How to: Implement a Trial Experience in a Silverlight Application for Windows Phone

In Visual Studio 2010 Express for Windows Phone, create a new project by selecting the File | New Project menu command.

The New Project window is displayed. Expand the Visual C# templates, and then select the Silverlight for Windows Phone templates.

Select the Windows Phone Application template. Fill in the Name with a name of your choice.

Click OK. A new project is created, and MainPage.xaml is opened in the Visual Studio designer window.

On MainPage.xaml, remove the XAML code for the Grid named “LayoutRoot” and replace it with the following code.

        <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title.-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="Trial Application Experience" Style="{StaticResource PhoneTextNormalStyle}" Margin="5"/>
            <TextBlock x:Name="PageTitle" Text="main page" Style="{StaticResource PhoneTextTitle1Style}" Margin="5"/>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Grid.RowDefinitions>
                <RowDefinition Height="200"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <StackPanel Grid.Row="0" Orientation="Horizontal"
                        HorizontalAlignment="Center" VerticalAlignment="Center">
                <TextBlock Text="License:" FontSize="{StaticResource PhoneFontSizeExtraLarge}" />
                <TextBlock x:Name="tbTrialStatus" FontSize="{StaticResource PhoneFontSizeExtraLarge}" />
            </StackPanel>
            <TextBlock Grid.Row="1" Text="My Application Features" HorizontalAlignment="Center"/>
            <StackPanel Grid.Row="2"  Orientation="Horizontal" HorizontalAlignment="Center">
                <Button Content=" A" Height="78" Width="100" x:Name="btnFeatureA" Click="btnFeatureA_Click"/>
                <Button Content=" B" Height="78" Width="100" x:Name="btnFeatureB" Click="btnFeatureB_Click"/>
                <Button Content=" C" Height="78" Width="100" x:Name="btnFeatureC" Click="btnFeatureC_Click"/>
            </StackPanel>
            <Button Grid.Row="3" x:Name="btnBuyApplication" Content="Buy the Application" Click="btnBuyApplication_Click" Height="78"/>
        </Grid>
    </Grid>

The preceding XAML code creates a simple user interface that looks like the following screenshot.

The application contains three buttons, each representing a feature of the application. The UI also contains status text showing the current license information and a button to buy the application. The preceding code and screenshot serve as a basic example to illustrate the core concepts of building a trial experience. The event handlers for each of the buttons will be defined in the following sections.

Open App.xaml.cs and add the following using directive to the top of the page.

using Microsoft.Phone.Marketplace;

In the App class, declare the following local static variable. The LicenseInformation class enables an application to determine if it is running under a trial license.

     private static LicenseInformation _licenseInfo = new LicenseInformation();

In the same App class in App.xaml.cs, add the following read-only property and local variable. This property is used to cache the license information while the application is running. The application uses the property whenever the current license information needs to be checked.

        private static bool _isTrial = true;
        public bool IsTrial
        {
            get
            {
                return _isTrial;
            }
        }

In the following sections, the license information will be checked in the Application_Launching and Application_Activated event handlers. Since this logic is used in two locations, we wrap it for convenience into its own method. In the App class located in App.xaml.cs, add the following method.

        /// <summary>
        /// Check the current license information for this application
        /// </summary>
        private void CheckLicense()
        {
            // When debugging, we want to simulate a trial mode experience. The following conditional allows us to set the _isTrial 
            // property to simulate trial mode being on or off. 
#if DEBUG
            string message = "This sample demonstrates the implementation of a trial mode in an application." +
                               "Press 'OK' to simulate trial mode. Press 'Cancel' to run the application in normal mode.";
            if (MessageBox.Show(message, "Debug Trial",
                 MessageBoxButton.OKCancel) == MessageBoxResult.OK)
            {
                _isTrial = true;
            }
            else
            {
                _isTrial = false;
            }
#else
            _isTrial = _licenseInfo.IsTrial();
#endif
        }

The preceding method consists of two code paths, depending on whether the application is run in Debug mode or not. In Debug mode, the code between the conditional compilation directive #if Debug and the #else directive is executed. The user is asked whether they would like to simulate trial mode. If the user selects OK, then the _isTrial variable is set to true; otherwise, it is set to false. If the application is built in release mode, the code between the #else and the #endif is executed and the _isTrial variable is set by examining the IsTrial property on the LicenseInformation object.

The license for the application should be checked whenever the application starts or resumes. This is done by checking the license information in the Application_Launching and Application_Activated event handlers. Replace the Application_Launching event handler in App.xaml.cs with the following code.

        private void Application_Launching(object sender, LaunchingEventArgs e)
        {
            CheckLicense();
        }

Replace the Application_Activated event handler in App.xaml.cs with the following code.

        private void Application_Activated(object sender, ActivatedEventArgs e)
        {
            CheckLicense();
        }

Open MainPage.xaml.cs and add the following using directive to the top of the page.

using Microsoft.Phone.Tasks;

At the top of the MainPage class in the MainPage.xaml.cs code-behind file, add the following variable.

        // Declare the MarketplaceDetailTask object with page scope
        // so we can access it from event handlers.
        MarketplaceDetailTask _marketPlaceDetailTask = new MarketplaceDetailTask();

In the MainPage.xaml.cs code-behind file, add the following method.

        private void btnBuyApplication_Click(object sender, RoutedEventArgs e)
        {
            _marketPlaceDetailTask.Show();
        }

When the btnBuyApplication button is clicked on the UI, the preceding code will show the Windows Phone Marketplace client application and display the details page for the specified product. The user will be able to buy the application. In this example, the application is not published to the Windows Phone Marketplace. As a result, the _marketPlaceDetailTask.Show() call will result in an error being displayed. If this error has the error code 805a0941, then the call was successful and will operate correctly when the application is published. When your application is published, the Show will automatically detect your application’s unique ID and launch the correct details page in the Windows Phone Marketplace client application.

On a device or emulator, run the application by selecting the Debug | Start Debugging menu command.

Note:
The option to select trial mode simulation is available only when the application is run in debug mode. This is done to prevent trial mode simulation from running in the release build of the application and accidentally being published to the Windows Phone Marketplace with this test feature enabled.

When the application starts, a message box is displayed. Click OK to simulate trial mode.

In the main page of the application observe that the License field is set to Trial and the Feature C button is disabled.

Click the Buy the Application button. An attempt is made to open the Windows Phone Marketplace client application.

You will see an error dialog that looks like the following image. This indicates that the application successfully opened the Windows Phone Marketplace client application. On a published application, this error will not occur and you will be brought to the details page of the application on the Windows Phone Marketplace where you can purchase the application.

Click Close on the error dialog. The application will resume.

To run the application to simulate a full license, click Cancel on the MessageBox that appears in step two of this procedure. Alternatively, you can start the application by selecting the Debug | Start without Debugging menu command. In this mode, the Buy the Application button will be hidden and the Feature C button will be enabled.