[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"
+
+namespace remoting {
+
+FlingAnimation::FlingAnimation(float time_constant,
+                               const FlingCallback& fling_callback)
+    : fling_tracker_(time_constant), fling_callback_(fling_callback) {}
+
+FlingAnimation::~FlingAnimation() {}
+
+void FlingAnimation::Reset(float velocity_x, float velocity_y) {
+  previous_position_x_ = 0.f;
+  previous_position_y_ = 0.f;
+  fling_tracker_.StartFling(velocity_x, velocity_y);
+}
+
+bool FlingAnimation::IsAnimationInProgress() const {
+  return fling_tracker_.IsFlingInProgress();
+}
+
+void FlingAnimation::Tick() {
+  float x, y;
+  bool in_progress =
+      fling_tracker_.TrackPositions(base::TimeTicks::Now(), &x, &y);
+  if (in_progress) {
+    fling_callback_.Run(x - previous_position_x_, y - previous_position_y_);
+    previous_position_x_ = x;
+    previous_position_y_ = y;
+  }
+}
+
+void FlingAnimation::Abort() {
+  fling_tracker_.StopFling();
+}
+
+}  // namespace remoting