Custom Text Encoding

Custom Text Encoding

This documentation outlines how to integrate a custom text encoding/decoding mechanism within Aspose.Medical .NET’s Encoding infrastructure. It enables developers to define and register custom text encodings that can be used when handling DICOM attributes with character sets that are not supported natively or need specialized handling.

Integration

The integration is composed of:

1. Custom Encoding
2. Custom EncodingProvider
3. Registering the EncodingProvider using Aspose.Medical.Common.Text.DicomEncoding.Current.RegisterProvider method.
4. Registering the Encoding using Aspose.Medical.Common.Text.DicomEncoding.Current.RegisterEncoding method.

Custom Encoding should override/implement:

1. GetBytes and all its overloads.
2. GetChars and all its overloads.
3. GetString and all its overloads.
4. GetMaxByteCount and all its overloads.
5. GetByteCount and all its overloads.
6. GetCharCount and all its overloads.

Custom EncodingProvider should override/implement:

1. Encoding? GetEncoding(string name)
2. Encoding? GetEncoding(int codepage)
3. Encoding? GetEncoding(int codepage, EncoderFallback encoderFallback, DecoderFallback decoderFallback)
4. Encoding? GetEncoding(string name, EncoderFallback encoderFallback, DecoderFallback decoderFallback)

Example:

public sealed class Iso_8859_6_Encoding : Encoding {
  // implementation skipped
}

public sealed class CustomEncodingProvider : EncodingProvider {
  public override Encoding? GetEncoding(string name)
    => string.Equals(name, "iso-8859-6", StringComparison.OrdinalIgnoreCase) ||
       string.Equals(name, Gb18030.WebName, StringComparison.OrdinalIgnoreCase)
           ? new Iso_8859_6_Encoding()
           : null;

  // implementation skipped
}

CustomEncodingProvider provider = new();
Aspose.Medical.Common.Text.DicomEncoding.Current.RegisterProvider(provider);
Aspose.Medical.Common.Text.DicomEncoding.Current.RegisterEncoding("ISO 2022 IR 127", "iso-8859-6");

// now Aspose.Medical will use the custom encoding to encode/decode text elements

Aspose.Medical.Dicom.Dataset dataset = [];
dataset.AddOrUpdate(Aspose.Medical.Dicom.Tags.Tag.SpecificCharacterSet, "ISO 2022 IR 127");
dataset.AddOrUpdate(Aspose.Medical.Dicom.Tags.Tag.PatientName, patientName);

Aspose.Medical.Dicom.DicomFile initial = new(dataset);
using System.IO.MemoryStream stream = new();

// Save uses custom encoding to encode PatientName
initial.Save(stream);

stream.Seek(0, System.IO.SeekOrigin.Begin);

Aspose.Medical.Dicom.DicomFile saved = Aspose.Medical.Dicom.DicomFile.Open(stream);

// PatientName will be decoded using custom encoding
patientName = saved.Dataset.GetValue<string>(Aspose.Medical.Dicom.Tags.Tag.PatientName, 0);