Orientation Aware Content Page

Orientation.cs

/// <summary>
/// Device Orientation.
/// </summary>
public enum Orientation
{
    /// <summary>
    /// Portrait Orientation.
    /// </summary>
    Portrait,

    /// <summary>
    /// Horizontal Orientation.
    /// </summary>
    Horizontal
}

OrientationContentPage.cs

public class ContentPageExtended : ContentPage
{
    #region Properties

    #region - Class Properties

    private double _width = 0;
    private double _height = 0;

    #endregion - Class Properties

    #endregion Properties

    public ContentPageExtended()
    {
    }

    #region Methods

    #region - Overridable Methods

    /// <summary>
    /// Called when the device orientation changes
    /// </summary>
    /// <param name="orientation">Orientation.</param>
    /// <param name="height">Height.</param>
    /// <param name="width">Width.</param>
    public virtual void OnOrientationChanged(Orientation orientation, double height, double width)
    {

    }

    #endregion - Overridable Methods

    #region - Base Class Methods

    //https://spin.atomicobject.com/2018/09/24/xamarin-forms-orientation-changes/
    protected override void OnSizeAllocated(double width, double height)
    {
        base.OnSizeAllocated(width, height);

        if (this._width != width || this._height != height)
        {
            this._width = width;
            this._height = height;

            var dimensions = GetScreenDimensions();

            OnOrientationChanged(dimensions.orientation, dimensions.height, dimensions.width);
        }
    }

    #endregion - Base Class Methods

    #region - Helper Methods

    /// <summary>
    /// Gets the popup dimensions.
    /// </summary>
    /// <returns>The popup dimensions.</returns>
    private (Orientation orientation, double height, double width) GetScreenDimensions()
    {
        var longestSide = Math.Max(Application.Current.MainPage.Height, Application.Current.MainPage.Width);
        var shortestSide = Math.Min(Application.Current.MainPage.Height, Application.Current.MainPage.Width);

        bool isPortrait = _height > _width;

        if (isPortrait)
        {
            return (Orientation.Portrait, longestSide, shortestSide);
        }
        else
        {
            return (Orientation.Horizontal, shortestSide, longestSide);
        }
    }

    #endregion - Helper Methods

    #endregion Methods
}