2016-03-02T18:53:01 LayoutPosition

third_party/WebKit/Source/core/editing/LayoutPosition.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef LayoutPosition_h
+#define LayoutPosition_h
+
+#include "core/CoreExport.h"
+#include "core/editing/Position.h"
+// TODO(yosin): Once we stop to cache caret rectangle, we should not include
+// "FloatQuad.h"
+#include "platform/geometry/FloatQuad.h"
+#include "wtf/Allocator.h"
+#include "wtf/Forward.h"
+
+#include <iosfwd>
+
+namespace blink {
+
+class Document;
+class LayoutObject;
+class InlineBox;
+struct InlineBoxPosition;
+class InlineTextBox;
+class Text;
+
+// LayoutPosition represents a position in layout tree.
+// TODO(yosin): We will replace |RenderedPosition| by |LayoutPosition|. We
+// should move functions in |RenderedPosition| to |LayoutPosition|.
+class CORE_EXPORT LayoutPosition final {
+    STACK_ALLOCATED();
+
+public:
+    LayoutPosition(const LayoutPosition& other);
+    LayoutPosition();
+    ~LayoutPosition();
+
+    bool operator==(const LayoutPosition& other) const;
+    bool operator!=(const LayoutPosition& other) const;
+
+    bool isAfterAnchor() const { return m_anchorType == PositionAnchorType::AfterAnchor; }
+    bool isBeforeAnchor() const { return m_anchorType == PositionAnchorType::BeforeAnchor; }
+    bool isBeforeChildren() const { return m_anchorType == PositionAnchorType::BeforeChildren; }
+    bool isNotNull() const { return !isNull(); }
+    bool isNull() const { return !m_layoutObject; }
+    bool isOffsetInAnchor() const { return m_anchorType == PositionAnchorType::OffsetInAnchor; }
+
+    // DOM Position related functions.
+    bool canBePosition() const;
+    Position toPosition(const Position&) const;
+    PositionInFlatTree toPosition(const PositionInFlatTree&) const;
+
+    static LayoutPosition create(const Position&);
+    static LayoutPosition create(const PositionInFlatTree&);
+
+    // Caret related functions
+    bool canPlaceCaret() const;
+    bool isCaretEquivalent(const LayoutPosition&) const;
+
+    // Text node related functions
+    UChar codeUnitAfter() const;
+
+    // BIDI related functions
+    bool isLeftToRightDirection() const;
+
+private:
+    friend class LayoutPositionPrinter;
+    friend class LayoutPositionTest;
+    friend class LayoutTreePrinter;
+    friend CORE_EXPORT LayoutPosition nextPositionOf(const LayoutPosition&);
+    friend CORE_EXPORT LayoutPosition previousPositionOf(const LayoutPosition&);
+
+    LayoutPosition(PositionAnchorType, LayoutObject*);
+    LayoutPosition(const InlineBoxPosition&);
+
+    const Document& document() const;
+    bool isTextPosition() const;
+    bool isValid() const;
+
+    // TODO(yosin): Once we have robust |canPlaceCaret()|, we should get rid
+    // of |canPlaceCaretInternal()|.
+    bool canPlaceCaretInternal() const;
+    FloatQuad computeCaretQuad() const;
+    InlineBoxPosition computeInlineBoxPosition() const;
+
+    template <typename Strategy>
+    static LayoutPosition createAlgorithm(const PositionTemplate<Strategy>&);
+
+    template <typename Strategy>
+    PositionTemplate<Strategy> toPositionAlgorithm(const PositionTemplate<Strategy>&) const;
+
+    static LayoutPosition afterAnchorOf(InlineBox*);
+    static LayoutPosition afterAnchorOf(LayoutObject*);
+    static LayoutPosition beforeAnchorOf(InlineBox*);
+    static LayoutPosition beforeAnchorOf(LayoutObject*);
+    static LayoutPosition beforeChildrenOf(LayoutObject*);
+    static LayoutObject* layoutObjectOf(const InlineBox&);
+    static LayoutPosition previousPositionOf(LayoutObject*);
+
+    // |m_anchorType| is one of |AfterAnchor|, |BeforeAnchor|, |BeforeChildren|,
+    // or |OffsetInAnchor|.
+    PositionAnchorType m_anchorType;
+    InlineBox* m_inlineBox = nullptr;
+    // |m_layoutObject| satisfies following restriction:
+    //  - |AfterAnchor| the last node in container.
+    //  - |BeforeAnchor| Any |LayoutObject| other than |LayoutText|.
+    //  - |BeforeChildren| the element without children
+    //  - |OffsetInAnchor| |LayoutText|
+    // Other than |OffsetInAnchor|, |m_layoutObject| can't be |LayoutText|.
+    LayoutObject* m_layoutObject = nullptr;
+    // |m_offsetInBox| holds offset in |m_inlineBox| to zero to
+    // |InlineTextBox::end()+1|. Note: Unlike |std::end()| in
+    // |InlineTextBox::end()| returns maximum offset rather than beyond
+    // maximum.
+    int m_offsetInBox = 0;
+
+    // TODO(yosin): We should measure execution time with and without caret
+    // caret rectangle cache.
+    mutable bool m_hasCaretQuad = false;
+    mutable FloatQuad m_caretQuad;
+
+#if ENABLE(ASSERT)
+    uint64_t m_domTreeVersion = 0;
+    uint64_t m_styleVersion = 0;
+#endif
+};
+
+// Logical movement with code unit. Caller of these functions should
+// handle Unicode surrogate pair and Unicode control format characters, e.g.
+// zero width characters, BiDi markers.
+CORE_EXPORT LayoutPosition nextPositionOf(const LayoutPosition&);
+CORE_EXPORT LayoutPosition previousPositionOf(const LayoutPosition&);
+
+// Physical movement for implementing arrow key. Logical movement depends
+// on CSS "writing-mode" property and "dir" DOM attribute.
+// These functions doesn't handle Unicode surrogate pair, Unicode control
+// format characters, e.g. zero width characters, BiDi markers.
+CORE_EXPORT LayoutPosition leftPositionOf(const LayoutPosition&);
+CORE_EXPORT LayoutPosition rightPositionOf(const LayoutPosition&);
+CORE_EXPORT LayoutPosition upPositionOf(const LayoutPosition&);
+CORE_EXPORT LayoutPosition downPositionOf(const LayoutPosition&);
+
+CORE_EXPORT std::ostream& operator<<(std::ostream&, const LayoutPosition&);
+
+} // namespace blink
+
+#endif // LayoutPosition_h