■サンプルの説明

起動すると、こんな画面が表示されます。自アプリケーション・他アプリケーション問わず、マウスポインタの位置にあるハンドルの座標を表示します。

■コード

Imports System.Runtime.InteropServices
''' <summary>
''' WindowFromPoint(user32.dll)
''' </summary>
Partial Public Class F0010_WindowFromPoint

    ''' <summary>
    ''' WindowFromPoint（指定された座標を含むウィンドウのハンドルを取得）の宣言
    ''' </summary>
    <DllImport("user32.dll", CharSet:=CharSet.Auto)> _
    Private Shared Function WindowFromPoint(ByVal lpPoint As POINT) _
                                            As IntPtr
    End Function

    ''' <summary>
    ''' GetCursorPos（マウスの座標を取得）の宣言
    ''' </summary>
    <DllImport("user32.dll", CharSet:=CharSet.Auto)> _
    Private Shared Function GetCursorPos(ByRef lpPoint As POINT) _
                                         As Boolean
    End Function

    ''' <summary>
    ''' POINT 構造体
    ''' </summary>
    Private Structure POINT
        Public X As Integer
        Public Y As Integer
    End Structure

    ''' <summary>
    ''' GetWindowRect（Window の位置等を取得）の宣言
    ''' </summary>
    <DllImport("user32.dll", CharSet:=CharSet.Auto)> _
    Private Shared Function GetWindowRect(ByVal hWnd As IntPtr, _
                                          ByRef lpRect As RECT) _
                                          As Boolean
    End Function

    ''' <summary>
    ''' RECT 構造体
    ''' </summary>
    Private Structure RECT
        Public Left As Integer
        Public Top As Integer
        Public Right As Integer
        Public Bottom As Integer
    End Structure

    ''' <summary>
    ''' ロード時のイベント
    ''' </summary>
    Private Sub F0010_WindowFromPoint_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Me.Text = "F0010_WindowFromPoint"
        Me.Label1.Text = ""
        Me.Label1.BackColor = Color.White
        Me.Label2.Text = ""
        Me.Label2.BackColor = Color.White
        Me.Timer1.Interval = 100
        Me.Timer1.Start()

    End Sub

    ''' <summary>
    ''' 指定したタイマの間隔が経過した時のイベント
    ''' </summary>
    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim lpPoint As POINT
        'マウス座標を取得
        GetCursorPos(lpPoint)
        Me.Label1.Text = "X:" + lpPoint.X.ToString() + " Y:" + lpPoint.Y.ToString()

        'マウス座標よりハンドル取得
        Dim hwnd As IntPtr
        hwnd = WindowFromPoint(lpPoint)
        If hwnd.ToInt32() <= 0 Then
            'ハンドル取得失敗
            Me.Label2.Text = ""
            Exit Sub
        End If

        '現在のハンドルの座標値を取得
        Dim lpRect As RECT
        GetWindowRect(hwnd, lpRect)

        Dim buff As System.Text.StringBuilder
        buff = New System.Text.StringBuilder
        buff.Append("現在のハンドルの座標値" + ControlChars.NewLine)
        buff.Append("Top : " + lpRect.Top.ToString() + ControlChars.NewLine)
        buff.Append("Left : " + lpRect.Left.ToString() + ControlChars.NewLine)
        buff.Append("Bottom : " + lpRect.Bottom.ToString() + ControlChars.NewLine)
        buff.Append("Right : " + lpRect.Right.ToString())
        Me.Label2.Text = buff.ToString()

    End Sub

End Class

■参考資料

WindowFromPoint