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Touch.FrameReported Event

Occurs when a touch message is sent.

Namespace:  System.Windows.Input
Assembly:  PresentationCore (in PresentationCore.dll)

public static event TouchFrameEventHandler FrameReported

A frame is one in a series of multitouch messages or touch points. You can respond to touches by handling the FrameReported event and accessing the details of the TouchPoint from the TouchFrameEventArgs event data.

The FrameReported event does not use the same event model as other WPF input events, such as TouchDown and TouchMove. Instead of being exposed as an element-specific event that potentially routes through the object tree of a UI, the FrameReported event is a single event that is handled at the application level. Therefore, you cannot use the sender parameter of the event handler to determine what element is touched.

The following example handles the FrameReported event. When a touch presses on the Canvas, the TouchDevice is captured to the Canvas. When the touch is lifted, the TouchDevice is released. When a touch moves across the Canvas, the Id is checked. If the move came from the first touch, its location is recorded. If the move came from the second touch, a line is drawn from the position of the first touch to the position of the second touch.

This example is part of a larger example that is available in the Touch class overview.

public partial class MainWindow : Window
{
    // Variables for tracking the position of two points.
    Point pt1, pt2 = new Point();

    public MainWindow()
    {
        InitializeComponent();
        Touch.FrameReported += new TouchFrameEventHandler(Touch_FrameReported);
    }

    void Touch_FrameReported(object sender, TouchFrameEventArgs e)
    {
        if (this.canvas1 != null)
        {
            foreach (TouchPoint _touchPoint in e.GetTouchPoints(this.canvas1))
            {
                if (_touchPoint.Action == TouchAction.Down)
                {
                    // Clear the canvas and capture the touch to it. 
                    this.canvas1.Children.Clear();
                    _touchPoint.TouchDevice.Capture(this.canvas1);
                }

                else if (_touchPoint.Action == TouchAction.Move && e.GetPrimaryTouchPoint(this.canvas1) != null)
                {   
                    // This is the first (primary) touch point. Just record its position. 
                    if (_touchPoint.TouchDevice.Id == e.GetPrimaryTouchPoint(this.canvas1).TouchDevice.Id)
                    {
                        pt1.X = _touchPoint.Position.X;
                        pt1.Y = _touchPoint.Position.Y;
                    }

                    // This is not the first touch point. Draw a line from the first point to this one. 
                    else if (_touchPoint.TouchDevice.Id != e.GetPrimaryTouchPoint(this.canvas1).TouchDevice.Id)
                    {
                        pt2.X = _touchPoint.Position.X;
                        pt2.Y = _touchPoint.Position.Y;

                        Line _line = new Line();
                        _line.Stroke = new RadialGradientBrush(Colors.White, Colors.Black);
                        _line.X1 = pt1.X;
                        _line.X2 = pt2.X;
                        _line.Y1 = pt1.Y;
                        _line.Y2 = pt2.Y;
                        _line.StrokeThickness = 2;
                        this.canvas1.Children.Add(_line);
                    }
                }

                else if (_touchPoint.Action == TouchAction.Up)
                {
                    // If this touch is captured to the canvas, release it. 
                    if (_touchPoint.TouchDevice.Captured == this.canvas1)
                    {
                        this.canvas1.ReleaseTouchCapture(_touchPoint.TouchDevice);
                    }
                }
            }                        
        }
    }
}

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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