Binding Data

[Sean Pales]

Hi ,
I am new to Silverlight and trying to use the Frequency Indicator control. I am getting data from the tables using a dataset. Can you advise how i can dynamically bind data to the control. Any sample code that you may have would be great.
Thanks,
SP

[Andrey]

Hi Sean,

The “Frequency Indicator” is not a control. It is a sample that demonstrates one possible usage of the RadGauge control, and generally the gauge control does not support databinding beyond binding values to single indicators like needle, bars, etc.

Regards,
Andrey Murzov
the Telerik team

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[Sean Pales]

Thanks Andrey,
So i am able to dynamically create number of bars and their height using dynamic values from tables....correct? Do you have some sample code for that?
SP

[Andrey]

Hello Sean Pales,

Unfortunately Silverlight 2 don’t support DataSet/DataTable, so you can’t use these traditional ADO.NET objects in your Silverlight application. You can use binding to the custom data objects or to the XML instead. For example, you can modify “Frequency Indicator” to bind every linear bar in it to the custom data object.

First of all you have to create custom data object with double value which will implement INotifyPropertyChanged interface:

using System;
using System.ComponentModel;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace TestGaugeApplication
{
    public class DoubleData : INotifyPropertyChanged
    {
        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion

        private double doubleValue;

        public DoubleData()
        {
            Value = 0;
        }

        public double Value
        {
            get
            {
                return doubleValue;
            }
            set
            {
                doubleValue = value;
                NotifyPropertyChanged("Value");
            }
        }

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

Since you need a bunch of bars (32 in case of Frequency Indicator example) be bound to the dynamic data you have to add array of data objects to the code of Frequency Indicator and initialize and array in the page class constructor:

// Array of data objects
private DoubleData[] columnValues = new DoubleData[32];

public Page()
{
    InitializeComponent();

    // Initialize data objects in array
    for (int counter = 0; counter < columnValues.Length; counter++)
    {
        columnValues[counter] = new DoubleData();
    }

    CreateBars(Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF),
        Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF));

    this.Loaded += new RoutedEventHandler(Page_Loaded);
}

Then you should modify AddBar method in example so it binds every linear bar to the Value property of the correspondent data object:

private void AddBar(int i, Color color)
{
    LinearBar bar = new LinearBar();
    bar.Value = 50d;
    bar.Background = new SolidColorBrush(color);
    bar.StrokeThickness = 0d;
    bar.Location = ScaleObjectLocation.OverOutside;
    bar.Offset = 0.018 + 0.03998 * 2 * (i - 1);
    bar.StartWidth = 0.05;
    bar.EndWidth = 0.05;

    // Bind linear bar to the Value property
    // of the data object.
    Binding binding = new Binding();
    binding.Source = columnValues[i - 1];
    binding.Path = new PropertyPath("Value");
    bar.SetBinding(LinearBar.ValueProperty, binding);

    linearScale.Indicators.Add(bar);
}

Now you can change value of the data objects and have linear bars change its value correspondingly. For example:

Random rnd = new Random();

for (int counter = 0; counter < barCounter; counter++)
{
    columnValues[counter].Value =
        linearScale.Min + (linearScale.Max - linearScale.Min) * rnd.NextDouble();
}

Greetings,
Andrey Murzov
the Telerik team

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