InkOverlay.NewPackets 事件

项目
11/04/2008

当 InkOverlay 接收到数据包时发生。

命名空间： Microsoft.Ink
程序集： Microsoft.Ink（在 Microsoft.Ink.dll 中）

语法

声明
Public Event NewPackets As InkCollectorNewPacketsEventHandler
用法
Dim instance As InkOverlay
Dim handler As InkCollectorNewPacketsEventHandler

AddHandler instance.NewPackets, handler

public event InkCollectorNewPacketsEventHandler NewPackets

public:
 event InkCollectorNewPacketsEventHandler^ NewPackets {
    void add (InkCollectorNewPacketsEventHandler^ value);
    void remove (InkCollectorNewPacketsEventHandler^ value);
}

/** @event */
public void add_NewPackets (InkCollectorNewPacketsEventHandler value)
/** @event */
public void remove_NewPackets (InkCollectorNewPacketsEventHandler value)

JScript 不支持事件。

备注

在收集笔画时，InkOverlay 对象接收到数据包。数据包事件会快速发生，NewPackets 事件处理程序必须快速执行，否则会降低性能。

事件处理程序接收 InkCollectorNewPacketsEventArgs 类型的参数，该参数包含有关此事件的数据。

创建 InkCollectorNewPacketsEventHandler 委托时，需要标识将处理该事件的方法。若要将该事件与事件处理程序关联，请将该委托的一个实例添加到事件中。除非移除了该委托，否则每当发生该事件时就会调用此事件处理程序。出于性能方面的原因，默认事件关注处于关闭状态，但如果添加事件处理程序，它将自动打开。

如果在事件处理程序中执行太多代码，则此事件可能对墨迹性能产生不利影响。

示例

此示例演示如何订阅 CursorInRange 事件，NewPackets 事件如何获取墨迹压力数据，以及如何使用该信息操作 DrawingAttributes 对象。

当 CursorInRange 事件激发时，将检查是否 InkCollector 对象是第一次与该特定 Cursor 对象相联系。如果是，则将 DefaultDrawingAttributes 属性的复本分配给 DrawingAttributes 属性。这将确保对 DrawingAttributes 属性的后续访问不会引发 null 引用异常。

Private Sub mInkObject_CursorInRange(ByVal sender As Object, ByVal e As InkCollectorCursorInRangeEventArgs)
    Const MOUSE_CURSOR_ID As Integer = 1
    If e.NewCursor Then
        ' 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) Then
            e.Cursor.DrawingAttributes.Color = Color.Red
        End If

    End If
End Sub

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;
        }
    }
}

当 NewPackets 事件激发时，将检查数据包数据中是否包含 NormalPressure。如果包含，则在状态标签上显示压力信息，并修改 DrawingAttributes 属性。

Private Sub mInkObject_NewPackets(ByVal sender As Object, ByVal e As InkCollectorNewPacketsEventArgs)

    ' find the NormalPressure PacketProperty
    ' Set NormalPressure to -1 if not there, as some digitizers won't support it
    Dim PacketDesc As Guid() = e.Stroke.PacketDescription
    Dim NormalPressure As Integer = -1

    For k As Integer = 0 To PacketDesc.Length - 1
        If PacketDesc(k) = PacketProperty.NormalPressure Then
            ' for simplicity, in case of multiple packets, use the first packet only
            NormalPressure = e.PacketData(k)
        End If
    Next 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 Then
        ' display the pressure on a status label
        Me.statusLabelPressure.Text = NormalPressure.ToString()
        e.Cursor.DrawingAttributes.Width = NormalPressure * 4
        ' if pressure is above 127, change color to Red
        If NormalPressure > 127 Then
            e.Cursor.DrawingAttributes.Color = Color.Red
        Else
            e.Cursor.DrawingAttributes.Color = mInkObject.DefaultDrawingAttributes.Color
        End If
    End If

End Sub

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;
        }
    }
}