Here are some packages I have published:
This library provides several widgets and utilities that enable you to create advanced layouts without in-depth knowledge of the framework and minimal boilerplate.
This package provides
AsyncBuilder, a widget similar to
FutureBuilder which is designed to reduce boilerplate and improve error handling.
It also provides
InitBuilder, which makes it easier to start async tasks safely.
This is a Dart implementation of the Solar Position Algorithm (SPA) by Ibrahim Reda and Afshin Andreas which is used by the U.S. government for radiology and energy purposes. See the paper here: https://www.nrel.gov/docs/fy08osti/34302.pdf
Given an observers coordinates and DateTime it can calculate the position of the sun and other information such as when the sun rises and sets.