Home / Community & Support / Developer Productivity Tools Forums / Silverlight > Gauge > guage wont refresh after update

• chris

  Posted on Sep 6, 2011 (permalink)

  im following the binding example in RadControls Silverlight Courseware. ive attached the project..
  
  when the timer is called and the stock quote is updated the gauge control does not reflect the change. any suggestion on what i might be doing wrong would greatly be appreciated
  
  mainpage.xaml
  
  <UserControl x:Class="Silverlightgauge.MainPage"
           xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Gauge"
           xmlns:abc="clr-namespace:Telerik.Windows;assembly=Telerik.Windows.Controls"   
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
          mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"
          Loaded="UserControl_Loaded" >
  
      <UserControl.Resources>
          <LinearGradientBrush x:Key="BackgroundBrush">
              <GradientStop Color="LightBlue" Offset="0.01" />
              <GradientStop Color="SkyBlue" Offset="0.02" />
              <GradientStop Color="SlateBlue" Offset="0.8" />
              <GradientStop Color="SkyBlue" Offset="0.99" />
              <GradientStop Color="LightBlue" Offset="1" />
          </LinearGradientBrush>
      </UserControl.Resources>
  
      <Grid x:Name="LayoutRoot">
          <telerik:RadGauge >
              <StackPanel Background="{StaticResource BackgroundBrush}"
                      HorizontalAlignment="Stretch">
                  <StackPanel x:Name="spScales"   Orientation="Horizontal"
                          HorizontalAlignment="Center" Margin="10" />
              </StackPanel>
          </telerik:RadGauge>
      </Grid>
  </UserControl>
  
  code behind
  
  Imports System.Windows.Controls
  Imports System.Windows.Data
  Imports System.Windows.Media
  Imports System.Windows.Threading
  Imports Telerik.Windows.Controls
  Imports Telerik.Windows.Controls.Data
  Imports Telerik.Windows.Controls.Gauges
  
  
  
  Partial Public Class MainPage
      Inherits UserControl
  
      Private _random As New Random()
      Private _timer As New DispatcherTimer()
      Private _stocks As New Stocks()
  
      Public Sub New()
          InitializeComponent()
      End Sub
  
  
      Private Sub UserControl_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
          ' Create a stack panel for each stock and populate
          ' with text label and linear bar
          For Each stock As Stock In _stocks
              ' initialize a linear scale
              Dim scale As New LinearScale()
              scale.Min = 0
              scale.Max = 100
              scale.Width = 70
              ' add a linear bar, already bound to the stock
              scale.Indicators.Add(GetLinearBar(stock))
              ' create a label to display stock symbol
              Dim tb As New TextBlock()
              tb.FontWeight = System.Windows.FontWeights.Bold
              tb.Text = stock.Symbol
              ' initialize a stack panel to contain a text label
              ' and scale. Add the stack panel to the stack panel
              ' already in the xaml markup
              Dim stackPanel As New StackPanel()
              stackPanel.VerticalAlignment = VerticalAlignment.Stretch
              stackPanel.Children.Add(tb)
              stackPanel.Children.Add(scale)
              spScales.Children.Add(stackPanel)
          Next stock
          ' initialize and start a timer to update the stocks
          AddHandler _timer.Tick, AddressOf _timer_Tick
          _timer.Interval = New TimeSpan(0, 0, 0, 1)
          _timer.Start()
      End Sub
  
      Private Function GetLinearBar(ByVal stock As Stock) As LinearBar
          Dim linearBar As New LinearBar()
          linearBar.Value = stock.Quote
          linearBar.Background = New SolidColorBrush(GetRandomColor())
          linearBar.StartWidth = 0.1
          linearBar.EndWidth = 0.1
          linearBar.RelativeHeight = 0.9
          ' Bind linear bar to the Quote property of the data object.
          Dim binding As New Binding()
          binding.Source = stock
          binding.Path = New PropertyPath("Quote")
          binding.Mode = BindingMode.OneWay
         
          linearBar.SetBinding(linearBar.ValueProperty, binding)
  
          Return linearBar
      End Function
  
      Private Function GetRandomColor() As Color
          Return Color.FromArgb(150, CByte(_random.Next(0, 255)), _
          CByte(_random.Next(0, 255)), CByte(_random.Next(0, 255)))
      End Function
  
      Private Sub _timer_Tick(ByVal sender As Object, ByVal e As EventArgs)
          For Each stock As Stock In _stocks ' update the symbols
          
              stock.Quote = _random.Next(0, 100)
             
           
          Next stock
      End Sub
  End Class
  
  stock.vb
  
  Imports System.ComponentModel
  
  Public Class Stock
      Implements INotifyPropertyChanged
  
      Public Event PropertyChanged As PropertyChangedEventHandler
      Private _quote As Double
      Private _symbol As String
      Public Sub New(ByVal symbol As String, ByVal quote As Double)
          Me.Quote = quote
          Me.Symbol = symbol
      End Sub
      Public Property Quote() As Double
          Get
              Return _quote
          End Get
          Set(ByVal value As Double)
              _quote = value
              NotifyPropertyChanged("Quote")
          End Set
      End Property
      Public Property Symbol() As String
          Get
              Return _symbol
          End Get
          Set(ByVal value As String)
              _symbol = value
              NotifyPropertyChanged("Symbol")
          End Set
      End Property
      Private Sub NotifyPropertyChanged(ByVal propertyName As String)
          RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
      End Sub
  
      Public Event PropertyChanged1(sender As Object, e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
  End Class
  
  
  stocks.vb
  
  Public Class Stocks
      Inherits List(Of Stock)
      Public Sub New()
          Dim symbols As List(Of String) = _
          New List(Of String)(New String() {"MSFT", "GOOG", "YHOO", "IBM", "AAPL"})
          Dim random As New Random()
          For Each symbol As String In symbols
              Me.Add(New Stock(symbol, random.Next(0, 100)))
          Next symbol
      End Sub
  End Class
  
  
  
  
  
  thanks
  
  chris

  Reply

• Ves Ves

  Posted on Sep 9, 2011 (permalink)

  Hi Chris,
  
  The reason ins in the INotifyPropertyChanged implementation. There is an event PropertyChanged in the Stock class, and there is another one, named PropertyChanged1 which actually implements the INotifyPropertyChanged.PropertyChanged and this seems to lead this undesired behavior. You can strip all the gauge-related obejcts and bind the Text property of a TextBlock - you will still see the same behavior. Changing the Stock class fixes it. Here is the code:
  
  

  Public Class Stock

      Implements INotifyPropertyChanged

   

      'Public Event PropertyChanged As PropertyChangedEventHandler

      Private _quote As Double

      Private _symbol As String

      Public Sub New(ByVal symbol As String, ByVal quote As Double)

          Me.Quote = quote

          Me.Symbol = symbol

      End Sub

      Public Property Quote() As Double

          Get

              Return _quote

          End Get

          Set(ByVal value As Double)

              _quote = value

              NotifyPropertyChanged("Quote")

          End Set

      End Property

      Public Property Symbol() As String

          Get

              Return _symbol

          End Get

          Set(ByVal value As String)

              _symbol = value

              NotifyPropertyChanged("Symbol")

          End Set

      End Property

      Private Sub NotifyPropertyChanged(ByVal propertyName As String)

          RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))

      End Sub

   

      Public Event PropertyChanged(sender As Object, e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

  End Class

  
  
  Kind regards,
  Ves
  the Telerik team

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