Public Class Bild_drehen
 
  ' PictureBox "pb1" W/H: 714/514, SizeMode: Zoom
 
 
  Dim gBitmap As Drawing.Bitmap
  Dim angle As Decimal = Nothing
 
 
  Private Sub Bild_drehen_Load(ByVal sender As Object, ByVal e As _
    System.EventArgs) Handles Me.Load
 
  gBitmap = New Bitmap("C:\***\*.JPG") _
    !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
  Me.pb1.Width = pb1.Height * (gBitmap.Width / gBitmap.Height)
  Me.pb1.Image = gBitmap
  End Sub
 
 
 
  Private Sub btn_R_Click(ByVal sender As System.Object,  ByVal e As _
    System.EventArgs) Handles btn_R.Click
    angle += 0.5
    Me.trbRotate.Value = angle
    Me.pb1.Image = Rotate_Bitmap(gBitmap, angle, Color.LightGray)
  End Sub
 
  Private Sub btn_0_Click(ByVal sender As System.Object,  ByVal e As _
    System.EventArgs) Handles btn_0.Click
    Me.trbRotate.Value = 0.0
    Me.pb1.Image = gBitmap
  End Sub
 
  Private Sub btn_L_Click(ByVal sender As System.Object,  ByVal e As _
    System.EventArgs) Handles btn_L.Click
    angle -= 0.5
    Me.trbRotate.Value = angle
    Me.pb1.Image = Rotate_Bitmap(gBitmap, angle, Color.LightGray)
  End Sub
 
  Public Function Rotate_Bitmap(ByVal bmp As Drawing.Bitmap, ByVal angle As _
    Decimal, ByVal BackGround As Drawing.Color, Optional ByVal Zoom_Factor As _
    Single = 1) As Drawing.Bitmap
 
  Try
    Dim rotate_width , rotate_height As Integer
    Dim draw_width As Integer = CInt(bmp.Width * Zoom_Factor)
    Dim draw_height As Integer = CInt(bmp.Height * Zoom_Factor)
 
    If Not Rotate_Bitmap_Size(draw_width, draw_height, angle, rotate_width, _
      rotate_height) Then Return Nothing
 
    Dim bmp_out As New Bitmap(rotate_width, rotate_height)
    Dim g As Drawing.Graphics = Graphics.FromImage(bmp_out)
 
    g.Clear(BackGround)
 
    Dim p_center As PointF
    p_center.X = CSng(bmp_out.Width / 2): p_center.Y = CSng(bmp_out.Height / 2)
 
    Dim m As New Drawing.Drawing2D.Matrix
    m.Scale(Zoom_Factor, Zoom_Factor): m.RotateAt(angle, p_center)
 
    g.Transform = m
 
    Dim source_rect As New Rectangle(0, 0, bmp.Width, bmp.Height)
 
    Dim x As Integer = CInt((rotate_width - draw_width) / 2)
    Dim y As Integer = CInt((rotate_height - draw_height) / 2)
    Dim destination_rect As New Rectangle(x, y, draw_width, draw_height)
 
    g.DrawImage(bmp, destination_rect, source_rect, GraphicsUnit.Pixel)
 
    m.Dispose
    g.Dispose
 
    Return bmp_out
 
  Catch ex As Exception
    Return Nothing
  End Try
  End Function
 
 
 
 
    Public Function Rotate_Bitmap_Size(ByVal width As Integer, ByVal height As _
      Integer, ByVal angle As Single, ByRef rotate_width As Integer, ByRef _
      rotate_height As Integer) As Boolean
 
    rotate_width = -1 : rotate_height = -1
 
    If width < 1 Or height < 1 Then Return False
'If width > 2048 Or height > 2048 Then Return False
    Dim pts(3) As PointF
    pts(0).X = 0 : pts(0).Y = 0: pts(1).X = 0 : pts(1).Y = height: pts(2).X = _
      width : pts(2).Y = height: pts(3).X = width : pts(3).Y = 0
 
    Dim p_center As Drawing.PointF
    p_center.X = CSng(width / 2): p_center.Y = CSng(height / 2)
 
    Dim m As New Drawing.Drawing2D.Matrix
    m.RotateAt(angle, p_center)
    m.TransformPoints(pts)
    m.Dispose()
 
 
    Dim xug As Single = Single.MaxValue 
    Dim xog As Single = Single.MinValue 
    Dim yug As Single = Single.MaxValue
    Dim yog As Single = Single.MinValue
 
    For i As Integer = 0 To 3
      xug = Math.Min(pts(i).X, xug): xog = Math.Max(pts(i).X, xog): yug = _
        Math.Min(pts(i).Y, yug): yog = Math.Max(pts(i).Y, yog)
    Next i
 
'--------------------------------------------
    Dim xug2, xog2, yug2, yog2 As Single
    xug2 = Single.MaxValue: xog2 = Single.MinValue: yug2 = Single.MaxValue: _
      yog2 = Single.MinValue
 
    For i As Integer = 0 To 3
      If pts(i).X > xug Then xug2 = Math.Min(pts(i).X, xug2)
      If pts(i).X < xog Then xog2 = Math.Max(pts(i).X, xog2)
      If pts(i).Y > yug Then yug2 = Math.Min(pts(i).Y, yug2)
      If pts(i).Y < yog Then yog2 = Math.Max(pts(i).Y, yog2)
    Next i
 
    If xug2 = Single.MaxValue Then xug2 = xug
    If xog2 = Single.MinValue Then xog2 = xog
    If yug2 = Single.MaxValue Then yug2 = yug
    If yog2 = Single.MinValue Then yog2 = yog
 
 
     'If chkCut.Checked Then
     xog = xog2 : yog = yog2
     xug = xug2 : yug = yug2
     'End If
'--------------------------------------------
 
    rotate_width = CInt(xog - xug)          
    If rotate_width < 1 Then Return False
 
    rotate_height = CInt(yog - yug)
    If rotate_height < 1 Then Return False
 
    Return True
    End Function
End Class