HitTestZone Method

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms.Ocr
Imports Leadtools.Forms
Imports Leadtools.Forms.DocumentWriters
Imports Leadtools.WinForms
Imports Leadtools.ImageProcessing.Core
Imports Leadtools.Drawing

' Assume Form1 is a Windwos.Forms form in your application
' The OCR engine we are using
Private _ocrEngine As IOcrEngine
Private _ocrDocument As IOcrDocument

' Our raster image viewer instance
Private _viewer As RasterImageViewer

Public Sub New()
   InitializeComponent()

   ' Initialize the raster image viewer
   ' Turn on use DPI, center the image, add border padding and frame shadow to show that our calculations will be
   ' independent on all of those extra options
   _viewer = New RasterImageViewer()
   _viewer.Dock = DockStyle.Fill
   _viewer.BackColor = SystemColors.AppWorkspace
   _viewer.UseDpi = True
   _viewer.BorderPadding.All = 8
   _viewer.FrameSize = New SizeF(1, 1)
   _viewer.FrameShadowSize = New SizeF(2, 2)
   _viewer.SizeMode = RasterPaintSizeMode.Normal
   _viewer.HorizontalAlignMode = RasterPaintAlignMode.Center
   _viewer.VerticalAlignMode = RasterPaintAlignMode.Center
   _viewer.AutoDisposeImages = True
   _viewer.InteractiveMode = RasterViewerInteractiveMode.None

   ' Turn on scale to gray painting in the viewer
   Dim props As RasterPaintProperties = _viewer.PaintProperties
   props.PaintDisplayMode = props.PaintDisplayMode Or RasterPaintDisplayModeFlags.ScaleToGray
   _viewer.PaintProperties = props

   ' Subscribe to the viewer events we need
   AddHandler _viewer.KeyDown, AddressOf _viewer_KeyDown
   AddHandler _viewer.MouseDown, AddressOf _viewer_MouseDown
   AddHandler _viewer.PostImagePaint, AddressOf _viewer_PostImagePaint

   Controls.Add(_viewer)
   _viewer.BringToFront()

   ' Create and startup the OCR engine
   _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False)
   _ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrAdvantageRuntimeDir)

   ' Create the OCR document
   _ocrDocument = _ocrEngine.DocumentManager.CreateDocument()

   ' Load an image into the document
   Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")
   Dim ocrPage As IOcrPage = _ocrDocument.Pages.AddPage(tifFileName, Nothing)

   ' Do auto zone
   ocrPage.AutoZone(Nothing)

   ' AutoZone does not specify a name for the zones, so loop through all the zones and set their names
   ' to a unique value. We will use the name in the paint code later
   Dim ocrZones As IOcrZoneCollection = ocrPage.Zones
   For i As Integer = 0 To ocrZones.Count - 1
      Dim ocrZone As OcrZone = ocrZones(i)

      ' Construct the name from the ID
      ocrZone.Name = String.Format("Zone {0}", ocrZone.Id)

      ocrZones(i) = ocrZone
   Next

   ' Show the same image in the viewer
   _viewer.Image = ocrPage.GetRasterImage()

   ' Note, the image we got from GetRasterImage is a copy of the image in the engine
   ' Since we set teh AutoDisposeImages of the viewer to "true", the image will be disposed
   ' when the viewer is disposed at application termination

   Text = "+ to zoom in, - to zoom out, enter to return to 100%. Select the zones with the mouse"
End Sub

Protected Overrides Sub OnFormClosed(ByVal e As FormClosedEventArgs)
   ' Destroy the document
   _ocrDocument.Dispose()

   ' Shutdown the OCR engine
   _ocrEngine.Shutdown()
   _ocrEngine.Dispose()

   MyBase.OnFormClosed(e)
End Sub

Private Sub _viewer_KeyDown(ByVal sender As Object, ByVal e As KeyEventArgs)
   Const zoomRatio As Double = 1.2
   Dim scaleFactor As Double = _viewer.ScaleFactor

   Select Case (e.KeyCode)
      Case Keys.Add, Keys.Oemplus
         ' Zoon in
         scaleFactor *= zoomRatio
         e.Handled = True

      Case Keys.Subtract, Keys.OemMinus
         ' Zone out
         scaleFactor /= zoomRatio
         e.Handled = True

      Case Keys.Enter
         scaleFactor = 1
         e.Handled = True
   End Select

   Const minimumScaleFactor As Double = 0.05
   Const maximumScaleFactor As Double = 11

   scaleFactor = Math.Max(minimumScaleFactor, Math.Min(maximumScaleFactor, scaleFactor))

   ' Check if scale factor has changed
   If (scaleFactor <> _viewer.ScaleFactor) Then
      _viewer.BeginUpdate()

      ' Yes, zoom keeping the center of the image

      ' Get what you see in physical coordinates
      Dim rc As Rectangle = Rectangle.Intersect(_viewer.PhysicalViewRectangle, _viewer.ClientRectangle)
      ' Get the center of what you see in physical coordinates
      Dim center As New PointF(rc.Left + rc.Width \ 2, rc.Top + rc.Height \ 2)
      Dim t As New Transformer(_viewer.Transform)
      ' Get the center of what you see in logical coordinates
      center = t.PointToLogical(center)

      _viewer.ScaleFactor = scaleFactor

      ' Bring the original center into the view center
      t = New Transformer(_viewer.Transform)
      ' Get the center of what you saw before the zoom in physical coordinates
      center = t.PointToPhysical(center)
      ' Bring the old center into the center of the view
      _viewer.CenterAtPoint(Point.Round(center))

      _viewer.EndUpdate()
   End If
End Sub

Private Sub _viewer_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)
   ' Perform hit-testing on the zones
   If (Not _ocrEngine Is Nothing) AndAlso (_ocrEngine.IsStarted) AndAlso (_ocrDocument.Pages.Count > 0) AndAlso e.Button = Windows.Forms.MouseButtons.Left Then
      ' Get the transform of the viewer
      ' Use the transform that takes the DPI into consideration since we turned that on
      Using matrix As Matrix = _viewer.GetTransformWithDpi()
         Dim t As New Transformer(matrix)

         ' Convert the mouse click coordinates from physical (viewer) to logical (image)
         Dim point As New PointF(e.X, e.Y)
         point = t.PointToLogical(point)

         ' Hit test the zones
         ' An alternitave to calling HitTestZone is to loop through all the zones
         ' and get the value of .Bounds in pixels, then check if the point is inside
         ' the boundaries.
         Dim ocrPage As IOcrPage = _ocrDocument.Pages(0)
         Dim lPoint As LeadPoint = New LeadPoint(CType(point.X, Integer), CType(point.Y, Integer))
         Dim zoneIndex As Integer = ocrPage.HitTestZone(New LogicalPoint(lPoint))

         If (zoneIndex <> -1) Then
            ' We hit a zone, loop through all the zones, unselect all but the hit tested zone
            For index As Integer = 0 To ocrPage.Zones.Count - 1
               ' Since OcrZone is a structure, we cannot simply do
               ' ocrZone.Zones[index].Selected = value
               ' We have to get a copy of the structure, modify it and set it back

               Dim ocrZone As OcrZone = ocrPage.Zones(index)

               If (index <> zoneIndex) Then
                  ocrZone.Selected = False
               Else
                  ocrZone.Selected = True
               End If

               ocrPage.Zones(index) = ocrZone
            Next

            ' Re-paint the viewer to show the new zones
            _viewer.Invalidate()
         End If
      End Using
   End If
End Sub

Private Sub _viewer_PostImagePaint(ByVal sender As Object, ByVal e As PaintEventArgs)
   ' Draw the zones on the viewer in their correct location
   If (Not _ocrEngine Is Nothing) AndAlso (_ocrEngine.IsStarted) AndAlso (_ocrDocument.Pages.Count > 0) Then
      ' Get the transform of the viewer
      ' Use the transform that takes the DPI into consideration since we turned that on
      Using matrix As Matrix = _viewer.GetTransformWithDpi()
         Dim t As New Transformer(matrix)

         Dim ocrPage As IOcrPage = _ocrDocument.Pages(0)

         Dim normalPen As New Pen(Color.Blue, 1)
         Dim selectedPen As New Pen(Color.Red, 2)
         selectedPen.DashStyle = DashStyle.Dash

         For Each ocrZone As OcrZone In ocrPage.Zones
            ' Get the zone bounds in pixels
            ' You can also use ocrPage.GetZoneBoundsInPixels here

            Dim ltzoneBounds As LeadRect = ocrZone.Bounds.ToRectangle(ocrPage.DpiX, ocrPage.DpiY)
            Dim zoneBounds As RectangleF = New RectangleF(ltzoneBounds.Left, ltzoneBounds.Top, ltzoneBounds.Width, ltzoneBounds.Height)

            ' This rectangle is in image (logical) coordinates with top-left view perspective
            ' Convert to the physical coordinates of the viewer
            zoneBounds = t.RectangleToPhysical(zoneBounds)

            ' Now draw this zone on the viewer surface
            If (ocrZone.Selected) Then
               e.Graphics.DrawRectangle(selectedPen, zoneBounds.X, zoneBounds.Y, zoneBounds.Width - 1, zoneBounds.Height - 1)
            Else
               e.Graphics.DrawRectangle(normalPen, zoneBounds.X, zoneBounds.Y, zoneBounds.Width - 1, zoneBounds.Height - 1)
            End If

            ' Draw the zone name on the left hand corner of the zone
            ' Note, in a real application you might want to have an option to show/hide the zone names (labels)
            Dim labelSize As SizeF = e.Graphics.MeasureString(ocrZone.Name, Font)
            Dim labelRectangle As New RectangleF(zoneBounds.X, zoneBounds.Y - labelSize.Height, labelSize.Width, labelSize.Height)
            e.Graphics.FillRectangle(Brushes.Yellow, labelRectangle)
            e.Graphics.DrawString(ocrZone.Name, Font, Brushes.Black, labelRectangle.X, labelRectangle.Y)
         Next
      End Using
   End If
End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
Public Const OcrAdvantageRuntimeDir As String = "C:\LEADTOOLS 18\Bin\Common\OcrAdvantageRuntime"
End Class