chromium/third_party/blink/renderer/platform/graphics/compositor_element_id.h

// Copyright 2016 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_PLATFORM_GRAPHICS_COMPOSITOR_ELEMENT_ID_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_GRAPHICS_COMPOSITOR_ELEMENT_ID_H_

#include <type_traits>

#include "cc/paint/element_id.h"
#include "third_party/blink/renderer/platform/graphics/dom_node_id.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/hash_traits.h"

namespace blink {

const int kCompositorNamespaceBitCount = …;

// The functions in this header requires cc::ElementId::InternalValue to be
// uint64_t.
static_assert …;

enum class CompositorElementIdNamespace { … };

static_assert …;

CompositorElementId;
ScrollbarId;
UniqueObjectId;
SyntheticEffectId;

// Call this to get a globally unique object id for a newly allocated object.
UniqueObjectId PLATFORM_EXPORT NewUniqueObjectId();

// Call this with an appropriate namespace if more than one CompositorElementId
// is required for the given UniqueObjectId.
CompositorElementId PLATFORM_EXPORT
    CompositorElementIdFromUniqueObjectId(UniqueObjectId,
                                          CompositorElementIdNamespace);
// ...and otherwise call this method if there is only one CompositorElementId
// required for the given UniqueObjectId.
CompositorElementId PLATFORM_EXPORT
    CompositorElementIdFromUniqueObjectId(UniqueObjectId);

// Returns a CompositorElementId with namespace of `element_id` replaced with
// `namespace_id`.
CompositorElementId PLATFORM_EXPORT
CompositorElementIdWithNamespace(CompositorElementId element_id,
                                 CompositorElementIdNamespace namespace_id);

// TODO(chrishtr): refactor ScrollState to remove this dependency.
CompositorElementId PLATFORM_EXPORT CompositorElementIdFromDOMNodeId(DOMNodeId);

CompositorElementIdNamespace PLATFORM_EXPORT
    NamespaceFromCompositorElementId(CompositorElementId);

// Maps a CompositorElementId in the kDOMNodeId namespace back to a DOMNodeId.
DOMNodeId PLATFORM_EXPORT DOMNodeIdFromCompositorElementId(CompositorElementId);

}  // namespace blink

namespace WTF {

template <>
struct PLATFORM_EXPORT HashTraits<blink::CompositorElementId>
    : GenericHashTraits<blink::CompositorElementId> { … };

}  // namespace WTF

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_GRAPHICS_COMPOSITOR_ELEMENT_ID_H_