SpeechSynthesizer.SpeakAsyncCancelAll()不取消

Question

我的表单上有一个按钮，标签是“对话”，当用户单击它时，synth.SpeakAsync(Textbox.text)会被触发，该按钮将其文本更改为“停止说话”。

但是，当用户单击“停止说话”，从而触发synth.speakAsyncCancelAll()时，它不会取消“中途发言”。

这是我的代码：

Private Sub btnSpeak_Click(sender As System.Object, e As System.EventArgs) Handles btnSpeak.Click
    If RTextBox.Text = "" Then Exit Sub

    Dim synth As New SpeechSynthesizer
    synth.Rate = -2

    If btnSpeak.Text = "Stop Speaking" Then
        btnSpeak.Text = "Speak"
        synth.SpeakAsyncCancelAll()

    ElseIf btnSpeak.Text = "Speak" Then
        btnSpeak.Text = "Stop Speaking"
        synth.SpeakAsync(RTextBox.Text)
    End If

Answer 1

每次单击该按钮时，都会创建一个新的语音合成器。将昏暗的合成器作为新的语音合成器从按钮单击事件。这样，每次都会引用相同的合成器，然后就会触发语音取消事件。

Answer 2

SpeakAsyncCancelAll()将在被调用后引发SpeakCompleted事件，您可以使用以下代码侦听它：

Imports System.Speech.Synthesis

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim synthesizer As New SpeechSynthesizer()
        AddHandler synthesizer.SpeakCompleted, AddressOf speakCompleted
    End Sub

    Private Sub speakCompleted(ByVal sender As Object, ByVal e As SpeakCompletedEventArgs)
        Dim cancelled = e.Cancelled
    End Sub
End Class