WPF OneWay Binding Part 3

In this part we will bind to a class. We will start off by creating a grid to display the properties of the class. Finally we will show how to get the form to update itself when a value changes in the class.


Lets start off creating a class that shows some info about the computer. Here is the class.

Public Class ComputerInfo

Public ReadOnly Property UserName() As String
Get
Return Environment.UserName
End Get
End Property
Public ReadOnly Property ComputerName() As String
Get
Return Environment.MachineName
End Get
End Property
Public ReadOnly Property UpTime() As Integer
Get
Return Environment.TickCount
End Get
End Property


End Class



Ok lets register the class with the form.

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WPFOneWayBindToVariable"
Title="WPFOneWayBindToVariable" Height="300" Width="300"
>




Now lets create a grid with 2 columns and 3 rows to show the class in.












Lets put the data in the grid we just created.











To get the form to update itself automatically when a value changes in the class the class has to inherit from DependencyObject. The properties values that can change must be stored in a DependencyProperty. In this class I want the UpTime property to update itself every second with a timer.



Imports System.Windows.Threading

Public Class ComputerInfo
Inherits DependencyObject

Public Shared TickCountProperty As DependencyProperty = DependencyProperty.Register("UpTime", GetType(Integer), GetType(ComputerInfo))


Public Sub New()
Dim dt As New DispatcherTimer
AddHandler dt.Tick, AddressOf TimerTick
With dt
.Interval = TimeSpan.FromSeconds(1)
.Start()
End With
End Sub

Public ReadOnly Property UserName() As String
Get
Return Environment.UserName
End Get
End Property
Public ReadOnly Property ComputerName() As String
Get
Return Environment.MachineName
End Get
End Property
Public ReadOnly Property UpTime() As Integer
Get
Return GetValue(TickCountProperty)
End Get
End Property

Public Sub TimerTick(ByVal sender As Object, ByVal e As EventArgs)
SetValue(TickCountProperty, Environment.TickCount)
End Sub

End Class


Here is the windows complete XAML



xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WPFOneWayBindToVariable"
Title="WPFOneWayBindToVariable" Height="300" Width="300"
>