LEADTOOLS OCR (Leadtools.Forms.Ocr assembly)
LEAD Technologies, Inc

HitTestZone Method

Example 





The test point in pixels.
Gets the zero-based index of the zone under a certain point. WinRT support
Syntax
int HitTestZone( 
   LeadPoint point
)
'Declaration
 
Function HitTestZone( _
   ByVal point As LeadPoint _
) As Integer
'Usage
 
Dim instance As IOcrPage
Dim point As LeadPoint
Dim value As Integer
 
value = instance.HitTestZone(point)
int HitTestZone( 
   LeadPoint point
)
function Leadtools.Forms.Ocr.IOcrPage.HitTestZone( 
   point 
)
int HitTestZone( 
   LeadPoint point
) 

Parameters

point
The test point in pixels.

Return Value

The zero-based index of the zone under point, if no zone is under the test point, this method will return -1.
Remarks

You can use this method to check whether a zone (either added manually or automatically) is under a given test point. For example, if you have a Windows Forms based application with the current IOcrPage in a Leadtools.WinForms.RasterImageViewer control. You might want to draw the zones on the surface of the viewer. For this, you can use the GetZoneBoundsInPixels methods. If you want to allow the user to click with the mouse on the viewer to select and de-select zones, you can use HitTestZone.

Example
Copy CodeCopy Code  
' 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.Plus, False)
         _ocrEngine.Startup(Nothing, Nothing, Nothing, Nothing)

         ' 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"
End Class
// Assume Form1 is a Windwos.Forms form in your application
      // The OCR engine we are using
      private IOcrEngine _ocrEngine;
      // The document we are using
      private IOcrDocument _ocrDocument;

      // Our raster image viewer instance
      private RasterImageViewer _viewer;

      public Form1()
      {
         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
         RasterPaintProperties props = _viewer.PaintProperties;
         props.PaintDisplayMode |= RasterPaintDisplayModeFlags.ScaleToGray;
         _viewer.PaintProperties = props;

         // Subscribe to the viewer events we need
         _viewer.KeyDown += new KeyEventHandler(_viewer_KeyDown);
         _viewer.MouseDown += new MouseEventHandler(_viewer_MouseDown);
         _viewer.PostImagePaint += new PaintEventHandler(_viewer_PostImagePaint);

         Controls.Add(_viewer);
         _viewer.BringToFront();

         // Create and startup the OCR engine
         _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Plus, false);
         _ocrEngine.Startup(null, null, null, null);

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

         // Load an image into the OCR document
         string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif");
         IOcrPage ocrPage = _ocrDocument.Pages.AddPage(tifFileName, null);

         // Do auto zone
         ocrPage.AutoZone(null);

         // 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
         IOcrZoneCollection ocrZones = ocrPage.Zones;
         for(int i = 0; i < ocrZones.Count; i++)
         {
            OcrZone ocrZone = ocrZones[i];

            // Construct the name from the ID
            ocrZone.Name = string.Format("Zone {0}", ocrZone.Id);

            ocrZones[i] = ocrZone;
         }

         // 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";
      }

      protected override void OnFormClosed(FormClosedEventArgs e)
      {
         // Dispose the document
         _ocrDocument.Dispose();

         // Shutdown the OCR engine
         _ocrEngine.Shutdown();
         _ocrEngine.Dispose();

         base.OnFormClosed(e);
      }

      private void _viewer_KeyDown(object sender, KeyEventArgs e)
      {
         const double zoomRatio = 1.2;
         double scaleFactor = _viewer.ScaleFactor;

         switch(e.KeyCode)
         {
            case Keys.Add:
            case Keys.Oemplus:
               // Zoon in
               scaleFactor *= zoomRatio;
               e.Handled = true;
               break;

            case Keys.Subtract:
            case Keys.OemMinus:
               // Zone out
               scaleFactor /= zoomRatio;
               e.Handled = true;
               break;

            case Keys.Enter:
               scaleFactor = 1;
               e.Handled = true;
               break;
         }

         const double minimumScaleFactor = 0.05;
         const double maximumScaleFactor = 11;

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

         // Check if scale factor has changed
         if(scaleFactor != _viewer.ScaleFactor)
         {
            _viewer.BeginUpdate();

            // Yes, zoom keeping the center of the image

            // Get what you see in physical coordinates
            Rectangle rc = Rectangle.Intersect(_viewer.PhysicalViewRectangle, _viewer.ClientRectangle);
            // Get the center of what you see in physical coordinates
            PointF center = new PointF(rc.Left + rc.Width / 2, rc.Top + rc.Height / 2);
            Transformer t = 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();
         }
      }

      private void _viewer_MouseDown(object sender, MouseEventArgs e)
      {
         // Perform hit-testing on the zones
         if(_ocrEngine != null && _ocrEngine.IsStarted && _ocrDocument != null && _ocrDocument.Pages.Count > 0 && e.Button == MouseButtons.Left)
         {
            // Get the transform of the viewer
            // Use the transform that takes the DPI into consideration since we turned that on
            using(Matrix matrix = _viewer.GetTransformWithDpi())
            {
               Transformer t = new Transformer(matrix);

               // Convert the mouse click coordinates from physical (viewer) to logical (image)
               PointF point = 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.
               IOcrPage ocrPage = _ocrDocument.Pages[0];

               LeadPoint lPoint = new LeadPoint((int)point.X, (int)point.Y);
               int zoneIndex = ocrPage.HitTestZone(new LogicalPoint(lPoint));
               if(zoneIndex != -1)
               {
                  // We hit a zone, loop through all the zones, unselect all but the hit tested zone
                  for(int index = 0; index < ocrPage.Zones.Count; index++)
                  {
                     // 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

                     OcrZone ocrZone = ocrPage.Zones[index];

                     if(index != zoneIndex)
                        ocrZone.Selected = false;
                     else
                        ocrZone.Selected = true;

                     ocrPage.Zones[index] = ocrZone;
                  }

                  // Re-paint the viewer to show the new zones
                  _viewer.Invalidate();
               }
            }
         }
      }

      private void _viewer_PostImagePaint(object sender, PaintEventArgs e)
      {
         // Draw the zones on the viewer in their correct location
         if(_ocrEngine != null && _ocrEngine.IsStarted && _ocrDocument != null && _ocrDocument.Pages.Count > 0)
         {
            // Get the transform of the viewer
            // Use the transform that takes the DPI into consideration since we turned that on
            using(Matrix matrix = _viewer.GetTransformWithDpi())
            {
               Transformer t = new Transformer(matrix);

               IOcrPage ocrPage = _ocrDocument.Pages[0];

               Pen normalPen = new Pen(Color.Blue, 1);
               Pen selectedPen = new Pen(Color.Red, 2);
               selectedPen.DashStyle = DashStyle.Dash;

               foreach(OcrZone ocrZone in ocrPage.Zones)
               {
                  // Get the zone bounds in pixels
                  // You can also use ocrPage.GetZoneBoundsInPixels here
                  LeadRect ltzoneBounds = ocrZone.Bounds.ToRectangle(ocrPage.DpiX, ocrPage.DpiY);
                  RectangleF zoneBounds = 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)
                     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);

                  // 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)
                  SizeF labelSize = e.Graphics.MeasureString(ocrZone.Name, Font);
                  RectangleF labelRectangle = 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);
               }
            }
         }
      }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
// Assume MainPage is a Windows.UI.Xaml.Controls.Page in your application
// Assume this is your main page canvas
private Canvas _canvas = null;

// The OCR engine we are using
private IOcrEngine _ocrEngine;
// The document we are using
private IOcrDocument _ocrDocument;

// Our raster image viewer instance
private RasterImageViewer _viewer = null;

public MainPage()
{
   InitializeComponent();

   _viewer.ImageHorizontalAlignment = ControlAlignment.Center;
   _viewer.ImageVerticalAlignment = ControlAlignment.Center;
   _viewer.Background = new SolidColorBrush(Windows.UI.Color.FromArgb(255, 255, 255, 255));
   _viewer.AutoDisposeImages = true;

   // Subscribe to the viewer events we need
   _viewer.PointerPressed += _viewer_PointerPressed;
   _viewer.TransformChanged += _viewer_TransformChanged;
   _viewer.Loaded += _viewer_Loaded;

   _canvas.Children.Add(_viewer);
}

private async void _viewer_Loaded(object sender, RoutedEventArgs e)
{
   // Create and startup the OCR engine
   _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);
   _ocrEngine.Startup(null, null, String.Empty, Tools.OcrEnginePath);

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

   // Load an image into the OCR document
   IOcrPage ocrPage = null;
   string tifFileName = @"Assets\Ocr1.tif";
   using (RasterCodecs codecs = new RasterCodecs())
   {
      StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(tifFileName);
      using (RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile)))
         ocrPage = _ocrDocument.Pages.AddPage(image, null);
   }

   // Do auto zone
   ocrPage.AutoZone(null);

   // 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
   IOcrZoneCollection ocrZones = ocrPage.Zones;
   for (int i = 0; i < ocrZones.Count; i++)
   {
      OcrZone ocrZone = ocrZones[i];

      // Construct the name from the ID
      ocrZone.Name = string.Format("Zone {0}", ocrZone.Id);

      ocrZones[i] = ocrZone;
   }

   // 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 the AutoDisposeImages of the viewer to "true", the image will be disposed
   // when the viewer is disposed at application termination
   this.Name = "+ to zoom in, - to zoom out, enter to return to 100%. Select the zones with the mouse";
}

protected override void OnNavigatedFrom(NavigationEventArgs e)
{
   // Shutdown the OCR engine
   _ocrEngine.Shutdown();

   base.OnNavigatedFrom(e);
}

private void _viewer_PointerPressed(object sender, PointerRoutedEventArgs e)
{
   // Perform hit-testing on the zones
   if(_ocrEngine != null && _ocrEngine.IsStarted && _ocrDocument != null && _ocrDocument.Pages.Count > 0)
   {
      PointerPoint pp = e.GetCurrentPoint(_viewer);
      LeadPointD leadPointD = LeadPointDHelper.Create(pp.Position.X, pp.Position.Y);
      LeadMatrix matrix = new LeadMatrix(_viewer.Transform.M11, _viewer.Transform.M12,
         _viewer.Transform.M21, _viewer.Transform.M22,
         _viewer.Transform.OffsetX, _viewer.Transform.OffsetY);

      leadPointD = matrix.TransformPoint(leadPointD);

      // 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.
      IOcrPage ocrPage = _ocrDocument.Pages[0];

      LeadPoint lPoint = LeadPointHelper.Create((int)leadPointD.X, (int)leadPointD.Y);
      int zoneIndex = ocrPage.HitTestZone(lPoint);
      if(zoneIndex != -1)
      {
         // We hit a zone, loop through all the zones, unselect all but the hit tested zone
         for(int index = 0; index < ocrPage.Zones.Count; index++)
         {
            // 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
            OcrZone ocrZone = ocrPage.Zones[index];

            if(index != zoneIndex)
               ocrZone.Selected = false;
            else
               ocrZone.Selected = true;

            ocrPage.Zones[index] = ocrZone;
         }

         // Re-paint the viewer to show the new zones
         _viewer.Invalidate();
      }
   }
}

void _viewer_TransformChanged(object sender, EventArgs e)
{
   // Draw the zones on the viewer in their correct location
   if (_ocrEngine != null && _ocrEngine.IsStarted && _ocrDocument != null && _ocrDocument.Pages.Count > 0)
   {
      IOcrPage ocrPage = _ocrDocument.Pages[0];

      foreach (OcrZone ocrZone in ocrPage.Zones)
      {
         // Get the zone bounds
         LeadRectD ltzoneBounds = new LeadRectD
         {
            X = ocrZone.Bounds.X,
            Y = ocrZone.Bounds.Y,
            Height = ocrZone.Bounds.Height,
            Width = ocrZone.Bounds.Width,
         };

         LeadMatrix matrix = new LeadMatrix(_viewer.Transform.M11, _viewer.Transform.M12,
            _viewer.Transform.M21, _viewer.Transform.M22,
            _viewer.Transform.OffsetX, _viewer.Transform.OffsetY);

         ltzoneBounds = matrix.TransformRect(ltzoneBounds);

         SolidColorBrush normalBrush = new SolidColorBrush(Windows.UI.Color.FromArgb(255, 255, 0, 0));
         SolidColorBrush selectedBrush = new SolidColorBrush(Windows.UI.Color.FromArgb(255, 255, 0, 0));

         Rectangle rect = new Rectangle
         {
            Width = ltzoneBounds.Width,
            Height = ltzoneBounds.Height,
            Stroke = (ocrZone.Selected) ? selectedBrush : normalBrush,
            StrokeThickness = (ocrZone.Selected) ? 2 : 1
         };

         _canvas.Children.Add(rect);
         Canvas.SetLeft(rect, ltzoneBounds.X);
         Canvas.SetTop(rect, ltzoneBounds.Y);

         // Add the zone name TextBlock 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)
         TextBlock textBlock = new TextBlock();
         textBlock.Name = ocrZone.Name;
         textBlock.InvalidateMeasure();
         textBlock.RenderTransformOrigin = new Point(ltzoneBounds.X, ltzoneBounds.Y - textBlock.Height);
      }
   }
}
Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

See Also

Reference

IOcrPage Interface
IOcrPage Members
IOcrPageCollection Interface
IOcrZoneCollection Interface
OcrZone Structure
Programming with the LEADTOOLS .NET OCR

 

 


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HitTestZone requires an OCR module license and unlock key. For more information, refer to: Imaging Pro/Document/Medical Features