Highlight a region in PDF or an image in VB.NET

This example shows how to draw highlighted regions on top of a document. A highlighted region is a special feature that’s modifiable by mouse. It can be used to specify areas and highlight them, and it’s especially useful in anchor and OMR applications.

VB.NET
 
'We assume that GdPicture has been correctly installed and unlocked.
'We assume the GdViewer object called GdViewer1 has been created and painted on the form.
Dim oGdPictureImaging As New GdPictureImaging
'Loading the image from a file.
Dim imageId As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("C:\\Image.tif")
'Checking if the image resource has been loaded correctly.
If oGdPictureImaging.GetStat() <> GdPictureStatus.OK
   MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Drawing regions Example", MessageBoxButtons.OK, MessageBoxIcon.Error)
Else
   'Displaying the image in the GdViewer.
   GdViewer1.DisplayFromGdPictureImage(imageId)
End If
oGdPictureImaging.Dispose()


'On the Mouse UP event on the GdViewer, create a highlighted region based on the rectangle of selection of the GdViewer.
'If no rectangle of selection is painted on the GdViewer, this event will do nothing.
Public Sub Draw_Region(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles GdViewer1.MouseUp
   'Initializing variables to hold the position of the rectangle of selection on the document.
   Dim leftArea As Integer, topArea As Integer, widthArea As Integer, heightArea As Integer
   'Checking if a rectangle of selection has been painted on the GdViewer.
   If GdViewer1.IsRect() Then
      'Getting the location of the selection on the document.
      GdViewer1.GetRectCoordinatesOnDocument(leftArea, topArea, widthArea, heightArea)
      'Setting the ROI on the document:
      'Adding a region in place of the rectangle of selection.
      Dim regionId As Integer = GdViewer1.AddRegion("Region", leftArea, topArea, widthArea, heightArea, GdPicture14.ForegroundMixMode.ForegroundMixModeMASKPEN, Color.Green)
      'Setting region border width.
      GdViewer1.SetRegionBorderWidth(regionId, 1)
      'Setting region border color.
      GdViewer1.SetRegionBorderColor(regionId, Color.Blue)
      'Redrawing the whole image.
      GdViewer1.ClearRect()
      GdViewer1.Redraw()
   End If
End Sub

This code sample is an example that illustrates how to use our SDK. Please adapt it to your specific use case.