Touch and Manipulation Tutorial

github Tutorial Data

NoesisGUI enables having user interfaces that receive multiple touches simultaneously. A touch is a type of user input generated by putting fingers on a touch-sensitive screen. You can manage touch events in NoesisGUI at three different levels that are explained in the following sections:

Native Controls

ScrollViewer defines the PanningMode attached property that enables you to specify whether touch panning is enabled horizontally, vertically, both, or neither. The PanningDeceleration property specifies how quickly the scrolling slows down when the user lifts the finger from the touchscreen. The PanningRatio attached property specifies the ratio of scrolling offset to translate manipulation offset.

PanningMode can be either set directly on a ScrollViewer or used as an attached property. When a control contains a ScrollViewer in its ControlTemplate, PanningMode is used as an attached property to specify the behavior of the ScrollViewer in the ControlTemplate. When you use a ScrollViewer outside of a ControlTemplate, PanningMode is directly set on the ScrollViewer.

The following example creates a ScrollViewer and adds several buttons to it. The example sets PanningMode to Both so that the user can scroll the ScrollViewer horizontally and vertically by using fingers.


    <ScrollViewer HorizontalScrollBarVisibility="Auto" Height="250" Width="125" PanningMode="Both">
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>
        <Button Width="150" Height="80">Push me if you dare</Button>


The next example creates a TextBox and uses PanningMode as an attached property. It sets PanningMode to VerticalOnly. This is so that when the user moves a finger horizontally before moving it vertically, the text is highlighted.


  <TextBox Height="300" Width="300" Name="textBox1" TextWrapping="Wrap" IsReadOnly="True"
    ScrollViewer.PanningMode="VerticalOnly" ScrollViewer.VerticalScrollBarVisibility="Auto"

      Hello world 1 Hello world 2 Hello world 3 Hello world 4 Hello world 5
      Hello world 6 Hello world 7 Hello world 8 Hello world 9 Hello world 10
      Hello world 11 Hello world 12 Hello world 13 Hello world 14 Hello world 15
      Hello world 16 Hello world 17 Hello world 18 Hello world 19 Hello world 20
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Touch Events

UIElement defines the following events that you can subscribe to so your application can respond to touch:

  • TouchDown: occurs when a finger touches the screen while the finger is over an element.
  • TouchMove: occurs when a finger moves on the screen while the finger is over an element.
  • TouchUp: occurs when a finger is raised off of the screen while the finger is over an element.
  • TouchEnter: occurs when a touch moves from outside to inside the bounds of an element.
  • TouchLeave: occurs when a touch moves from inside to outside the bounds of an element.
  • PreviewTouchDown: preview event for TouchDown.
  • PreviewTouchMove: preview event for TouchMove.
  • PreviewTouchUp: preview event for TouchUp.
  • GotTouchCapture: occurs when a touch is captured to an element.
  • LostTouchCapture: occurs when this element loses a touch capture.

Note that the coordinates of each touch are given in screen space. The method Visual::PointFromScreen must be used to convert them to local coordinates.

Like keyboard and mouse events, touch events are routed events. The events whose name begins with Preview are tunneling events and the events that begin with Touch are bubbling events. The sequence is as follows:

  • The TouchEnter event occurs one time when the user puts a finger on the element.
  • The TouchDown event occurs one time.
  • The TouchMove event occurs multiple times as the user moves the finger within the element.
  • The TouchUp event occurs one time when the user lifts the finger from the element.
  • The TouchLeave event occurs one time.

When more than two fingers are used, the events occur for each finger.


In NoeisGUI, if a touch event is not handled, it is promoted to a mouse event.

Manipulation Events

For cases where an application enables an user to manipulate an object, the UIElement class defines manipulation events. Unlike touch events that simply report the position of touch, manipulation events report how the input can be interpreted. There are three types of manipulations: translation, expansion, and rotation. The following list describes how to invoke the three types of manipulations:

  • Put a finger on an object and move the finger across the touchscreen to invoke a translation manipulation. This moves the object.
  • Put two fingers on an object and move the fingers closer together or farther apart from one another to resize the object.
  • Put two fingers on an object and rotate the fingers around each other to invoke a rotation manipulation. This rotates the object.

The UIElement defines the following manipulation routed events:

  • ManipulationStarting: occurs when the manipulation processor is first created.
  • ManipulationStarted: occurs when an input device begins a manipulation on the UIElement object.
  • ManipulationDelta: occurs when the input device changes position during a manipulation.
  • ManipulationInertiaStarting: occurs when the input device loses contact with the UIElement object during a manipulation.
  • ManipulationCompleted: occurs when a manipulation and inertia on the UIElement object is complete.

By default, these manipulation events are not generated. To receive manipulation events on an UIElement, set the dependency property IsManipulationEnabled to true in the XAML or by code.


The manipulation logic does not generate manipulation events if TouchDown events are consumed (handled member set to True)


The ManipulationStarting event occurs when the user places a finger on the object. Among other things, this event allows you to set the ManipulationContainer property. In the subsequent events, the position of the manipulation will be relative to this ManipulationContainer. You can also set the Mode property to indicate the types of manipulations that are possible (Translate, Rotate or Scale).


The ManipulationStarted event occurs next to ManipulationStarting. This event reports the origin of the manipulation.


The ManipulationDelta event occurs multiple times as a user's fingers move on a touchscreen. The DeltaManipulation property of the ManipulationDeltaEventArgs class reports whether the manipulation is interpreted as movement, expansion, or translation. This is where you perform most of the work of manipulating an object. Note that ManipulationDelta occurs before and after the ManipulationInertiaStarting event. ManipulationDeltaEventArgs.isInertial property reports whether the ManipulationDelta event occurs during inertia, so you can check that property and perform different actions, depending on its value.


The ManipulationInertiaStarting event occurs when the user's fingers lose contact with the object. This event enables you to specify the deceleration of the manipulations during inertia. This is so your object can emulate different physical spaces or attributes if you choose. For example, suppose your application has two objects that represent items in the physical world, and one is heavier than the other. You can make the heavier object decelerate faster than the lighter object.


The ManipulationCompleted event occurs when the manipulation and any inertia ends. That is, after all the ManipulationDelta events occur, this event signals that the manipulation is complete.


You can cancel the manipulation by setting the cancel property on the event arguments in any manipulation event. When set to true, the manipulation events are no longer raised and mouse events occur for the canceled manipulation.




  <Canvas x:Name="root">
    <Rectangle Fill="Red" Width="200" Height="200" RenderTransform="1 0 0 1 50 50" IsManipulationEnabled="True"/>
    <Rectangle Fill="Blue" Width="200" Height="200" RenderTransform="1 0 0 1 200 300" IsManipulationEnabled="True"/>

class MyTouch: public Grid
    void OnManipulationStarting(const ManipulationStartingEventArgs& e)
        e.mode = ManipulationModes_All;
        e.manipulationContainer = (Visual*)FindName("root");
        e.handled = true;

    void OnManipulationInertiaStarting(const ManipulationInertiaStartingEventArgs& e)
        e.translationBehavior.desiredDeceleration = 100.0f / (1000.0f * 1000.0f);
        e.rotationBehavior.desiredDeceleration = 360.0f / (1000.0f * 1000.0f);
        e.expansionBehavior.desiredDeceleration = 300.0f / (1000.0f * 1000.0f);
        e.handled = true;

    void OnManipulationDelta(const ManipulationDeltaEventArgs& e)
        UIElement* rectangle = (UIElement*)e.source;
        MatrixTransform* tr = (MatrixTransform*)rectangle->GetRenderTransform();
        Transform2f mtx = tr->GetMatrix();

        mtx.RotateAt(e.deltaManipulation.rotation * DegToRad_f, e.manipulationOrigin.x,
        mtx.ScaleAt(e.deltaManipulation.scale, e.deltaManipulation.scale,
            e.manipulationOrigin.x, e.manipulationOrigin.y);
        mtx.Translate(e.deltaManipulation.translation.x, e.deltaManipulation.translation.y);

        e.handled = true;


extern "C" NS_DLL_EXPORT void NsRegisterReflection(ComponentFactory* factory, NsBool registerComponents)



  <Canvas x:Name="root">
    <Rectangle Fill="Red" Width="200" Height="200" RenderTransform="1 0 0 1 50 50" IsManipulationEnabled="True"/>
    <Rectangle Fill="Blue" Width="200" Height="200" RenderTransform="1 0 0 1 200 300" IsManipulationEnabled="True"/>

public class Touch: MonoBehaviour
    Grid _root;

    void Start()
        _root = (Grid)GetComponent<NoesisGUIPanel>().GetContent();
        _root.ManipulationStarting += this.ManipulationStarting;
        _root.ManipulationInertiaStarting += this.ManipulationInertiaStarting;
        _root.ManipulationDelta += this.ManipulationDelta;

    void ManipulationStarting(object sender, ManipulationStartingEventArgs e)
        e.Mode = Noesis.ManipulationModes.All;
        e.ManipulationContainer = (UIElement)_root.FindName("root");
        e.Handled = true;

    void ManipulationInertiaStarting(object sender, ManipulationInertiaStartingEventArgs e)
        e.TranslationBehavior.DesiredDeceleration = 100.0f / (1000.0f * 1000.0f);
        e.RotationBehavior.DesiredDeceleration = 360.0f / (1000.0f * 1000.0f);
        e.ExpansionBehavior.DesiredDeceleration = 300.0f / (1000.0f * 1000.0f);
        e.Handled = true;

    void ManipulationDelta(object sender, ManipulationDeltaEventArgs e)
        var rectangle = (Rectangle)e.Source;
        var transform = (MatrixTransform)rectangle.RenderTransform;
        var matrix = transform.Matrix;

        float rotation = e.DeltaManipulation.Rotation * Mathf.Deg2Rad;
        float originX = e.ManipulationOrigin.X;
        float originY = e.ManipulationOrigin.Y;
        float scale = e.DeltaManipulation.Scale;
        float translationX = e.DeltaManipulation.Translation.X;
        float translationY = e.DeltaManipulation.Translation.Y;

        matrix.RotateAt(rotation, originX, originY);
        matrix.ScaleAt(scale, scale, originX, originY);
        matrix.Translate(translationX, translationY);

        transform.Matrix = matrix;
        e.Handled = true;
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