Callback

Hyphenation.Callback property

Gets or sets callback interface used to request dictionaries when page layout of the document is built. This allows delay loading of dictionaries which may be useful when processing documents in many languages.

public static IHyphenationCallback Callback { get; set; }

Examples

Shows how to open and register a dictionary from a file.

{
    // Set up a callback that tracks warnings that occur during hyphenation dictionary registration.
    WarningInfoCollection warningInfoCollection = new WarningInfoCollection();
    Hyphenation.WarningCallback = warningInfoCollection;

    // Register an English (US) hyphenation dictionary by stream.
    Stream dictionaryStream = new FileStream(MyDir + "hyph_en_US.dic", FileMode.Open);
    Hyphenation.RegisterDictionary("en-US", dictionaryStream);

    Assert.AreEqual(0, warningInfoCollection.Count);

    // Open a document with a locale that Microsoft Word may not hyphenate on an English machine, such as German.
    Document doc = new Document(MyDir + "German text.docx");

    // To hyphenate that document upon saving, we need a hyphenation dictionary for the "de-CH" language code.
    // This callback will handle the automatic request for that dictionary.
    Hyphenation.Callback = new CustomHyphenationDictionaryRegister();

    // When we save the document, German hyphenation will take effect.
    doc.Save(ArtifactsDir + "Hyphenation.RegisterDictionary.pdf");

    // This dictionary contains two identical patterns, which will trigger a warning.
    Assert.AreEqual(1, warningInfoCollection.Count);
    Assert.AreEqual(WarningType.MinorFormattingLoss, warningInfoCollection[0].WarningType);
    Assert.AreEqual(WarningSource.Layout, warningInfoCollection[0].Source);
    Assert.AreEqual("Hyphenation dictionary contains duplicate patterns. The only first found pattern will be used. " +
                    "Content can be wrapped differently.", warningInfoCollection[0].Description);
}

/// <summary>
/// Associates ISO language codes with local system filenames for hyphenation dictionary files.
/// </summary>
private class CustomHyphenationDictionaryRegister : IHyphenationCallback
{
    public CustomHyphenationDictionaryRegister()
    {
        mHyphenationDictionaryFiles = new Dictionary<string, string>
        {
            { "en-US", MyDir + "hyph_en_US.dic" },
            { "de-CH", MyDir + "hyph_de_CH.dic" }
        };
    }

    public void RequestDictionary(string language)
    {
        Console.Write("Hyphenation dictionary requested: " + language);

        if (Hyphenation.IsDictionaryRegistered(language))
        {
            Console.WriteLine(", is already registered.");
            return;
        }

        if (mHyphenationDictionaryFiles.ContainsKey(language))
        {
            Hyphenation.RegisterDictionary(language, mHyphenationDictionaryFiles[language]);
            Console.WriteLine(", successfully registered.");
            return;
        }

        Console.WriteLine(", no respective dictionary file known by this Callback.");
    }

    private readonly Dictionary<string, string> mHyphenationDictionaryFiles;
}

See Also