transition.h

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#pragma once
 
#include "fl/namespace.h"
#include <stdint.h>
 
namespace fl {
 
// Logic to control the progression of a transition over time.
class Transition {
  public:
    Transition() : mStart(0), mDuration(0), mNotStarted(true) {}
    ~Transition() {}
 
    uint8_t getProgress(uint32_t now) {
        if (mNotStarted) {
            return 0;
        }
        if (now < mStart) {
            return 0;
        } else if (now >= mStart + mDuration) {
            return 255;
        } else {
            return ((now - mStart) * 255) / mDuration;
        }
    }
 
    void start(uint32_t now, uint32_t duration) {
        mNotStarted = false;
        mStart = now;
        mDuration = duration;
    }
 
    void end() { mNotStarted = true; }
 
    bool isTransitioning(uint32_t now) {
        if (mNotStarted) {
            return false;
        }
        return now >= mStart && now < mStart + mDuration;
    }
 
  private:
    uint32_t mStart;
    uint32_t mDuration;
    bool mNotStarted;
};
 
} // namespace fl