RedirectPaint Method

'Declaration
 
Public Overridable Sub RedirectPaint( _
   ByVal graphics As Graphics, _
   ByVal src As Rectangle, _
   ByVal dest As Rectangle, _
   ByVal destClip As Rectangle, _
   ByVal transform As Matrix _
) 

Private Class MyForm2 : Inherits Form
      Private Class MyPanel : Inherits Panel
         Protected Overrides Sub OnPaintBackground(ByVal pe As PaintEventArgs)
            ' do nothing
         End Sub
      End Class

      Private viewer As RasterImageViewer
      Private panel As MyPanel

      Public Sub New(ByVal title As String)
         Text = title
         Size = New Size(750, 450)

         ' Create the raster viewer
         viewer = New RasterImageViewer()
         viewer.DoubleBuffer = True
         viewer.Dock = DockStyle.Fill

         ' Load an image into the viewer
         Dim codecs As RasterCodecs = New RasterCodecs()
         viewer.Image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Sample1.cmp"))
         codecs.Dispose()

         ' Create the panel
         panel = New MyPanel()
         panel.Parent = Me
         panel.Width = 400
         panel.Height = 400
         panel.Dock = DockStyle.Right
         panel.BackColor = Color.Beige
         panel.BorderStyle = BorderStyle.Fixed3D

         Controls.Add(panel)
         panel.BringToFront()

         Controls.Add(viewer)
         viewer.BringToFront()

         AddHandler panel.Paint, AddressOf panel_Paint
         AddHandler viewer.PostImagePaint, AddressOf viewer_PostImagePaint
         AddHandler viewer.RedirectImagePaint, AddressOf viewer_RedirectImagePaint
      End Sub

      Private Sub viewer_RedirectImagePaint(ByVal sender As Object, ByVal e As EventArgs)
         panel.Invalidate()
      End Sub

      Private Sub panel_Paint(ByVal sender As Object, ByVal e As PaintEventArgs)
         If Not viewer.Image Is Nothing Then
            Dim dx As Integer = viewer.Image.Width \ 2
            Dim dy As Integer = viewer.Image.Height \ 2
            Dim dest As Rectangle = viewer.SourceRectangle

            ' move center of image to origin
            Dim m1 As Matrix = New Matrix(1, 0, 0, 1, -dx, -dy)

            ' mirror the image
            Dim m2 As Matrix = New Matrix(-1, 0, 0, 1, 0, 0)
            m1.Multiply(m2, MatrixOrder.Append)

            ' move back to original location
            Dim m3 As Matrix = New Matrix(1, 0, 0, 1, dx, dy)
            m1.Multiply(m3, MatrixOrder.Append)

            ' scale image to fit on panel
            Dim scaleX As Single = CSng(panel.Width) / CSng(viewer.Image.Width)
            Dim scaleY As Single = CSng(panel.Height) / CSng(viewer.Image.Height)
            Dim m4 As Matrix = New Matrix(scaleX, 0, 0, scaleY, 0, 0)
            m1.Multiply(m4, MatrixOrder.Append)

            ' display contents of RaserImageViewer on panel
            viewer.RedirectPaint(e.Graphics, Rectangle.Empty, Rectangle.Empty, Rectangle.Empty, m1)
         End If
      End Sub

      Private Sub viewer_PostImagePaint(ByVal sender As Object, ByVal e As PaintEventArgs)
         Dim graphics As Graphics = e.Graphics
         Dim graphicsState As GraphicsState = graphics.Save()

         Dim font As Font = New Font("Arial", 16)
         e.Graphics.DrawString("This text stays with the window", font, Brushes.Yellow, New PointF(100, 100))

         graphics.MultiplyTransform(viewer.Transform)
         e.Graphics.DrawString("This text stays with the image.", font, Brushes.White, New PointF(100, 200))

         graphics.Restore(graphicsState)
         graphics.Flush()
      End Sub
   End Class

   Public Sub RasterImageViewer_RedirectPaint(ByVal title As String)
      Dim form As MyForm2 = New MyForm2(title)
      form.ShowDialog()
   End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class