Question

How do you perform databinding against the MonthCalendar.SelectionRange property? Given the property is of type ‘SelectionRange’ which is a class I am not sure how to go about it. Any examples would be much appreciated.

Answer 1

Well, there don’t seem to be any obvious events for this either on the MonthCalendar or the SelectionRange, and neither implements INotifyPropertyChanged, so it looks like data-binding might not be possible here.

Update: It does, however, raise the DateChanged, so you could hook some stuff together manually, or (more usefully) by subclassing the control to expose the values and events in a fashion suitable for binding. Note the Actual(...) are useful because the end (otherwise) is just before midnight, rather than midnight itself…

using System; using System.Collections.Generic; using System.ComponentModel; using System.Diagnostics; using System.Windows.Forms; class Foo : INotifyPropertyChanged {     public event PropertyChangedEventHandler PropertyChanged;     protected virtual void OnPropertyChanged(string propertyName)     {         var handler = PropertyChanged;         if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));         Debug.WriteLine(ToString());     }     private void SetField<T>(ref T field, T value, string propertyName)     {         if (!EqualityComparer<T>.Default.Equals(field, value))         {             field = value;             OnPropertyChanged(propertyName);                     }     }     private DateTime start, end;     public DateTime Start { get { return start; } set { SetField(ref start, value, 'Start'); } }     public DateTime End { get { return end; } set { SetField(ref end, value, 'End'); } } }  class BindableCalendar : MonthCalendar {     public DateTime ActualSelectionStart     {         get { return SelectionRange.Start; }         set { if (ActualSelectionStart != value) { SetSelectionRange(value, ActualSelectionEnd); } }     }     public DateTime ActualSelectionEnd     {         get { return SelectionRange.End; }         set { if (ActualSelectionEnd != value) { SetSelectionRange(ActualSelectionStart, value); } }     }     // should really use EventHandlerList here...     public event EventHandler ActualSelectionStartChanged, ActualSelectionEndChanged;      DateTime lastKnownStart, lastKnownEnd;     protected override void OnDateChanged(DateRangeEventArgs drevent)     {         base.OnDateChanged(drevent);         if (lastKnownStart != drevent.Start)         {             if (ActualSelectionStartChanged != null) ActualSelectionStartChanged(this, EventArgs.Empty);             lastKnownStart = drevent.Start;         }         if (lastKnownEnd != drevent.End)         {             if (ActualSelectionEndChanged != null) ActualSelectionEndChanged(this, EventArgs.Empty);             lastKnownEnd = drevent.End;         }     }  }  static class Program {     [STAThread]     static void Main()     {          Application.EnableVisualStyles();         MonthCalendar cal;         Button btn;         using (Form form = new Form         {             Controls = {                 (cal = new BindableCalendar { Dock = DockStyle.Fill, MaxSelectionCount = 10 }),                 (btn = new Button { Dock = DockStyle.Bottom, Text = 'thwack'})             }         })         {             Foo foo = new Foo { Start = DateTime.Today, End = DateTime.Today.AddDays(1) };             cal.DataBindings.Add('ActualSelectionStart', foo, 'Start').DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;             cal.DataBindings.Add('ActualSelectionEnd', foo, 'End').DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;             btn.Click += delegate             {                 foo.Start = foo.Start.AddDays(1);                 foo.End = foo.End.AddDays(1);             };             Application.Run(form);         }     } }