ReadTagsWithOffsets(string,int,out long[]) Method

Summary

Reads all the tags stored in a TIFF file, along with the offsets for each tag.

Syntax

Objective-C

C++/CLI

Python

public IList<RasterTagMetadata> ReadTagsWithOffsets( 
   string fileName, 
   int pageNumber, 
   out long[] offsets 
)

- (nullable NSArray<LTRasterTagMetadata *> *)readTagsFromFile:(NSString *)file  
                                                   pageNumber:(NSInteger)pageNumber  
                                                      offsets:(NSMutableArray<NSNumber *> *)offsets  
                                                        error:(NSError **)error

public: 
IList<RasterTagMetadata^>^ ReadTagsWithOffsets(  
   String^ fileName, 
   int pageNumber, 
   [Out] array<int64> offsets 
)

def ReadTagsWithOffsets(self,fileName,pageNumber,offsets):

Parameters

fileName
A String containing the input file name.

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

offsets
An array that contains the offsets for each tag.

Return Value

A collection of RasterTagMetadata containing all the tags found in the file. If the file does not contain any tags, an empty collection will be returned. If the file format does not support tags, an exception will be thrown.

Remarks

To read a specific tag stored in a file, use ReadTag and to enumerate all the tag ids (but not the data) stored in a file use EnumTags.

This method will throw an exception if the file format does not support tags. To determine whether a file format supports tags, use TagsSupported. You can also automatically load all the tags stored in a file during a load operation by setting the CodecsLoadOptions.Tags property to true. The tags data will be stored in the resulting image RasterImage.Tags collection.

To load all the tags stored in a stream containing the image data, use ReadTags.

Example

This example will load all the tags, with their offsets, from a file.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
public void ReadTagsWithOffsetsExample() 
{ 
   // Prompt the user for an image file 
   string imageFileName = PromptForFileName(); 
 
   // Initialize LEADTOOLS 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      // Get the file format 
      RasterImageFormat format; 
 
      using (CodecsImageInfo info = codecs.GetInformation(imageFileName, false)) 
      { 
         format = info.Format; 
      } 
 
      // Load the tags, with their offsets 
      IList<RasterTagMetadata> tags = null; 
      long[] offsets = null; 
      if (RasterCodecs.TagsSupported(format)) 
         tags = codecs.ReadTagsWithOffsets(imageFileName, 1, out offsets); 
 
      string txtFileName = Path.Combine( 
         Path.GetDirectoryName(imageFileName), 
         Path.GetFileNameWithoutExtension(imageFileName) + "_metadata.txt"); 
 
      using (StreamWriter writer = File.CreateText(txtFileName)) 
      { 
         // Write the tags 
         WriteTags(writer, "Tags", tags, offsets); 
      } 
 
      // Show the text file we created 
      System.Diagnostics.Process.Start(txtFileName); 
   } 
} 
 
private static void WriteTags(StreamWriter writer, string name, IList<RasterTagMetadata> tags, long[] offsets) 
{ 
   writer.WriteLine("{0}:", name); 
 
   if (tags != null) 
   { 
      int x = 0; 
      foreach (RasterTagMetadata tag in tags) 
      { 
         writer.WriteLine("Id: 0x{0}, offset: {1}", tag.Id.ToString("X"), offsets[x]); 
         x++; 
      } 
   } 
   else 
   { 
      writer.WriteLine("Not supported"); 
   } 
 
   writer.WriteLine(); 
}