Animation.h

#pragma once

#include "ofEventUtils.h"
#include "ofEvents.h"
#include "ofAppRunner.h"

template<typename T>
class Animation
{
public:
	Animation():ptr_(&value_){}
	Animation(T &t):ptr_(&t){}
	~Animation() { if(animating_) removeListener(); }
	operator const T&() { return *ptr_; }
	bool isEnd() { return !animating_; }
	void to(T v, float time) {
		from_ = *ptr_;
		to_ = v;
		time_ = time;
		elapsed_ = 0;
		if(!animating_) {
			animating_ = true;
			addListener();
		}
	}
	void stop() {
		if(animating_) {
			animating_ = false;
			removeListener();
		}
	}
	void set(const T &t) { *ptr_ = t; stop(); }
	void setReference(T &t) { ptr_ = &t; }
protected:
	virtual T interpolate(const T &from, const T &to, float ratio) {
		return from*(1-ratio) + to*ratio;
	}
private:
	void addListener() { ofAddListener(ofEvents().update, this, &Animation::update); }
	void removeListener() { ofRemoveListener(ofEvents().update, this, &Animation::update); }
	void update(ofEventArgs &arg) {
		elapsed_ += ofGetLastFrameTime();
		float time_ratio = elapsed_/time_;
		if(time_ratio >= 1) {
			*ptr_ = to_;
			stop();
		}
		else {
			*ptr_ = interpolate(from_, to_, time_ratio);
		}
	}
	T value_, from_, to_, *ptr_;
	float time_, elapsed_;
	bool animating_;
};