VB.NET Snippet to Rotate annotations in .NET

Private Sub RotateImageAndAnnotation(ByVal angle As Integer, ByVal container As AnnContainer, ByVal viewer As RasterImageViewer)

    ' Round the angle

    angle = angle Mod 360

    If angle = 0 Then Exit Sub ' nothing to do

    ' when we rotate an image, this is what happens:

    '   1. The image is rotated around its center (width / 2, height / 2)

    '   2. The image is translated so that its top, left position is at 0, 0

    '

    ' To calculate this translation, we:

    '   1. Find the 4 end points of the container

    '   2. Rotate these points

    '   3. Find the minimum/maximum "out of range" point

    '   4. Calculate the translation (amount to bring this "out of range" point back into view)

    Dim pts As PointF() = { _

        New PointF(0, 0), _

        New PointF(viewer.Image.ImageWidth, 0), _

        New PointF(viewer.Image.ImageWidth, viewer.Image.ImageHeight), _

        New PointF(0, viewer.Image.ImageHeight) _

    }

    Dim origin As New PointF(viewer.Image.ImageWidth / 2, viewer.Image.ImageHeight / 2)

    Dim m As New System.Drawing.Drawing2D.Matrix

    With m

        .RotateAt(angle, origin)

        .TransformPoints(pts)

    End With

    Dim xMin As Single = pts(0).X

    Dim yMin As Single = pts(0).Y

    Dim i As Integer

    For i = 1 To pts.Length - 1

        If pts(i).X < xMin Then xMin = pts(i).X

        If pts(i).Y < yMin Then yMin = pts(i).Y

    Next

    Dim xTranslate As Single = -xMin

    Dim yTranslate As Single = -yMin

    ' Now, rotate the image

    Dim cmd As New Leadtools.ImageProcessing.RotateCommand

    With cmd

        .Angle = angle * 100

        .Flags = ImageProcessing.RotateCommandFlags.Resize,

        .FillColor = RasterColor.FromGdiPlusColor(Color.White)

        .Run(viewer.Image)

    End With

    ' Rotate and translate the annotations

    Dim obj As AnnObject

    For Each obj In container.Objects

        obj.Rotate(angle, New AnnPoint(origin))

        If xTranslate <> 0 OrElse yTranslate <> 0 Then obj.Translate(xTranslate, yTranslate)

    Next

    ' Reset the container bounds

    container.Bounds = New AnnRectangle(0, 0, viewer.Image.ImageWidth, viewer.Image.ImageHeight)

End Sub

If you have any questions about this example, please post them back to this thread. Thanks,

Gabriel

Gabe
Developer Support
LEAD Technologies, Inc.