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// Copyright 2024 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_FRAME_PAGINATION_STATE_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_PAGINATION_STATE_H_
#include "third_party/blink/renderer/platform/heap/collection_support/heap_vector.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/wtf/wtf_size_t.h"
namespace blink {
class ClipPaintPropertyNodeOrAlias;
class ComputedStyle;
class Document;
class LayoutBlockFlow;
class LayoutObject;
class LayoutView;
class ObjectPaintProperties;
class PropertyTreeState;
class TransformPaintPropertyNodeOrAlias;
// Holds structures and state needed during pagination (layout and painting).
//
// Created before layout for pagination, and destroyed when leaving paginated
// layout.
//
// For each page box that is being laid out, layout objects will be created for
// each part of a page box that may need to paint something (page container,
// page border box, and any @page margins).
//
// PaginationState also keeps track of the current page to print, and the paint
// properties (translation, scaling and clipping) that are to be applied to the
// document contents. Nothing outside the page area (@page margin, border and
// padding) is affected by these properties.
//
// The paint properties are placed in the tree between the properties of the
// LayoutView and its children. They are created during pre-paint, and updated
// for each page printed. They affect all paginated content, but not things
// outside the page area, such as @page decorations / margins.
class PaginationState : public GarbageCollected<PaginationState> {
public:
PaginationState();
void Trace(Visitor*) const;
// Create an anonymous layout object to measure, lay out and paint some part
// of a page box. A page box (and its margins) does not exist in the DOM, but
// is created by layout. Such layout objects will not be attached to the
// layout object tree. PaginationState "owns" the layout objects returned from
// this function, so that they are destroyed in a controlled manner (layout
// objects cannot simply be garbage collected).
LayoutBlockFlow* CreateAnonymousPageLayoutObject(Document&,
const ComputedStyle&);
// Destroy all layout objects created and returned from
// CreateAnonymousPageLayoutObject().
void DestroyAnonymousPageLayoutObjects();
void SetCurrentPageIndex(wtf_size_t n) { current_page_index_ = n; }
wtf_size_t CurrentPageIndex() const { return current_page_index_; }
ObjectPaintProperties& ContentAreaProperties() {
return *content_area_paint_properties_;
}
// Make sure that the content area properties have been created, so that they
// can be inserted into the tree.
ObjectPaintProperties& EnsureContentAreaProperties(
const TransformPaintPropertyNodeOrAlias& parent_transform,
const ClipPaintPropertyNodeOrAlias& parent_clip);
// Update transform (translation + scaling) and clipping for the current page
// (see CurrentPageIndex()). This will update the translation into the
// stitched coordinate system for paginated content (where all pages are
// imagined to be laid out stacked after oneanother in the block direction, to
// accommodate for overflow from one page into another). Furthermore, all
// pages don't necessarily have the same size or margins, so the clip
// rectangle needs to be updated as well. These properties will be applied to
// everything inside the page area [1] (but not to e.g. page margins).
//
// [1] https://drafts.csswg.org/css-page-3/#page-model
void UpdateContentAreaPropertiesForCurrentPage(const LayoutView&);
PropertyTreeState ContentAreaPropertyTreeStateForCurrentPage(
const LayoutView&) const;
private:
HeapVector<Member<LayoutObject>> anonymous_page_objects_;
Member<ObjectPaintProperties> content_area_paint_properties_;
wtf_size_t current_page_index_ = 0;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_PAGINATION_STATE_H_
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