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RasterCommentMetadata Class
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Leadtools Namespace : RasterCommentMetadata Class



Extends the RasterMetadata class to provide functionality for dealing with comment metadata stored within various image file formats. Supported in Silverlight, Windows Phone 7

Object Model

RasterCommentMetadata Class

Syntax

Visual Basic (Declaration) 
<SerializableAttribute()>
Public Class RasterCommentMetadata 
   Inherits RasterMetadata
Visual Basic (Usage)Copy Code
Dim instance As RasterCommentMetadata
C# 
[SerializableAttribute()]
public class RasterCommentMetadata : RasterMetadata
C++/CLI 
[SerializableAttribute()]
public ref class RasterCommentMetadata : public RasterMetadata

Example

This example will write comments of different data types to an existing tif file then read them as a test.

Visual BasicCopy Code
Public Sub RasterCommentMetadataExample()
      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_comments.tif")

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

      image.Dispose()

      ' Write some comments to the existing tif file
      Dim comment As RasterCommentMetadata = New RasterCommentMetadata()
      comment.Type = RasterCommentMetadataType.Artist
      Dim artistNameWrite As String = "Artist name"
      comment.FromAscii(artistNameWrite)
      Console.WriteLine("Writing Artist")
      codecs.WriteComment(destFileName, 1, comment)

      comment.Type = RasterCommentMetadataType.GpsLatitude
      Dim rationalsWrite As RasterMetadataRational() = New RasterMetadataRational(2) {}
      Dim i As Integer = 0
      Do While i < rationalsWrite.Length
         rationalsWrite(i) = New RasterMetadataRational(i + 3, i + 2)
         i += 1
      Loop

      comment.FromRational(rationalsWrite)
      Console.WriteLine("Writing GpsLatitude")
      codecs.WriteComment(destFileName, 1, comment)

      ' Now read the comments from the tif file

      ' read ASCII
      comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.Artist)
      Dim artistNameRead As String = comment.ToAscii()
      Console.WriteLine("Artist: {0}", artistNameRead)
      Debug.Assert(artistNameRead = artistNameWrite)

      ' read rationals
      comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.GpsLatitude)
      Dim rationalsRead As RasterMetadataRational() = comment.ToRational()

      Dim size As Integer = rationalsRead.Length
      Console.WriteLine("GpsLatitude: size = {0} ", size)
      i = 0
      Do While i < size
         Console.WriteLine("{0}/{1}", rationalsRead(i).Numerator, rationalsRead(i).Denominator)
         i += 1
      Loop

      Debug.Assert(rationalsRead.Length = rationalsWrite.Length)
      i = 0
      Do While i < rationalsRead.Length
         Debug.Assert(rationalsRead(i).Numerator = rationalsWrite(i).Numerator)
         Debug.Assert(rationalsRead(i).Denominator = rationalsWrite(i).Denominator)
         i += 1
      Loop
   End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class
C#Copy Code
public void RasterCommentMetadataExample()
   {
      RasterCodecs codecs = new RasterCodecs();
      codecs.ThrowExceptionsOnInvalidImages = true;

      string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp");
      string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_comments.tif");

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

      image.Dispose();

      // Write some comments to the existing tif file
      RasterCommentMetadata comment = new RasterCommentMetadata();
      comment.Type = RasterCommentMetadataType.Artist;
      string artistNameWrite = "Artist name";
      comment.FromAscii(artistNameWrite);
      Console.WriteLine("Writing Artist");
      codecs.WriteComment(destFileName, 1, comment);

      comment.Type = RasterCommentMetadataType.GpsLatitude;
      RasterMetadataRational[] rationalsWrite = new RasterMetadataRational[3];
      for(int i = 0; i < rationalsWrite.Length; i++)
         rationalsWrite[i] = new RasterMetadataRational(i + 3, i + 2);

      comment.FromRational(rationalsWrite);
      Console.WriteLine("Writing GpsLatitude");
      codecs.WriteComment(destFileName, 1, comment);

      // Now read the comments from the tif file

      // read ASCII
      comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.Artist);
      string artistNameRead = comment.ToAscii();
      Console.WriteLine("Artist: {0}", artistNameRead);
      Debug.Assert(artistNameRead == artistNameWrite);

      // read rationals
      comment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.GpsLatitude);
      RasterMetadataRational[] rationalsRead = comment.ToRational();

      int size = rationalsRead.Length;
      Console.WriteLine("GpsLatitude: size = {0} ", size);
      for(int i = 0; i < size; i++)
         Console.WriteLine("{0}/{1}", rationalsRead[i].Numerator, rationalsRead[i].Denominator);

      Debug.Assert(rationalsRead.Length == rationalsWrite.Length);
      for(int i = 0; i < rationalsRead.Length; i++)
      {
         Debug.Assert(rationalsRead[i].Numerator == rationalsWrite[i].Numerator);
         Debug.Assert(rationalsRead[i].Denominator == rationalsWrite[i].Denominator);
      }
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
SilverlightCSharpCopy Code
public void RasterCommentMetadataExample(RasterImage image, Stream destStream)
{
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, destStream, RasterImageFormat.Tif, 24);
   image.Dispose();
   // Write some comments to the existing tif file
   RasterCommentMetadata comment = new RasterCommentMetadata();
   comment.Type = RasterCommentMetadataType.Artist;
   string artistNameWrite = "Artist name";
   comment.FromAscii(artistNameWrite);
   Debug.WriteLine("Writing Artist");
   codecs.WriteComment(destStream, 1, comment);

   comment.Type = RasterCommentMetadataType.GpsLatitude;
   RasterMetadataRational[] rationalsWrite = new RasterMetadataRational[3];
   for(int i = 0; i < rationalsWrite.Length; i++)
      rationalsWrite[i] = new RasterMetadataRational(i + 3, i + 2);

   comment.FromRational(rationalsWrite);
   Debug.WriteLine("Writing GpsLatitude");
   codecs.WriteComment(destStream, 1, comment);

   // Now read the comments from the tif file

   // read ASCII
   comment = codecs.ReadComment(destStream, 1, RasterCommentMetadataType.Artist);
   string artistNameRead = comment.ToAscii();
   Debug.WriteLine("Artist: {0}", artistNameRead);
   Debug.Assert(artistNameRead == artistNameWrite);

   // read rationals
   comment = codecs.ReadComment(destStream, 1, RasterCommentMetadataType.GpsLatitude);
   RasterMetadataRational[] rationalsRead = comment.ToRational();

   int size = rationalsRead.Length;
   Debug.WriteLine("GpsLatitude: size = {0} ", size);
   for(int i = 0; i < size; i++)
      Debug.WriteLine("{0}/{1}", rationalsRead[i].Numerator, rationalsRead[i].Denominator);

   Debug.Assert(rationalsRead.Length == rationalsWrite.Length);
   for(int i = 0; i < rationalsRead.Length; i++)
   {
      Debug.Assert(rationalsRead[i].Numerator == rationalsWrite[i].Numerator);
      Debug.Assert(rationalsRead[i].Denominator == rationalsWrite[i].Denominator);
   }
}
SilverlightVBCopy Code
Public Sub RasterCommentMetadataExample(ByVal image As RasterImage, ByVal destStream As Stream)
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, destStream, RasterImageFormat.Tif, 24)
   image.Dispose()
   ' Write some comments to the existing tif file
   Dim comment As RasterCommentMetadata = New RasterCommentMetadata()
   comment.Type = RasterCommentMetadataType.Artist
   Dim artistNameWrite As String = "Artist name"
   comment.FromAscii(artistNameWrite)
   Debug.WriteLine("Writing Artist")
   codecs.WriteComment(destStream, 1, comment)

   comment.Type = RasterCommentMetadataType.GpsLatitude
   Dim rationalsWrite As RasterMetadataRational() = New RasterMetadataRational(2){}
   Dim i As Integer = 0
   Do While i < rationalsWrite.Length
      rationalsWrite(i) = New RasterMetadataRational(i + 3, i + 2)
      i += 1
   Loop

   comment.FromRational(rationalsWrite)
   Debug.WriteLine("Writing GpsLatitude")
   codecs.WriteComment(destStream, 1, comment)

   ' Now read the comments from the tif file

   ' read ASCII
   comment = codecs.ReadComment(destStream, 1, RasterCommentMetadataType.Artist)
   Dim artistNameRead As String = comment.ToAscii()
   Debug.WriteLine("Artist: {0}", artistNameRead)
   Debug.Assert(artistNameRead = artistNameWrite)

   ' read rationals
   comment = codecs.ReadComment(destStream, 1, RasterCommentMetadataType.GpsLatitude)
   Dim rationalsRead As RasterMetadataRational() = comment.ToRational()

   Dim size As Integer = rationalsRead.Length
   Debug.WriteLine("GpsLatitude: size = {0} ", size)
   i = 0
   Do While i < size
      Debug.WriteLine("{0}/{1}", rationalsRead(i).Numerator, rationalsRead(i).Denominator)
      i += 1
   Loop

   Debug.Assert(rationalsRead.Length = rationalsWrite.Length)
   i = 0
   Do While i < rationalsRead.Length
      Debug.Assert(rationalsRead(i).Numerator = rationalsWrite(i).Numerator)
      Debug.Assert(rationalsRead(i).Denominator = rationalsWrite(i).Denominator)
      i += 1
   Loop
End Sub

Remarks

The TIFF file formats support a number of comments that are saved and loaded using predefined tags.

If the comments do not meet your needs, you can define your own tag for saving additional non-raster data in a TIFF file. For example, you may want to define a tag to save annotations.

The TIFF 6.0 Specification sets aside a range of private tags that developers can define. To avoid conflicts with files created by other developers, you can register your tag by contacting Adobe Developer Relations. The E-Mail address posted on The Unofficial TIFF Home Page is gapdevsup@adobe.com.

Some restrictions apply to this function if you use an IFD to indicate to which page to write the metadata. See the Loading And Saving Large TIFF Files topic for more information.

Inheritance Hierarchy

System.Object
   Leadtools.RasterMetadata
      Leadtools.RasterCommentMetadata

Requirements

Target Platforms: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only), Windows Phone 7

See Also