Enhancing Apps with Multi-touch

The interaction between computers and humans has reached new proportions, as

is evident from the new forms of interaction that are emerging. Apart from

standard input devices (like keyboards and mouse) an emerging technique to input

information is via touchscreens. These can be further divided into two

types: single touch and multi-touch. In a single touch device, information can

be fed using a single instance of touch while multi touch allows for more than

one touch simultaneously; this means one can use more than one finger to feed

information or more than one user can input information. A multi-touch device

has a touch screen and software that recognizes multiple simultaneous touches.

As an example, just look at the 'iPhone, ' where Multi-touch is garnering a lot

of attention. The future of this technology looks bright as more and more work

is being done in this area. Microsoft is soon going to include Multi-touch

functionality in its next version of Windows, 'Windows 7.' As the cost

associated with multi-touch devices is decreasing, the need to develop

applications that harness multi-touch functionality is also increasing. In this

article, we shall develop a sample program that shows how easily one can develop

a multi-touch application that can run on Windows Vista or XP.

Implementing Multi-touch



To build this application we used Visual Studio 2008 with C# as the

programming language and the .NET framework 3.5. We started with creating a 'WPF

Application,' named as 'FirstMultitouch'. The next step is to add reference to

this application. This can be done by right clicking on 'References' and then

clicking on 'Add reference'. We have to add 'Multitouch.Framework.WPF.dll' to

this project. This required file can be downloaded from http://tinyurl.com/

6enfy6 . One can find this file at 'MultiTouchVista\Framework'. After adding the

reference, open 'Window1.axml' file now and add the following code to the file:

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"



xmlns:mt="http://schemas.multitouch.com/Multitouch/2008/04"


Title="Window1" Height="300" Width="300">








Background="Red" Height />

Open 'Window1.cs' file and change it to the following:



namespace sandeep


{


public partial class Window1 : Multitouch.Framework.WPF.Controls.Window


{


public Window1()


{


InitializeComponent();


}


}


}

To show output we need 'Multotouch.Console.Service.exe' running in the

background. This service is located at 'MultiTouchVista\Service'. Once all this

has been done just run your application. It will show a 'PCQuest' logo that can

be touched and moved around (red dot will act as touch point that can be used

with mouse). Now let's move towards a more complex and visually appealing

application. In this application, we shall be moving five photographs (.JPEG)

using multi-touch technique. The first step is to keep five photographs in

'MyPicture' folder inside 'MyDocuments'. Then create a 'WPF Application' in

Visual studio 2008 and name it 'SecondMultitouch,' and then again add reference

'Multitouch.Framework.WPF.dll'. Now open 'Window1.axml' file and replace the

code with:

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"


xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"


xmlns:mt="http://schemas.multitouch.com/Multitouch/2008/04"


xmlns:sys="clr-namespace:System;assembly=mscorlib"


Title="Window1" Height="300" Width="300">

Save this file and then move to 'Window1.cs' file and change it to the

following:

using System.Collections.ObjectModel;



using System.IO;


namespace SecondMultitouch


{


public partial class Window1 : Multitouch.Framework.WPF.Controls.Window


{


public Window1()


{


DataContext = this;


Photos = new ObservableCollection();


InitializeComponent();


}


public ObservableCollection Photos


{


get {return (ObservableCollection)GetValue(PhotosProperty); }


set { SetValue(PhotosProperty, value); }


}

public static readonly DependencyProperty

PhotosProperty =

DependencyProperty.Register("Photos",typeof(ObservableCollection),

typeof(Window));



protected override void OnInitialized(EventArgs e)

{



base.OnInitialized(e);


foreach (string file in
Directory.GetFiles(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures),

"*.jpg").Take(5))



{


Photos.Add(file);


}


}

Now we are ready with the application. Just run 'Windows.Service. Console.exe'

in the back ground and then run 'SecondMultitouch' application. One can easily

rotate, zoom and move pictures. This application gives a feel of a multi-touch

device where the 'touching' part is done through mouse. Multi-touch is clearly

futuristic and a very appealing technology that makes computing really

interesting and in a way 'sensitive.'