Question

I need a feature in silverlight text box, simillar functionality as in Ask Question “Title” textbox in stalkoverflow. When there’s no text in textbox then it should display “Search”. When user clicked on the textbox then textbox text should be empty and in textbox lost focus if the text is empty then show “Search”. I wrote the following code, but is there any code which handles all possible conditions?

private void txtAvailable_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
 {
            txtAvailable.Text = "";
 }

 private void txtAvailable_LostFocus(object sender, RoutedEventArgs e)
 {
            if (txtAvailable.Text.Trim() == "")
                txtAvailable.Text = "Search";
 }

Answer 1

You could use the Textbox GotFocus and LostFocus events – they should be generic enough to cover off all of your potentials..

The specialness comes when you want to search on every keystroke – you have to enable and disable searching on those events.

    private bool IsBusy
    {
        get;
        set;
    }

    private bool CanSearch
    {
        get;
        set;
    }

    public Constructor()
    {
        InitializeComponent();

        this.IsBusy = false;

        txtSearch.GotFocus += new RoutedEventHandler( txtSearch_GotFocus );
        txtSearch.LostFocus += new RoutedEventHandler( txtSearch_LostFocus );
        txtSearch.KeyUp += new System.Windows.Input.KeyEventHandler( txtSearch_KeyUp );
        txtSearch.Text = "Search »";
    }

    private void txtSearch_LostFocus( object sender, RoutedEventArgs e )
    {
        if( string.IsNullOrEmpty( txtSearch.Text ) )
        {
            CanSearch = false;
            txtSearch.Text = "Search »";
        }
    }

    private void txtSearch_GotFocus( object sender, RoutedEventArgs e )
    {
        txtSearch.Text = string.Empty;
        CanSearch = true;
    }

    private void OnFilterCommand()
    {
        try
        {
            if( !IsBusy && CanSearch )
            {
                AppMessages.FilterAssetMessage.Send( txtSearch.Text );
            }
        }
        catch( Exception ex )
        {
            // Notify user if there is any error
            AppMessages.RaiseErrorMessage.Send( ex );
        }
    }

    private void txtSearch_KeyUp( object sender, System.Windows.Input.KeyEventArgs e )
    {
        OnFilterCommand();
    }