Programming Windows Mobile 5.0 Applications Using the .NET Compact Framework

Programming Windows Mobile 5.0 Applications Using the .NET Compact Framework

icrosoft has recently launched the Windows Mobile 5.0 platform for Pocket PCs and Smartphones. With the proliferation of Windows Mobile-based devices in the marketplace, companies are gradually mobilizing their enterprising applications to let their staff gain the competitive mobile advantage. Coupled with the launch of Visual Studio 2005, the .NET Compact Framework is now in its second generation?version 2.0.

This article?demonstrates some of the new managed APIs made available by Windows Mobile 5.0 and the .NET Compact Framework 2.0. I’ll focus on the classes that are of interest to managed developers. (I won’t cover the new APIs that are available only to native developers.)

Figure 1: The i-Mate JASJAR.

In recent months, vendors have been busy pushing out new Windows Mobile 5 devices and consumers now have many choices. The market seems to favor Pocket PC Phone Edition devices as these devices can easily replace your mobile phone with more functionality.

When the JASJAR from i-Mate (see Figure 1) was launched, it was the world’s first Windows Mobile 5.0 3G-enabled GSM/GPRS Pocket PC with Wi-Fi capability. It basically has everything you want on a Pocket PC?Wi-Fi, Bluetooth, USB, SD slot, VGA-resolution screen, swivel screen, landscape and portrait modes, phone capability, built-in cameras (it has two?one on the back and one at the front of the screen for video conferencing), as well as an illuminated QWERTY keyboard.

I tested all of the code examples in this article on the i-Mate JASJAR.

Visual Studio 2005
Microsoft’s release of Visual Studio 2005 makes developing Windows Mobile applications much easier. Using Visual Studio 2005, developers can target different platforms (Pocket PC 2003, Smartphone 2003, Windows Mobile 5.0 Pocket PC, and Windows Mobile 5.0 Smartphone (see Figure 2). In addition, you can use either the latest .NET Compact Framework 2.0, or the older version 1.0.

Figure 2: Developing mobile applications on the different mobile platforms.

Once the two SDKs are installed, you will see the new Windows Mobile 5.0 Pocket PC and Windows Mobile 5.0 Smartphone project types in Visual Studio 2005.

The Windows Mobile 5 SDK ships with emulators of different flavors?Pocket PC as well as Phone Edition emulators, each with QVGA or VGA screen, and the emulators come in rectangular and square form factors. In addition, you can also download the various localized Windows Mobile 5.0 Pocket PC emulator images for testing your applications on localized Windows Mobile platforms.

Visual Studio 2005 also makes it easy for developers to change the target platform of their application. For example, if you’ve designed an application for the Windows Mobile 5.0 platform, you can convert it to the Pocket PC 2003 platform, perhaps to support users that are still using the older devices. To convert the target platform of an application, you simply need to right-click on the project name in Solution Explorer and select Change Target Platform.

Improved Emulator Support
Visual Studio 2005 offers better emulator support than did previous versions of Visual Studio. You can use the Device Emulator Manager from the Tools menu and then choose Device Emulator Manager?) to synchronize with ActiveSync on your desktop. This ability allows you to better test your applications, such as testing how a setup application will install your application on a real device, etc.

Screen Orientation
Beginning with Windows Mobile 2003 Second Edition, devices now support portrait and landscape screen orientations. Developers targeting the latest platform should ensure that their applications are orientation-aware and are able to use the changes in screen estate. To make life simpler for developers, Visual Studio 2005 supports the change of screen orientation during design-time. Using the “Rotate Left” and “Rotate Right” buttons, you can change the orientation of the form (see Figure 3).

Figure 3: Changing the orientation of the form during design-time.

To ensure that you’ve properly positioned controls on a form during a screen orientation change, you should use the Anchor property of each control to anchor it against the four edges of the form. In the example shown in Figure 3, the three controls are aligned so that a change in screen orientation ensures that the controls display properly. You can anchor the control by modifying the Anchor property (found in the Property window) or set them programmatically during run time, like this:

   Label1.Anchor = AnchorStyles.Left + _      AnchorStyles.Top   Button1.Anchor = AnchorStyles.Left + _      AnchorStyles.Right + _      AnchorStyles.Top   PictureBox1.Anchor = _      AnchorStyles.Right + _      AnchorStyles.Bottom

You can also manually handle screen orientation by repositioning each control depending on the screen orientation. This method requires more work, but allows you to position the controls wherever they want. To do so, you need to handle the Resize event of the form and then set the Location and Size properties of each control depending on whether it is landscape mode or portrait mode.

   Private Sub Form1_Resize( _      ByVal sender As Object, _      ByVal e As System.EventArgs) _      Handles MyBase.Resize         If Me.Width > Me.Height Then         '---landscape mode---         Me.Label1.Location = New _            System.Drawing.Point(100, 4)         Me.Label1.Size = New _            System.Drawing.Size(100, 20)      Else         '---portrait mode---         Me.Label1.Location = New _            System.Drawing.Point(4, 4)         Me.Label1.Size = New _            System.Drawing.Size(100, 20)      End If   End Sub

Screen Resolution
You also need to consider screen resolution when deploying your applications to the newer Windows Mobile devices. Some newer devices in the market come with VGA screens (480*640; 192 dpi). By default, the controls on a form will scale automatically depending on the screen resolution. This behavior is indicated by the AutoScaleMode property, which is set to Dpi by default. That is, a form designed to work on a QVGA screen (240*320; 96 dpi) will appear the same as on a VGA screen. The increase in resolution is to improve the readability of the screen, and not to squeeze more information into the same screen estate.

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When I test the application shown in Figure 3 on a VGA screen device, notice what happens (see Figure 4).

Figure 4: Testing the application on a VGA-screen device.

The Label and TextBox controls scale correctly while the PictureBox control does not automatically scale the image. This is important if you want to target users with different screen resolution. To fix the problem, you need to maintain two different images?one for a QVGA screen and one for a VGA screen. You can detect the type of screen resolution by using the following code segment:

   If Me.Width = 640 Or _      Me.Width = 480 Then      '---VGA      PictureBox1.Image = New _         Bitmap("ImagesImage_VGA.jpg")   Else      '---QVGA      PictureBox1.Image = New _         Bitmap("ImagesImage_QVGA.jpg")   End If

One significant improvement in the support of mobile development in Visual Studio is drag-and-drop data binding. Displaying data from a database is now an easy task that requires no more than just some drag-and-drop effort. As an example, you can add a new SQL Mobile database to your application by selecting Data and then choosing “Add New Data Source?.” Follow the steps in the wizard to add a SQL Mobile database. (A sample Northwind SQL Mobile database shipped with Visual Studio 2005.)

Once you’ve added the database to the project, you can drag the data source from the Data Sources window and drop it onto the form (see Figure 5). Visual Studio will create a DataGrid control to display the rows of records from the selected database.

By default, the DataGrid control displays the records in the database in read-only mode. However, you can also make changes to the data in the database. To do so, simply click on the Generate Data Forms? link in the DataGrid’s smart tag (see Figure 6) to auto-generate a series of forms that allow users to edit/add records to the database.

Figure 5: Drag-and-drop data binding.
Figure 6: Clicking the Generate Data Forms… link in the DataGrid’s smart tag.
Figure 7: Adding and editing records.

Once you’ve done this, you can tap the New menu to add a new record during run time, or simply tap on a record displayed within the DataGrid control to edit its content (see Figure 7).

Integration with Outlook Mobile
In the past, integrating your application with the PIM functionality on your device was a hair-pulling experience. Windows Mobile 5.0 now exposes the functionality in Outlook Mobile through managed classes found in the Microsoft.WindowsMobile.PocketOutlook namespace. .NET Compact Framework developers can now easily integrate data from Outlook Mobile into their application using these managed classes.

As an example, let’s build an application that allows a user to select a contact from Contacts and then send an e-mail to the selected contact.

First, add a reference to the Microsoft.WindowsMobile.Forms and Microsoft.WindowsMobile.PocketOutlook assemblies and import the required namespaces.

From a developer’s viewpoint, Windows Mobile 5.0 exposes many of its APIs as managed classes, thereby allowing developers using the .NET Compact Framework to easily build compelling applications that were once only possible to native developers.
   Imports Microsoft.WindowsMobile.Forms   Imports Microsoft.WindowsMobile. _      PocketOutlook

To select a contact, use the ChooseContactDialog class.

   Private Sub btnSelectContact_Click( _      ByVal sender As System.Object, _      ByVal e As System.EventArgs) _      Handles btnSelectContact.Click      Dim contactPicker As New _         ChooseContactDialog      Dim result As DialogResult = _         contactPicker.ShowDialog      If result = Windows.Forms.DialogResult.OK Then         lblName.Text = contactPicker.SelectedContactName         lblEmail.Text = contactPicker.SelectedContact.Email1Address         PictureBox1.Image = contactPicker.SelectedContact.Picture      End If   End Sub

Figure 8 shows the flow of the application.

Figure 8: Selecting a contact from the Contact application

To send an e-mail, you use the EmailMessage class.

   Private Sub MenuItem1_Click( _      ByVal sender As System.Object, _      ByVal e As System.EventArgs) _      Handles MenuItem1.Click      Dim message As New EmailMessage      message.Subject = "Generated Email"      message.BodyText = txtMessage.Text         Dim client As New Recipient(lblEmail.Text)      message.To.Add(client)      Dim currentSession As New OutlookSession      currentSession.EmailAccounts(0).Send(message)      MsgBox("Message sent!")   End Sub

Figure 9 shows the flow of the application. Once the e-mail is sent, you can go to Messaging (choose the Outbox folder) to verify that an e-mail has indeed been created.

Figure 9: Sending an e-mail.

Intercepting SMS Messages
For managed developers, Windows Mobile 5.0 can intercept incoming SMS messages. For example, you might write your own custom push-email solution by sending yourself an SMS message whenever a new e-mail is received. When your Windows Mobile 5 device receives the message, your application can intercept the message and then automatically fire up your Web browser to navigate to your Web e-mail.

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You can use the MessageInterceptor class to intercept incoming messages and then perform a check on its content so that if it fulfills your criteria, you can perform a specific action. Listing 1 shows how you can intercept incoming SMS messages by checking to see if the message body starts with the word “invoke”. If it does, the code launches Pocket Internet Explorer to navigate to (For this example, you need to add a reference to the Microsoft.WindowsMobile and Microsoft.WindowsMobile.PocketOutlook assemblies.)

The MessageInterceptor class is useful for automation purposes. Suppose your device contains confidential information and you are worried that the information may fall into the wrong hands if you lose your device. You could write an application that will wipe out all the sensitive data on the device if it receives a specially-coded SMS message.

Integrating with Calendar
You can now easily integrate your application with the Calendar application. The following code segment shows how easy it is to create an appointment in Calendar. (This example requires you to add a reference to the Microsoft.WindowsMobile.PocketOutlook assembly.)

   Imports Microsoft.WindowsMobile.PocketOutlook   ...   Dim appt As New Appointment   appt.Subject = "Meeting with Jeff"   appt.Start = New DateTime(2006, 7, 15, 9, 0, 0)   appt.End = New DateTime(2006, 7, 15, 11, 0, 0)      '---vibrate the device as a reminder   appt.ReminderVibrate = True      '---repeat the reminder   appt.ReminderRepeat = True   Dim currentSession As New OutlookSession      currentSession.Appointments.Items.Add(appt)

Camera APIs
In the past, integrating your application with the built-in camera on your device was not an easy task. In Windows Mobile 5, you can now invoke the built-in camera using the CameraCaptureDialog class. (This example requires you to add a reference to the Microsoft.WindowsMobile.Forms assembly.)

Figure 10: Image captured using the built-in camera
   Imports Microsoft.WindowsMobile.Forms   ...   Private Sub btnPicture_Click( _      ByVal sender As System.Object, _      ByVal e As System.EventArgs) _      Handles btnPicture.Click      Dim ccd As New CameraCaptureDialog      ccd.Resolution = New Size(100, 200)      ccd.Mode = CameraCaptureMode.Still       ccd.ShowDialog()      If ccd.FileName <> String.Empty Then         PictureBox1.Image = New Bitmap(ccd.FileName)      End If   End Sub

Besides capturing still images, CameraCaptureDialog also supports video capture, which you can enable by setting the Mode property to CameraCaptureMode.VideoWithAudio.

Figure 10 shows a PictureBox control showing the picture that was taken using the built-in camera.

Serial Communication

Figure 11: A chat application using the SerialPort class.

In .NET Compact Framework 1.1, accessing the serial ports on the device involves performing a Platform Invoke (P/Invoke) operation, which is often an arduous and error-prone process. With .NET Compact Framework 2.0, you can access serial ports using the SerialPort class.

Figure 11 shows a Chat application that allows two Pocket PC users to chat over Bluetooth.

You can create it like this. First, create an instance of the SerialPort class.

   Dim WithEvents serialPort As New IO.Ports.SerialPort

When the form is loaded, open the serial port (this example assumes that your Pocket PC has an available COM4 associated with the Bluetooth connection) and initialize the SerialPort object.

   Private Sub Form6_Load( _      ByVal sender As System.Object, _      ByVal e As System.EventArgs) _      Handles MyBase.Load      If serialPort.IsOpen Then         serialPort.Close()      End If      With serialPort         .PortName = "COM4"         .BaudRate = 9600         .Parity = IO.Ports.Parity.None         .DataBits = 8         .StopBits = IO.Ports.StopBits.One      End With      serialPort.Open()   End Sub

The SerialPort object has an event?DataReceived?that fires whenever incoming data is detected. When data is received, you call a delegate to update the received data in the TextBox control on the form. Note, you cannot directly update the Windows controls in this event as they are not running in the same thread as the main form.

   Private Sub DataReceived( _      ByVal sender As Object, _      ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _      Handles serialPort.DataReceived      txtReceivedMessage. _      BeginInvoke(New myDelegate(         AddressOf updateTextBox), _         New Object() {})   End Sub

Define the delegate and the actual subroutine to update the received data on the form. The ReadExisting() method obtains the received data from the SerialPort object.

   Public Delegate Sub myDelegate()   Public Sub updateTextBox()   txtReceivedMessage.Text = serialPort.ReadExisting & _      vbCrLf & txtReceivedMessage.Text   End Sub

To send an outgoing message, use the WriteLine() method from the SerialPort object.

   Private Sub MenuItem1_Click( _      ByVal sender As System.Object, _      ByVal e As System.EventArgs) _      Handles MenuItem1.Click      serialPort.WriteLine(txtMessageToSend.Text)      txtReceivedMessage.Text = ">" & txtMessageToSend.Text & _          vbCrLf & txtReceivedMessage.Text      txtMessageToSend.Text = String.Empty   End Sub
Figure 12: Making a phone call.

To test the application, load two Windows Mobile 5.0 Pocket PCs with the application. Pair up the two devices with Bluetooth and ensure that each device has an available serial port (which I hard-coded as COM4 for simplicity). You can now chat wirelessly with each other using Bluetooth!

For Windows Mobile 5.0 Phone Edition devices, you can integrate telephony functionality into your applications using the Phone class (located in the Microsoft.WindowsMobile.Telephony assembly).

For example, the following code segment makes a phone call by first prompting the user (see Figure 12) (the example requires you to add a reference to the Microsoft.WindowsMobile.Telephony assembly).

   Imports Microsoft.WindowsMobile.Telephony   ...   Dim phone As New Phone   phone.Talk("+6512345678", True)

Monitoring Changes in System State
Windows Mobile 5.0 contains the SystemState (found in the Microsoft.WindowsMobile.Status assembly) class that provides the ability to get the current value of a system state as well as the ability to be notified when that state changes. For example, you might want to synchronize your Pocket PC with ActiveSync when the user connects the Pocket PC to the cradle (or synching cable). As such, your application needs to monitor if there is a change in the cradle state.

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Figure 13 shows an application that displays the cradle state of the device as well as the IP address of itself and the host. Using such an application, you can write an application that synchronizes the content of the device with the desktop.

Figure 13: Monitoring changes in system states.

Let’s look at the source code of the application. First, import the necessary namespaces. (This example requires you to add a reference to the Microsoft.WindowsMobile, Microsoft.WindowsCE.Forms, and Microsoft.WindowsMobile.Status assemblies.)

   Imports Microsoft.WindowsMobile   Imports Microsoft.WindowsMobile.Status   Imports System.Net   Imports System.Text

Declare two SystemState variables?one to keep track of the cradle state, and one to keep track of the network connection state. Next, the code creates an instance of the Notification class to display notifications to the user.

   Private WithEvents cradleState As SystemState   Private WithEvents networkConnectionState As SystemState   Private WithEvents notification1 As New Microsoft.WindowsCE. _      Forms.Notification

Declare the DisplayGetOwnIPAddresses() subroutine to display the IP address(es) assigned to the Pocket PC.

   '---display own IP address   Private Sub DisplayGetOwnIPAddresses()      lblIPAddresses.Text = String.Empty      Try         Dim ownAddr() As IPAddress = Dns.GetHostEntry( _            Dns.GetHostName()).AddressList         If ownAddr Is Nothing Then            Exit Sub         End If         For i As Integer = 0 To _            ownAddr.Length - 1            lblIPAddresses.Text &= ownAddr(i).ToString & vbCrLf         Next      Catch ex As Exception         MsgBox(ex.ToString)      End Try   End Sub

Declare the DisplayHostIPAddresses() subroutine to display the IP address(es) of the host computer:

   '---display host IP address   Private Sub DisplayHostIPAddresses()      lblHostIPAddress.Text = String.Empty      Try         Dim hostAddr() As IPAddress = Dns.GetHostEntry( _            "PPP_PEER").AddressList         If hostAddr Is Nothing Then            Exit Sub         End If         For i As Integer = 0 To _            hostAddr.Length - 1            lblHostIPAddress.Text = hostAddr(i).ToString         Next      Catch ex As Exception         MsgBox(ex.ToString)      End Try   End Sub

When the form loads, you instantiate the cradleState and networkConnectionState objects (see Listing 2) so that any changes in the cradle state or network connection state will trigger the necessary events (you will service them next).

When the IP address of the device changes (such as when it is connected to a Wi-Fi network and assigned a new IP address), the Changed event of the networkConnectionState object will be fired. The new IP address of the device and the host PC will be updated.

   '---event handler for handling changes   ' in network connection state   Private Sub networkConnectionState_Changed( _      ByVal sender As Object, _      ByVal args As Microsoft.WindowsMobile.Status.ChangeEventArgs) _      Handles networkConnectionState.Changed         '---display own and host IP addresses      DisplayGetOwnIPAddresses()      DisplayHostIPAddresses()   End Sub

Likewise, when the cradle’s state changes (when you connect or disconnect your Pocket PC from the host computer), the Changed event of the cradleState object will fire (see Listing 3). Here you will display a notification balloon to the user if the device is cradled to the computer. Notice that the content of the notification is coded in HTML. To dismiss a notification, you use the identifier cmd:2 as the name for an input element. This identifier has special meaning in Windows CE and is used to dismiss notifications. The content of the notification allows the user to select the update frequency through a drop-down list box.

The code uses the DisplayNotification() subroutine to display a notification balloon on the Pocket PC.

   '---display the notification   Private Sub DisplayNotification( _      ByVal caption As String, _      ByVal text As String)      With notification1         .Caption = caption         .Text = text         .InitialDuration = 20         .Visible = True      End With   End Sub

When the user submits the information in a notification balloon, it fires the ResponseSubmitted event via the notification1 object variable. Here you’ll add the logic to do whatever you are supposed to do, such as communicate with the host application to synchronize the content on the Pocket PC with the desktop.

   Private Sub OnResponseSubmitted( _      ByVal sender As Object, _      ByVal args As Microsoft.WindowsCE.Forms. _         ResponseSubmittedEventArgs) _      Handles notification1.ResponseSubmitted      '---A sample reply---   ' notify?lstIntervals=2      If (args.Response. Substring(0, 6) = "notify") Then         Dim choice As Integer = Convert.ToInt32( _            args.Response.Substring(20, 1))         Select Case choice            Case 0 '---do something            Case 1 '---do something            Case 2 '---do something         End Select      End If      notification1.Visible = False   End Sub

In this article, I’ve shown you some of the new features available on the Windows Mobile 5.0 platform. With Visual Studio 2005, developers using the .NET Compact Framework can now develop compelling applications with ease, as most of the important APIs are exposed as managed classes. If you have not started on mobile application development yet, now is a good time to get started!


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