| /* |
| * Copyright 2015 Google Inc. All Rights Reserved. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef COBALT_RENDER_TREE_ANIMATIONS_ANIMATION_LIST_H_ |
| #define COBALT_RENDER_TREE_ANIMATIONS_ANIMATION_LIST_H_ |
| |
| #include <list> |
| |
| #include "base/callback.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/time.h" |
| #include "cobalt/render_tree/movable.h" |
| |
| namespace cobalt { |
| namespace render_tree { |
| namespace animations { |
| |
| // An animation list is simply that, a list of animations. Its usefulness over |
| // a raw std::list or std::vector is that it is a ref counted object and also |
| // guaranteed to be immutable (and thus, must be created by the associated |
| // builder object). The property of being an immutable reference counted object |
| // allows this object to safely persist while being shared between multiple |
| // threads. |
| |
| template <typename T> |
| class Animation { |
| public: |
| // An Animation<T>::Function represents a single animation that can be applied |
| // on any render_tree::Node object of the specified template type argument. |
| // |
| // As an example, one could create an animation that linearly interpolates |
| // between two color values on a TextNode object by first definining the |
| // animation function (assuming ColorRGBA has operator*() defined): |
| // |
| // void InterpolateTextColor( |
| // ColorRGBA final_color, base::TimeDelta duration, |
| // TextNode::Builder* text_node, base::TimeDelta time_elapsed) { |
| // if (time_elapsed < duration) { |
| // double progress = time_elapsed.InSecondsF() / duration.InSecondsF(); |
| // text_node->color = |
| // text_node->color * (1 - progress) + final_color * progress; |
| // } else { |
| // text_node->color = final_color; |
| // } |
| // } |
| // |
| // You can then use base::Bind to package this function into a base::Callback |
| // that matches the Animation<T>::Function signature: |
| // |
| // AnimationList<TextNode>::Builder animation_list_builder; |
| // animation_list_builder.push_back( |
| // base::Bind(&InterpolateTextColor, |
| // ColorRGBA(0.0f, 1.0f, 0.0f), |
| // base::TimeDelta::FromSeconds(1))); |
| // |
| // You can now create an AnimationList object from the AnimationList::Builder |
| // and ultimately add that to a AnimateNode::Builder object so that it can be |
| // mapped to a specific TextNode that it should be applied to. |
| typedef base::Callback<void(typename T::Builder*, base::TimeDelta)> Function; |
| }; |
| |
| // The AnimationListBase is used so that we can acquire a non-template handle |
| // to an AnimationList, which helps reduce code required in node_animation.h by |
| // letting us collect animation lists in a single collection, at the cost of |
| // needing to type cast in a few places. |
| class AnimationListBase : public base::RefCountedThreadSafe<AnimationListBase> { |
| public: |
| virtual base::TimeDelta GetExpiry() const = 0; |
| |
| protected: |
| virtual ~AnimationListBase() {} |
| friend class base::RefCountedThreadSafe<AnimationListBase>; |
| }; |
| |
| // Since animation functions are templated on a specific render tree Node type, |
| // so must AnimationLists. |
| template <typename T> |
| class AnimationList : public AnimationListBase { |
| public: |
| // The actual data structure used internally to store the list of animations. |
| // The decision to use a std::list here instead of say, an std::vector, is |
| // because it is anticipated that AnimationLists will commonly have only |
| // 1 element in them, since std::list does not make an attempt to reserve |
| // capacity in advance, it can save on memory in these instances. |
| typedef std::list<typename Animation<T>::Function> InternalList; |
| |
| // An object that provides a means to setting up a list before constructing |
| // the immutable AnimationList. |
| struct Builder { |
| DECLARE_AS_MOVABLE(Builder); |
| |
| Builder() : expiry(base::TimeDelta::Max()) {} |
| explicit Builder(Moved moved) { animations.swap(moved->animations); } |
| explicit Builder(const typename Animation<T>::Function& single_animation, |
| base::TimeDelta expiry) |
| : expiry(expiry) { |
| animations.push_back(single_animation); |
| } |
| |
| InternalList animations; |
| // When do the animations expire? base::TimeDelta::Max() implies that they |
| // never expire. |
| base::TimeDelta expiry; |
| }; |
| |
| explicit AnimationList(typename Builder::Moved builder) : data_(builder) {} |
| // Convenience constructor to allow for easy construction of AnimationLists |
| // containing a single Animation. |expiry| indicates the time at which the |
| // animation ceases, or base::TimeDelta::Max() if that never occurs. |
| explicit AnimationList( |
| const typename Animation<T>::Function& single_animation, |
| base::TimeDelta expiry) |
| : data_(single_animation, expiry) {} |
| |
| const Builder& data() const { return data_; } |
| |
| base::TimeDelta GetExpiry() const OVERRIDE { return data_.expiry; } |
| |
| private: |
| ~AnimationList() OVERRIDE {} |
| |
| const Builder data_; |
| |
| friend class AnimationListBase; |
| }; |
| |
| } // namespace animations |
| } // namespace render_tree |
| } // namespace cobalt |
| |
| #endif // COBALT_RENDER_TREE_ANIMATIONS_ANIMATION_LIST_H_ |