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InkOverlay.NewPackets Event

Occurs when the InkOverlay receives packets.

Namespace:  Microsoft.Ink
Assembly:  Microsoft.Ink (in Microsoft.Ink.dll)
public event InkCollectorNewPacketsEventHandler NewPackets

An InkOverlay object receives packet while a stroke is being collected. Packet events occur rapidly, and a NewPackets event handler must be fast or performance suffers.

The event handler receives an argument of type InkCollectorNewPacketsEventArgs containing data about this event.

When you create an InkCollectorNewPacketsEventHandler delegate, you identify the method that handles the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For performance reasons, the default event interest is off but is turned on automatically if you add an event handler.

This event may have an adverse effect on ink performance if too much code is executed in the event handlers.

This example demonstrates how you can subscribe to the CursorInRange event, and the NewPackets event obtain ink pressure data, and use that information to manipulate an DrawingAttributes object.

When the CursorInRange event fires, a check is made to see if this is the first time that the InkCollector object has come in contact with this particular Cursor object. If so, the DrawingAttributes property is assigned with a clone of the DefaultDrawingAttributes property. This ensures that subsequent access to the DrawingAttributes property does not throw a null reference exception.

private void mInkObject_CursorInRange(object sender, InkCollectorCursorInRangeEventArgs e)
{
    const int MOUSE_CURSOR_ID = 1;

    if (e.NewCursor)
    {
        // mInkObject can be InkCollector, InkOverlay, or InkPicture
        e.Cursor.DrawingAttributes = mInkObject.DefaultDrawingAttributes.Clone();
        // if this cursor is the mouse, we'll set color to red 
        if (MOUSE_CURSOR_ID == e.Cursor.Id)
        {
            e.Cursor.DrawingAttributes.Color = Color.Red;
        }
    }
}

When the NewPackets event fires, a check is made to see if NormalPressure is included in the packet data. If so, pressure information is displayed on a status label, and the DrawingAttributes property is modified.

private void mInkObject_NewPackets(object sender, InkCollectorNewPacketsEventArgs e)
{
    // find the NormalPressure PacketProperty 
    // Set NormalPressure to -1 if not there, as some digitizers won't support it
    Guid[] PacketDesc = e.Stroke.PacketDescription;
    int NormalPressure = -1;
    for (int k = 0; k < PacketDesc.Length; k++)
    {
        if (PacketDesc[k] == PacketProperty.NormalPressure)
        {
            // for simplicity, in case of multiple packets, use the first packet only
            NormalPressure = e.PacketData[k];
        }
    }

    // If we have the NormalPressure information 
    // change DrawingAttributes according to the NormalPressure 
    // Note that the change does not take effect until the next stroke 
    if (NormalPressure != -1)
    {
        // display the pressure on a status label 
        this.statusLabelPressure.Text = NormalPressure.ToString();
        e.Cursor.DrawingAttributes.Width = NormalPressure * 4;
        // if pressure is above 127, change color to Red 
        if (NormalPressure > 127)
        {
            e.Cursor.DrawingAttributes.Color = Color.Red;
        }
        else
        {
            e.Cursor.DrawingAttributes.Color = mInkObject.DefaultDrawingAttributes.Color;
        }
    }
}

Windows 7, Windows Vista, Windows Server 2008 R2, Windows Server 2008

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

.NET Framework

Supported in: 3.0
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