adding in elinux files

elinux/runner/flutter_window.cc

@@ -0,0 +1,79 @@
+// Copyright 2021 Sony Corporation. 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_window.h"
+
+#include <chrono>
+#include <cmath>
+#include <iostream>
+#include <thread>
+
+#include "flutter/generated_plugin_registrant.h"
+
+FlutterWindow::FlutterWindow(
+    const flutter::FlutterViewController::ViewProperties view_properties,
+    const flutter::DartProject project)
+    : view_properties_(view_properties), project_(project) {}
+
+bool FlutterWindow::OnCreate() {
+  flutter_view_controller_ = std::make_unique<flutter::FlutterViewController>(
+      view_properties_, project_);
+
+  // Ensure that basic setup of the controller was successful.
+  if (!flutter_view_controller_->engine() ||
+      !flutter_view_controller_->view()) {
+    return false;
+  }
+
+  // Register Flutter plugins.
+  RegisterPlugins(flutter_view_controller_->engine());
+
+  return true;
+}
+
+void FlutterWindow::OnDestroy() {
+  if (flutter_view_controller_) {
+    flutter_view_controller_ = nullptr;
+  }
+}
+
+void FlutterWindow::Run() {
+  // Main loop.
+  auto next_flutter_event_time =
+      std::chrono::steady_clock::time_point::clock::now();
+  while (flutter_view_controller_->view()->DispatchEvent()) {
+    // Wait until the next event.
+    {
+      auto wait_duration =
+          std::max(std::chrono::nanoseconds(0),
+                   next_flutter_event_time -
+                       std::chrono::steady_clock::time_point::clock::now());
+      std::this_thread::sleep_for(
+          std::chrono::duration_cast<std::chrono::milliseconds>(wait_duration));
+    }
+
+    // Processes any pending events in the Flutter engine, and returns the
+    // number of nanoseconds until the next scheduled event (or max, if none).
+    auto wait_duration = flutter_view_controller_->engine()->ProcessMessages();
+    {
+      auto next_event_time = std::chrono::steady_clock::time_point::max();
+      if (wait_duration != std::chrono::nanoseconds::max()) {
+        next_event_time =
+            std::min(next_event_time,
+                     std::chrono::steady_clock::time_point::clock::now() +
+                         wait_duration);
+      } else {
+        // Wait for the next frame if no events.
+        auto frame_rate = flutter_view_controller_->view()->GetFrameRate();
+        next_event_time = std::min(
+            next_event_time,
+            std::chrono::steady_clock::time_point::clock::now() +
+                std::chrono::milliseconds(
+                    static_cast<int>(std::trunc(1000000.0 / frame_rate))));
+      }
+      next_flutter_event_time =
+          std::max(next_flutter_event_time, next_event_time);
+    }
+  }
+}