RasterMarkerMetadata Class

Extends the RasterMetadata class to provide functionality for dealing with marker metadata stored within various image file formats.

Object Model

Syntax

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

[SerializableAttribute()]
public class RasterMarkerMetadata : RasterMetadata

'Declaration
 
<SerializableAttribute()>
Public Class RasterMarkerMetadata 
   Inherits RasterMetadata

'Usage
 
Dim instance As RasterMarkerMetadata

public sealed class RasterMarkerMetadata : RasterMetadata

function Leadtools.RasterMarkerMetadata()

[SerializableAttribute()]
public ref class RasterMarkerMetadata : public RasterMetadata

Remarks

JPEG files contain metadata information in user-defined markers.

The user-defined markers are in the range 0xE0 to 0xFE. These markers can have a maximum size of 0xFFFD, or 65533 bytes.

The markers below 0xE0 are reserved for the encoding of the image and inserting a reserved marker can make a file invalid. Therefore, you should not use reserved markers unless you are well acquainted with markers and image encoding in JPEG files.

TIFF files do not contain markers, however, LEADTOOLS provides a "workaround" for transferring Exif comments from JPEG files to TIFF files, and vice versa. The Exif metadata information from a TIFF file will be loaded as an APP1 marker. Therefore, you can load Exif metadata from an uncompressed file and store it in a compressed Exif file.

You can also take metadata information from a compressed Exif file and store it in an uncompressed Exif file. Please note however, that some information cannot be stored inside uncompressed Exif files. For example, audio data is stored in APP2 markers and there is no built-in support for saving APP2 markers in TIFF files. However, you can still save the audio data yourself, using a custom tag.

Example

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

Public Sub RasterMarkerMetadataExample()
      Dim codecs As RasterCodecs = New RasterCodecs()
      codecs.ThrowExceptionsOnInvalidImages = True

      Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")
      Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1_markers.tif")

      ' Load the image
      Dim image As RasterImage = codecs.Load(srcFileName)
      codecs.Save(image, destFileName, RasterImageFormat.ExifJpeg, 24)

      image.Dispose()

      ' write a marker to the file
      Dim markerWrite As RasterMarkerMetadata = New RasterMarkerMetadata()
      Dim data As Byte() = New Byte(99) {}
      Dim i As Integer = 0
      Do While i < data.Length
         data(i) = CByte(i + 1)
         i += 1
      Loop
      markerWrite.Id = &HE0
      markerWrite.SetData(data)

      Console.WriteLine("Writing the marker")
      codecs.WriteMarker(destFileName, 1, markerWrite)

      ' read the markers from the file and check for ours
      Dim markers As RasterCollection(Of RasterMarkerMetadata) = codecs.ReadMarkers(destFileName)
      Dim markerRead As RasterMarkerMetadata = Nothing
      i = 0
      Do While i < markers.Count AndAlso markerRead Is Nothing
         If markers(i).Id = markerWrite.Id Then
            markerRead = markers(i)
         End If
         i += 1
      Loop

      Debug.Assert(markerRead.Id = markerWrite.Id)
      Dim dataRead As Byte() = markerRead.GetData()
      Dim dataWrite As Byte() = markerWrite.GetData()
      Debug.Assert(dataRead.Length = dataWrite.Length)
      i = 0
      Do While i < dataRead.Length
         Debug.Assert(dataRead(i) = dataWrite(i))
         i += 1
      Loop
   End Sub

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

public void RasterMarkerMetadataExample()
   {
      RasterCodecs codecs = new RasterCodecs();
      codecs.ThrowExceptionsOnInvalidImages = true;

      string srcFileName = Path.Combine(LEAD_VARS.ImagesDir,"Image1.cmp");
      string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_markers.tif");

      // Load the image
      RasterImage image = codecs.Load(srcFileName);
      codecs.Save(image, destFileName, RasterImageFormat.ExifJpeg, 24);

      image.Dispose();

      // write a marker to the file
      RasterMarkerMetadata markerWrite = new RasterMarkerMetadata();
      byte[] data = new byte[100];
      for(int i=0; i < data.Length; i++ )
         data[i] = (byte)(i + 1);
      markerWrite.Id = 0xE0;
      markerWrite.SetData(data);

      Console.WriteLine("Writing the marker");
      codecs.WriteMarker(destFileName, 1, markerWrite);

      // read the markers from the file and check for ours
      RasterCollection<RasterMarkerMetadata> markers = codecs.ReadMarkers(destFileName);
      RasterMarkerMetadata markerRead = null;
      for(int i = 0; i < markers.Count && markerRead == null; i++)
      {
         if(markers[i].Id == markerWrite.Id)
            markerRead = markers[i];
      }

      Debug.Assert(markerRead.Id == markerWrite.Id);
      byte[] dataRead = markerRead.GetData();
      byte[] dataWrite = markerWrite.GetData();
      Debug.Assert(dataRead.Length == dataWrite.Length);
      for(int i = 0; i < dataRead.Length; i++)
         Debug.Assert(dataRead[i] == dataWrite[i]);
   }

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

RasterMarkerMetadataExamples.prototype.RasterMarkerMetadataExample = function ( )
{
    Tools.SetLicense ( ) ;
    with ( Leadtools ) { with ( Leadtools.Codecs ) { 
        var codecs = new RasterCodecs();
        codecs.throwExceptionsOnInvalidImages = true;

        var srcFileName = "Assets\\Image1.cmp";
        var destFileName = "Image1_markers.tif";
        var image;
        var saveFile;
        var markerWrite = new RasterMarkerMetadata();
        // Load the image
        return Tools.AppInstallFolder().getFileAsync(srcFileName).then ( function ( loadFile ) {
            return codecs.loadAsync(LeadStreamFactory.create(loadFile))})
            .then ( function ( img ) {
                image = img;
                //Save the file as exif
                return Tools.AppLocalFolder().createFileAsync(destFileName)})
            .then(function (sfile) {
                saveFile = sfile;
                return codecs.saveAsync(image, LeadStreamFactory.create(saveFile), RasterImageFormat.exifJpeg, 24)})
            .then ( function ( ) {

                image.close();

                // write a marker to the file
                
                var data = new Array(100);
                for(var  i=0; i < data.length; i++ )
                    data[i] = (i + 1);
                markerWrite.id = 0xE0;
                markerWrite.setData(data);

                console.info("Writing the marker");
                return codecs.writeMarkerAsync(LeadStreamFactory.create(saveFile), 1, markerWrite)})
            .then ( function ( ) {
         
                // read the markers from the file and check for ours
                return codecs.readMarkersAsync(LeadStreamFactory.create(saveFile))})
            .then ( function ( markers ) {
                var markerRead = null;
                for(var i = 0; i < markers.size && markerRead == null; i++)
                {
                    if(markers[i].id == markerWrite.id)
                        markerRead = markers[i];
                }

                console.assert(markerRead.id == markerWrite.id, "markerRead.id == markerWrite.id");
                var dataRead = markerRead.getData();
                var dataWrite = markerWrite.getData();
                console.assert(dataRead.length == dataWrite.length, "dataRead.length == dataWrite.length");

                for(var i = 0; i < dataRead.length; i++)
                    console.assert (dataRead[i] == dataWrite[i], "dataRead[i] == dataWrite[i]");
            });
    }
    }
}

[TestMethod]
public async Task RasterMarkerMetadataExample()
{
   RasterCodecs codecs = new RasterCodecs();
   codecs.ThrowExceptionsOnInvalidImages = true;
   string srcFileName = @"Assets\Image1.cmp";
   string destFileName = @"Image1_markers.tif";

   // Load the image
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName);
   RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile));

   //Save the file as exif
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(destFileName);
   await codecs.SaveAsync(image, LeadStreamFactory.Create(saveFile), RasterImageFormat.ExifJpeg, 24);

   image.Dispose();

   // write a marker to the file
   RasterMarkerMetadata markerWrite = new RasterMarkerMetadata();
   byte[] data = new byte[100];
   for(int i=0; i < data.Length; i++ )
      data[i] = (byte)(i + 1);
   markerWrite.Id = 0xE0;
   markerWrite.SetData(data);

   Debug.WriteLine("Writing the marker");
   await codecs.WriteMarkerAsync(LeadStreamFactory.Create(saveFile), 1, markerWrite);

   // read the markers from the file and check for ours
   IList<RasterMarkerMetadata> markers = await codecs.ReadMarkersAsync(LeadStreamFactory.Create(saveFile));
   RasterMarkerMetadata markerRead = null;
   for(int i = 0; i < markers.Count && markerRead == null; i++)
   {
      if(markers[i].Id == markerWrite.Id)
         markerRead = markers[i];
   }

   Assert.IsTrue(markerRead.Id == markerWrite.Id);
   byte[] dataRead = markerRead.GetData();
   byte[] dataWrite = markerWrite.GetData();
   Assert.IsTrue(dataRead.Length == dataWrite.Length);
   for(int i = 0; i < dataRead.Length; i++)
      Assert.IsTrue(dataRead[i] == dataWrite[i]);
}

public void RasterMarkerMetadataExample(RasterImage image, Stream destStream)
{
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, destStream, RasterImageFormat.ExifJpeg, 24);
   image.Dispose();

   // write a marker to the file
   RasterMarkerMetadata markerWrite = new RasterMarkerMetadata();
   byte[] data = new byte[100];
   for(int i=0; i < data.Length; i++ )
      data[i] = (byte)(i + 1);
   markerWrite.Id = 0xE0;
   markerWrite.SetData(data);

   Console.WriteLine("Writing the marker");
   codecs.WriteMarker(destStream, 1, markerWrite);

   // read the markers from the file and check for ours
   RasterCollection<RasterMarkerMetadata> markers = codecs.ReadMarkers(destStream);
   RasterMarkerMetadata markerRead = null;
   for(int i = 0; i < markers.Count && markerRead == null; i++)
   {
      if(markers[i].Id == markerWrite.Id)
         markerRead = markers[i];
   }

   Debug.Assert(markerRead.Id == markerWrite.Id);
   byte[] dataRead = markerRead.GetData();
   byte[] dataWrite = markerWrite.GetData();
   Debug.Assert(dataRead.Length == dataWrite.Length);
   for(int i = 0; i < dataRead.Length; i++)
      Debug.Assert(dataRead[i] == dataWrite[i]);
}

Public Sub RasterMarkerMetadataExample(ByVal image As RasterImage, ByVal destStream As Stream)
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, destStream, RasterImageFormat.ExifJpeg, 24)
   image.Dispose()

   ' write a marker to the file
   Dim markerWrite As RasterMarkerMetadata = New RasterMarkerMetadata()
   Dim data As Byte() = New Byte(99){}
   Dim i As Integer=0
   Do While i < data.Length
      data(i) = CByte(i + 1)
      i += 1
   Loop
   markerWrite.Id = &HE0
   markerWrite.SetData(data)

   Console.WriteLine("Writing the marker")
   codecs.WriteMarker(destStream, 1, markerWrite)

   ' read the markers from the file and check for ours
   Dim markers As RasterCollection(Of RasterMarkerMetadata) = codecs.ReadMarkers(destStream)
   Dim markerRead As RasterMarkerMetadata = Nothing
   i = 0
   Do While i < markers.Count AndAlso markerRead Is Nothing
      If markers(i).Id = markerWrite.Id Then
         markerRead = markers(i)
      End If
      i += 1
   Loop

   Debug.Assert(markerRead.Id = markerWrite.Id)
   Dim dataRead As Byte() = markerRead.GetData()
   Dim dataWrite As Byte() = markerWrite.GetData()
   Debug.Assert(dataRead.Length = dataWrite.Length)
   i = 0
   Do While i < dataRead.Length
      Debug.Assert(dataRead(i) = dataWrite(i))
      i += 1
   Loop
End Sub

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

Reference

RasterMarkerMetadata Members
Leadtools Namespace