Binding a Windows Phone 7 button's action to a method in Expression Blend 4

Question

I'm trying out Windows Phone 7 dev for the first time. I decided to try and port a Silverlight Timer example from the default examples in Expression Blend 4. The timer example for full-blown silverlight binds a TimerModel class to the timer, the start/stop toggle switch, etc. I've figured out how to create the datasource/datacontext and bind the properties to things on the screen. However, the Reset() method, which is a void doesn't show up in the bindable options for the Windows Phone 7 app. It's the exact same class in both, but for some reason the void method isn't bindable. Is there something I need to enable that was in the full Silverlight app that's not in Windows Phone 7? Is there something in particular that makes a class' properties or methods bindable when it's a data source? Is this just one of the limitations of Windows Phone 7's subset of Silverlight's features?

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Below is the class, which is the same in both applications. I want to bind a button's click to the Reset() method.

namespace Time
{
    using System;
    using System.ComponentModel;
    using System.Windows.Threading;
    using System.Windows.Data;

    public class TimerModel : INotifyPropertyChanged
    {
        private bool isRunning;
        private DispatcherTimer timer;
        private TimeSpan time;
        private DateTime lastTick;

        public string FormattedTime
        {
            get 
            {
                return string.Format("{0:#0}:{1:00}:{2:00.00}", this.time.Hours, this.time.Minutes, (this.time.Seconds + (this.time.Milliseconds / 1000.0d)));
            }
        }

        private void UpdateTimes()
        {
            this.NotifyPropertyChanged("FormattedTime");
            this.NotifyPropertyChanged("Hours");
            this.NotifyPropertyChanged("Minutes");
            this.NotifyPropertyChanged("Seconds");
        }

        public bool Increment
        {
            get;
            set;
        }

        public int Hours
        {
            get
            {
                return this.time.Hours;
            }
            set
            {
                this.time = this.time.Add(TimeSpan.FromHours(value - this.time.Hours));
                this.UpdateTimes();
            }
        }

        public int Minutes
        {
            get
            {
                return this.time.Minutes;
            }
            set
            {
                this.time = this.time.Add(TimeSpan.FromMinutes(value - this.time.Minutes));
                this.UpdateTimes();
            }
        }

        public int Seconds
        {
            get
            {
                return this.time.Seconds;
            }
            set
            {
                this.time = this.time.Add(TimeSpan.FromSeconds(value - this.time.Seconds));
                this.UpdateTimes();
            }
        }

        public bool IsRunning
        {
            get { return this.isRunning; }
            set
            {
                if (this.isRunning != value)
                {
                    this.isRunning = value;
                    if (this.isRunning)
                    {
                        this.StartTimer();
                    }
                    else
                    {
                        this.StopTimer();
                    }
                    this.NotifyPropertyChanged("IsRunning");
                }
            }
        }

        private void StartTimer()
        {
            if (this.timer != null)
            {
                this.StopTimer();
            }
            this.timer = new DispatcherTimer();
            this.timer.Interval = TimeSpan.FromMilliseconds(1);
            this.timer.Tick += this.OnTimerTick;
            this.lastTick = DateTime.Now;
            this.timer.Start();
        }

        private void StopTimer()
        {
            if (this.timer != null)
            {
                this.timer.Stop();
                this.timer = null;
            }
        }

        private void OnTimerTick(object sender, EventArgs e)
        {
            DateTime now = DateTime.Now;
            TimeSpan diff = now - this.lastTick;
            this.lastTick = now;

            if (this.Increment)
            {
                this.time = this.time.Add(diff);
            }
            else
            {
                this.time = this.time.Subtract(diff);
            }
            if (this.time.TotalMilliseconds <= 0)
            {
                this.time = TimeSpan.FromMilliseconds(0);
                this.IsRunning = false;
            }
            this.UpdateTimes();
        }

        public void Reset()
        {
            this.time = new TimeSpan();
            this.UpdateTimes();
        }

        public TimerModel()
        {
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

}

Answer 1

I use the Caliburn Micro MVVM framework. It allows binding by convention so if you call your button RefreshButton and you have a method in your view model called RefreshButton it will get bound to the Click event automatically. Very powerful and easy.