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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_VIZ_COMMON_SURFACES_PARENT_LOCAL_SURFACE_ID_ALLOCATOR_H_
#define COMPONENTS_VIZ_COMMON_SURFACES_PARENT_LOCAL_SURFACE_ID_ALLOCATOR_H_
#include <stdint.h>
#include "base/macros.h"
#include "base/unguessable_token.h"
#include "components/viz/common/surfaces/surface_id.h"
#include "components/viz/common/viz_common_export.h"
namespace viz {
// This is a helper class for generating local surface IDs for a single
// FrameSink. This is not threadsafe, to use from multiple threads wrap this
// class in a mutex.
// The parent embeds a child's surface. The parent allocates a surface for the
// child when the parent needs to change surface parameters, for example.
class VIZ_COMMON_EXPORT ParentLocalSurfaceIdAllocator {
public:
ParentLocalSurfaceIdAllocator();
ParentLocalSurfaceIdAllocator(ParentLocalSurfaceIdAllocator&& other) =
default;
ParentLocalSurfaceIdAllocator& operator=(
ParentLocalSurfaceIdAllocator&& other) = default;
~ParentLocalSurfaceIdAllocator() = default;
// When a child-allocated LocalSurfaceId arrives in the parent, the parent
// needs to update its understanding of the last generated message so the
// messages can continue to monotonically increase. Returns whether the
// current LocalSurfaceId has been updated.
bool UpdateFromChild(const LocalSurfaceId& child_allocated_local_surface_id);
// Resets this allocator with the provided |local_surface_id| as a seed.
void Reset(const LocalSurfaceId& local_surface_id);
// Marks the last known LocalSurfaceId as invalid until the next call to
// GenerateId. This is used to defer commits until some LocalSurfaceId is
// provided from an external source.
void Invalidate();
const LocalSurfaceId& GenerateId();
const LocalSurfaceId& GetCurrentLocalSurfaceId() const;
bool is_allocation_suppressed() const { return is_allocation_suppressed_; }
private:
static const LocalSurfaceId invalid_local_surface_id_;
LocalSurfaceId current_local_surface_id_;
// When true, the last known LocalSurfaceId is an invalid LocalSurfaceId.
// TODO(fsamuel): Once the parent sequence number is only monotonically
// increasing for a given embed_token then we should just reset
// |current_local_surface_id_| to an invalid state.
bool is_invalid_ = false;
bool is_allocation_suppressed_ = false;
friend class ScopedSurfaceIdAllocator;
DISALLOW_COPY_AND_ASSIGN(ParentLocalSurfaceIdAllocator);
};
} // namespace viz
#endif // COMPONENTS_VIZ_COMMON_SURFACES_PARENT_LOCAL_SURFACE_ID_ALLOCATOR_H_
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