// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "flutter/flow/layers/layer.h"

#include "flutter/flow/paint_utils.h"

namespace flutter {

Layer::Layer() : unique_id_(NextUniqueID()), original_layer_id_(unique_id_) {}

Layer::~Layer() = default;

uint64_t Layer::NextUniqueID() {
  static std::atomic<uint64_t> next_id(1);
  uint64_t id;
  do {
    id = next_id.fetch_add(1);
  } while (id == 0);  // 0 is reserved for an invalid id.
  return id;
}

Layer::AutoPrerollSaveLayerState::AutoPrerollSaveLayerState(
    PrerollContext* preroll_context,
    bool save_layer_is_active,
    bool layer_itself_performs_readback)
    : preroll_context_(preroll_context),
      save_layer_is_active_(save_layer_is_active),
      layer_itself_performs_readback_(layer_itself_performs_readback) {
  if (save_layer_is_active_) {
    prev_surface_needs_readback_ = preroll_context_->surface_needs_readback;
    preroll_context_->surface_needs_readback = false;
  }
}

Layer::AutoPrerollSaveLayerState Layer::AutoPrerollSaveLayerState::Create(
    PrerollContext* preroll_context,
    bool save_layer_is_active,
    bool layer_itself_performs_readback) {
  return Layer::AutoPrerollSaveLayerState(preroll_context, save_layer_is_active,
                                          layer_itself_performs_readback);
}

Layer::AutoPrerollSaveLayerState::~AutoPrerollSaveLayerState() {
  if (save_layer_is_active_) {
    preroll_context_->surface_needs_readback =
        (prev_surface_needs_readback_ || layer_itself_performs_readback_);
  }
}

}  // namespace flutter