VB.NET WinForm如何跨窗体调用源窗体的UpdatePosition方法

你已经通过TypeOf判断了控件的类型为Projectile，只需要把通用Control类型的变量强制转换为Projectile类型，即可调用自定义的UpdatePosition方法，修改后的完整代码如下：

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    For Each control As Control In Controls
        If TypeOf control Is Projectile Then
            ' 将Control类型强制转换为Projectile类型后调用自定义方法
            Dim currentProjectile As Projectile = DirectCast(control, Projectile)
            currentProjectile.UpdatePosition()
        End If
    Next
End Sub

额外说明 #

• 这里使用DirectCast做类型转换是安全的：前面的TypeOf判断已经确保当前遍历到的控件一定是Projectile类的实例，不会触发类型转换异常
• 你也可以用更简洁的写法，省略单独的TypeOf判断，用TryCast尝试转换后判断结果是否为空再执行逻辑：

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    For Each control As Control In Controls
        Dim currentProjectile As Projectile = TryCast(control, Projectile)
        If currentProjectile IsNot Nothing Then
            currentProjectile.UpdatePosition()
        End If
    Next
End Sub

内容的提问来源于stack exchange，提问作者schnefff boi