' OHOX/OHOY are the variables that define the Picture Hold Offset X/Y
' MouseDown is the boolean that determines whether the Mouse is still pressed or not
' CFrm is the Current Form that the player is viewing
' DX/DY are the variables that define the Destination X/Y
' SPIGSS is the System Paramaters Info Action Variables used to get the Screen Size excluding the taskbar

Public Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, lpvParam As Any, ByVal fuWinIni As Long) As Long
Public Const SPIGSS = 48

Private Type CScreenRec
    Top As Long
    Left As Long
    Right As Long
    Bottom As Long
End Type

Public CScreen As CScreenRec
Public DX, DY As Long
Public OHOX, OHOY As Long
Public MouseDown As Boolean

Public Sub FormMove(CFrm As Form, Button As Integer, Shift As Integer, X As Long, Y As Long)

    If Button = 1 And MouseDown = True Then
        GetScreenSize
        DX = CFrm.Left + X - OHOX
        DY = CFrm.Top + Y - OHOY
        If DX < CScreen.Left Then DX = CScreen.Left
        If DY < CScreen.Top Then DY = CScreen.Top
        If DX + CFrm.Width > CScreen.Right Then DX = CScreen.Right - CFrm.Width
        If DY + CFrm.Height > CScreen.Bottom Then DY = CScreen.Bottom - CFrm.Height
        CFrm.Left = DX
        CFrm.Top = DY
    End If

End Sub

Public Sub GetScreenSize()
Dim ScreenRect As RECT
   
    SystemParametersInfo SPIGSS, 0, ScreenRect, 0
    CScreen.Bottom = 15 * ScreenRect.Bottom
    CScreen.Right = 15 * ScreenRect.Right
    CScreen.Top = 15 * ScreenRect.Top
    CScreen.Left = 15 * ScreenRect.Left
End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then
    MouseDown = True
    OHOX = CLng(X)
    OHOY = CLng(Y)
End If
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If MouseDown = True Then Call FormMove(Me, Button, Shift, CLng(X), CLng(Y))
End Sub

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    MouseDown = False
End Sub