Basic support for animating window properties in Mus.

components/mus/ws/animation_runner.h

+// Copyright 2014 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 COMPONENTS_MUS_WS_ANIMATION_RUNNER_H_
+#define COMPONENTS_MUS_WS_ANIMATION_RUNNER_H_
+
+#include <algorithm>
+#include <map>
+#include <memory>
+#include <set>
+#include <unordered_map>
+#include <vector>
+
+#include "base/observer_list.h"
+#include "base/time/time.h"
+
+namespace mus {
+namespace mojom {
+class AnimationGroup;
+}
+
+namespace ws {
+
+class AnimationRunnerObserver;
+class ScheduledAnimationGroup;
+class ServerWindow;
+
+// AnimationRunner is responsible for maintaining and running a set of
+// animations. The animations are represented as a set of AnimationGroups. New
+// animations are scheduled by way of Schedule(). A |window| may only have one
+// animation running at a time. Schedule()ing a new animation for a window
+// already animating implicitly cancels the current animation for the window.
+// Animations progress by way of the Tick() function.
+class AnimationRunner {
+ public:
+  using AnimationId = uint32_t;
+  using WindowAndAnimationPair =
+      std::pair<ServerWindow*, const mojom::AnimationGroup*>;
+
+  explicit AnimationRunner(base::TimeTicks now);
+  ~AnimationRunner();
+
+  void AddObserver(AnimationRunnerObserver* observer);
+  void RemoveObserver(AnimationRunnerObserver* observer);
+
+  // Schedules animations. If any of the groups are not valid no animations are
+  // scheuled and 0 is returned. If there is an existing animation in progress
+  // for any of the windows it is canceled and any properties that were
+  // animating but are no longer animating are set to their target value.
+  AnimationId Schedule(const std::vector<WindowAndAnimationPair>& groups,
+                       base::TimeTicks now);
+
+  // Cancels an animation scheduled by an id that was previously returned from
+  // Schedule().
+  void CancelAnimation(AnimationId id);
+
+  // Cancels the animation scheduled for |window|. Does nothing if there is no
+  // animation scheduled for |window|. This does not change |window|. That is,
+  // any in progress animations are stopped.
+  void CancelAnimationForWindow(ServerWindow* window);
+
+  // Advance the animations updating values appropriately.
+  void Tick(base::TimeTicks time);
+
+  // Returns true if there are animations currently scheduled.
+  bool HasAnimations() const { return !window_to_animation_map_.empty(); }
+
+  // Returns true if the animation identified by |id| is valid and animating.
+  bool IsAnimating(AnimationId id) const {
+    return id_to_windows_map_.count(id) > 0;
+  }
+
+  // Returns the windows that are currently animating for |id|. Returns an empty
+  // set if |id| does not identify a valid animation.
+  std::set<ServerWindow*> GetWindowsAnimating(AnimationId id) {
+    return IsAnimating(id) ? id_to_windows_map_.find(id)->second
+                           : std::set<ServerWindow*>();
+  }
+
+ private:
+  enum CancelSource {
+    // Cancel is the result of scheduling another animation for the window.
+    CANCEL_SOURCE_SCHEDULE,
+
+    // Cancel originates from an explicit call to cancel.
+    CANCEL_SOURCE_CANCEL,
+  };
+
+  using WindowToAnimationMap =
+      std::unordered_map<ServerWindow*,
+                         std::unique_ptr<ScheduledAnimationGroup>>;
+  using IdToWindowsMap = std::map<AnimationId, std::set<ServerWindow*>>;
+
+  void CancelAnimationForWindowImpl(ServerWindow* window, CancelSource source);
+
+  // Removes |window| from both |window_to_animation_map_| and
+  // |id_to_windows_map_|.
+  // Returns true if there are no more windows animating with the animation id
+  // the window is associated with.
+  bool RemoveWindowFromMaps(ServerWindow* window);
+
+  AnimationId next_id_;
+
+  base::TimeTicks last_tick_time_;
+
+  base::ObserverList<AnimationRunnerObserver> observers_;
+
+  WindowToAnimationMap window_to_animation_map_;
+
+  IdToWindowsMap id_to_windows_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(AnimationRunner);
+};
+
+}  // namespace ws
+}  // namespace mus
+
+#endif  // COMPONENTS_MUS_WS_ANIMATION_RUNNER_H_