Convert MHTML to PDF – C#

MHTML to PDF conversion is often required to take advantage of PDF format for specific tasks. PDF comes with many benefits that other files don’t have. For example, many programs and apps support PDF documents; PDF files are optimized for printing, and they are ideal for creating physical copies of your documents; you can configure the security settings for PDF files – disable printing, editing, using an electronic signature, etc.

In this article, you find information on how to convert MHTML to PDF using ConvertMHTML() methods of the Converter class and how to apply PdfSaveOptions and ICreateStreamProvider parameters.

Online MHTML Converter

You can check the Aspose.HTML API functionality and convert MHTML in real-time. Please load an MHTML file from the local file system, select the output format and run the example. In the example, the save options are set by default. You will immediately receive the result as a separate file.

If you want to convert MHTML to PDF format programmatically, please see the following C# code examples.

MHTML to PDF by two lines of code

The static methods of the Converter class are primarily used as the easiest way to convert an MHTML code into various formats. For example, you can convert MHTML to PDF in your C# application literally with two lines of code!

// Open an existing MHTML file for reading
using var stream = File.OpenRead(DataDir + "sample.mht");

// Invoke the ConvertMHTML() method to convert MHTML to PDF
Converter.ConvertMHTML(stream, new PdfSaveOptions(), Path.Combine(OutputDir, "convert-by-two-lines.pdf"));

Convert MHTML to PDF

Using Converter.ConvertMHTML() methods is the most common way to convert MHTML code into various formats. With Aspose.HTML, you can convert MHTML to PDF format programmatically with full control over a wide range of conversion parameters.

The following C# code snippet shows how to convert MHTML to PDF using Aspose.HTML for .NET.

1. Open an existing MHTML file.
2. Create an instance of the PdfSaveOptions class.
3. Use the ConvertMHTML() method of the Converter class to save MHTML as a PDF file. You need to pass the MHTML file stream, PdfSaveOptions, and output file path to the ConvertMHTML() method method for MHTML to PDF conversion.

In the example, we use the OpenRead() method of System.IO.FileStream class to open and read files from the file system at the specified path.

// Open an existing MHTML file for reading
using var stream = File.OpenRead(DataDir + "sample.mht");

// Prepare a path to save the converted file
string savePath = Path.Combine(OutputDir, "sample-output.pdf");

// Create an instance of PdfSaveOptions
var options = new PdfSaveOptions();

// Call the ConvertMHTML() method to convert MHTML to PDF
Converter.ConvertMHTML(stream, options, savePath);

Save Options

Aspose.HTML allows converting MHTML to PDF using default or custom save options. PdfSaveOptions usage enables you to customize the rendering process; you can specify the page size, margins, file permissions, CSS media-type, etc.

Property	Description
JpegQuality	Specifies the quality of JPEG compression for images. The default value is 95.
Css	Gets a CssOptions object which is used for configuration of CSS properties processing.
DocumentInfo	This property contains information about the output PDF document.
BackgroundColor	This property sets the color that will fill the background of every page. By default, this property is Transparent.
PageSetup	This property gets a page setup object and uses it for configuration output page-set.
HorizontalResolution	Sets horizontal resolution for output images in pixels per inch. The default value is 300 dpi.
VerticalResolution	Sets vertical resolution for output images in pixels per inch. The default value is 300 dpi.
Encryption	This property gets or sets encryption details. If it is not set, then no encryption will be performed.

To learn more about PdfSaveOptions, please read the Fine-Tuning Converters article.

Convert MHTML to PDF using PdfSaveOptions

To convert MHTML to PDF with PdfSaveOptions specifying, you should follow a few steps:

1. Open an existing MHTML file.
2. Create a new PdfSaveOptions object and specify save options.
3. Use the ConvertMHTML() method to save MHTML as a PDF file. You need to pass the MHTML file stream, PdfSaveOptions, and output file path to the ConvertMHTML() method for MHTML to PDF conversion.

The following example shows how to use PdfSaveOptions and create a PDF file with custom save options:

// Open an existing MHTML file for reading
using var stream = File.OpenRead(DataDir + "sample.mht");

// Prepare a path to save the converted file
string savePath = Path.Combine(OutputDir, "sample-options.pdf");

// Create an instance of PdfSaveOptions. Set up the page-size and change the background color to AliceBlue
var options = new PdfSaveOptions()
{
    PageSetup =
        {
            AnyPage = new Page()
            {
                Size = new Aspose.Html.Drawing.Size(Length.FromPixels(3000), Length.FromPixels(1000))
            }
        },
    BackgroundColor = System.Drawing.Color.AliceBlue
};

// Call the ConvertMHTML() method to convert MHTML to PDF
Converter.ConvertMHTML(stream, options, savePath);

In the example, we use the OpenRead() method of System.IO.FileStream class to open and read source files from the file system at the specified path. The PdfSaveOptions() constructor initializes an instance of the PdfSaveOptions class that is passed to ConvertMHTML() method. The ConvertMHTML() method takes the stream, options, output file path savePath and performs the conversion operation. The PdfSaveOptions class provides numerous properties that give you full control over a wide range of parameters and improve the process of converting MHTML to PDF format.

In the above example, we use:

• BackgroundColor property that specifies the color that the background will be filled in. The default BackgroundColor is Transparent.
• PageSetup property that specifies the page size in pixels.

Output Stream Providers

If it is required to save files in the remote storage (e.g., cloud, database, etc.) you can implement ICreateStreamProvider interface to have manual control over the file creating process. This interface is designed as a callback object to create a stream at the beginning of the document/page (depending on the output format) and release the early created stream after rendering the document/page.

Aspose.HTML for .NET provides various types of output formats for rendering operations. Some of these formats produce a single output file (for instance PDF, XPS), others create multiple files (Image formats JPG, PNG, etc.).

The example below shows how to implement and use your own MemoryStreamProvider in the application:

class MemoryStreamProvider : Aspose.Html.IO.ICreateStreamProvider
{
    // List of MemoryStream objects created during the document rendering
    public List<MemoryStream> Streams { get; } = new List<MemoryStream>();

    public Stream GetStream(string name, string extension)
    {
        // This method is called when only one output stream is required, for instance for XPS, PDF or TIFF formats
        MemoryStream result = new MemoryStream();
        Streams.Add(result);
        return result;
    }

    public Stream GetStream(string name, string extension, int page)
    {
        // This method is called when the creation of multiple output streams are required. For instance, during the rendering HTML to list of image files (JPG, PNG, etc.)
        MemoryStream result = new MemoryStream();
        Streams.Add(result);
        return result;
    }

    public void ReleaseStream(Stream stream)
    {
        // Here you can release the stream filled with data and, for instance, flush it to the hard-drive
    }

    public void Dispose()
    {
        // Releasing resources
        foreach (var stream in Streams)
            stream.Dispose();
    }
}

The following C# code demonstrates how to use the MemoryStreamProvider class and the Aspose.HTML for .NET library to convert MHTML to PDF and save the result to a file.

// Create an instance of MemoryStreamProvider
using var streamProvider = new MemoryStreamProvider();

// Open an existing MHTML file for reading
using var stream = File.OpenRead(DataDir + "sample.mht");

// Prepare a path to save the converted file
string savePath = Path.Combine(OutputDir, "stream-provider.pdf");

// Convert MHTML to PDF by using the MemoryStreamProvider class
Converter.ConvertMHTML(stream, new PdfSaveOptions(), streamProvider);

// Get access to the memory stream that contains the result data
var memory = streamProvider.Streams.First();
memory.Seek(0, SeekOrigin.Begin);

// Flush the result data to the output file
using (FileStream fs = File.Create(savePath))
{
    memory.CopyTo(fs);
}

You can download the complete examples and data files from GitHub.

Aspose.HTML offers a free online MHTML to PDF Converter that converts MHTML to PDF file with high quality, easy and fast. Just upload, convert your files and get results in a few seconds!