Animation (#355)

include/ftxui/component/animation.hpp

@@ -0,0 +1,119 @@
+#ifndef FTXUI_ANIMATION_HPP
+#define FTXUI_ANIMATION_HPP
+
+#include <chrono>      // for milliseconds, duration, steady_clock, time_point
+#include <functional>  // for function
+
+#include "ftxui/component/event.hpp"
+
+namespace ftxui {
+
+namespace animation {
+// Components who haven't completed their animation can call this function to
+// request a new frame to be drawn later.
+//
+// When there is no new events and no animations to complete, no new frame is
+// drawn.
+void RequestAnimationFrame();
+
+using Clock = std::chrono::steady_clock;
+using TimePoint = std::chrono::time_point<Clock>;
+using Duration = std::chrono::duration<double>;
+
+// Parameter of Component::OnAnimation(param).
+class Params {
+ public:
+  Params(Duration duration) : duration_(duration) {}
+
+  /// The duration this animation step represents.
+  Duration duration() const { return duration_; }
+
+ private:
+  Duration duration_;
+};
+
+namespace easing {
+using Function = std::function<float(float)>;
+// Linear interpolation (no easing)
+float Linear(float p);
+
+// Quadratic easing; p^2
+float QuadraticIn(float p);
+float QuadraticOut(float p);
+float QuadraticInOut(float p);
+
+// Cubic easing; p^3
+float CubicIn(float p);
+float CubicOut(float p);
+float CubicInOut(float p);
+
+// Quartic easing; p^4
+float QuarticIn(float p);
+float QuarticOut(float p);
+float QuarticInOut(float p);
+
+// Quintic easing; p^5
+float QuinticIn(float p);
+float QuinticOut(float p);
+float QuinticInOut(float p);
+
+// Sine wave easing; sin(p * PI/2)
+float SineIn(float p);
+float SineOut(float p);
+float SineInOut(float p);
+
+// Circular easing; sqrt(1 - p^2)
+float CircularIn(float p);
+float CircularOut(float p);
+float CircularInOut(float p);
+
+// Exponential easing, base 2
+float ExponentialIn(float p);
+float ExponentialOut(float p);
+float ExponentialInOut(float p);
+
+// Exponentially-damped sine wave easing
+float ElasticIn(float p);
+float ElasticOut(float p);
+float ElasticInOut(float p);
+
+// Overshooting cubic easing;
+float BackIn(float p);
+float BackOut(float p);
+float BackInOut(float p);
+
+// Exponentially-decaying bounce easing
+float BounceIn(float p);
+float BounceOut(float p);
+float BounceInOut(float p);
+}  // namespace easing
+
+class Animator {
+ public:
+  Animator(float* from,
+           float to = 0.f,
+           Duration duration = std::chrono::milliseconds(250),
+           easing::Function easing_function = easing::Linear,
+           Duration delay = std::chrono::milliseconds(0));
+
+  void OnAnimation(Params&);
+
+  float to() const { return to_; }
+
+ private:
+  float* value_;
+  float from_;
+  float to_;
+  Duration duration_;
+  easing::Function easing_function_;
+  Duration current_;
+};
+
+}  // namespace animation
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_ANIMATION_HPP */
+
+// Copyright 2022 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.