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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_GENERATOR_H_
#define COBALT_LAYOUT_BOX_GENERATOR_H_
#include "cobalt/cssom/css_computed_style_declaration.h"
#include "cobalt/cssom/string_value.h"
#include "cobalt/dom/html_element.h"
#include "cobalt/dom/node.h"
#include "cobalt/layout/box.h"
#include "third_party/icu/source/common/unicode/brkiter.h"
namespace cobalt {
namespace dom {
class HTMLVideoElement;
} // namespace dom
namespace layout {
class Box;
class LayoutStatTracker;
class Paragraph;
class UsedStyleProvider;
// In the visual formatting model, each element in the document tree generates
// zero or more boxes.
// https://www.w3.org/TR/CSS21/visuren.html#box-gen
//
// A box generator recursively visits an HTML subtree that starts with a given
// element, creates a matching forest of boxes, and returns zero or more root
// boxes.
//
// As a side-effect, computed styles of visited HTML elements are updated.
class BoxGenerator : public dom::NodeVisitor {
public:
struct Context {
Context(UsedStyleProvider* used_style_provider,
LayoutStatTracker* layout_stat_tracker,
icu::BreakIterator* line_break_iterator,
icu::BreakIterator* character_break_iterator,
dom::HTMLElement* ignore_background_element,
int dom_max_element_depth)
: used_style_provider(used_style_provider),
layout_stat_tracker(layout_stat_tracker),
line_break_iterator(line_break_iterator),
character_break_iterator(character_break_iterator),
ignore_background_element(ignore_background_element),
dom_max_element_depth(dom_max_element_depth) {}
UsedStyleProvider* used_style_provider;
LayoutStatTracker* layout_stat_tracker;
icu::BreakIterator* line_break_iterator;
icu::BreakIterator* character_break_iterator;
// The HTML and BODY tags may have had their background style properties
// propagated up to the initial containing block. If so, we should not
// re-use those properties on that element. This value will track that
// element.
dom::HTMLElement* ignore_background_element;
// The maximum element depth for layout.
int dom_max_element_depth;
};
BoxGenerator(const scoped_refptr<cssom::CSSComputedStyleDeclaration>&
parent_css_computed_style_declaration,
// Parent animations are passed separately in order to enable
// grandparent inheritance of color property animations when the
// parent is a pseudo element.
// TODO: Remove this parameter when full support for
// animation inheritance is implemented.
const scoped_refptr<const web_animations::AnimationSet>&
parent_animations,
scoped_refptr<Paragraph>* paragraph,
const int dom_element_depth_, const Context* context);
~BoxGenerator();
void Visit(dom::CDATASection* cdata_section) override;
void Visit(dom::Comment* comment) override;
void Visit(dom::Document* document) override;
void Visit(dom::DocumentType* document_type) override;
void Visit(dom::Element* element) override;
void Visit(dom::Text* text) override;
const Boxes& boxes() const { return boxes_; }
private:
void VisitVideoElement(dom::HTMLVideoElement* video_element);
void VisitBrElement(dom::HTMLBRElement* br_element);
void VisitLottiePlayer(dom::LottiePlayer* lottie_player);
void VisitNonReplacedElement(dom::HTMLElement* html_element);
void AppendChildBoxToLine(const scoped_refptr<Box>& child_box);
void AppendPseudoElementToLine(dom::HTMLElement* html_element,
dom::PseudoElementType pseudo_element_type);
const scoped_refptr<cssom::CSSComputedStyleDeclaration>
parent_css_computed_style_declaration_;
const scoped_refptr<const web_animations::AnimationSet> parent_animations_;
scoped_refptr<Paragraph>* paragraph_;
// The current element depth.
const int dom_element_depth_;
const Context* context_;
scoped_refptr<dom::HTMLElement> generating_html_element_;
// The result of a box generator is zero or more root boxes.
Boxes boxes_;
DISALLOW_COPY_AND_ASSIGN(BoxGenerator);
};
} // namespace layout
} // namespace cobalt
#endif // COBALT_LAYOUT_BOX_GENERATOR_H_