cc/document_transition/document_transition_request.h

// Copyright 2020 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 CC_DOCUMENT_TRANSITION_DOCUMENT_TRANSITION_REQUEST_H_
#define CC_DOCUMENT_TRANSITION_DOCUMENT_TRANSITION_REQUEST_H_

#include <memory>
#include <utility>

#include "base/callback.h"
#include "cc/cc_export.h"
#include "components/viz/common/quads/compositor_frame_transition_directive.h"

namespace cc {

// This class represents a document transition request. It is constructed in
// Blink with an intent of translating this request into a viz directive for the
// transition to occur.
class CC_EXPORT DocumentTransitionRequest {
 public:
  using Effect = viz::CompositorFrameTransitionDirective::Effect;

  // Creates a Type::kPrepare type of request.
  static std::unique_ptr<DocumentTransitionRequest> CreatePrepare(
      Effect effect,
      base::TimeDelta duration,
      base::OnceClosure commit_callback);

  // Creates a Type::kSave type of request.
  static std::unique_ptr<DocumentTransitionRequest> CreateStart(
      base::OnceClosure commit_callback);

  DocumentTransitionRequest(DocumentTransitionRequest&) = delete;
  ~DocumentTransitionRequest();

  DocumentTransitionRequest& operator=(DocumentTransitionRequest&) = delete;

  // The callback is run when the request is committed from the main thread onto
  // the compositor thread. This is used to indicate that the request has been
  // submitted for processing and that script may now change the page in some
  // way. In other words, this callback would resolve the prepare promise that
  // script may be waiting for.
  base::OnceClosure TakeCommitCallback() { return std::move(commit_callback_); }

  // This constructs a viz directive. Note that repeated calls to this function
  // would create a new sequence id for the directive, which means it would be
  // processed again by viz.
  viz::CompositorFrameTransitionDirective ConstructDirective() const;

 private:
  using Type = viz::CompositorFrameTransitionDirective::Type;

  DocumentTransitionRequest(Effect effect,
                            base::TimeDelta duration,
                            base::OnceClosure commit_callback);
  explicit DocumentTransitionRequest(base::OnceClosure commit_callback);

  const Type type_;
  const Effect effect_ = Effect::kNone;
  const base::TimeDelta duration_;
  base::OnceClosure commit_callback_;

  static uint32_t s_next_sequence_id_;
};

}  // namespace cc

#endif  // CC_DOCUMENT_TRANSITION_DOCUMENT_TRANSITION_REQUEST_H_