[Meadow mocked pseudocode] Cycle hue on onboardLed

HueColorDemo.linq

// Copyright(c) 2018 Nicolò Carandini (aka TPCWare)

// Content
// ======================================================================================================
// This "not for production code" is just an example on how to run an async task that can be cancelled.
// Moreover, in this example there is an implementation of HSL to RGB color conversion.

// Build and test
// =========================================================================================================
// Run it on LinqPad (https://www.linqpad.net/) or use the code to create a Console app on Visual Studio.

// MIT License
// ======================================================================================================
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files(the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/ or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

async Task Main() // C# 7.1 and up
{
	var app = new RGBApp();
	await app.RunAsync();
}

public class RGBApp : AppBase<F7Micro, RGBApp>
{
	protected bool _running;
	protected RgbPwmLed onboardLed;

	private CancellationTokenSource cts;

	public RGBApp()
	{
		onboardLed = new RgbPwmLed(Pins.OnBoardLEDRed, Pins.OnBoardLEDGreen, Pins.OnBoardLEDBlue);
	}

	public async override Task RunAsync()
	{
		// Instantiate the CancellationTokenSource.
		cts = new CancellationTokenSource();
		
		// We can cancel immediately with this code, put inside a method that has subsribed an event that is triggered by something (a sensor, a button, ...):
		// cts.Cancel();

		// Because we don't have such an event, we will set automatic cancellation after some time (5 seconds)
		cts.CancelAfter(5000);

		await CycleHueOnOnboardLed(cts);
	}

	private async Task CycleHueOnOnboardLed(CancellationTokenSource cts)
	{
		int pauseMilliseconds = 18;
		
		// Note that because we are using HSL,
		// with lightness = 1 all color will be white regardless of the hue,
        // with lightness = 0 all colors will be black.
		double lightness = 0.5;

		double saturation = 1.0;
		
		try
		{
			while (true)
			{
				for (int hue = 0; hue < 360; hue++)
				{
					cts.Token.ThrowIfCancellationRequested();

					onboardLed.SetColorFromHSL(hue, saturation, lightness);
					await Task.Delay(pauseMilliseconds);
				}
			}
		}
		catch (OperationCanceledException)
		{
			// Don't throw any exception
			// we are here because the task was cancelled
		}
		catch (Exception e)
		{
			throw new Exception($"An error occurred: {e.Message}");
		}
	}
}

// *****************************
// Extension methods
// *****************************

public static class ExtendRgbPwmLed
{
	public static void SetColorFromHSL(this RgbPwmLed RgbPwmLed, int hue, double sat, double lum)
	{
		RgbPwmLed.SetColor(ColorConversion.FromHSL(hue, sat, lum));
	}

}

// *****************************
// Utils methods
// *****************************

public static class ColorConversion
{
	public static Color FromHSL(int hue, double sat, double lum)
	{
		Color result;
		
		// Check parameters for value range
		if (hue < 0 || hue > 360)
		{
			throw new ArgumentOutOfRangeException(nameof(hue));
		}

		if (sat < 0 || sat > 1)
		{
			throw new ArgumentOutOfRangeException(nameof(sat));
		}

		if (lum < 0 || lum > 1)
		{
			throw new ArgumentOutOfRangeException(nameof(lum));
		}

		// Convert HSL to RGB
		double r1, g1, b1;
		double m;
		try
		{
			double h1 = hue / 60.0;
			double c = (1 - Math.Abs(2 * lum - 1)) * sat;
			double x = c * (1 - Math.Abs(h1 % 2 - 1));
			m = lum - 0.5 * c;
			
			if (h1 <= 1)
			{
				r1 = c;
				g1 = x;
				b1 = 0;
			}
			else if (h1 <= 2)
			{
				r1 = x;
				g1 = c;
				b1 = 0;
			}
			else if (h1 <= 3)
			{
				r1 = 0;
				g1 = c;
				b1 = x;
			}
			else if (h1 <= 4)
			{
				r1 = 0;
				g1 = x;
				b1 = c;
			}
			else if (h1 <= 5)
			{
				r1 = x;
				g1 = 0;
				b1 = c;
			}
			else
			{
				r1 = c;
				g1 = 0;
				b1 = x;
			}
			
			result = Color.FromArgb(255, Convert.ToInt32(255 * (r1 + m)), Convert.ToInt32(255 * (g1 + m)), Convert.ToInt32(255 * (b1 + m)));
		}
		catch (Exception ex)
		{
			throw new Exception("Convert from HSL to RGB failed", ex);
		}

		return result;
	}
}

// *****************************
// Mocked classes
// *****************************

public class AppBase<TDevice, TApp> where TApp : AppBase<TDevice, TApp>
{
	public static TApp Current { get; private set; }
	
	public AppBase()
	{
		Current = (TApp)this;
	}
	
	public virtual Task RunAsync()
	{
		return Task.Delay(1);
	}
}

public class RgbPwmLed
{
	private Pins redPin;
	private Pins greenPin;
	private Pins bluePin;

	public RgbPwmLed(Pins redPin, Pins greenPin, Pins bluePin)
	{
		this.redPin = redPin;
		this.greenPin = greenPin;
		this.bluePin = bluePin;
	}

	public void SetColor(Color color)
	{
		// For test pourpose
		Console.WriteLine(color.ToString());
	}
}

public class F7Micro
{ }

public enum Pins
{
	OnBoardLEDRed = 4,
	OnBoardLEDGreen = 7,
	OnBoardLEDBlue = 12
}