRectForCaret(localCaretRect());
    
    RenderObject* caretPainter = caretRenderer();
    if (caretPainter)
        return caretPainter->localToAbsoluteQuad(FloatRect(localRect)).enclosingBoundingBox();

    return IntRect();
}