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

 // Copyright 2017 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 NGInlineBoxState_h
 #define NGInlineBoxState_h

 #include "third_party/blink/renderer/core/layout/ng/geometry/ng_logical_size.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/core/style/computed_style_constants.h"
 #include "third_party/blink/renderer/platform/fonts/font_baseline.h"
 #include "third_party/blink/renderer/platform/geometry/layout_unit.h"
 #include "third_party/blink/renderer/platform/wtf/vector.h"

 namespace blink {

 class LayoutObject;
 class NGInlineItem;
 struct NGInlineItemResult;
 class ShapeResultView;

 // Fragments that require the layout position/size of ancestor are packed in
 // this struct.
 struct NGPendingPositions {
   unsigned fragment_start;
   unsigned fragment_end;
   NGLineHeightMetrics metrics;
   EVerticalAlign vertical_align;
 };

 // Represents the current box while NGInlineLayoutAlgorithm performs layout.
 // Used 1) to cache common values for a box, and 2) to layout children that
 // require ancestor position or size.
 // This is a transient object only while building line boxes in a block.
 struct NGInlineBoxState {
   DISALLOW_NEW();

  public:
   unsigned fragment_start = 0;
   const NGInlineItem* item = nullptr;
   const ComputedStyle* style = nullptr;

   // The united metrics for the current box. This includes all objects in this
   // box, including descendants, and adjusted by placement properties such as
   // 'vertical-align'.
   NGLineHeightMetrics metrics;

   // The metrics of the font for this box. This includes leadings as specified
   // by the 'line-height' property.
   NGLineHeightMetrics text_metrics;

   // The distance between the text-top and the baseline for this box. The
   // text-top does not include leadings.
   LayoutUnit text_top;

   // The height of the text fragments.
   LayoutUnit text_height;

   // These values are to create a box fragment. Set only when needs_box_fragment
   // is set.
   bool has_start_edge = false;
   bool has_end_edge = false;
   LayoutUnit margin_inline_start;
   LayoutUnit margin_inline_end;
   NGLineBoxStrut borders;
   NGLineBoxStrut padding;

   Vector<NGPendingPositions> pending_descendants;
   bool include_used_fonts = false;
   bool needs_box_fragment = false;

   // True if this box has a metrics, including pending ones. Pending metrics
   // will be activated in |EndBoxState()|.
   bool HasMetrics() const {
     return !metrics.IsEmpty() || !pending_descendants.IsEmpty();
   }

   // Compute text metrics for a box. All text in a box share the same
   // metrics.
   // The computed metrics is included into the line height of the current box.
   void ComputeTextMetrics(const ComputedStyle& style,
                           FontBaseline baseline_type);
   void EnsureTextMetrics(const ComputedStyle&, FontBaseline);
   void ResetTextMetrics();

   void AccumulateUsedFonts(const ShapeResultView*, FontBaseline);

   // 'text-top' offset for 'vertical-align'.
   LayoutUnit TextTop(FontBaseline baseline_type) const;

   // Create a box fragment for this box.
   void SetNeedsBoxFragment();

   // Returns if the text style can be added without open-tag.
   // Text with different font or vertical-align needs to be wrapped with an
   // inline box.
   bool CanAddTextOfStyle(const ComputedStyle&) const;

 #if DCHECK_IS_ON()
   void CheckSame(const NGInlineBoxState&) const;
 #endif
 };

 // Represents the inline tree structure. This class provides:
 // 1) Allow access to fragments belonging to the current box.
 // 2) Performs layout when the positin/size of a box was computed.
 // 3) Cache common values for a box.
 class CORE_EXPORT NGInlineLayoutStateStack {
   STACK_ALLOCATED();

  public:
   // The box state for the line box.
   NGInlineBoxState& LineBoxState() { return stack_.front(); }

   void SetIsEmptyLine(bool is_empty_line) { is_empty_line_ = is_empty_line; }

   // Initialize the box state stack for a new line.
   // @return The initial box state for the line.
   NGInlineBoxState* OnBeginPlaceItems(const ComputedStyle*, FontBaseline, bool);

   // Push a box state stack.
   NGInlineBoxState* OnOpenTag(const NGInlineItem&,
                               const NGInlineItemResult&,
                               const NGLineBoxFragmentBuilder::ChildList&);
   NGInlineBoxState* OnOpenTag(const ComputedStyle&,
                               const NGLineBoxFragmentBuilder::ChildList&);

   // Pop a box state stack.
   NGInlineBoxState* OnCloseTag(NGLineBoxFragmentBuilder::ChildList*,
                                NGInlineBoxState*,
                                FontBaseline,
                                bool has_end_edge = true);

   // Compute all the pending positioning at the end of a line.
   void OnEndPlaceItems(NGLineBoxFragmentBuilder::ChildList*, FontBaseline);

   LayoutObject* ContainingLayoutObjectForAbsolutePositionObjects() const;

   bool HasBoxFragments() const { return !box_data_list_.IsEmpty(); }

   // This class keeps indexes to fragments in the line box, and that only
   // appending is allowed. Call this function to move all such data to the line
   // box, so that outside of this class can reorder fragments in the line box.
   void PrepareForReorder(NGLineBoxFragmentBuilder::ChildList*);

   // When reordering was complete, call this function to re-construct the box
   // data from the line box. Callers must call |PrepareForReorder()| before
   // reordering.
   void UpdateAfterReorder(NGLineBoxFragmentBuilder::ChildList*);

   // Update start/end of the first BoxData found at |index|.
   //
   // If inline fragmentation is found, a new BoxData is added.
   //
   // Returns the index to process next. It should be given to the next call to
   // this function.
   unsigned UpdateBoxDataFragmentRange(NGLineBoxFragmentBuilder::ChildList*,
                                       unsigned index);

   // Update edges of inline fragmented boxes.
   void UpdateFragmentedBoxDataEdges();

   // Compute inline positions of fragments and boxes.
   LayoutUnit ComputeInlinePositions(NGLineBoxFragmentBuilder::ChildList*);

   // Create box fragments. This function turns a flat list of children into
   // a box tree.
   void CreateBoxFragments(NGLineBoxFragmentBuilder::ChildList*);

 #if DCHECK_IS_ON()
   void CheckSame(const NGInlineLayoutStateStack&) const;
 #endif

  private:
   // End of a box state, either explicitly by close tag, or implicitly at the
   // end of a line.
   void EndBoxState(NGInlineBoxState*,
                    NGLineBoxFragmentBuilder::ChildList*,
                    FontBaseline);

   void AddBoxFragmentPlaceholder(NGInlineBoxState*,
                                  NGLineBoxFragmentBuilder::ChildList*,
                                  FontBaseline);

   enum PositionPending { kPositionNotPending, kPositionPending };

   // Compute vertical position for the 'vertical-align' property.
   // The timing to apply varies by values; some values apply at the layout of
   // the box was computed. Other values apply when the layout of the parent or
   // the line box was computed.
   // https://www.w3.org/TR/CSS22/visudet.html#propdef-vertical-align
   // https://www.w3.org/TR/css-inline-3/#propdef-vertical-align
   PositionPending ApplyBaselineShift(NGInlineBoxState*,
                                      NGLineBoxFragmentBuilder::ChildList*,
                                      FontBaseline);

   // Compute the metrics for when 'vertical-align' is 'top' and 'bottom' from
   // |pending_descendants|.
   NGLineHeightMetrics MetricsForTopAndBottomAlign(
       const NGInlineBoxState&,
       const NGLineBoxFragmentBuilder::ChildList&) const;

   // Data for a box fragment. See AddBoxFragmentPlaceholder().
   // This is a transient object only while building a line box.
   struct BoxData {
     BoxData(unsigned start,
             unsigned end,
             const NGInlineItem* item,
             NGLogicalSize size)
         : fragment_start(start), fragment_end(end), item(item), size(size) {}

     BoxData(const BoxData& other, unsigned start, unsigned end)
         : fragment_start(start),
           fragment_end(end),
           item(other.item),
           size(other.size),
           offset(other.offset) {}

     // The range of child fragments this box contains.
     unsigned fragment_start;
     unsigned fragment_end;

     const NGInlineItem* item;
     NGLogicalSize size;

     bool has_line_left_edge = false;
     bool has_line_right_edge = false;
     NGLineBoxStrut padding;
     // |CreateBoxFragment()| needs margin, border+padding, and the sum of them.
     LayoutUnit margin_line_left;
     LayoutUnit margin_line_right;
     LayoutUnit margin_border_padding_line_left;
     LayoutUnit margin_border_padding_line_right;

     NGLogicalOffset offset;
     unsigned parent_box_data_index = 0;
     unsigned fragmented_box_data_index = 0;

     void UpdateFragmentEdges(Vector<BoxData, 4>& list);

     scoped_refptr<NGLayoutResult> CreateBoxFragment(
         NGLineBoxFragmentBuilder::ChildList*);
   };

   Vector<NGInlineBoxState, 4> stack_;
   Vector<BoxData, 4> box_data_list_;

   bool is_empty_line_ = false;
 };

 }  // namespace blink

 #endif  // NGInlineBoxState_h
	// Copyright 2017 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 NGInlineBoxState_h
	#define NGInlineBoxState_h

	#include "third_party/blink/renderer/core/layout/ng/geometry/ng_logical_size.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/core/style/computed_style_constants.h"
	#include "third_party/blink/renderer/platform/fonts/font_baseline.h"
	#include "third_party/blink/renderer/platform/geometry/layout_unit.h"
	#include "third_party/blink/renderer/platform/wtf/vector.h"

	namespace blink {

	class LayoutObject;
	class NGInlineItem;
	struct NGInlineItemResult;
	class ShapeResultView;

	// Fragments that require the layout position/size of ancestor are packed in
	// this struct.
	struct NGPendingPositions {
	unsigned fragment_start;
	unsigned fragment_end;
	NGLineHeightMetrics metrics;
	EVerticalAlign vertical_align;
	};

	// Represents the current box while NGInlineLayoutAlgorithm performs layout.
	// Used 1) to cache common values for a box, and 2) to layout children that
	// require ancestor position or size.
	// This is a transient object only while building line boxes in a block.
	struct NGInlineBoxState {
	DISALLOW_NEW();

	public:
	unsigned fragment_start = 0;
	const NGInlineItem* item = nullptr;
	const ComputedStyle* style = nullptr;

	// The united metrics for the current box. This includes all objects in this
	// box, including descendants, and adjusted by placement properties such as
	// 'vertical-align'.
	NGLineHeightMetrics metrics;

	// The metrics of the font for this box. This includes leadings as specified
	// by the 'line-height' property.
	NGLineHeightMetrics text_metrics;

	// The distance between the text-top and the baseline for this box. The
	// text-top does not include leadings.
	LayoutUnit text_top;

	// The height of the text fragments.
	LayoutUnit text_height;

	// These values are to create a box fragment. Set only when needs_box_fragment
	// is set.
	bool has_start_edge = false;
	bool has_end_edge = false;
	LayoutUnit margin_inline_start;
	LayoutUnit margin_inline_end;
	NGLineBoxStrut borders;
	NGLineBoxStrut padding;

	Vector<NGPendingPositions> pending_descendants;
	bool include_used_fonts = false;
	bool needs_box_fragment = false;

	// True if this box has a metrics, including pending ones. Pending metrics
	// will be activated in \|EndBoxState()\|.
	bool HasMetrics() const {
	return !metrics.IsEmpty() \|\| !pending_descendants.IsEmpty();
	}

	// Compute text metrics for a box. All text in a box share the same
	// metrics.
	// The computed metrics is included into the line height of the current box.
	void ComputeTextMetrics(const ComputedStyle& style,
	FontBaseline baseline_type);
	void EnsureTextMetrics(const ComputedStyle&, FontBaseline);
	void ResetTextMetrics();

	void AccumulateUsedFonts(const ShapeResultView*, FontBaseline);

	// 'text-top' offset for 'vertical-align'.
	LayoutUnit TextTop(FontBaseline baseline_type) const;

	// Create a box fragment for this box.
	void SetNeedsBoxFragment();

	// Returns if the text style can be added without open-tag.
	// Text with different font or vertical-align needs to be wrapped with an
	// inline box.
	bool CanAddTextOfStyle(const ComputedStyle&) const;

	#if DCHECK_IS_ON()
	void CheckSame(const NGInlineBoxState&) const;
	#endif
	};

	// Represents the inline tree structure. This class provides:
	// 1) Allow access to fragments belonging to the current box.
	// 2) Performs layout when the positin/size of a box was computed.
	// 3) Cache common values for a box.
	class CORE_EXPORT NGInlineLayoutStateStack {
	STACK_ALLOCATED();

	public:
	// The box state for the line box.
	NGInlineBoxState& LineBoxState() { return stack_.front(); }

	void SetIsEmptyLine(bool is_empty_line) { is_empty_line_ = is_empty_line; }

	// Initialize the box state stack for a new line.
	// @return The initial box state for the line.
	NGInlineBoxState* OnBeginPlaceItems(const ComputedStyle*, FontBaseline, bool);

	// Push a box state stack.
	NGInlineBoxState* OnOpenTag(const NGInlineItem&,
	const NGInlineItemResult&,
	const NGLineBoxFragmentBuilder::ChildList&);
	NGInlineBoxState* OnOpenTag(const ComputedStyle&,
	const NGLineBoxFragmentBuilder::ChildList&);

	// Pop a box state stack.
	NGInlineBoxState* OnCloseTag(NGLineBoxFragmentBuilder::ChildList*,
	NGInlineBoxState*,
	FontBaseline,
	bool has_end_edge = true);

	// Compute all the pending positioning at the end of a line.
	void OnEndPlaceItems(NGLineBoxFragmentBuilder::ChildList*, FontBaseline);

	LayoutObject* ContainingLayoutObjectForAbsolutePositionObjects() const;

	bool HasBoxFragments() const { return !box_data_list_.IsEmpty(); }

	// This class keeps indexes to fragments in the line box, and that only
	// appending is allowed. Call this function to move all such data to the line
	// box, so that outside of this class can reorder fragments in the line box.
	void PrepareForReorder(NGLineBoxFragmentBuilder::ChildList*);

	// When reordering was complete, call this function to re-construct the box
	// data from the line box. Callers must call \|PrepareForReorder()\| before
	// reordering.
	void UpdateAfterReorder(NGLineBoxFragmentBuilder::ChildList*);

	// Update start/end of the first BoxData found at \|index\|.
	//
	// If inline fragmentation is found, a new BoxData is added.
	//
	// Returns the index to process next. It should be given to the next call to
	// this function.
	unsigned UpdateBoxDataFragmentRange(NGLineBoxFragmentBuilder::ChildList*,
	unsigned index);

	// Update edges of inline fragmented boxes.
	void UpdateFragmentedBoxDataEdges();

	// Compute inline positions of fragments and boxes.
	LayoutUnit ComputeInlinePositions(NGLineBoxFragmentBuilder::ChildList*);

	// Create box fragments. This function turns a flat list of children into
	// a box tree.
	void CreateBoxFragments(NGLineBoxFragmentBuilder::ChildList*);

	#if DCHECK_IS_ON()
	void CheckSame(const NGInlineLayoutStateStack&) const;
	#endif

	private:
	// End of a box state, either explicitly by close tag, or implicitly at the
	// end of a line.
	void EndBoxState(NGInlineBoxState*,
	NGLineBoxFragmentBuilder::ChildList*,
	FontBaseline);

	void AddBoxFragmentPlaceholder(NGInlineBoxState*,
	NGLineBoxFragmentBuilder::ChildList*,
	FontBaseline);

	enum PositionPending { kPositionNotPending, kPositionPending };

	// Compute vertical position for the 'vertical-align' property.
	// The timing to apply varies by values; some values apply at the layout of
	// the box was computed. Other values apply when the layout of the parent or
	// the line box was computed.
	// https://www.w3.org/TR/CSS22/visudet.html#propdef-vertical-align
	// https://www.w3.org/TR/css-inline-3/#propdef-vertical-align
	PositionPending ApplyBaselineShift(NGInlineBoxState*,
	NGLineBoxFragmentBuilder::ChildList*,
	FontBaseline);

	// Compute the metrics for when 'vertical-align' is 'top' and 'bottom' from
	// \|pending_descendants\|.
	NGLineHeightMetrics MetricsForTopAndBottomAlign(
	const NGInlineBoxState&,
	const NGLineBoxFragmentBuilder::ChildList&) const;

	// Data for a box fragment. See AddBoxFragmentPlaceholder().
	// This is a transient object only while building a line box.
	struct BoxData {
	BoxData(unsigned start,
	unsigned end,
	const NGInlineItem* item,
	NGLogicalSize size)
	: fragment_start(start), fragment_end(end), item(item), size(size) {}

	BoxData(const BoxData& other, unsigned start, unsigned end)
	: fragment_start(start),
	fragment_end(end),
	item(other.item),
	size(other.size),
	offset(other.offset) {}

	// The range of child fragments this box contains.
	unsigned fragment_start;
	unsigned fragment_end;

	const NGInlineItem* item;
	NGLogicalSize size;

	bool has_line_left_edge = false;
	bool has_line_right_edge = false;
	NGLineBoxStrut padding;
	// \|CreateBoxFragment()\| needs margin, border+padding, and the sum of them.
	LayoutUnit margin_line_left;
	LayoutUnit margin_line_right;
	LayoutUnit margin_border_padding_line_left;
	LayoutUnit margin_border_padding_line_right;

	NGLogicalOffset offset;
	unsigned parent_box_data_index = 0;
	unsigned fragmented_box_data_index = 0;

	void UpdateFragmentEdges(Vector<BoxData, 4>& list);

	scoped_refptr<NGLayoutResult> CreateBoxFragment(
	NGLineBoxFragmentBuilder::ChildList*);
	};

	Vector<NGInlineBoxState, 4> stack_;
	Vector<BoxData, 4> box_data_list_;

	bool is_empty_line_ = false;
	};

	} // namespace blink

	#endif // NGInlineBoxState_h