third_party/WebKit/Source/core/paint/PaintLayerFragment.h

/*
 * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 */

#ifndef PaintLayerFragment_h
#define PaintLayerFragment_h

#include "core/layout/ClipRect.h"
#include "wtf/Allocator.h"
#include "wtf/Vector.h"

namespace blink {

// PaintLayerFragment is the representation of a fragment.
// https://drafts.csswg.org/css-break/#fragment
//
// Fragments are a paint/hit-testing only concept in Blink.
// Every box has at least one fragment, even if it is not paginated/fragmented.
// If a box has more than one fragment (i.e. is paginated by an ancestor), the
// fragments are called "paginated fragments". Note that this is a Blink
// vocabulary extension and doesn't come from the specification.
//
// The fragments are collected by calling PaintLayer::collectFragments
// on every box once per paint/hit-testing operation.
struct PaintLayerFragment {
    DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
public:
    void setRects(const LayoutRect& bounds, const ClipRect& background, const ClipRect& foreground)
    {
        layerBounds = bounds;
        backgroundRect = background;
        foregroundRect = foreground;
    }

    void moveBy(const LayoutPoint& offset)
    {
        layerBounds.moveBy(offset);
        backgroundRect.moveBy(offset);
        foregroundRect.moveBy(offset);
        paginationClip.moveBy(offset);
    }

    void intersect(const LayoutRect& rect)
    {
        backgroundRect.intersect(rect);
        foregroundRect.intersect(rect);
    }

    // Set on all fragments.
    //
    // The PaintLayer's size in the associated ClipRectsContext's
    // rootLayer coordinate system. See PaintLayer::m_size for the
    // exact rectangle.
    //
    // TODO(jchaffraix): We should store the rootLayer here to ensure we don't
    // mix coordinate systems by mistake.
    LayoutRect layerBounds;

    // Set on all fragments.
    //
    // The rectangle used to clip the background.
    //
    // The rectangle is the rectangle-to-paint if no clip applies to the
    // fragment. It is the intersection between the visual overflow rect
    // and any overflow clips or 'clip' properties. It is also intersected with
    // |paginationClip| if it is present.
    //
    // See PaintLayerClipper::calculateRects.
    ClipRect backgroundRect;

    // Set on all fragments.
    //
    // The rectangle used to clip the content (foreground).
    //
    // The rectangle is the rectangle-to-paint if no clip applies to the
    // fragment. If there is an overflow clip, the rectangle-to-paint is
    // intersected with the border box rect without the scrollbars (content gets
    // clipped at their edge). Also any enclosing 'clip' properties get applied
    // to the intersected rectangle. It is also intersected with
    // |paginationClip| if it is present.
    //
    // See PaintLayerClipper::calculateRects.
    ClipRect foregroundRect;

    // Only set on paginated fragments.
    //
    // The physical translation to apply to shift the layer when
    // painting/hit-testing.
    LayoutPoint paginationOffset;

    // Only set on paginated fragments.
    //
    // This is the additional clip from the fragmentainer (i.e. column or
    // page) that applies to the layer. |backgroundRect| and |foregroundRect|
    // are intersected with it (see collectFragments).
    //
    // It is in layer-local (physical) coordinates.
    LayoutRect paginationClip;
};

typedef Vector<PaintLayerFragment, 1> PaintLayerFragments;

} // namespace blink

#endif // PaintLayerFragment_h