Windows 7 Multitouch Application Development (Part - I)

Prerequisite

XAML Implementation

<Grid>
    <Image Source="images/Hydrangeas.jpg"/>
</Grid>

<Grid>
    <Image Source="images/Hydrangeas.jpg" RenderTransformOrigin="0.5,0.5" Width="400">
        <Image.RenderTransform>
            <TransformGroup>
                <ScaleTransform x:Name="trScale" ScaleX="1" ScaleY="1"/>
                <RotateTransform x:Name="trRotate" Angle="0"/>
                <TranslateTransform x:Name="trTranslate" X="0" Y="0"/>
                <SkewTransform AngleX="0" AngleY="0"/>
            </TransformGroup>
        </Image.RenderTransform>
    </Image>
</Grid>

Code Implementation

Add two project references i.e. “Windows7.Multitouch” & “Windows7.Multitouch.WPF” from the extracted zip folder to your solution. These are the managed API codes for multitouch application development. Go to your Window1.xaml.cs & be sure that following namespaces are already included. You may have to add some of them. 

using System; 
using System.Windows; 
using Windows7.Multitouch; 
using Windows7.Multitouch.Manipulation; 
using Windows7.Multitouch.WPF; 

Create two private members inside your partial class: 

// object of a .Net Wrapper class for processing multitouch manipulation 
private ManipulationProcessor manipulationProcessor = new ManipulationProcessor(ProcessorManipulations.ALL);

// boolean value to check whether you have a multitouch enabled screen 
private static bool IsMultitouchEnabled = TouchHandler.DigitizerCapabilities.IsMultiTouchReady;

Now inside the Window Loaded event write the following lines of code: 

// check to see whether multitouch is enabled 
if (IsMultitouchEnabled) 
{ 
    // enables stylus events for processor manipulation 
    Factory.EnableStylusEvents(this); 

    // add the stylus events 
    StylusDown += (s, e) => 
    { 
        manipulationProcessor.ProcessDown((uint)e.StylusDevice.Id, e.GetPosition(this).ToDrawingPointF()); 
    }; 
    StylusUp += (s, e) => 
    { 
        manipulationProcessor.ProcessUp((uint)e.StylusDevice.Id, e.GetPosition(this).ToDrawingPointF()); 
    }; 
    StylusMove += (s, e) => 
    { 
        manipulationProcessor.ProcessMove((uint)e.StylusDevice.Id, e.GetPosition(this).ToDrawingPointF()); 
    }; 

    // register the ManipulationDelta event with the manipulation processor 
    manipulationProcessor.ManipulationDelta += ProcessManipulationDelta; 

    // set the rotation angle for single finger manipulation 
    manipulationProcessor.PivotRadius = 2; 
}

Write your logic inside the manipulation event handler implementation block. Here I will do rotation, scaling & positioning of the image. Here is my code: 

private void ProcessManipulationDelta(object sender, ManipulationDeltaEventArgs e)
{
    trTranslate.X += e.TranslationDelta.Width;
    trTranslate.Y += e.TranslationDelta.Height;

    trRotate.Angle += e.RotationDelta * 180 / Math.PI;

    trScale.ScaleX *= e.ScaleDelta;
    trScale.ScaleY *= e.ScaleDelta;
}

Conclusion