StartOverlay Method

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public void StartOverlay( 
   CodecsOverlayCallback callback,
   CodecsOverlayCallbackMode mode
)

'Declaration
 
Public Sub StartOverlay( _
   ByVal callback As CodecsOverlayCallback, _
   ByVal mode As CodecsOverlayCallbackMode _
)

'Usage
 
Dim instance As RasterCodecs
Dim callback As CodecsOverlayCallback
Dim mode As CodecsOverlayCallbackMode
 
instance.StartOverlay(callback, mode)

public void StartOverlay( 
   CodecsOverlayCallback callback,
   CodecsOverlayCallbackMode mode
)

 function Leadtools.Codecs.RasterCodecs.StartOverlay( 
   callback ,
   mode 
)

public:
void StartOverlay( 
   CodecsOverlayCallback^ callback,
   CodecsOverlayCallbackMode mode
)

Parameters

callback: The method which should be called when an overlay is detected. Use a null reference (Nothing in Visual Basic) to indicate that LEADTOOLS should handle overlays automatically.
mode: Indicates when should this method be called. See CodecsOverlayCallbackMode for possible values.

Currently, only PTOCA files are known to use such overlays.

PTOCA files contain file references (i.e. filenames) to external files that contain overlay bitmaps. (These files are typically in IOCA format)

These external overlay files will be resized and placed on the current page according to the information from the PTOCA files. By default, LEADTOOLS will load these external overlay files from disk. You should override this behavior if you load files that are not stored locally (for example, on a remote storage or in a database).

To load overlays stored on other storage, you have to pass your overlay callback to this method and load the overlays in your overlay callback.

The overlay callback will be used until StopOverlay is called.

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Private Sub PtokaOverlayExample(ByVal ptokaFileName As String, ByVal ptokaFilesPath As String)
      Dim codecs As RasterCodecs = New RasterCodecs()
      Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "PtokaOverlay.tif")

      ' Set up the private variables used in the callback
      myCodecs = codecs
      myPtokaFilesPath = ptokaFilesPath

      ' Set the overlay callback
      codecs.StartOverlay(AddressOf MyOverlayCallback, CodecsOverlayCallbackMode.CallLoad)

      ' Load the PTOKA file
      Dim image As RasterImage = codecs.Load(ptokaFileName)

      ' Stop the overlay by resetting the old callback.
      codecs.StopOverlay()

      ' Save the image as TIFF
      codecs.Save(image, destFileName, RasterImageFormat.Tif, 1)
      image.Dispose()

      ' Clean up
      codecs.Dispose()
   End Sub

   Private myCodecs As RasterCodecs
   Private myPtokaFilesPath As String

   Private Sub MyOverlayCallback(ByVal data As CodecsOverlayData)
      ' Show overlay information
      Console.WriteLine("File: {0}", data.FileName)
      Console.WriteLine("Page Number: {0}", data.PageNumber)
      Console.WriteLine("Info: {0}", data.Info)

      ' Construct the overlay file name
      Dim overlayFileName As String = Path.Combine(myPtokaFilesPath, data.FileName)

      If data.Info Then
         ' Info, we only need to fill in the .InfoXXX members of the data
         Dim imageInfo As CodecsImageInfo = myCodecs.GetInformation(overlayFileName, False)
         data.InfoWidth = imageInfo.Width
         data.InfoHeight = imageInfo.Height
         data.InfoXResolution = imageInfo.XResolution
         data.InfoYResolution = imageInfo.YResolution
      Else
         ' We need to load the overlay image into the .Image member
         data.Image = myCodecs.Load(overlayFileName)
      End If
   End Sub

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

void PtokaOverlayExample(string ptokaFileName, string ptokaFilesPath)
     {
         RasterCodecs codecs = new RasterCodecs();
         string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "PtokaOverlay.tif");

         // Set up the private variables used in the callback
         myCodecs = codecs;
         myPtokaFilesPath = ptokaFilesPath;

         // Set the overlay callback
         codecs.StartOverlay(MyOverlayCallback, CodecsOverlayCallbackMode.CallLoad);

         // Load the PTOKA file
         RasterImage image = codecs.Load(ptokaFileName);

         // Stop the overlay by resetting the old callback.
         codecs.StopOverlay();

         // Save the image as TIFF
         codecs.Save(image, destFileName, RasterImageFormat.Tif, 1);
         image.Dispose();

         // Clean up
         codecs.Dispose();
     }

     RasterCodecs myCodecs;
     string myPtokaFilesPath;

     void MyOverlayCallback(CodecsOverlayData data)
     {
         // Show overlay information
         Console.WriteLine("File: {0}", data.FileName);
         Console.WriteLine("Page Number: {0}", data.PageNumber);
         Console.WriteLine("Info: {0}", data.Info);

         // Construct the overlay file name
         string overlayFileName = Path.Combine(myPtokaFilesPath, data.FileName);

         if (data.Info)
         {
             // Info, we only need to fill in the .InfoXXX members of the data
             CodecsImageInfo imageInfo = myCodecs.GetInformation(overlayFileName, false);
             data.InfoWidth = imageInfo.Width;
             data.InfoHeight = imageInfo.Height;
             data.InfoXResolution = imageInfo.XResolution;
             data.InfoYResolution = imageInfo.YResolution;
         }
         else
         {
             // We need to load the overlay image into the .Image member
             data.Image = myCodecs.Load(overlayFileName);
         }
     }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

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

Reference

RasterCodecs Class
RasterCodecs Members