ReadComment(string,int,RasterCommentMetadataType) Method

Summary

Gets a comment field from a file.

Syntax

Objective-C

C++/CLI

Python

public RasterCommentMetadata ReadComment( 
   string fileName, 
   int pageNumber, 
   RasterCommentMetadataType type 
)

- (nullable LTRasterCommentMetadata *)readCommentFromFile:(NSString *)file  
                                               pageNumber:(NSInteger)pageNumber  
                                                     type:(LTRasterCommentMetadataType)type  
                                                    error:(NSError **)error

public: 
RasterCommentMetadata^ ReadComment(  
   String^ fileName, 
   int pageNumber, 
   RasterCommentMetadataType type 
)

def ReadComment(self,fileName,pageNumber,type):

Parameters

fileName
A String containing the input file name.

pageNumber
1-based index of the page from which to read the comment.

type
The type of comment. Refer to Types of File Comments.

Return Value

A RasterCommentMetadata object containing the comment field information. If no such comment is found in the file, this method will return a null reference.

Remarks

Some file formats can contain comments, and some cannot, and each file format has its own set of comment types. When you save a file, the comments in the RasterImage object can be saved in the file. The index into the array (specified using a constant) determines the type of comment.

You can use CommentsSupported to determine whether a certain file format supports tags.

To read all the comments stored in a file, use ReadComments.

Example

This example demonstrates all of the methods related to comments for TIFF files. It saves a few comments to a file before loading them back

Java

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
 
public void CommentsExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
   string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_Comments.tif"); 
 
   // Convert the source file to TIF 
   Debug.WriteLine("Converting the source file to TIF"); 
   codecs.Convert(srcFileName, destFileName, RasterImageFormat.Tif, 0, 0, 24, null); 
 
   // Add the artist comment 
   RasterCommentMetadata writeComment = new RasterCommentMetadata(); 
   writeComment.Type = RasterCommentMetadataType.Artist; 
   writeComment.FromAscii("LEADTOOLS"); 
 
   Debug.WriteLine("Writing the following comment:"); 
   Debug.WriteLine(" Type:{0}, Data:{1}", writeComment.Type, writeComment.ToAscii()); 
 
   codecs.WriteComment(destFileName, 1, writeComment); 
 
   // Read the comment back 
   RasterCommentMetadata readComment = codecs.ReadComment(destFileName, 1, RasterCommentMetadataType.Artist); 
   Debug.WriteLine("The following comment has been read:"); 
   Debug.WriteLine(" Type:{0}, Data:{1}", readComment.Type, readComment.ToAscii()); 
 
   // Write a few comments to the file in one pass 
   IList<RasterCommentMetadata> comments = new List<RasterCommentMetadata>(); 
   writeComment = new RasterCommentMetadata(); 
   writeComment.Type = RasterCommentMetadataType.Artist; 
   writeComment.FromAscii("LEADTOOLS Again"); 
   comments.Add(writeComment); 
 
   writeComment = new RasterCommentMetadata(); 
   writeComment.Type = RasterCommentMetadataType.Copyright; 
   writeComment.FromAscii("(c) 2006"); 
   comments.Add(writeComment); 
 
   Debug.WriteLine("Writing the following comments to the file:"); 
   foreach (RasterCommentMetadata comment in comments) 
      Debug.WriteLine(" Type:{0}, Data:{1}", comment.Type, comment.ToAscii()); 
 
   codecs.WriteComments(destFileName, 1, comments); 
 
   // Now get all the comments in the file and show them: 
   Debug.WriteLine("Reading all comments from the file:"); 
 
   RasterCommentMetadataType[] tifComments = 
   { 
   RasterCommentMetadataType.Artist, 
   RasterCommentMetadataType.Copyright, 
   RasterCommentMetadataType.DateTime, 
   RasterCommentMetadataType.Description, 
   RasterCommentMetadataType.HostComputer, 
   RasterCommentMetadataType.Make, 
   RasterCommentMetadataType.Model, 
   RasterCommentMetadataType.NameOfDocument, 
   RasterCommentMetadataType.NameOfPage, 
   RasterCommentMetadataType.Software, 
 }; 
 
   foreach (RasterCommentMetadataType tifComment in tifComments) 
   { 
      RasterCommentMetadata comment = codecs.ReadComment(destFileName, 1, tifComment); 
      if (comment != null) 
      { 
         Console.Write("Found comment, Type:{0}, Data:", comment.Type); 
 
         RasterCommentMetadataDataType dataType = RasterCommentMetadata.GetDataType(comment.Type); 
 
         byte[] byteData; 
         short[] shortData; 
         RasterMetadataRational[] rationalData; 
         RasterMetadataURational[] urationalData; 
 
         switch (dataType) 
         { 
            case RasterCommentMetadataDataType.Ascii: 
               Debug.WriteLine(comment.ToAscii()); 
               break; 
 
            case RasterCommentMetadataDataType.Byte: 
               byteData = comment.ToByte(); 
               for (int i = 0; i < byteData.Length; i++) 
                  Console.Write("{0:X} ", byteData[i]); 
               Debug.WriteLine("  "); 
               break; 
 
            case RasterCommentMetadataDataType.Int16: 
               shortData = comment.ToInt16(); 
               for (int i = 0; i < shortData.Length; i++) 
                  Console.Write("{0:X} ", shortData[i]); 
               Debug.WriteLine("  "); 
               break; 
 
            case RasterCommentMetadataDataType.Rational: 
               rationalData = comment.ToRational(); 
               for (int i = 0; i < rationalData.Length; i++) 
                  Console.Write(@"{0}/{1) ", rationalData[i].Numerator, rationalData[i].Denominator); 
               Debug.WriteLine("  "); 
               break; 
 
            case RasterCommentMetadataDataType.URational: 
               urationalData = comment.ToURational(); 
               for (int i = 0; i < urationalData.Length; i++) 
                  Console.Write(@"{0}/{1) ", urationalData[i].Numerator, urationalData[i].Denominator); 
               Debug.WriteLine("  "); 
               break; 
         } 
      } 
   } 
 
   // Clean up 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
}

 
import java.io.*; 
import java.net.*; 
import java.nio.file.Paths; 
import java.util.*; 
import java.time.Instant; 
import java.time.Duration; 
 
import org.junit.*; 
import org.junit.runner.JUnitCore; 
import org.junit.runner.Result; 
import org.junit.runner.notification.Failure; 
import static org.junit.Assert.*; 
 
import leadtools.*; 
import leadtools.codecs.*; 
import leadtools.codecs.RasterCodecs.FeedCallbackThunk; 
import leadtools.drawing.internal.*; 
import leadtools.imageprocessing.*; 
import leadtools.imageprocessing.color.ChangeIntensityCommand; 
import leadtools.svg.*; 
 
 
public void commentsExample() throws IOException { 
   final String LEAD_VARS_IMAGES_DIR = "C:\\LEADTOOLS23\\Resources\\Images"; 
   RasterCodecs codecs = new RasterCodecs(); 
 
   String srcFileName = combine(LEAD_VARS_IMAGES_DIR, "Image1.cmp"); 
   String destFileName = combine(LEAD_VARS_IMAGES_DIR, "Image1_Comments.tif"); 
 
   // Convert the source file to TIF 
   System.out.println("Converting the source file to TIF"); 
   codecs.convert(srcFileName, destFileName, RasterImageFormat.TIF, 0, 0, 24, null); 
 
   // Add the artist comment 
   RasterCommentMetadata writeComment = new RasterCommentMetadata(); 
   writeComment.setType(RasterCommentMetadataType.ARTIST); 
   writeComment.fromAscii("LEADTOOLS"); 
 
   System.out.println("Writing the following comment:"); 
   System.out.printf(" Type:%s, Data:%s%n", writeComment.getType(), writeComment.toAscii()); 
 
   ILeadStream destFileStream = LeadStreamFactory.create(destFileName); 
   codecs.writeComment(destFileStream, 1, writeComment); 
 
   // Read the comment back 
   RasterCommentMetadata readComment = codecs.readComment(destFileStream, 1, RasterCommentMetadataType.ARTIST); 
   System.out.println("The following comment has been read:"); 
   System.out.printf(" Type:%s, Data:%s%n", readComment.getType(), readComment.toAscii()); 
 
   // Write a few comments to the file in one pass 
   RasterCollection<RasterCommentMetadata> comments = new RasterCollection<RasterCommentMetadata>(); 
   writeComment = new RasterCommentMetadata(); 
   writeComment.setType(RasterCommentMetadataType.ARTIST); 
   writeComment.fromAscii("LEADTOOLS Again"); 
   comments.add(writeComment); 
 
   writeComment = new RasterCommentMetadata(); 
   writeComment.setType(RasterCommentMetadataType.COPYRIGHT); 
   writeComment.fromAscii("(c) 2006"); 
   comments.add(writeComment); 
 
   System.out.println("Writing the following comments to the file:"); 
   for (RasterCommentMetadata comment : comments) 
      System.out.printf(" Type:%s, Data:%s%n", comment.getType(), comment.toAscii()); 
 
   codecs.writeComments(destFileStream, 1, comments); 
 
   // Now get all the comments in the file and show them: 
   System.out.println("Reading all comments from the file:"); 
 
   RasterCommentMetadataType[] tifComments = { 
         RasterCommentMetadataType.ARTIST, 
         RasterCommentMetadataType.COPYRIGHT, 
         RasterCommentMetadataType.DATE_TIME, 
         RasterCommentMetadataType.DESCRIPTION, 
         RasterCommentMetadataType.HOST_COMPUTER, 
         RasterCommentMetadataType.MAKE, 
         RasterCommentMetadataType.MODEL, 
         RasterCommentMetadataType.NAME_OF_DOCUMENT, 
         RasterCommentMetadataType.NAME_OF_PAGE, 
         RasterCommentMetadataType.SOFTWARE, 
   }; 
 
   for (RasterCommentMetadataType tifComment : tifComments) { 
      RasterCommentMetadata comment = codecs.readComment(destFileStream, 1, tifComment); 
      if (comment != null) { 
         System.out.printf("Found comment, Type:%s, Data:%n", comment.getType()); 
 
         RasterCommentMetadataDataType dataType = RasterCommentMetadata.getDataType(comment.getType()); 
 
         byte[] byteData; 
         short[] shortData; 
         RasterMetadataRational[] rationalData; 
         RasterMetadataURational[] urationalData; 
 
         switch (dataType) { 
            case ASCII: 
               System.out.println(comment.toAscii()); 
               break; 
 
            case BYTE: 
               byteData = comment.toByte(); 
               for (int i = 0; i < byteData.length; i++) 
                  System.out.println(byteData[i]); 
               System.out.println("  "); 
               break; 
 
            case INT_16: 
               shortData = comment.toInt16(); 
               for (int i = 0; i < shortData.length; i++) 
                  System.out.println(shortData[i]); 
               System.out.println("  "); 
               break; 
 
            case RATIONAL: 
               rationalData = comment.toRational(); 
               for (int i = 0; i < rationalData.length; i++) 
                  System.out.println((double) rationalData[i].getNumerator() / rationalData[i].getDenominator()); 
               System.out.println("  "); 
               break; 
 
            case URATIONAL: 
               urationalData = comment.toURational(); 
               for (int i = 0; i < urationalData.length; i++) 
                  System.out.println(urationalData[i].getNumerator() / urationalData[i].getDenominator()); 
               System.out.println("  "); 
               break; 
         } 
         assertTrue("dataType is not ASCII, BYTE, INT_16, RATIONAL, or URATIONAL", 
               dataType == RasterCommentMetadataDataType.ASCII 
                     || dataType == RasterCommentMetadataDataType.BYTE 
                     || dataType == RasterCommentMetadataDataType.INT_16 
                     || dataType == RasterCommentMetadataDataType.RATIONAL || 
                     dataType == RasterCommentMetadataDataType.URATIONAL); 
      } 
   } 
   // Clean up 
   destFileStream.close(); 
   codecs.dispose(); 
}