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Creating a Windows Mobile Wireless Remote PowerPoint Clicker : Page 2

Imagine giving a presentation from your cellphone! Learn how to write a PowerPoint clicker application for your Bluetooth-enabled Windows Mobile device.


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Creating the PowerPoint Remote Controller
First, let's create the controller on the desktop so that it can launch a PowerPoint slide deck. Using Visual Studio 2005, create a new Windows application and name it RemoteController. Populate the default Form1 with the following controls (see Figure 1):
  1. Label
  2. Button
  3. GroupBox
Figure 1. The Default Form1: Populated with the various controls.

In order to interact with Microsoft Office XP applications through your .NET code, you need to download the Primary Interop Assemblies (PIAs).

Once the PIA package is downloaded, expand them into a folder and add the following libraries (see also Figure 2):

  • office.dll
  • Microsoft.Office.Interop.PowerPoint.dll
Figure 2. The PIA Package: Importing the relevant libraries to the project.



Switch to the code-behind of Form1 and import the following namespace:

Imports Microsoft.Office.Interop.PowerPoint

Define the following enumerations:

Public Enum Directions PrevSlide NextSlide FirstSlide LastSlide End Enum

Declare the following member variables:

Public Class Form1 Private PowerPTApp As New Application Private PowerPTPres As Presentation '---total no. of slides--- Private TotalSlides As Integer = 0 '---serial port for Bluetooth comms--- Private WithEvents serialPort As New IO.Ports.SerialPort

In the Form1_Load event, code the following:

Private Sub Form1_Load( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) _ Handles MyBase.Load btnSelect.Enabled = False GroupBox1.Enabled = False End Sub

Double-click the "Open Serial Port" button and use the following code to establish a serial connection (through Bluetooth) with the Windows Mobile device (see Listing 1).

Author's Note: The COM18 is dependent on which COM port you have selected to use on your computer. Refer to the last section of this article to determine which COM port to use.

Double-click the "Select PowerPoint file to load" button and use the following code to let users choose and load a PowerPoint slide deck (see Listing 2).

Define the NavigateSlides() subroutine to programmatically manipulate the PowerPoint slides (see Listing 3).

Define the ShowSlideNo() subroutine to display the current slide number (see Listing 4).

You need to define a delegate to update the slide number because the ShowSlideNo() subroutine may be called by the DataReceived event (to be defined next) of the SerialPort object when incoming data is received. The delegate and the UpdateLabel() subroutine are defined as follows:

'---delegate and subroutine to display slide no.--- Public Delegate Sub myDelegate(ByVal str As String) Public Sub UpdateLabel(ByVal str As String) lblSlideNo.Text = str End Sub

When the user clicks on one of the four navigational buttons, you need to navigate the slides accordingly. This is serviced by the Buttons_Click event, which is defined as follows:

Private Sub Buttons_Click( _ ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles _ btnPrev.Click, btnNext.Click, btnLast.Click, btnFirst.Click Select Case CType(sender, Button).Name Case "btnPrev" NavigateSlides(Directions.PrevSlide) Case "btnNext" NavigateSlides(Directions.NextSlide) Case "btnFirst" NavigateSlides(Directions.FirstSlide) Case "btnLast" NavigateSlides(Directions.LastSlide) End Select End Sub

When incoming data is received from the serial port, you need to retrieve the incoming data. The incoming data contains commands sent from the Windows Mobile device instructing your application to navigate the slides. The DataReceived event is defined as follows:

'---data received from Bluetooth serial port--- Private Sub DataReceived( _ ByVal sender As Object, _ ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _ Handles serialPort.DataReceived '---retrieve the command sent--- Dim command As String = serialPort.ReadLine() Select Case command Case "Prev" NavigateSlides(Directions.PrevSlide) Case "Next" NavigateSlides(Directions.NextSlide) Case "First" NavigateSlides(Directions.FirstSlide) Case "Last" NavigateSlides(Directions.LastSlide) End Select End Sub

Last, but not least, service the Form1_FormClosing event so that the slide deck can be closed when the application is shut down:

'---when the app is closed, close the slide deck too--- Private Sub Form1_FormClosing( _ ByVal sender As Object, _ ByVal e As System.Windows.Forms.FormClosingEventArgs) _ Handles Me.FormClosing PowerPTApp.Quit() End Sub

That's it! Now, the desktop portion of the application is done!



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