[CRD iOS] Viewport fling animation

remoting/client/fling_animation.cc

+// 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.
+
+#include "remoting/client/fling_animation.h"
+
+#include "base/time/default_tick_clock.h"
+
+namespace remoting {
+
+FlingAnimation::FlingAnimation(float time_constant,
+                               const FlingCallback& fling_callback)
+    : fling_tracker_(time_constant),
+      fling_callback_(fling_callback),
+      clock_(new base::DefaultTickClock()) {}
+
+FlingAnimation::~FlingAnimation() {}
+
+void FlingAnimation::SetVelocity(float velocity_x, float velocity_y) {
+  fling_tracker_.StartFling(velocity_x, velocity_y);
+  fling_start_time_ = clock_->NowTicks();
+}
+
+bool FlingAnimation::IsAnimationInProgress() const {
+  return fling_tracker_.IsFlingInProgress();
+}
+
+void FlingAnimation::Tick() {
+  float dx, dy;
+  bool in_progress = fling_tracker_.TrackMovement(
+      clock_->NowTicks() - fling_start_time_, &dx, &dy);
+  if (in_progress) {
+    fling_callback_.Run(dx, dy);
+  }
+}
+
+void FlingAnimation::Abort() {
+  fling_tracker_.StopFling();
+}
+
+void FlingAnimation::SetTickClockForTest(
+    std::unique_ptr<base::TickClock> clock) {
+  clock_ = std::move(clock);
+}
+
+}  // namespace remoting