third_party/blink/renderer/core/layout/ng/inline/ng_fragment_item.h - chromium/src - Git at Google

 // Copyright 2019 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 THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_

 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/layout/geometry/logical_offset.h"
 #include "third_party/blink/renderer/core/layout/layout_object.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_line_box_fragment_builder.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_line_height_metrics.h"
 #include "third_party/blink/renderer/platform/graphics/paint/display_item_client.h"

 namespace blink {

 class NGFragmentItems;
 class NGInlineBreakToken;
 struct NGTextFragmentPaintInfo;

 // This class represents a text run or a box in an inline formatting context.
 //
 // This class consumes less memory than a full fragment, and can be stored in a
 // flat list (NGFragmentItems) for easier and faster traversal.
 class CORE_EXPORT NGFragmentItem : public DisplayItemClient {
  public:
   // Represents regular text that exists in the DOM.
   struct TextItem {
     scoped_refptr<const ShapeResultView> shape_result;
     // TODO(kojii): |start_offset| and |end_offset| should match to the offset
     // in |shape_result|. Consider if we should remove them, or if keeping them
     // is easier.
     const unsigned start_offset;
     const unsigned end_offset;
   };
   // Represents text generated by the layout engine, e.g., hyphen or ellipsis.
   struct GeneratedTextItem {
     scoped_refptr<const ShapeResultView> shape_result;
     String text;
   };
   // A start marker of a line box.
   struct LineItem {
     NGLineHeightMetrics metrics;
     scoped_refptr<const NGInlineBreakToken> inline_break_token;
     wtf_size_t children_count;
   };
   // Represents a box fragment appeared in a line. This includes inline boxes
   // (e.g., <span>text</span>) and atomic inlines.
   struct BoxItem {
     // If this item is an inline box, its children are stored as following
     // items. |children_count_| has the number of such items.
     //
     // If this item is a root of another IFC/BFC, children are stored normally,
     // as children of |box_fragment|.
     scoped_refptr<const NGPhysicalBoxFragment> box_fragment;
     wtf_size_t children_count;
   };

   enum ItemType { kText, kGeneratedText, kLine, kBox };

   // TODO(kojii): Should be able to create without once creating fragments.
   NGFragmentItem(const NGPhysicalTextFragment& text);
   NGFragmentItem(const NGPhysicalBoxFragment& box, wtf_size_t item_count);
   NGFragmentItem(const NGPhysicalLineBoxFragment& line, wtf_size_t item_count);

   ~NGFragmentItem() final;

   ItemType Type() const { return static_cast<ItemType>(type_); }

   bool IsHiddenForPaint() const { return is_hidden_for_paint_; }

   NGStyleVariant StyleVariant() const {
     return static_cast<NGStyleVariant>(style_variant_);
   }
   bool UsesFirstLineStyle() const {
     return StyleVariant() == NGStyleVariant::kFirstLine;
   }
   // Returns the style for this fragment.
   //
   // For a line box, this returns the style of the containing block. This mostly
   // represents the style for the line box, except 1) |style.Direction()| maybe
   // incorrect, use |BaseDirection()| instead, and 2) margin/border/padding,
   // background etc. do not apply to the line box.
   const ComputedStyle& Style() const {
     return layout_object_->EffectiveStyle(StyleVariant());
   }
   const LayoutObject* GetLayoutObject() const { return layout_object_; }

   const PhysicalRect& Rect() const { return rect_; }
   const PhysicalOffset& Offset() const { return rect_.offset; }
   const PhysicalSize& Size() const { return rect_.size; }
   void SetOffset(const PhysicalOffset& offset) { rect_.offset = offset; }

   PhysicalRect LocalRect() const { return {PhysicalOffset(), Size()}; }
   PhysicalRect SelfInkOverflow() const;

   // Count of following items that are descendants of this item in the box tree,
   // including this item. 1 means this is a box (box or line box) without
   // children. 0 if this item type cannot have children.
   wtf_size_t ChildrenCount() const {
     if (Type() == kBox)
       return box_.children_count;
     if (Type() == kLine)
       return line_.children_count;
     return 0;
   }

   // Returns |NGPhysicalBoxFragment| if one is associated with this item.
   const NGPhysicalBoxFragment* BoxFragment() const {
     if (Type() == kBox)
       return box_.box_fragment.get();
     return nullptr;
   }

   Node* GetNode() const { return layout_object_->GetNode(); }

   NGTextFragmentPaintInfo TextPaintInfo(const NGFragmentItems& items) const;

   // DisplayItemClient overrides
   String DebugName() const override;
   IntRect VisualRect() const override;

   // Find |NGFragmentItem|s that are associated with a |LayoutObject|.
   class CORE_EXPORT ItemsForLayoutObject {
     STACK_ALLOCATED();

    public:
     ItemsForLayoutObject() = default;
     ItemsForLayoutObject(const Vector<std::unique_ptr<NGFragmentItem>>& items,
                          unsigned first_index,
                          const NGFragmentItem* first_item)
         : items_(&items), first_item_(first_item), first_index_(first_index) {}

     bool IsEmpty() const { return !items_; }

     class CORE_EXPORT Iterator {
      public:
       Iterator(const Vector<std::unique_ptr<NGFragmentItem>>* items,
                unsigned index,
                const NGFragmentItem* item)
           : current_(item), items_(items), index_(index) {}
       const NGFragmentItem& operator*() const { return *current_; }
       const NGFragmentItem& operator->() const { return *current_; }
       Iterator& operator++();
       bool operator==(const Iterator& other) const {
         return current_ == other.current_;
       }
       bool operator!=(const Iterator& other) const {
         return current_ != other.current_;
       }

      private:
       const NGFragmentItem* current_;
       const Vector<std::unique_ptr<NGFragmentItem>>* items_;
       unsigned index_;
     };
     using iterator = Iterator;
     iterator begin() const {
       return Iterator(items_, first_index_, first_item_);
     }
     iterator end() const { return Iterator(nullptr, 0, nullptr); }

    private:
     const Vector<std::unique_ptr<NGFragmentItem>>* items_;
     const NGFragmentItem* first_item_;
     unsigned first_index_;
   };
   static ItemsForLayoutObject ItemsFor(const LayoutObject& layout_object);
   static PhysicalRect LocalVisualRectFor(const LayoutObject& layout_object);

   // Painters can use const methods only, except for these explicitly declared
   // methods.
   class MutableForPainting {
     STACK_ALLOCATED();

    public:
     // TODO(kojii): Add painter functions.

    private:
     friend class NGFragmentItem;
     MutableForPainting(const NGFragmentItem& item) {}
   };
   MutableForPainting GetMutableForPainting() const {
     return MutableForPainting(*this);
   }

   // Functions for |TextItem| and |GeneratedTextItem|

   bool IsFlowControl() const {
     DCHECK_EQ(Type(), kText);
     return is_flow_control_;
   }

   bool IsHorizontal() const {
     return IsHorizontalWritingMode(GetWritingMode());
   }

   WritingMode GetWritingMode() const {
     DCHECK_EQ(Type(), kText);
     return Style().GetWritingMode();
   }

   // TODO(yosin): We'll implement following functions.
   bool IsLineBreak() const { return false; }
   bool IsEllipsis() const { return false; }
   bool IsSymbolMarker() const { return false; }

   const ShapeResultView* TextShapeResult() const;

   unsigned StartOffset() const;
   unsigned EndOffset() const;
   unsigned TextLength() const { return EndOffset() - StartOffset(); }
   StringView Text(const NGFragmentItems& items) const;

   // Compute the inline position from text offset, in logical coordinate
   // relative to this fragment.
   LayoutUnit InlinePositionForOffset(StringView text,
                                      unsigned offset,
                                      LayoutUnit (*round_function)(float),
                                      AdjustMidCluster) const;

   LayoutUnit InlinePositionForOffset(StringView text, unsigned offset) const;

   // Compute line-relative coordinates for given offsets, this is not
   // flow-relative:
   // https://drafts.csswg.org/css-writing-modes-3/#line-directions
   std::pair<LayoutUnit, LayoutUnit> LineLeftAndRightForOffsets(
       StringView text,
       unsigned start_offset,
       unsigned end_offset) const;

   // The layout box of text in (start, end) range in local coordinate.
   // Start and end offsets must be between StartOffset() and EndOffset().
   PhysicalRect LocalRect(StringView text,
                          unsigned start_offset,
                          unsigned end_offset) const;

  private:
   const LayoutObject* layout_object_;

   // TODO(kojii): We can make them sub-classes if we need to make the vector of
   // pointers. Sub-classing from DisplayItemClient prohibits copying and that we
   // cannot create a vector of this class.
   union {
     TextItem text_;
     GeneratedTextItem generated_text_;
     LineItem line_;
     BoxItem box_;
   };

   PhysicalRect rect_;

   struct NGInkOverflowModel {
     USING_FAST_MALLOC(NGInkOverflowModel);

    public:
     NGInkOverflowModel(const PhysicalRect& self_ink_overflow,
                        const PhysicalRect& contents_ink_overflow);

     PhysicalRect self_ink_overflow;
     // TODO(kojii): Some types (e.g., kText) never have |contents_ink_overflow|.
     // Can/should we optimize the memory usage for those cases?
     PhysicalRect contents_ink_overflow;
   };
   mutable std::unique_ptr<NGInkOverflowModel> ink_overflow_;
   // TOOD(kojii): mutable because this is lazily computed, but it may not be
   // needed if we use |MutableForPainting|. TBD.

   // Item index delta to the next item for the same |LayoutObject|.
   // wtf_size_t delta_to_next_for_same_layout_object_ = 0;

   unsigned type_ : 2;           // ItemType
   unsigned style_variant_ : 2;  // NGStyleVariant
   // TODO(yosin): We will change |is_flow_control_| to call |IsLineBreak()| and
   // |TextType() == kFlowControl|.
   unsigned is_flow_control_ : 1;
   unsigned is_hidden_for_paint_ : 1;
 };

 }  // namespace blink

 #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_
	// Copyright 2019 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 THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_
	#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_

	#include "third_party/blink/renderer/core/core_export.h"
	#include "third_party/blink/renderer/core/layout/geometry/logical_offset.h"
	#include "third_party/blink/renderer/core/layout/layout_object.h"
	#include "third_party/blink/renderer/core/layout/ng/inline/ng_line_box_fragment_builder.h"
	#include "third_party/blink/renderer/core/layout/ng/inline/ng_line_height_metrics.h"
	#include "third_party/blink/renderer/platform/graphics/paint/display_item_client.h"

	namespace blink {

	class NGFragmentItems;
	class NGInlineBreakToken;
	struct NGTextFragmentPaintInfo;

	// This class represents a text run or a box in an inline formatting context.
	//
	// This class consumes less memory than a full fragment, and can be stored in a
	// flat list (NGFragmentItems) for easier and faster traversal.
	class CORE_EXPORT NGFragmentItem : public DisplayItemClient {
	public:
	// Represents regular text that exists in the DOM.
	struct TextItem {
	scoped_refptr<const ShapeResultView> shape_result;
	// TODO(kojii): \|start_offset\| and \|end_offset\| should match to the offset
	// in \|shape_result\|. Consider if we should remove them, or if keeping them
	// is easier.
	const unsigned start_offset;
	const unsigned end_offset;
	};
	// Represents text generated by the layout engine, e.g., hyphen or ellipsis.
	struct GeneratedTextItem {
	scoped_refptr<const ShapeResultView> shape_result;
	String text;
	};
	// A start marker of a line box.
	struct LineItem {
	NGLineHeightMetrics metrics;
	scoped_refptr<const NGInlineBreakToken> inline_break_token;
	wtf_size_t children_count;
	};
	// Represents a box fragment appeared in a line. This includes inline boxes
	// (e.g., <span>text</span>) and atomic inlines.
	struct BoxItem {
	// If this item is an inline box, its children are stored as following
	// items. \|children_count_\| has the number of such items.
	//
	// If this item is a root of another IFC/BFC, children are stored normally,
	// as children of \|box_fragment\|.
	scoped_refptr<const NGPhysicalBoxFragment> box_fragment;
	wtf_size_t children_count;
	};

	enum ItemType { kText, kGeneratedText, kLine, kBox };

	// TODO(kojii): Should be able to create without once creating fragments.
	NGFragmentItem(const NGPhysicalTextFragment& text);
	NGFragmentItem(const NGPhysicalBoxFragment& box, wtf_size_t item_count);
	NGFragmentItem(const NGPhysicalLineBoxFragment& line, wtf_size_t item_count);

	~NGFragmentItem() final;

	ItemType Type() const { return static_cast<ItemType>(type_); }

	bool IsHiddenForPaint() const { return is_hidden_for_paint_; }

	NGStyleVariant StyleVariant() const {
	return static_cast<NGStyleVariant>(style_variant_);
	}
	bool UsesFirstLineStyle() const {
	return StyleVariant() == NGStyleVariant::kFirstLine;
	}
	// Returns the style for this fragment.
	//
	// For a line box, this returns the style of the containing block. This mostly
	// represents the style for the line box, except 1) \|style.Direction()\| maybe
	// incorrect, use \|BaseDirection()\| instead, and 2) margin/border/padding,
	// background etc. do not apply to the line box.
	const ComputedStyle& Style() const {
	return layout_object_->EffectiveStyle(StyleVariant());
	}
	const LayoutObject* GetLayoutObject() const { return layout_object_; }

	const PhysicalRect& Rect() const { return rect_; }
	const PhysicalOffset& Offset() const { return rect_.offset; }
	const PhysicalSize& Size() const { return rect_.size; }
	void SetOffset(const PhysicalOffset& offset) { rect_.offset = offset; }

	PhysicalRect LocalRect() const { return {PhysicalOffset(), Size()}; }
	PhysicalRect SelfInkOverflow() const;

	// Count of following items that are descendants of this item in the box tree,
	// including this item. 1 means this is a box (box or line box) without
	// children. 0 if this item type cannot have children.
	wtf_size_t ChildrenCount() const {
	if (Type() == kBox)
	return box_.children_count;
	if (Type() == kLine)
	return line_.children_count;
	return 0;
	}

	// Returns \|NGPhysicalBoxFragment\| if one is associated with this item.
	const NGPhysicalBoxFragment* BoxFragment() const {
	if (Type() == kBox)
	return box_.box_fragment.get();
	return nullptr;
	}

	Node* GetNode() const { return layout_object_->GetNode(); }

	NGTextFragmentPaintInfo TextPaintInfo(const NGFragmentItems& items) const;

	// DisplayItemClient overrides
	String DebugName() const override;
	IntRect VisualRect() const override;

	// Find \|NGFragmentItem\|s that are associated with a \|LayoutObject\|.
	class CORE_EXPORT ItemsForLayoutObject {
	STACK_ALLOCATED();

	public:
	ItemsForLayoutObject() = default;
	ItemsForLayoutObject(const Vector<std::unique_ptr<NGFragmentItem>>& items,
	unsigned first_index,
	const NGFragmentItem* first_item)
	: items_(&items), first_item_(first_item), first_index_(first_index) {}

	bool IsEmpty() const { return !items_; }

	class CORE_EXPORT Iterator {
	public:
	Iterator(const Vector<std::unique_ptr<NGFragmentItem>>* items,
	unsigned index,
	const NGFragmentItem* item)
	: current_(item), items_(items), index_(index) {}
	const NGFragmentItem& operator() const { return current_; }
	const NGFragmentItem& operator->() const { return *current_; }
	Iterator& operator++();
	bool operator==(const Iterator& other) const {
	return current_ == other.current_;
	}
	bool operator!=(const Iterator& other) const {
	return current_ != other.current_;
	}

	private:
	const NGFragmentItem* current_;
	const Vector<std::unique_ptr<NGFragmentItem>>* items_;
	unsigned index_;
	};
	using iterator = Iterator;
	iterator begin() const {
	return Iterator(items_, first_index_, first_item_);
	}
	iterator end() const { return Iterator(nullptr, 0, nullptr); }

	private:
	const Vector<std::unique_ptr<NGFragmentItem>>* items_;
	const NGFragmentItem* first_item_;
	unsigned first_index_;
	};
	static ItemsForLayoutObject ItemsFor(const LayoutObject& layout_object);
	static PhysicalRect LocalVisualRectFor(const LayoutObject& layout_object);

	// Painters can use const methods only, except for these explicitly declared
	// methods.
	class MutableForPainting {
	STACK_ALLOCATED();

	public:
	// TODO(kojii): Add painter functions.

	private:
	friend class NGFragmentItem;
	MutableForPainting(const NGFragmentItem& item) {}
	};
	MutableForPainting GetMutableForPainting() const {
	return MutableForPainting(*this);
	}

	// Functions for \|TextItem\| and \|GeneratedTextItem\|

	bool IsFlowControl() const {
	DCHECK_EQ(Type(), kText);
	return is_flow_control_;
	}

	bool IsHorizontal() const {
	return IsHorizontalWritingMode(GetWritingMode());
	}

	WritingMode GetWritingMode() const {
	DCHECK_EQ(Type(), kText);
	return Style().GetWritingMode();
	}

	// TODO(yosin): We'll implement following functions.
	bool IsLineBreak() const { return false; }
	bool IsEllipsis() const { return false; }
	bool IsSymbolMarker() const { return false; }

	const ShapeResultView* TextShapeResult() const;

	unsigned StartOffset() const;
	unsigned EndOffset() const;
	unsigned TextLength() const { return EndOffset() - StartOffset(); }
	StringView Text(const NGFragmentItems& items) const;

	// Compute the inline position from text offset, in logical coordinate
	// relative to this fragment.
	LayoutUnit InlinePositionForOffset(StringView text,
	unsigned offset,
	LayoutUnit (*round_function)(float),
	AdjustMidCluster) const;

	LayoutUnit InlinePositionForOffset(StringView text, unsigned offset) const;

	// Compute line-relative coordinates for given offsets, this is not
	// flow-relative:
	// https://drafts.csswg.org/css-writing-modes-3/#line-directions
	std::pair<LayoutUnit, LayoutUnit> LineLeftAndRightForOffsets(
	StringView text,
	unsigned start_offset,
	unsigned end_offset) const;

	// The layout box of text in (start, end) range in local coordinate.
	// Start and end offsets must be between StartOffset() and EndOffset().
	PhysicalRect LocalRect(StringView text,
	unsigned start_offset,
	unsigned end_offset) const;

	private:
	const LayoutObject* layout_object_;

	// TODO(kojii): We can make them sub-classes if we need to make the vector of
	// pointers. Sub-classing from DisplayItemClient prohibits copying and that we
	// cannot create a vector of this class.
	union {
	TextItem text_;
	GeneratedTextItem generated_text_;
	LineItem line_;
	BoxItem box_;
	};

	PhysicalRect rect_;

	struct NGInkOverflowModel {
	USING_FAST_MALLOC(NGInkOverflowModel);

	public:
	NGInkOverflowModel(const PhysicalRect& self_ink_overflow,
	const PhysicalRect& contents_ink_overflow);

	PhysicalRect self_ink_overflow;
	// TODO(kojii): Some types (e.g., kText) never have \|contents_ink_overflow\|.
	// Can/should we optimize the memory usage for those cases?
	PhysicalRect contents_ink_overflow;
	};
	mutable std::unique_ptr<NGInkOverflowModel> ink_overflow_;
	// TOOD(kojii): mutable because this is lazily computed, but it may not be
	// needed if we use \|MutableForPainting\|. TBD.

	// Item index delta to the next item for the same \|LayoutObject\|.
	// wtf_size_t delta_to_next_for_same_layout_object_ = 0;

	unsigned type_ : 2; // ItemType
	unsigned style_variant_ : 2; // NGStyleVariant
	// TODO(yosin): We will change \|is_flow_control_\| to call \|IsLineBreak()\| and
	// \|TextType() == kFlowControl\|.
	unsigned is_flow_control_ : 1;
	unsigned is_hidden_for_paint_ : 1;
	};

	} // namespace blink

	#endif // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_FRAGMENT_ITEM_H_