.net/vb.net picture rotates around the center at any angle

Renderings:

Radian conversion: rad= angle * Math.PI / 180

Digression : I have been using the angle system to pass in the trigonometric function before, and the result is overturned, because the trigonometric functions such as sin cos tan must be passed in the radian system

First calculate the rotated rectangle

    ''' <summary>
    ''' 计算矩形在旋转任意角之后的区间
    ''' </summary>
    ''' <param name="width">原图片的宽度</param>
    ''' <param name="height">原图片的高度</param>
    ''' <param name="angle">顺时针旋转的较多</param>
    ''' <returns>旋转后的区间</returns>
    Public Function GetRotateRect(width As Integer, height As Integer, angle As Integer) As Rectangle
        Dim rad = angle * Math.PI / 180
        Dim cos As Double = Math.Cos(rad)
        Dim sin As Double = Math.Sin(rad)
        Dim newWidth As Integer = CInt(Math.Max(Math.Abs(width * cos - height * sin), Math.Abs(width * cos + height * sin)))
        Dim newHeight As Integer = CInt(Math.Max(Math.Abs(width * sin - height * cos), Math.Abs(width * sin + height * cos)))
        Return New Rectangle(0, 0, newWidth, newHeight)
    End Function

After the calculation, it is necessary to draw the picture. Since we want this effect, we need to start drawing from the middle

''' <summary>
''' 输出原图中心旋转后的图片
''' </summary>
''' <param name="bmp">原图</param>
''' <param name="angle">旋转角度</param>
''' <returns>返回旋转后的图片</returns>
Public Function DrawRatateRect(bmp As Bitmap, angle As Integer) As Bitmap
    Dim w As Integer = bmp.Width
    Dim h As Integer = bmp.Height
    Dim RotateRect As Rectangle = GetRotateRect(w, h, angle)
    Dim RW As Integer = RotateRect.Width
    Dim RH As Integer = RotateRect.Height
    Dim Dest As New Bitmap(RW, RH)
    Dim g As Graphics = Graphics.FromImage(Dest)
    Dim CenterPoint As New Point(RW / 2, RH / 2)
    g.TranslateTransform(CenterPoint.X, CenterPoint.Y)
    g.RotateTransform(angle)
    g.TranslateTransform(-CenterPoint.X, -CenterPoint.Y)

    Dim offset As New Point((RW - w) / 2, (RH - h) / 2)
    g.DrawImage(bmp, New Rectangle(offset, New Size(w, h)))
    g.ResetTransform()
    g.Save()
    Return Dest
End Function

good results!

The main form calls:

DrawRatateRect(New Bitmap("C:\Users\Abfun\Desktop\tmp.png"), 20).Save("C:\Users\Abfun\Desktop\tmp2.png")