Learning Silverlight – Miscellaneous Tips

How to use OpenFileDialog?

OpenFileDialog ofd = new OpenFileDialog();
ofd.Multiselect = false;
ofd.Filter = "xml files (*.xml)|*.xml";
if (ofd.ShowDialog()==true)
{
    string fileContent = ofd.File.OpenText().ReadToEnd();
    // do some thing
}

How to use SaveFileDialog?

SaveFileDialog sfd = new SaveFileDialog();
sfd.Filter = "xml files (*.xml)|*.xml";
if (sfd.ShowDialog() == true)
{
    byte[] fileBytes = System.Text.Encoding.UTF8.GetBytes(fileString); // fileString would be something you want to save to the file

    using (Stream fs = (Stream)sfd.OpenFile())
    {
        fs.Write(fileBytes, 0, fileBytes.Length);
        fs.Close();
    }
}

How to parse XML?

To parse a XML file like this:

<List type="DotNetIdeas.CF.RecipeBox.RecipeBox">
    <category name="Breakfast" order="0">
       <item name="pan cake"/>
       <item name="milk"/>
    <category name="Desert" order="1">
</List>

You can do something like this:

XDocument xd = XDocument.Parse(xml);

XElement node = xd.Root;

var categories = (from category in xd.Descendants("category")
                  select new Category()
                  {
                      Name = category.Attribute("name").Value,
                      Order = Convert.ToInt32(category.Attribute("order").Value),
                      Items = FromXml(category.Elements("item"))
                  }).ToList();
       

If you happened to be like me, migrating the code from some old programs, don’t forget to add “using System.Linq” which is in System.Core.dll. Otherwise you will get a compiler error.

How to use TreeView? 

To create a TreeView like this one, you will need to use HierarchicalDataTemplate. It is in System.Windows.Controls. So add the following namespace first:

xmlns:control="clr-namespace:System.Windows;assembly=System.Windows.Controls"

<controls:TreeView x:Name="ingredientList" Height="330" Width="248" Canvas.Left="17" Canvas.Top="18">
    <controls:TreeView.ItemTemplate>
        <control:HierarchicalDataTemplate ItemsSource="{Binding Items}">
            <StackPanel Orientation="Horizontal">
                <CheckBox x:Name="itemCheckbox" IsChecked="{Binding ItemChecked, Mode=TwoWay}"/>
                <TextBlock Text="{Binding Path=Name}" />
            </StackPanel>
        </control:HierarchicalDataTemplate>

    </controls:TreeView.ItemTemplate>
</controls:TreeView>

 

How to force data binding in TextChanged event?

When a text box has data binding, it will not update the source until it lost the focus. Sometimes we want the source to change as soon as we type something. Here is how to do it:

private void ingredientName_TextChanged(object sender, System.Windows.Controls.TextChangedEventArgs e)
{
    BindingExpression bExp = ingredientName.GetBindingExpression(TextBox.TextProperty);
    if (bExp != null)
    {
        bExp.UpdateSource();
    }
}