Imports System.Drawing
Imports System.Windows.Forms


Public Class ClassSnapPanel
    Inherits Panel

    Private _ShowGrid As Boolean = True
    Private _GridSize As Integer = 16
    Private _NeedsScrollUpdate As Boolean = False

    Public Sub New()
        Me.AutoScroll = True
        Me.DoubleBuffered = True ' Flackern reduzieren
    End Sub

    Public Property GridSize As Integer
        Get
            Return _GridSize
        End Get
        Set(value As Integer)
            If value > 0 AndAlso value <> _GridSize Then
                _GridSize = value
                Invalidate()
            End If
        End Set
    End Property

    Public Property ShowGrid As Boolean
        Get
            Return _ShowGrid
        End Get
        Set(value As Boolean)
            If value <> _ShowGrid Then
                _ShowGrid = value
                Invalidate()
            End If
        End Set
    End Property

    Protected Overrides Sub OnControlAdded(e As ControlEventArgs)
        MyBase.OnControlAdded(e)
        AddHandler e.Control.LocationChanged, AddressOf AlignToGrid
        AddHandler e.Control.MouseUp, AddressOf AlignToGrid
        ScheduleScrollUpdate()
    End Sub

    Protected Overrides Sub OnControlRemoved(e As ControlEventArgs)
        MyBase.OnControlRemoved(e)
        RemoveHandler e.Control.LocationChanged, AddressOf AlignToGrid
        RemoveHandler e.Control.MouseUp, AddressOf AlignToGrid
        ScheduleScrollUpdate()
    End Sub

    Protected Overrides Sub OnLayout(levent As LayoutEventArgs)
        MyBase.OnLayout(levent)
        ScheduleScrollUpdate()
    End Sub

    Protected Overrides Sub OnPaint(e As PaintEventArgs)
        MyBase.OnPaint(e)

        If Not Me.DesignMode AndAlso _ShowGrid Then
            Dim scrollOffset As Point = Me.AutoScrollPosition
            Dim gridRect As New Rectangle(-scrollOffset.X, -scrollOffset.Y, Me.ClientSize.Width, Me.ClientSize.Height)
            ControlPaint.DrawGrid(e.Graphics, gridRect, New Size(_GridSize, _GridSize), Me.BackColor)
        End If
    End Sub

    Private Sub AlignToGrid(sender As Object, e As EventArgs)
        If Not _ShowGrid OrElse Me.DesignMode Then Return

        Dim ctrl As Control = CType(sender, Control)
        Dim x As Integer = Math.Floor(ctrl.Left / _GridSize) * _GridSize
        Dim y As Integer = Math.Floor(ctrl.Top / _GridSize) * _GridSize
        ctrl.Location = New Point(x, y)
        ScheduleScrollUpdate()
    End Sub

    Private Sub ScheduleScrollUpdate()
        If Not _NeedsScrollUpdate Then
            _NeedsScrollUpdate = True
            BeginInvoke(New MethodInvoker(Sub()
                                              UpdateScrollArea()
                                              _NeedsScrollUpdate = False
                                          End Sub))
        End If
    End Sub

    Private Sub UpdateScrollArea()
        Dim maxWidth As Integer = 0
        Dim maxHeight As Integer = 0

        For Each ctrl As Control In Me.Controls
            maxWidth = Math.Max(maxWidth, ctrl.Right)
            maxHeight = Math.Max(maxHeight, ctrl.Bottom)
        Next

        Me.AutoScrollMinSize = New Size(maxWidth, maxHeight)
    End Sub
End Class

'Public Class ClassSnapPanel
'    Inherits Panel

'    Private _ShowGrid As Boolean = True
'    Private _GridSize As Integer = 16
'    Public Sub New()
'        Me.AutoScroll = True ' Scrollbars aktivieren
'    End Sub
'    Public Property GridSize As Integer
'        Get
'            Return _GridSize
'        End Get
'        Set(value As Integer)
'            _GridSize = value
'            Refresh()
'        End Set
'    End Property

'    Public Property ShowGrid As Boolean
'        Get
'            Return _ShowGrid
'        End Get
'        Set(value As Boolean)
'            _ShowGrid = value
'            Refresh()
'        End Set
'    End Property

'    Protected Overrides Sub OnControlAdded(e As ControlEventArgs)
'        AddHandler e.Control.LocationChanged, AddressOf AlignToGrid
'        AddHandler e.Control.DragDrop, AddressOf AlignToGrid
'        MyBase.OnControlAdded(e)
'        UpdateScrollArea()
'    End Sub

'    Protected Overrides Sub OnControlRemoved(e As ControlEventArgs)
'        RemoveHandler e.Control.LocationChanged, AddressOf AlignToGrid
'        RemoveHandler e.Control.DragDrop, AddressOf AlignToGrid
'        MyBase.OnControlRemoved(e)
'        UpdateScrollArea()
'    End Sub
'    Protected Overrides Sub OnPaint(e As System.Windows.Forms.PaintEventArgs)
'        If _ShowGrid Then
'            ControlPaint.DrawGrid(e.Graphics, ClientRectangle, New Size(_GridSize, _GridSize), BackColor)
'        End If
'        MyBase.OnPaint(e)
'    End Sub

'    Private Sub AlignToGrid(sender As Object, e As EventArgs)
'        If _ShowGrid Then
'            Dim item As Control = CType(sender, Control)
'            Dim x As Integer = Math.Round(item.Left / _GridSize) * _GridSize
'            Dim y As Integer = Math.Round(item.Top / _GridSize) * _GridSize
'            item.Location = New Point(x, y)
'            UpdateScrollArea()
'        End If
'    End Sub
'    Private Sub UpdateScrollArea()
'        Dim maxWidth As Integer = 0
'        Dim maxHeight As Integer = 0

'        ' Größte X- und Y-Koordinate der enthaltenen Controls bestimmen
'        For Each ctrl As Control In Controls
'            Dim right As Integer = ctrl.Right
'            Dim bottom As Integer = ctrl.Bottom

'            If right > maxWidth Then maxWidth = right
'            If bottom > maxHeight Then maxHeight = bottom
'        Next

'        ' Scrollbereich setzen
'        Me.AutoScrollMinSize = New Size(maxWidth, maxHeight)
'    End Sub
'End Class