Handle loading of external resources documents Leave feedback

GroupDocs.Parser provides the functionality to handle loading of HTML external resources.

Here are the steps to handle loading of HTML external resources.

• Instantiate the ParserSettings object and pass External Resource Handler;
• Create Parser object and call GetImages method.

The following code sample shows how to handle loading of HTML external resources.

// Create an instance of ParserSettings to pass External Resource Handler
ParserSettings settings = new ParserSettings(new Handler());

// Create an instance of Parser class to generate spreadsheet page previews
using (Parser parser = new Parser(Constants.SampleHtmlWithImages, settings))
{
    // Extract images from HTML document
    IEnumerable<PageImageArea> images = parser.GetImages();

    // Iterate over extracted images
    foreach (PageImageArea i in images)
    {
        // Print the type of image
        Console.WriteLine(i.FileType);
    }
}

/// <summary>
/// This class provides the ability to filter extracted images.
/// </summary>
private class Handler : ExternalResourceHandler
{
    /// <summary>
    /// Called before any external resource loads. It allows to skip unnesesary file loading.
    /// </summary>
    public override void OnLoading(ExternalResourceLoadingArgs args)
    {
        // Check if the file name ends with installation.png
        if (!args.Uri.EndsWith("installation.png"))
        {
            // Otherwise skip this file
            args.Skipped = true;
        }

        base.OnLoading(args);
    }
}

Warning

Loading of external resources is enabled by default, which means that parsing a document from an untrusted source may cause outbound HTTP requests to hosts named inside that document — for example remote images or stylesheets referenced by an HTML or MHTML file or by the HTML body of an email, linked images in Word processing documents, and INCLUDEPICTURE fields.

As of version 26.6.1, ExternalResourceHandler intercepts image extraction from HTML and MHTML only; other extraction methods and other formats do not route through it. To guarantee that no outbound request is made, block egress at the network or process level. See Network access and data privacy for the measured per-format behaviour.

You may easily run the code above and see the feature in action in our GitHub examples:

• GroupDocs.Parser for .NET examples
• GroupDocs.Parser for Java examples

Along with full featured .NET library we provide simple, but powerful free Apps.

You are welcome to parse documents and extract data from PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX, Emails and more with our free online Free Online Document Parser App.