创建一个事件。当某个字符串发生变化时应该发生此事件

Question

我回到很远的地方来弄清楚上下文。首先，我今天注意到，如果窗体上有多个控件，则不能使用箭头键，因为控件（例如组合框、文本框）会占用光标和焦点。因此，我创建了第二个表格（“SteuerForm”（转向表格））。对此没有控制。我还发现您只能通过 KeyDown 事件获得箭头键。 KeyDown 事件在涉及某些字符时是不利的：输出“Shiftkey”和“Oem7”而不是特定字母（例如 Ä）。这就是为什么我实际上想使用 KeyPress。最终，我写了一个class(Class_Key")。它包含一个 list(Of string) 和我必须拥有的某些键名。

现在我希望在字符串 letzte_Taste (last_key) 更改时调用 Form1 中的 Private Sub new_message()。

编辑： 我想要 Class_Key Class 中的某些事件来触发主窗体中的方法 (new_message)。我怎样才能做到这一点？当字符串 letzte_Taste 从一个（例如 "Up"）更改为另一个（例如 "Down"）时，应该会触发该事件。

SteuerForm.vb

Public NotInheritable Class SteuerForm
    Private Sub SteuerForm_KeyPress(sender As Object, e As KeyPressEventArgs) Handles MyBase.KeyPress
        If Class_Key.Tasten.Contains(e.KeyChar.ToString) Then
            Class_Key.letzte_Taste = e.KeyChar.ToString
        End If
    End Sub

    Private Sub SteuerForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.KeyPreview = True
        Me.Location = New Point(500, 0)
    End Sub

    Private Sub SteuerForm_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
        If Class_Key.Tasten.Contains(e.KeyCode.ToString) Then
            Class_Key.letzte_Taste = e.KeyCode.ToString
        End If
    End Sub
End Class

Class_Key.vb

Public NotInheritable Class Class_Key
    Public Shared Tasten As New List(Of String) From {
        "Up",
        "Down",
        "Left",
        "Right",
        "Return",
        "Back",
        "Space",
        "Add",
        "Subtract",
        "a"} 'and another alphabetic characters... (I shortened this...)

    Public Shared letzte_Taste As String = ""
End Class

Answer 1

我做到了！这是我的解决方案。

Public NotInheritable Class Class_Key
    Public Shared Tasten As New List(Of String) From {
        "Up",
        "Down",
        "Left",
        "Right",
        "Return",
        "Back",
        "Space",
        "Add",
        "Subtract",
        "a"}

    Public Shared Property letzte_Taste As String = ""
    Public Shared Property vorletzte_Taste As String = ""
    Public Shared Event AnEvent()
    Public Shared Zaehler As UInt16 = 0
    Public Shared Sub Pruefung()
        If Not letzte_Taste = vorletzte_Taste Then
            RaiseEvent AnEvent()
            Zaehler += Convert.ToUInt16(1)
        End If
    End Sub
End Class

Public NotInheritable Class SteuerForm
    Private Sub SteuerForm_KeyPress(sender As Object, e As KeyPressEventArgs) Handles MyBase.KeyPress
        If Class_Key.Tasten.Contains(e.KeyChar.ToString) Then
            Class_Key.letzte_Taste = e.KeyChar.ToString
        End If
        Class_Key.Pruefung()
        Class_Key.vorletzte_Taste = Class_Key.letzte_Taste
    End Sub

    Private Sub SteuerForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.KeyPreview = True
        Me.Location = New Point(500, 0)
    End Sub

    Private Sub SteuerForm_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
        If Class_Key.Tasten.Contains(e.KeyCode.ToString) Then
            Class_Key.letzte_Taste = e.KeyCode.ToString
        End If
        Class_Key.Pruefung()
        Class_Key.vorletzte_Taste = Class_Key.letzte_Taste
    End Sub
End Class

在Form1_Load

AddHandler Class_Key.AnEvent, AddressOf neue_Nachricht

Form1

Private Sub neue_Nachricht()
    Debug.WriteLine($"caught event. Nr. {Class_Key.Zaehler}")
End Sub

创建一个事件。当某个字符串发生变化时应该发生此事件

Create an event. This event should occur when a certain string has changed

vb.net

event-handling