grid_track_collection.h | Explore in Territory

// Copyright 2020 The Chromium Authors
// 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_GRID_GRID_TRACK_COLLECTION_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_GRID_GRID_TRACK_COLLECTION_H_

#include "base/check_op.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/style/computed_style.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"

namespace blink {

class GridLineResolver;

// |GridTrackCollectionBase| provides an implementation for some shared
// functionality on grid collections, specifically binary search on the
// collection to get the range that contains a specific grid line.
class CORE_EXPORT GridTrackCollectionBase { … };

class CORE_EXPORT TrackSpanProperties { … };

struct CORE_EXPORT GridRange { … };

GridRangeVector;

class CORE_EXPORT GridRangeBuilder { … };

class CORE_EXPORT GridLayoutTrackCollection : public GridTrackCollectionBase { … };

// |GridRangeBuilder::EnsureTrackCoverage| may introduce a range start and/or
// end at the middle of any repeater from the block collection. This will affect
// how some repeated tracks within the same repeater group resolve their track
// sizes; e.g. consider the track list 'repeat(10, auto)' with a grid item
// spanning from the 3rd to the 7th track in the repeater, every track within
// the item's range will grow to fit the content of that item first.
//
// For the track sizing algorithm we want to have separate data (e.g. base size,
// growth limit, etc.) between tracks in different ranges; instead of trivially
// expanding the repeaters, which will limit our implementation to support
// relatively small track counts, we introduce the concept of a "set".
//
// A "set" is a collection of distinct track definitions that compose a range in
// |GridSizingTrackCollection|; each set element stores the number of tracks
// within the range that share its definition. The |GridSet| class represents
// a single element from a set.
//
// As an example, consider the following grid definition:
//   - 'grid-template-columns: repeat(4, 5px 1fr)'
//   - Grid item 1 with 'grid-column: 1 / span 5'
//   - Grid item 2 with 'grid-column: 2 / span 1'
//   - Grid item 3 with 'grid-column: 6 / span 8'
//
// Expanding the track definitions above we would look at the explicit grid:
//   | 5px | 1fr | 5px | 1fr | 5px | 1fr | 5px | 1fr |
//
// This example would produce the following ranges and their respective sets:
//   Range 1:  [1-1], Set 1: {  5px (1) }
//   Range 2:  [2-2], Set 2: {  1fr (1) }
//   Range 3:  [3-5], Set 3: {  5px (2) , 1fr (1) }
//   Range 4:  [6-8], Set 4: {  1fr (2) , 5px (1) }
//   Range 5: [9-13], Set 5: { auto (5) }
//
// Note that, since |GridRangeBuilder|'s ranges are assured to span a single
// repeater and to not cross any grid item's boundary in the respective
// dimension, tracks within a set are "commutative" and can be sized evenly.
struct CORE_EXPORT GridSet { … };

class CORE_EXPORT GridSizingTrackCollection final
    : public GridLayoutTrackCollection { … };

template <>
struct DowncastTraits<GridSizingTrackCollection> { … };

}  // namespace blink

WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(…)
WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(…)

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_GRID_GRID_TRACK_COLLECTION_H_
chromium/third_party/blink/renderer/core/layout/grid/grid_track_collection.h
