How to Scope Input in Your Windows Phone Application

Introduction

While today's mobile devices have processing power comparable to some desktops, it lags on one front - screen real estate. Physical keyboards now no longer in vogue, the touch screen keyboard has become the norm.

Since touch based keyboards have to compete for screen real estate, it makes sense to have the keyboard render only those keys which are applicable for the input.

Fortunately, like other popular mobile operating systems, Windows Phone allows input scoping.

Input scoping can be achieved by adding the tag InputScope to your control.

For example, if we have a TextBox control where you only want to have numbers as input, you will tag your control as shown below.

<TextBox InputScope="Number" Name="txtCellPhone" />

Alternately, you can also specify the input scope via code.

Here is how you can do it via code.

TextBox txtCellPhone;

InputScope scope = new InputScope();

InputScopeName scopeName = new InputScopeName();

scopeName.NameValue = InputScopeNameValue.Number;

scope.Names.Add(scopeName);

txtCellPhone.InputScope = scope;

To see how you can leverage this feature in your Windows Phone application, let's walk through a sample application where we will have our input scoped.

Hand-On

Create a Windows Phone application called WindowsPhoneInputScopeDemo.

Add a Textbox control to the MainPage. Let's call it txtBoxCellPhone.

Open the XAML for MainPage and change the XAML for txtBoxCellPhone as shown below.

<TextBox InputScope="Number" B Height="72" HorizontalAlignment="Left" Margin="9,96,0,0" Name="txtBoxCellPhone" Text="TextBox" VerticalAlignment="Top" Width="426" />

When you run your application, you'll get the following screen.

Figure 1: Input Scoping

However, as soon as you focus on the textbox, the contextual keyboard will appear:

Figure 2: Windows Phone contextual keyboard

You will notice that the contextual keyboard only has numeric input. Hence, users are not prompted with irrelevant keys (alphabets), thereby making the application more user-friendly.

Note that TextBox control in Windows Phone supports various input scopes, which determine the keyboard layout for the input panel.

Let's look at how the input scope panel looks for various scopes.

Scope: URL

Notice that for URL inputs, we get the full alphabet keys, as well as .com key.

Figure 3: Windows Phone Input Scoping: URL

Scope: Text

Text scope has autocorrect and text suggestions.

Figure 4: Windows Phone Input Scoping: Text

Application developers can look at the MSDN page for InputScopeNameValue enumeration to see the full range of input scoping available on Windows Phone.

Summary

In this article, we saw how to set input scoping in a Windows Phone application. I hope you have found this information useful.