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// Copyright 2014 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef COBALT_LAYOUT_BOX_H_
#define COBALT_LAYOUT_BOX_H_
#include <iosfwd>
#include <memory>
#include <ostream>
#include <string>
#include <vector>
#include "base/memory/ref_counted.h"
#include "base/optional.h"
#include "cobalt/cssom/css_computed_style_declaration.h"
#include "cobalt/cssom/css_style_declaration.h"
#include "cobalt/dom/node.h"
#include "cobalt/layout/base_direction.h"
#include "cobalt/layout/box_intersection_observer_module.h"
#include "cobalt/layout/insets_layout_unit.h"
#include "cobalt/layout/layout_stat_tracker.h"
#include "cobalt/layout/layout_unit.h"
#include "cobalt/layout/line_wrapping.h"
#include "cobalt/layout/rect_layout_unit.h"
#include "cobalt/layout/size_layout_unit.h"
#include "cobalt/layout/vector2d_layout_unit.h"
#include "cobalt/math/matrix3_f.h"
#include "cobalt/math/point_f.h"
#include "cobalt/math/rect_f.h"
#include "cobalt/math/vector2d.h"
#include "cobalt/math/vector2d_f.h"
#include "cobalt/render_tree/animations/animate_node.h"
#include "cobalt/render_tree/composition_node.h"
#include "cobalt/ui_navigation/nav_item.h"
#include "cobalt/web_animations/animation_set.h"
namespace cobalt {
namespace render_tree {
struct RoundedCorners;
} // namespace render_tree
namespace layout {
class AnonymousBlockBox;
class BlockContainerBox;
class ContainerBox;
class TextBox;
class UsedStyleProvider;
struct LayoutParams {
LayoutParams()
: shrink_to_fit_width_forced(false),
freeze_width(false),
freeze_height(false),
containing_block_direction(kLeftToRightBaseDirection) {}
// Normally the used values of "width", "margin-left", and "margin-right" are
// calculated by choosing the 1 out of 10 algorithms based on the computed
// values of "display", "position", "overflow", and the fact whether the box
// is replaced or not, as per:
// https://www.w3.org/TR/CSS21/visudet.html#Computing_widths_and_margins
//
// If this flag is set, block container boxes will follow the algorithm
// for inline-level, non-replaced block container boxes, which involves
// the calculation of shrink-to-fit width, as per:
// https://www.w3.org/TR/CSS21/visudet.html#inlineblock-width
//
// This override is used during the first pass of layout to calculate
// the content size of "inline-block" elements. It's an equivalent of
// "trying all possible line breaks", as described by:
// https://www.w3.org/TR/CSS21/visudet.html#shrink-to-fit-float
bool shrink_to_fit_width_forced;
// These overrides are used for flex items when they are sized by the
// container.
bool freeze_width;
bool freeze_height;
// Many box positions and sizes are calculated with respect to the edges of
// a rectangular box called a containing block.
// https://www.w3.org/TR/CSS21/visuren.html#containing-block
SizeLayoutUnit containing_block_size;
// Margin calculations can depend on the direction property of the containing
// block.
// https://www.w3.org/TR/CSS21/visudet.html#blockwidth
BaseDirection containing_block_direction;
bool operator==(const LayoutParams& rhs) const {
return shrink_to_fit_width_forced == rhs.shrink_to_fit_width_forced &&
freeze_width == rhs.freeze_width &&
freeze_height == rhs.freeze_height &&
containing_block_size == rhs.containing_block_size &&
containing_block_direction == rhs.containing_block_direction;
}
base::Optional<LayoutUnit> maybe_margin_top;
base::Optional<LayoutUnit> maybe_margin_bottom;
base::Optional<LayoutUnit> maybe_height;
};
inline std::ostream& operator<<(std::ostream& stream,
const LayoutParams& params) {
stream << "{shrink_to_fit_width_forced=" << params.shrink_to_fit_width_forced
<< " freeze_width=" << params.freeze_width
<< " freeze_height=" << params.freeze_height
<< " containing_block_size=" << params.containing_block_size << "}";
return stream;
}
// A base class for all boxes.
//
// The CSS box model describes the rectangular boxes that are generated
// for elements in the document tree and laid out according to the visual
// formatting model.
// https://www.w3.org/TR/CSS21/box.html
// Boxes are reference counted, because they are referred to by both parent
// boxes and LayoutBoxes objects stored with html elements in the DOM tree to
// allow incremental box generation.
class Box : public base::RefCounted<Box> {
public:
// Defines the formatting context in which the box should participate.
// Do not confuse with the formatting context that the element may establish.
enum Level {
// The "block" value of the "display" property makes an element block-level.
// Block-level boxes participate in a block formatting context.
// https://www.w3.org/TR/CSS21/visuren.html#block-boxes
kBlockLevel,
// The "inline" and "inline-block" values of the "display" property make
// an element inline-level. Inline-level boxes that participate in an inline
// formatting context.
// https://www.w3.org/TR/CSS21/visuren.html#inline-boxes
kInlineLevel,
};
enum MarginCollapsingStatus {
kCollapseMargins,
kIgnore,
kSeparateAdjoiningMargins,
};
enum RelationshipToBox {
kIsBoxAncestor,
kIsBox,
kIsBoxDescendant,
};
enum TransformAction {
kEnterTransform,
kExitTransform,
};
// Info tracked on container boxes encountered when a stacking context is
// generating its cross references.
struct StackingContextContainerBoxInfo {
StackingContextContainerBoxInfo(ContainerBox* container_box,
bool is_absolute_containing_block,
bool has_absolute_position,
bool has_overflow_hidden)
: container_box(container_box),
is_absolute_containing_block(is_absolute_containing_block),
is_usable_as_child_container(is_absolute_containing_block),
has_absolute_position(has_absolute_position),
has_overflow_hidden(has_overflow_hidden) {}
ContainerBox* container_box;
bool is_absolute_containing_block;
bool is_usable_as_child_container;
bool has_absolute_position;
bool has_overflow_hidden;
};
typedef std::vector<StackingContextContainerBoxInfo>
StackingContextContainerBoxStack;
// List of containing blocks with overflow hidden property. Used by stacking
// context children that are added to a stacking context container higher up
// the tree than their containing block, so that they can still have the
// overflow hidden from those containing blocks applied.
typedef std::vector<ContainerBox*> ContainingBlocksWithOverflowHidden;
// The RenderSequence of a box is used to compare the relative drawing order
// of boxes. It stores a value for the box's drawing order position at each
// stacking context up to the root of the render tree. As a result, starting
// from the root ancestor, the box for which the render sequence ends first,
// or for which the draw order position at a stacking context is lower is
// drawn before the other box.
typedef std::vector<size_t> RenderSequence;
Box(const scoped_refptr<cssom::CSSComputedStyleDeclaration>&
css_computed_style_declaration,
UsedStyleProvider* used_style_provider,
LayoutStatTracker* layout_stat_tracker);
virtual ~Box();
// Computed style contains CSS values from the last stage of processing
// before the layout. The computed value resolves the specified value as far
// as possible without laying out the document or performing other expensive
// or hard-to-parallelize operations, such as resolving network requests or
// retrieving values other than from the element and its parent.
// https://www.w3.org/TR/css-cascade-3/#computed
const scoped_refptr<cssom::CSSComputedStyleDeclaration>&
css_computed_style_declaration() const {
return css_computed_style_declaration_;
}
const scoped_refptr<const cssom::CSSComputedStyleData>& computed_style()
const {
return css_computed_style_declaration_->data();
}
// The animation set specifies all currently active animations applying
// to this box's computed_style() CSS Style Declaration.
// https://w3c.github.io/web-animations
const web_animations::AnimationSet* animations() const {
return css_computed_style_declaration_->animations().get();
}
// Specifies the formatting context in which the box should participate.
// Do not confuse with the formatting context that the element may establish.
virtual Level GetLevel() const = 0;
virtual MarginCollapsingStatus GetMarginCollapsingStatus() const {
return Box::kCollapseMargins;
}
// Returns true if the box is positioned (e.g. position is non-static or
// transform is not None). Intuitively, this is true if the element does
// not follow standard layout flow rules for determining its position.
// https://www.w3.org/TR/CSS21/visuren.html#positioned-element.
bool IsPositioned() const;
// Returns true if the box has a non-"none" value for its transform property.
// https://www.w3.org/TR/css3-transforms/#transform-property
bool IsTransformed() const;
// Absolutely positioned box implies that the element's "position" property
// has the value "absolute" or "fixed".
// https://www.w3.org/TR/CSS21/visuren.html#absolutely-positioned
bool IsAbsolutelyPositioned() const;
// Returns true if the box serves as a stacking context for descendant
// elements. The core stacking context creation criteria is given here
// (https://www.w3.org/TR/CSS21/visuren.html#z-index) however it is extended
// by various other specification documents such as those describing opacity
// (https://www.w3.org/TR/css3-color/#transparency) and transforms
// (https://www.w3.org/TR/css3-transforms/#transform-rendering).
virtual bool IsStackingContext() const { return false; }
// Updates the size of margin, border, padding, and content boxes. Lays out
// in-flow descendants, estimates static positions (but not sizes) of
// out-of-flow descendants. Does not update the position of the box.
void UpdateSize(const LayoutParams& layout_params);
// Returns the offset from root to this box's containing block.
Vector2dLayoutUnit GetContainingBlockOffsetFromRoot(
bool transform_forms_root) const;
// Returns the offset from the containing block (which can be either the
// containing block's content box or padding box) to its content box.
Vector2dLayoutUnit GetContainingBlockOffsetFromItsContentBox(
const ContainerBox* containing_block) const;
InsetsLayoutUnit GetContainingBlockInsetFromItsContentBox(
const ContainerBox* containing_block) const;
// Returns boxes relative to the root or containing block, that take into
// account transforms.
RectLayoutUnit GetTransformedBoxFromRoot(
const RectLayoutUnit& box_from_margin_box) const;
RectLayoutUnit GetTransformedBoxFromRootWithScroll(
const RectLayoutUnit& box_from_margin_box,
bool transform_forms_root = false) const;
RectLayoutUnit GetTransformedBoxFromContainingBlock(
const ContainerBox* containing_block,
const RectLayoutUnit& box_from_margin_box) const;
RectLayoutUnit GetTransformedBoxFromContainingBlockContentBox(
const ContainerBox* containing_block,
const RectLayoutUnit& box_from_margin_box) const;
// Used values of "left" and "top" are publicly readable and writable so that
// they can be calculated and adjusted by the formatting context of the parent
// box.
void set_left(LayoutUnit left) {
margin_box_offset_from_containing_block_.set_x(left);
}
LayoutUnit left() const {
return margin_box_offset_from_containing_block_.x();
}
void set_top(LayoutUnit top) {
margin_box_offset_from_containing_block_.set_y(top);
}
LayoutUnit top() const {
return margin_box_offset_from_containing_block_.y();
}
// The following static position functions are only used with absolutely
// positioned boxes.
// https://www.w3.org/TR/CSS21/visuren.html#absolute-positioning
// The static position for 'left' is the distance from the left edge of the
// containing block to the left margin edge of a hypothetical box that would
// have been the first box of the element if its 'position' property had been
// 'static' and 'float' had been 'none'. The value is negative if the
// hypothetical box is to the left of the containing block.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
void SetStaticPositionLeftFromParent(LayoutUnit left);
void SetStaticPositionLeftFromContainingBlockToParent(LayoutUnit left);
LayoutUnit GetStaticPositionLeft() const;
// The static position for 'right' is the distance from the right edge of the
// containing block to the right margin edge of the same hypothetical box as
// above. The value is positive if the hypothetical box is to the left of the
// containing block's edge.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
void SetStaticPositionRightFromParent(LayoutUnit right);
void SetStaticPositionRightFromContainingBlockToParent(LayoutUnit right);
LayoutUnit GetStaticPositionRight() const;
// For the purposes of this section and the next, the term "static position"
// (of an element) refers, roughly, to the position an element would have had
// in the normal flow. More precisely, the static position for 'top' is the
// distance from the top edge of the containing block to the top margin edge
// of a hypothetical box that would have been the first box of the element if
// its specified 'position' value had been 'static'.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-height
void SetStaticPositionTopFromParent(LayoutUnit top);
void SetStaticPositionTopFromContainingBlockToParent(LayoutUnit top);
LayoutUnit GetStaticPositionTop() const;
// Each box has a content area and optional surrounding padding, border,
// and margin areas.
// https://www.w3.org/TR/CSS21/box.html#box-dimensions
//
// Methods below provide read-only access to dimensions and edges of margin,
// border, padding, and content boxes.
// Margin box.
LayoutUnit margin_left() const { return margin_insets_.left(); }
LayoutUnit margin_top() const { return margin_insets_.top(); }
LayoutUnit margin_right() const { return margin_insets_.right(); }
LayoutUnit margin_bottom() const { return margin_insets_.bottom(); }
LayoutUnit GetMarginBoxWidth() const;
LayoutUnit GetMarginBoxHeight() const;
// Used values of "margin" properties are set by overriders
// of |UpdateContentSizeAndMargins| method.
void set_margin_left(LayoutUnit margin_left) {
margin_insets_.set_left(margin_left);
}
void set_margin_top(LayoutUnit margin_top) {
margin_insets_.set_top(margin_top);
}
void set_margin_right(LayoutUnit margin_right) {
margin_insets_.set_right(margin_right);
}
void set_margin_bottom(LayoutUnit margin_bottom) {
margin_insets_.set_bottom(margin_bottom);
}
math::Matrix3F GetMarginBoxTransformFromContainingBlock(
const ContainerBox* containing_block) const;
math::Matrix3F GetMarginBoxTransformFromContainingBlockWithScroll(
const ContainerBox* containing_block, bool transform_forms_root) const;
Vector2dLayoutUnit GetMarginBoxOffsetFromRoot(
bool transform_forms_root) const;
const Vector2dLayoutUnit& margin_box_offset_from_containing_block() const {
return margin_box_offset_from_containing_block_;
}
LayoutUnit GetMarginBoxRightEdgeOffsetFromContainingBlock() const;
LayoutUnit GetMarginBoxBottomEdgeOffsetFromContainingBlock() const;
LayoutUnit GetMarginBoxStartEdgeOffsetFromContainingBlock(
BaseDirection base_direction) const;
LayoutUnit GetMarginBoxEndEdgeOffsetFromContainingBlock(
BaseDirection base_direction) const;
// Border box.
LayoutUnit border_left_width() const { return border_insets_.left(); }
LayoutUnit border_top_width() const { return border_insets_.top(); }
LayoutUnit border_right_width() const { return border_insets_.right(); }
LayoutUnit border_bottom_width() const { return border_insets_.bottom(); }
RectLayoutUnit GetBorderBoxFromRoot(bool transform_forms_root) const;
LayoutUnit GetBorderBoxWidth() const;
LayoutUnit GetBorderBoxHeight() const;
SizeLayoutUnit GetClampedBorderBoxSize() const;
RectLayoutUnit GetBorderBoxFromMarginBox() const;
Vector2dLayoutUnit GetBorderBoxOffsetFromRoot(
bool transform_forms_root) const;
Vector2dLayoutUnit GetBorderBoxOffsetFromMarginBox() const;
void ResetBorderInsets() { border_insets_ = InsetsLayoutUnit(); }
// Padding box.
LayoutUnit padding_left() const { return padding_insets_.left(); }
LayoutUnit padding_top() const { return padding_insets_.top(); }
LayoutUnit padding_right() const { return padding_insets_.right(); }
LayoutUnit padding_bottom() const { return padding_insets_.bottom(); }
LayoutUnit GetPaddingBoxWidth() const;
LayoutUnit GetPaddingBoxHeight() const;
RectLayoutUnit GetClampedPaddingBox(bool transform_forms_root) const;
SizeLayoutUnit GetClampedPaddingBoxSize() const;
RectLayoutUnit GetPaddingBoxFromMarginBox() const;
Vector2dLayoutUnit GetPaddingBoxOffsetFromRoot(
bool transform_forms_root) const;
Vector2dLayoutUnit GetPaddingBoxOffsetFromBorderBox() const;
LayoutUnit GetPaddingBoxLeftEdgeOffsetFromMarginBox() const;
LayoutUnit GetPaddingBoxTopEdgeOffsetFromMarginBox() const;
// Set padding insets in InlineContainerBox UpdatePaddings to an empty
// LayoutUnit or the computed_style value using is_split_on_*_.
void SetPaddingInsets(LayoutUnit left, LayoutUnit top, LayoutUnit right,
LayoutUnit bottom);
// Content box.
LayoutUnit width() const { return content_size_.width(); }
LayoutUnit height() const { return content_size_.height(); }
const SizeLayoutUnit& content_box_size() const { return content_size_; }
RectLayoutUnit GetContentBoxFromMarginBox() const;
Vector2dLayoutUnit GetContentBoxOffsetFromRoot(
bool transform_forms_root) const;
Vector2dLayoutUnit GetContentBoxOffsetFromMarginBox() const;
Vector2dLayoutUnit GetContentBoxOffsetFromBorderBox() const;
Vector2dLayoutUnit GetContentBoxOffsetFromPaddingBox() const;
LayoutUnit GetContentBoxLeftEdgeOffsetFromMarginBox() const;
LayoutUnit GetContentBoxTopEdgeOffsetFromMarginBox() const;
Vector2dLayoutUnit GetContentBoxOffsetFromContainingBlockContentBox(
const ContainerBox* containing_block) const;
InsetsLayoutUnit GetContentBoxInsetFromContainingBlockContentBox(
const ContainerBox* containing_block) const;
Vector2dLayoutUnit GetContentBoxOffsetFromContainingBlock() const;
InsetsLayoutUnit GetContentBoxInsetFromContainingBlock(
const ContainerBox* containing_block) const;
LayoutUnit GetContentBoxLeftEdgeOffsetFromContainingBlock() const;
LayoutUnit GetContentBoxTopEdgeOffsetFromContainingBlock() const;
LayoutUnit GetContentBoxStartEdgeOffsetFromContainingBlock(
BaseDirection base_direction) const;
LayoutUnit GetContentBoxEndEdgeOffsetFromContainingBlock(
BaseDirection base_direction) const;
// Return the size difference between the content and margin box on an axis.
LayoutUnit GetContentToMarginHorizontal() const;
LayoutUnit GetContentToMarginVertical() const;
// The height of each inline-level box in the line box is calculated. For
// replaced elements, inline-block elements, and inline-table elements, this
// is the height of their margin box; for inline boxes, this is their
// 'line-height'.
// http://www.w3.org/TR/CSS21/visudet.html#line-height
virtual LayoutUnit GetInlineLevelBoxHeight() const;
virtual LayoutUnit GetInlineLevelTopMargin() const;
// When an element is blockified, that should not affect the static position.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
// https://www.w3.org/TR/CSS21/visuren.html#dis-pos-flo
// Return true if the element's outer display type was inline before any
// optional blockificiation has occurred.
bool is_inline_before_blockification() const {
return css_computed_style_declaration_->data()
->is_inline_before_blockification();
}
// Attempts to wrap the box based upon the provided wrap policies.
// If |is_line_existence_justified| is true, then the line does not require
// additional content before wrapping is possible. Otherwise, content
// justifying the line must be encountered first.
// |available_width| indicates the amount of width remaining on the line
// before the boxes overflow it.
// If |should_collapse_trailing_white_space| is true, the trailing whitespace
// of the box will be collapsed and should not be included in width
// calculations.
//
// Returns the result of the wrap attempt. If the result is
// |kWrapResultSplitWrap|, then the box has been split, and the portion of the
// box split from the initial box is available via GetSplitSibling().
//
// Note that only inline boxes are wrappable.
virtual WrapResult TryWrapAt(WrapAtPolicy wrap_at_policy,
WrapOpportunityPolicy wrap_opportunity_policy,
bool is_line_existence_justified,
LayoutUnit available_width,
bool should_collapse_trailing_white_space) = 0;
// Returns the next box in a linked list of sibling boxes produced from
// splits of the original box.
//
// Note that only inline boxes are splittable. All other box types will return
// NULL.
virtual Box* GetSplitSibling() const { return NULL; }
// Verifies that either an ellipsis can be placed within the box, or that an
// ellipsis has already been placed in a previous box in the line, and calls
// DoPlaceEllipsisOrProcessPlacedEllipsis() to handle ellipsis placement and
// updating of ellipsis-related state within the box. It also sets
// |is_placement_requirement_met| to true if the box fulfills the requirement
// that the first character or atomic inline-level element must appear on a
// line before an ellipsis
// (https://www.w3.org/TR/css3-ui/#propdef-text-overflow), regardless of
// whether or not the ellipsis can be placed within this specific box.
void TryPlaceEllipsisOrProcessPlacedEllipsis(
BaseDirection base_direction, LayoutUnit desired_offset,
bool* is_placement_requirement_met, bool* is_placed,
LayoutUnit* placed_offset);
// Whether or not the box fulfills the ellipsis requirement that it not be
// be placed until after the "the first character or atomic inline-level
// element on a line."
// https://www.w3.org/TR/css3-ui/#propdef-text-overflow
virtual bool DoesFulfillEllipsisPlacementRequirement() const { return false; }
// Do any processing needed prior to ellipsis placement. This involves caching
// the old value and resetting the current value so it can be determined
// whether or not the ellipsis state within a box changed as a a result of
// ellipsis placement.
virtual void DoPreEllipsisPlacementProcessing() {}
// Do any processing needed following ellipsis placement. This involves
// checking the old value against the new value and resetting the cached
// render tree node if the ellipsis state changed.
virtual void DoPostEllipsisPlacementProcessing() {}
// Whether or not the box is fully hidden by an ellipsis. This applies to
// atomic inline-level elements that have had an ellipsis placed before them
// on a line. https://www.w3.org/TR/css3-ui/#propdef-text-overflow
virtual bool IsHiddenByEllipsis() const { return false; }
// Initial splitting of boxes between bidi level runs prior to layout, so that
// they will not need to occur during layout.
virtual void SplitBidiLevelRuns() = 0;
// Attempt to split the box at the second level run within it.
// Returns true if a split occurs. The second box produced by the split is
// retrievable by calling GetSplitSibling().
// NOTE: The splits that occur at the intersection of bidi level runs is
// unrelated to line-wrapping and does not introduce wrappable locations.
// It is used to facilitate bidi level reordering of the boxes within a
// line.
virtual bool TrySplitAtSecondBidiLevelRun() = 0;
// Retrieve the bidi level for the box, if it has one.
virtual base::Optional<int> GetBidiLevel() const = 0;
// Sets whether a leading white space in the box or its first non-collapsed
// descendant should be collapsed.
virtual void SetShouldCollapseLeadingWhiteSpace(
bool should_collapse_leading_white_space) = 0;
// Sets whether a trailing white space in the box or its last non-collapsed
// descendant should be collapsed.
virtual void SetShouldCollapseTrailingWhiteSpace(
bool should_collapse_trailing_white_space) = 0;
// Whether the box or its first non-collapsed descendant starts with a white
// space.
//
// WARNING: undefined, unless the box's size is up-to-date.
virtual bool HasLeadingWhiteSpace() const = 0;
// Whether the box or its last non-collapsed descendant ends with a white
// space.
//
// WARNING: undefined, unless the box's size is up-to-date.
virtual bool HasTrailingWhiteSpace() const = 0;
// A box is collapsed if it has no text or white space, nor have its children.
// A collapsed box may still have a non-zero width. Atomic inline-level boxes
// are never collapsed, even if empty.
//
// This is used to decide whether two white spaces are following each other in
// an inline formatting context.
//
// WARNING: undefined, unless the box's size is up-to-date.
virtual bool IsCollapsed() const = 0;
// Line boxes that contain no text, no preserved white space, no inline
// elements with non-zero margins, padding, or borders, and no other in-flow
// content must be treated as zero-height line boxes for the purposes
// of determining the positions of any elements inside of them, and must be
// treated as not existing for any other purpose.
// https://www.w3.org/TR/CSS21/visuren.html#inline-formatting
virtual bool JustifiesLineExistence() const = 0;
// Whether or not the box or its last descendant has a trailing line break,
// disallowing additional boxes on the same line.
virtual bool HasTrailingLineBreak() const { return false; }
// Boxes that don't establish a baseline (such as empty blocks or lines)
// should not affect the baseline calculation in the block formatting context.
virtual bool AffectsBaselineInBlockFormattingContext() const = 0;
// Returns the vertical offset of the baseline relatively to the top margin
// edge. If the box does not have a baseline, returns the bottom margin edge,
// as per https://www.w3.org/TR/CSS21/visudet.html#line-height.
virtual LayoutUnit GetBaselineOffsetFromTopMarginEdge() const = 0;
// Marks the current set of UpdateSize parameters (which includes the
// LayoutParams parameter as well as object member variable state) as valid.
// Returns true if previously calculated results from UpdateSize() are still
// valid. This is used to avoid redundant recalculations, and is an extremely
// important optimization since it applies to all levels of the box hierarchy.
// Derived classes may override this method to check if local box state has
// changed as well.
virtual bool ValidateUpdateSizeInputs(const LayoutParams& params);
// Invalidating the sizes causes them to be re-calculated the next time they
// are needed.
void InvalidateUpdateSizeInputsOfBox();
void InvalidateUpdateSizeInputsOfBoxAndAncestors();
// Invalidating the cross references causes them to be re-calculated the next
// time they are needed.
virtual void InvalidateCrossReferencesOfBoxAndAncestors();
// Invalidating the render tree nodes causes them to be re-generated the next
// time they are needed.
void InvalidateRenderTreeNodesOfBoxAndAncestors();
// Converts a layout subtree into a render subtree.
// This method defines the overall strategy of the conversion and relies
// on the subclasses to provide the actual content.
void RenderAndAnimate(
render_tree::CompositionNode::Builder* parent_content_node_builder,
const math::Vector2dF& offset_from_parent_node,
ContainerBox* stacking_context);
scoped_refptr<render_tree::Node> RenderAndAnimateOverflow(
const scoped_refptr<render_tree::Node>& content_node,
const math::Vector2dF& border_offset);
// Poor man's reflection.
virtual AnonymousBlockBox* AsAnonymousBlockBox();
virtual const AnonymousBlockBox* AsAnonymousBlockBox() const;
virtual BlockContainerBox* AsBlockContainerBox();
virtual const BlockContainerBox* AsBlockContainerBox() const;
virtual ContainerBox* AsContainerBox();
virtual const ContainerBox* AsContainerBox() const;
virtual TextBox* AsTextBox();
virtual const TextBox* AsTextBox() const;
#ifdef COBALT_BOX_DUMP_ENABLED
// Used by box generator to set a DOM node that produced this box.
void SetGeneratingNode(dom::Node* generating_node);
// Used by derived classes to dump their children.
void DumpWithIndent(std::ostream* stream, int indent) const;
#endif // COBALT_BOX_DUMP_ENABLED
ContainerBox* parent() { return parent_; }
const ContainerBox* parent() const { return parent_; }
const ContainerBox* GetAbsoluteContainingBlock() const;
ContainerBox* GetAbsoluteContainingBlock() {
// Return a mutable ContainerBox.
return const_cast<ContainerBox*>(
static_cast<const Box*>(this)->GetAbsoluteContainingBlock());
}
const ContainerBox* GetFixedContainingBlock() const;
ContainerBox* GetFixedContainingBlock() {
// Return a mutable ContainerBox.
return const_cast<ContainerBox*>(
static_cast<const Box*>(this)->GetFixedContainingBlock());
}
const ContainerBox* GetContainingBlock() const;
ContainerBox* GetContainingBlock() {
// Return a mutable ContainerBox.
return const_cast<ContainerBox*>(
static_cast<const Box*>(this)->GetContainingBlock());
}
const ContainerBox* GetStackingContext() const;
ContainerBox* GetStackingContext() {
// Return a mutable ContainerBox.
return const_cast<ContainerBox*>(
static_cast<const Box*>(this)->GetStackingContext());
}
// Returns the z-index of this box, based on its computed style.
int GetZIndex() const;
// Returns the order value of this box, based on its computed style.
int GetOrder() const;
// Invalidates the parent of the box, used in box generation for partial
// layout.
void InvalidateParent() { parent_ = NULL; }
// Returns true if the box is positioned under the passed in coordinate.
bool IsUnderCoordinate(const Vector2dLayoutUnit& coordinate) const;
// Returns a data structure that can be used by Box::IsRenderedLater().
RenderSequence GetRenderSequence() const;
// Returns true if the box for the given render_sequence is rendered after
// the box for the other_render_sequence. The boxes must be from the same
// layout tree.
static bool IsRenderedLater(RenderSequence render_sequence,
RenderSequence other_render_sequence);
// Applies the specified transform action to the provided coordinates.
// Returns false if the transform is not invertible and the action requires
// it being inverted.
bool ApplyTransformActionToCoordinate(TransformAction action,
math::Vector2dF* coordinate) const;
bool ApplyTransformActionToCoordinates(
TransformAction action, std::vector<math::Vector2dF>* coordinates) const;
// Intended to be set to false on the initial containing block, this indicates
// that when the background color is rendered, it will be blended with what,
// is behind it (only relevant when the color is not opaque). As an example,
// if set to false, a background color of transparent will replace any
// previous pixel values instead of being a no-op.
void set_blend_background_color(bool value) {
blend_background_color_ = value;
}
// Configure the box's UI navigation item with the box's position, size, etc.
void UpdateUiNavigationItem();
void SetUiNavItem(const scoped_refptr<ui_navigation::NavItem>& item) {
ui_nav_item_ = item;
}
void AddIntersectionObserverRootsAndTargets(
BoxIntersectionObserverModule::IntersectionObserverRootVector&& roots,
BoxIntersectionObserverModule::IntersectionObserverTargetVector&&
targets);
bool ContainsIntersectionObserverRoot(
const scoped_refptr<IntersectionObserverRoot>& intersection_observer_root)
const;
base::Optional<LayoutUnit> collapsed_margin_top_;
base::Optional<LayoutUnit> collapsed_margin_bottom_;
base::Optional<LayoutUnit> collapsed_empty_margin_;
static bool IsBorderStyleNoneOrHidden(
const scoped_refptr<cssom::PropertyValue>& border_style);
protected:
UsedStyleProvider* used_style_provider() const {
return used_style_provider_;
}
LayoutStatTracker* layout_stat_tracker() const {
return layout_stat_tracker_;
}
// Updates used values of "width", "height", and "margin" properties based on
// https://www.w3.org/TR/CSS21/visudet.html#Computing_widths_and_margins and
// https://www.w3.org/TR/CSS21/visudet.html#Computing_heights_and_margins.
// Limits set by "min-width" and "max-width" are honored for non-replaced
// boxes, based on https://www.w3.org/TR/CSS21/visudet.html#min-max-widths.
virtual void UpdateContentSizeAndMargins(
const LayoutParams& layout_params) = 0;
// Content box setters.
//
// Used values of "width" and "height" properties are set by overriders
// of |UpdateContentSizeAndMargins| method.
void set_width(LayoutUnit width) { content_size_.set_width(width); }
void set_height(LayoutUnit height) { content_size_.set_height(height); }
// Used to determine whether this box justifies the existence of a line,
// as per:
//
// Line boxes that contain no inline elements with non-zero margins, padding,
// or borders must be treated as not existing.
// https://www.w3.org/TR/CSS21/visuren.html#phantom-line-box
bool HasNonZeroMarginOrBorderOrPadding() const;
// Add a box and all of its descendants that are contained within the
// specified stacking context to the stacking context's draw order. This is
// used when a render tree node that is already cached is encountered to
// ensure that it maintains the proper draw order in its stacking context.
virtual void AddBoxAndDescendantsToDrawOrderInStackingContext(
ContainerBox* stacking_context);
// Renders the content of the box.
virtual void RenderAndAnimateContent(
render_tree::CompositionNode::Builder* border_node_builder,
ContainerBox* stacking_context) const = 0;
// A transformable element is an element whose layout is governed by the CSS
// box model which is either a block-level or atomic inline-level element.
// https://www.w3.org/TR/css3-transforms/#transformable-element
virtual bool IsTransformable() const = 0;
#ifdef COBALT_BOX_DUMP_ENABLED
void DumpIndent(std::ostream* stream, int indent) const;
virtual void DumpClassName(std::ostream* stream) const = 0;
// Overriders must call the base method.
virtual void DumpProperties(std::ostream* stream) const;
// Overriders must call the base method.
virtual void DumpChildrenWithIndent(std::ostream* stream, int indent) const;
#endif // COBALT_BOX_DUMP_ENABLED
// Updates the source container box's cross references with its descendants in
// the box tree that have it as their containing block or stacking context.
// This function is called recursively.
virtual void UpdateCrossReferencesOfContainerBox(
ContainerBox* source_box, RelationshipToBox nearest_containing_block,
RelationshipToBox nearest_absolute_containing_block,
RelationshipToBox nearest_fixed_containing_block,
RelationshipToBox nearest_stacking_context,
StackingContextContainerBoxStack* stacking_context_container_box_stack);
// Updates the horizontal margins for block level in-flow boxes. This is used
// for both non-replaced and replaced elements. See
// https://www.w3.org/TR/CSS21/visudet.html#blockwidth and
// https://www.w3.org/TR/CSS21/visudet.html#block-replaced-width.
void UpdateHorizontalMarginsAssumingBlockLevelInFlowBox(
BaseDirection containing_block_direction,
LayoutUnit containing_block_width, LayoutUnit border_box_width,
const base::Optional<LayoutUnit>& possibly_overconstrained_margin_left,
const base::Optional<LayoutUnit>& possibly_overconstrained_margin_right);
// Set border insets in InlineContainerBox UpdateBorders to an empty
// LayoutUnit or the computed_style value using is_split_on_*_.
void SetBorderInsets(LayoutUnit left, LayoutUnit top, LayoutUnit right,
LayoutUnit bottom);
private:
struct CachedRenderTreeNodeInfo {
explicit CachedRenderTreeNodeInfo(const math::Vector2dF& offset)
: offset_(offset) {}
math::Vector2dF offset_;
scoped_refptr<render_tree::Node> node_;
};
// Updates used values of "border" properties.
virtual void UpdateBorders();
// Updates used values of "padding" properties.
virtual void UpdatePaddings(const LayoutParams& layout_params);
// Computes the normalized "outer" rounded corners (if there are any) from the
// border radii.
base::Optional<render_tree::RoundedCorners> ComputeRoundedCorners() const;
// Computes the corresponding "inner" rounded corners.
base::Optional<render_tree::RoundedCorners> ComputePaddingRoundedCorners(
const base::Optional<render_tree::RoundedCorners>& rounded_corners) const;
// Called after TryPlaceEllipsisOrProcessPlacedEllipsis() determines that the
// box is impacted by the ellipsis. This handles both determining the location
// of the ellipsis, if it has not already been placed, and updating the
// ellipsis-related state of the box, such as whether or not it should be
// fully or partially hidden.
virtual void DoPlaceEllipsisOrProcessPlacedEllipsis(
BaseDirection base_direction, LayoutUnit desired_offset,
bool* is_placement_requirement_met, bool* is_placed,
LayoutUnit* placed_offset) {}
// Get the rectangle for which gives the region that background-color
// and background-image would populate.
math::RectF GetBackgroundRect();
// Get the transform for this box from the specified containing block (which
// may be null to indicate root).
math::Matrix3F GetMarginBoxTransformFromContainingBlockInternal(
const ContainerBox* containing_block, bool transform_forms_root,
bool include_scroll) const;
// Some custom CSS transform functions require a UI navigation focus item as
// input. This computes the appropriate UI navigation item for this box's
// transform. This should only be called if the box IsTransformed().
scoped_refptr<ui_navigation::NavItem> ComputeUiNavFocusForTransform() const;
// Returns whether the overflow is animated by a UI navigation item.
bool IsOverflowAnimatedByUiNavigation() const {
return ui_nav_item_ && ui_nav_item_->IsContainer();
}
// Helper methods used by |RenderAndAnimate|.
void RenderAndAnimateBorder(
const base::Optional<render_tree::RoundedCorners>& rounded_corners,
render_tree::CompositionNode::Builder* border_node_builder,
render_tree::animations::AnimateNode::Builder* animate_node_builder);
void RenderAndAnimateOutline(
render_tree::CompositionNode::Builder* border_node_builder,
render_tree::animations::AnimateNode::Builder* animate_node_builder);
void RenderAndAnimateBackgroundColor(
const base::Optional<render_tree::RoundedCorners>& rounded_corners,
render_tree::CompositionNode::Builder* border_node_builder,
render_tree::animations::AnimateNode::Builder* animate_node_builder);
struct RenderAndAnimateBackgroundImageResult {
// The node representing the background image (may be a CompositionNode if
// there are multiple layers).
scoped_refptr<render_tree::Node> node;
// Returns whether the background image opaquely fills the entire frame.
// If true, then we don't need to even consider rendering the background
// color, since it will be occluded by the image.
bool is_opaque;
};
RenderAndAnimateBackgroundImageResult RenderAndAnimateBackgroundImage(
const base::Optional<render_tree::RoundedCorners>& rounded_corners);
void RenderAndAnimateBoxShadow(
const base::Optional<render_tree::RoundedCorners>& outer_rounded_corners,
const base::Optional<render_tree::RoundedCorners>& inner_rounded_corners,
render_tree::CompositionNode::Builder* border_node_builder,
render_tree::animations::AnimateNode::Builder* animate_node_builder);
// If opacity is animated or other than 1, wraps a border node into a filter
// node. Otherwise returns the original border node.
scoped_refptr<render_tree::Node> RenderAndAnimateOpacity(
const scoped_refptr<render_tree::Node>& border_node,
render_tree::animations::AnimateNode::Builder* animate_node_builder,
float opacity, bool opacity_animated);
scoped_refptr<render_tree::Node> RenderAndAnimateOverflow(
const base::Optional<render_tree::RoundedCorners>& rounded_corners,
const scoped_refptr<render_tree::Node>& content_node,
render_tree::animations::AnimateNode::Builder* animate_node_builder,
const math::Vector2dF& border_node_offset);
// If transform is not "none", wraps a border node in a MatrixTransformNode.
// If transform is "none", returns the original border node and leaves
// |border_node_transform| intact.
scoped_refptr<render_tree::Node> RenderAndAnimateTransform(
const scoped_refptr<render_tree::Node>& border_node,
render_tree::animations::AnimateNode::Builder* animate_node_builder,
const math::Vector2dF& border_node_offset);
// This adds an animation to reflect content scrolling by the UI navigation
// system. Call this only if IsOverflowAnimatedByUiNavigation().
scoped_refptr<render_tree::Node> RenderAndAnimateUiNavigationContainer(
const scoped_refptr<render_tree::Node>& node_to_animate,
render_tree::animations::AnimateNode::Builder* animate_node_builder);
// The css_computed_style_declaration_ member references the
// cssom::CSSComputedStyleDeclaration object owned by the HTML Element from
// which this box is derived.
const scoped_refptr<cssom::CSSComputedStyleDeclaration>
css_computed_style_declaration_;
UsedStyleProvider* const used_style_provider_;
LayoutStatTracker* const layout_stat_tracker_;
#ifdef COBALT_BOX_DUMP_ENABLED
std::string generating_html_;
#endif // COBALT_BOX_DUMP_ENABLED
// The parent of this box is the box that owns this child and is the direct
// parent. If DOM element A is a parent of DOM element B, and box A is
// derived from DOM element A and box B is derived from DOM element B, then
// box A will be the parent of box B.
ContainerBox* parent_;
// Used values of "left" and "top" properties.
Vector2dLayoutUnit margin_box_offset_from_containing_block_;
// The following static position variables are only used with absolutely
// positioned boxes.
// https://www.w3.org/TR/CSS21/visuren.html#absolute-positioning
// The static position for 'left' is the distance from the left edge of the
// containing block to the left margin edge of a hypothetical box that would
// have been the first box of the element if its 'position' property had been
// 'static' and 'float' had been 'none'. The value is negative if the
// hypothetical box is to the left of the containing block.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
// The static position for 'right' is the distance from the right edge of the
// containing block to the right margin edge of the same hypothetical box as
// above. The value is positive if the hypothetical box is to the left of the
// containing block's edge.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
// For the purposes of this section and the next, the term "static position"
// (of an element) refers, roughly, to the position an element would have had
// in the normal flow. More precisely, the static position for 'top' is the
// distance from the top edge of the containing block to the top margin edge
// of a hypothetical box that would have been the first box of the element if
// its specified 'position' value had been 'static'.
// https://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-height
InsetsLayoutUnit static_position_offset_from_parent_;
InsetsLayoutUnit static_position_offset_from_containing_block_to_parent_;
// Used values of "margin-left", "margin-top", "margin-right",
// and "margin-bottom".
InsetsLayoutUnit margin_insets_;
// Used values of "border-left-width", "border-top-width",
// "border-right-width", and "border-bottom-width".
InsetsLayoutUnit border_insets_;
// Used values of "padding-left", "padding-top", "padding-right",
// and "padding-bottom".
InsetsLayoutUnit padding_insets_;
// Used values of "width" and "height" properties.
SizeLayoutUnit content_size_;
// Referenced and updated by ValidateUpdateSizeInputs() to memoize the
// parameters we were passed during in last call to UpdateSizes().
base::Optional<LayoutParams> last_update_size_params_;
// Render tree node caching is used to prevent the node from needing to be
// recalculated during each call to RenderAndAnimateContent.
base::Optional<CachedRenderTreeNodeInfo> cached_render_tree_node_info_;
// A value that indicates the drawing order relative to other boxes in the
// same stacking context. Smaller values indicate boxes that are drawn
// earlier.
size_t draw_order_position_in_stacking_context_;
// Determines whether the background should be rendered as a clear (i.e. with
// blending disabled). It is expected that this may only be set on the
// initial containing block.
bool blend_background_color_ = true;
// UI navigation items are used to help animate certain elements.
scoped_refptr<ui_navigation::NavItem> ui_nav_item_;
std::unique_ptr<BoxIntersectionObserverModule>
box_intersection_observer_module_;
// For write access to parent/containing_block members.
friend class ContainerBox;
friend class LayoutBoxes;
friend class FlexContainerBox;
friend class FlexFormattingContext;
friend class FlexLine;
friend class MainAxisHorizontalFlexItem;
friend class MainAxisVerticalFlexItem;
DISALLOW_COPY_AND_ASSIGN(Box);
};
#ifdef COBALT_BOX_DUMP_ENABLED
// Dumps a box tree recursively to a stream.
// Used for layout debugging, not intended for production.
inline std::ostream& operator<<(std::ostream& stream, const Box& box) {
box.DumpWithIndent(&stream, 0);
return stream;
}
#endif // COBALT_BOX_DUMP_ENABLED
typedef std::vector<scoped_refptr<Box> > Boxes;
} // namespace layout
} // namespace cobalt
#endif // COBALT_LAYOUT_BOX_H_