Source/WebCore/editing/VisiblePosition.h

/*
 * Copyright (C) 2004-2020 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 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 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. 
 */

#pragma once

#include "EditingBoundary.h"
#include "Position.h"

namespace WebCore {

class VisiblePosition {
public:
    // VisiblePosition default affinity is downstream for callers that do not really care because it is more efficient than upstream.
    static constexpr auto defaultAffinity = Affinity::Downstream;

    VisiblePosition() = default;

    // This constructor will ignore the passed-in affinity if the position is not at the end of a line.
    WEBCORE_EXPORT VisiblePosition(const Position&, Affinity = defaultAffinity);

    bool isNull() const { return m_deepPosition.isNull(); }
    bool isNotNull() const { return m_deepPosition.isNotNull(); }
    bool isOrphan() const { return m_deepPosition.isOrphan(); }

    Position deepEquivalent() const { return m_deepPosition; }
    Affinity affinity() const { return m_affinity; }

    void setAffinity(Affinity affinity) { m_affinity = affinity; }

    // FIXME: Change the following functions' parameter from a boolean to StayInEditableContent.

    // next() and previous() increment/decrement by a character cluster.
    WEBCORE_EXPORT VisiblePosition next(EditingBoundaryCrossingRule = CanCrossEditingBoundary, bool* reachedBoundary = nullptr) const;
    WEBCORE_EXPORT VisiblePosition previous(EditingBoundaryCrossingRule = CanCrossEditingBoundary, bool* reachedBoundary = nullptr) const;

    VisiblePosition honorEditingBoundaryAtOrBefore(const VisiblePosition&, bool* reachedBoundary = nullptr) const;
    VisiblePosition honorEditingBoundaryAtOrAfter(const VisiblePosition&, bool* reachedBoundary = nullptr) const;

    WEBCORE_EXPORT VisiblePosition left(bool stayInEditableContent = false, bool* reachedBoundary = nullptr) const;
    WEBCORE_EXPORT VisiblePosition right(bool stayInEditableContent = false, bool* reachedBoundary = nullptr) const;

    WEBCORE_EXPORT UChar32 characterAfter() const;
    UChar32 characterBefore() const { return previous().characterAfter(); }

    // FIXME: This does not handle [table, 0] correctly.
    Element* rootEditableElement() const { return m_deepPosition.isNotNull() ? m_deepPosition.deprecatedNode()->rootEditableElement() : 0; }

    InlineBoxAndOffset inlineBoxAndOffset() const;
    InlineBoxAndOffset inlineBoxAndOffset(TextDirection primaryDirection) const;

    struct LocalCaretRect {
        LayoutRect rect;
        RenderObject* renderer { nullptr };
    };
    WEBCORE_EXPORT LocalCaretRect localCaretRect() const;

    // Bounds of (possibly transformed) caret in absolute coords.
    WEBCORE_EXPORT IntRect absoluteCaretBounds(bool* insideFixed = nullptr) const;

    // Abs x/y position of the caret ignoring transforms.
    // FIXME: navigation with transforms should be smarter.
    WEBCORE_EXPORT int lineDirectionPointForBlockDirectionNavigation() const;

    WEBCORE_EXPORT FloatRect absoluteSelectionBoundsForLine() const;

    // This is a tentative enhancement of operator== to account for affinity.
    // FIXME: Combine this function with operator==.
    bool equals(const VisiblePosition&) const;

#if ENABLE(TREE_DEBUGGING)
    void debugPosition(const char* msg = "") const;
    String debugDescription() const;
    void showTreeForThis() const;
#endif

private:
    static Position canonicalPosition(const Position&);

    Position leftVisuallyDistinctCandidate() const;
    Position rightVisuallyDistinctCandidate() const;

    Position m_deepPosition;
    Affinity m_affinity { defaultAffinity };
};

bool operator==(const VisiblePosition&, const VisiblePosition&);
bool operator!=(const VisiblePosition&, const VisiblePosition&);

WEBCORE_EXPORT PartialOrdering documentOrder(const VisiblePosition&, const VisiblePosition&);
bool operator<(const VisiblePosition&, const VisiblePosition&);
bool operator>(const VisiblePosition&, const VisiblePosition&);
bool operator<=(const VisiblePosition&, const VisiblePosition&);
bool operator>=(const VisiblePosition&, const VisiblePosition&);

WEBCORE_EXPORT std::optional<BoundaryPoint> makeBoundaryPoint(const VisiblePosition&);

WEBCORE_EXPORT Element* enclosingBlockFlowElement(const VisiblePosition&);

bool isFirstVisiblePositionInNode(const VisiblePosition&, const Node*);
bool isLastVisiblePositionInNode(const VisiblePosition&, const Node*);

bool areVisiblePositionsInSameTreeScope(const VisiblePosition&, const VisiblePosition&);

Node* commonInclusiveAncestor(const VisiblePosition&, const VisiblePosition&);

WTF::TextStream& operator<<(WTF::TextStream&, Affinity);
WEBCORE_EXPORT WTF::TextStream& operator<<(WTF::TextStream&, const VisiblePosition&);

struct VisiblePositionRange {
    VisiblePosition start;
    VisiblePosition end;

    bool isNull() const { return start.isNull() || end.isNull(); }
};

WEBCORE_EXPORT std::optional<SimpleRange> makeSimpleRange(const VisiblePositionRange&);
WEBCORE_EXPORT VisiblePositionRange makeVisiblePositionRange(const std::optional<SimpleRange>&);

Node* commonInclusiveAncestor(const VisiblePositionRange&);

WEBCORE_EXPORT bool intersects(const VisiblePositionRange&, const VisiblePositionRange&);
WEBCORE_EXPORT bool contains(const VisiblePositionRange&, const VisiblePosition&);
WEBCORE_EXPORT VisiblePositionRange intersection(const VisiblePositionRange&, const VisiblePositionRange&);
WEBCORE_EXPORT VisiblePosition midpoint(const VisiblePositionRange&);

// inlines

inline bool operator==(const VisiblePosition& a, const VisiblePosition& b)
{
    // FIXME: Is it correct and helpful for this to be ignoring differences in affinity?
    return a.deepEquivalent() == b.deepEquivalent();
}

inline bool operator!=(const VisiblePosition& a, const VisiblePosition& b)
{
    return !(a == b);
}

inline bool operator<(const VisiblePosition& a, const VisiblePosition& b)
{
    return is_lt(documentOrder(a, b));
}

inline bool operator>(const VisiblePosition& a, const VisiblePosition& b)
{
    return is_gt(documentOrder(a, b));
}

inline bool operator<=(const VisiblePosition& a, const VisiblePosition& b)
{
    return is_lteq(documentOrder(a, b));
}

inline bool operator>=(const VisiblePosition& a, const VisiblePosition& b)
{
    return is_gteq(documentOrder(a, b));
}

} // namespace WebCore

#if ENABLE(TREE_DEBUGGING)
// Outside the WebCore namespace for ease of invocation from the debugger.
void showTree(const WebCore::VisiblePosition*);
void showTree(const WebCore::VisiblePosition&);
#endif