WPF Databinding Calculated Value sometimes minutes sometimes hours

Question

I have a WPF window with a textbox, using standard WPF Databinding to an object. This all works fine, the issue is this:

The user is entering a time estimate, I would like to give the user the option to enter the data in hours or minutes (through a drop down list). I'd like to keep the data in minutes, and if the user selects hours, multiply their input by 60 and store the data.

How can I achieve that with WPF databinding? Is this even possible?

edit

For example, 90 minutes would show up as 1.5 if the dropdown list is set to hours, but 90 if miutes is selected.

Answer 1

You could use a special property on your window:

<ComboBox x:Name="Units">
    <sys:String>Hours</sys:String>
    <sys:String>Minutes</sys:String>
</ComboBox>
<TextBox x:Name="Value" Text="{Binding Path=Estimate, ElementName=ThisWindow}" />

And then implement the special property:

public double Estimate
{
    get
    {
        switch(this.Units.SelectedItem as String)
        {
        case "Hours":
            return this.estimate / 60.0;
        default:
            return this.estimate;
        }
    }

    set
    {
        switch(this.Units.SelectedItem as String)
        {
        case "Hours":
            this.estimate = value * 60.0;
            break;
        default:
            this.estimate = value;
            break;
        }

        this.OnPropertyChanged("Estimate");
    }
}