Question

我正在尝试使用visual studio创建一个Windows窗体应用程序来捕获活动窗口应用程序的屏幕截图。我创建了一个捕获按钮，它捕获表单本身而不是Previous活动窗口。因此，我想切换到之前的活动窗口，并且应该捕获屏幕截图，将其视为当前活动窗口。我对VB比较新。请帮我解决这个问题。

谢谢。

Answer 1

一种方法是防止您的表单获得焦点，从而将“上一个”表单保留为活动的选定表单。

请参阅WS_EX_NOACTIVATE：

使用此样式创建的顶级窗口不会成为用户点击它时的前景窗口。

Public Class Form1

    Private Structure RECT
        Public Left As Integer
        Public Top As Integer
        Public Right As Integer
        Public Bottom As Integer
    End Structure

    Private Const WM_MOVING As Integer = &H216
    Private Const WS_EX_NOACTIVATE As Integer = &H8000000

    Protected Overrides ReadOnly Property CreateParams() As System.Windows.Forms.CreateParams
        Get
            Dim cp As CreateParams = MyBase.CreateParams
            cp.ExStyle = cp.ExStyle Or WS_EX_NOACTIVATE
            Return cp
        End Get
    End Property

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = WM_MOVING Then
            Dim r As RECT = DirectCast(Runtime.InteropServices.Marshal.PtrToStructure(m.LParam, GetType(RECT)), RECT)
            Me.Location = New Point(r.Left, r.Top)
        End If

        MyBase.WndProc(m)
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Console.WriteLine("...your active screen capture code here...")
    End Sub

End Class

如何在VB中激活以前的活动窗口？

1 个答案: