Find and Minimize or Maximize or Restore a Window

Introduction

GetWindowPlacement, SetWindowPlacement, and FindWindow: using these API functions, we can minimize or maximize or restore a window.

Using the functions

• GetWindowPlacement

The GetWindowPlacement function retrieves the show state and the restored, minimized, and maximized positions of the specified window.

GetWindowPlacement (ByVal hwnd As Integer, ByRef lpwndpl As WINDOWPLACEMENT) As Integer

• SetWindowPlacement

The SetWindowPlacement function sets the show state and the restored, minimized, and maximized positions of the specified window.

SetWindowPlacement (ByVal hwnd As Integer, ByRef lpwndpl As WINDOWPLACEMENT) As Integer

• FindWindow

The FindWindow function retrieves a handle to the top-level window whose class name and window name matches the specified strings. This function does not search child windows. This function does not perform a case-sensitive search.

FindWindow(string lpClassName,string lpWindowName)

Usage

Public Class Minimize

    Private Declare Function FindWindow Lib "user32" Alias _
            "FindWindowA" (ByVal lpClassName As String, _
            ByVal lpWindowName As String) As Integer
    Private Declare Function GetWindowPlacement Lib _
            "user32" (ByVal hwnd As Integer, _
            ByRef lpwndpl As WINDOWPLACEMENT) As Integer
    Private Declare Function SetWindowPlacement Lib "user32" _
           (ByVal hwnd As Integer, ByRef lpwndpl As WINDOWPLACEMENT) As Integer
    Private Const SW_SHOWMINIMIZED As Short = 2
    Private Const SW_SHOWMAXIMIZED As Short = 3
    Private Const SW_SHOWNORMAL As Short = 1

    Private Structure POINTAPI
        Dim X As Integer
        Dim Y As Integer
    End Structure

    Private Structure RECT
        Dim Left_Renamed As Integer
        Dim Top_Renamed As Integer
        Dim Right_Renamed As Integer
        Dim Bottom_Renamed As Integer
    End Structure

    Private Structure WINDOWPLACEMENT
        Dim length As Integer
        Dim flags As Integer
        Dim showCmd As Integer
        Dim ptMinPosition As POINTAPI
        Dim ptMaxPosition As POINTAPI
        Dim rcNormalPosition As RECT
    End Structure

   
    Public Sub windowAction(ByVal classname As String, ByVal action As String)

        Dim app_hwnd As Integer
        Dim wp As WINDOWPLACEMENT
        app_hwnd = FindWindow(classname, vbNullString)
        wp.length = Len(wp)
        GetWindowPlacement(app_hwnd, wp)

        Select Case action

            Case "Minimize"
                 wp.showCmd = SW_SHOWMINIMIZED
            Case "Maximize"

                 wp.showCmd = SW_SHOWMAXIMIZED

            Case "Restore"
                wp.showCmd = SW_SHOWNORMAL
        End Select
        SetWindowPlacement(app_hwnd, wp)

    End Sub
End Class
'Use this Class
'This is sample for Minimize the notepad window

Private Sub Button1_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button1.Click
    Dim test As New Minimize
    test.windowAction("Notepad", "Minimize")
End Sub