ExtendedDatePicker.cs

namespace NeuroAccessMaui.UI.Controls.Extended
{
    public class ExtendedDatePicker : DatePicker
    {
        public static readonly BindableProperty FontProperty =
             BindableProperty.Create(nameof(Font), typeof(Microsoft.Maui.Font), typeof(ExtendedDatePicker), new Microsoft.Maui.Font());
 
        public static readonly BindableProperty NullableDateProperty =
             BindableProperty.Create(nameof(NullableDate), typeof(DateTime?), typeof(ExtendedDatePicker), null, BindingMode.TwoWay,
             propertyChanged: DatePropertyChanged);
 
        public static readonly BindableProperty XAlignProperty =
             BindableProperty.Create(nameof(XAlign), typeof(TextAlignment), typeof(ExtendedDatePicker),
             TextAlignment.Start);
 
        public static readonly BindableProperty HasBorderProperty =
             BindableProperty.Create(nameof(HasBorder), typeof(bool), typeof(ExtendedDatePicker), true);
 
        public static readonly BindableProperty PlaceholderProperty =
             BindableProperty.Create(nameof(Placeholder), typeof(string), typeof(ExtendedDatePicker), string.Empty, BindingMode.OneWay);
 
        public static readonly BindableProperty PlaceholderTextColorProperty =
             BindableProperty.Create(nameof(PlaceholderTextColor), typeof(Color), typeof(ExtendedDatePicker), Colors.Transparent);
 
 
        public Microsoft.Maui.Font Font
        {
            get { return (Microsoft.Maui.Font)this.GetValue(FontProperty); }
            set { this.SetValue(FontProperty, value); }
        }
 
        public DateTime? NullableDate
        {
            get { return (DateTime?)this.GetValue(NullableDateProperty); }
            set
            {
                if (value != this.NullableDate)
                {
                    this.SetValue(NullableDateProperty, value);
                    this.UpdateDate();
                }
            }
        }
 
        public TextAlignment XAlign
        {
            get { return (TextAlignment)this.GetValue(XAlignProperty); }
            set { this.SetValue(XAlignProperty, value); }
        }
 
 
        public bool HasBorder
        {
            get { return (bool)this.GetValue(HasBorderProperty); }
            set { this.SetValue(HasBorderProperty, value); }
        }
 
        public string Placeholder
        {
            get { return (string)this.GetValue(PlaceholderProperty); }
            set { this.SetValue(PlaceholderProperty, value); }
        }
 
        public Color PlaceholderTextColor
        {
            get { return (Color)this.GetValue(PlaceholderTextColorProperty); }
            set { this.SetValue(PlaceholderTextColorProperty, value); }
        }
 
        public ExtendedDatePicker() : base()
        {
            this.SetDefaultDate();
        }
 
        public event EventHandler<NullableDateChangedEventArgs>? NullableDateSelected;
 
        static void DatePropertyChanged(BindableObject bindable, object oldValue, object newValue)
        {
            ExtendedDatePicker Picker = (ExtendedDatePicker)bindable;
            EventHandler<NullableDateChangedEventArgs>? selected = Picker.NullableDateSelected;
 
            selected?.Invoke(Picker, new NullableDateChangedEventArgs((DateTime?)oldValue, (DateTime?)newValue));
        }
 
        private bool isDefaultDateSet = false;
 
        protected override void OnPropertyChanged(string? propertyName = null)
        {
            base.OnPropertyChanged(propertyName);
 
            if (propertyName == IsFocusedProperty.PropertyName)
            {
                // we don't know if the date picker was closed by the Ok or Cancel button,
                // so we presuppose it was an Ok.
                if (!this.IsFocused)
                {
                    this.OnPropertyChanged(DateProperty.PropertyName);
                }
            }
 
            if (propertyName == DateProperty.PropertyName && !this.isDefaultDateSet)
            {
                this.NullableDate = this.Date;
            }
 
            if (propertyName == NullableDateProperty.PropertyName)
            {
                if (this.NullableDate.HasValue)
                {
                    this.Date = this.NullableDate.Value;
                }
            }
        }
 
        private void UpdateDate()
        {
            if (this.NullableDate.HasValue)
            {
                this.Date = this.NullableDate.Value;
            }
            else
            {
                this.isDefaultDateSet = true;
                this.SetDefaultDate();
                this.isDefaultDateSet = false;
            }
        }
 
        private void SetDefaultDate()
        {
            DateTime now = DateTime.Now;
            this.Date = new DateTime(now.Year, now.Month, now.Day);
        }
    }
}