Convert a Document to HTML, MHTML or EPUB

Documents in HTML and MHTML flow-layout formats are also very popular and can be used on any web platform. For that reason, converting documents to HTML and MHTML is an important feature of Aspose.Words.

EPUB (short for “Electronic Publication”) is an HTML-based format commonly used for electronic book distribution. This format is fully supported in Aspose.Words for exporting electronic books that are compatible with most reading devices.

Convert a Document

For simple conversion to HTML, MHTML, or EPUB, one of the Save method overloads is used. You can save the document to a file or stream and explicitly set the output document save format or define it from the file name extension.

The following example shows how to convert DOCX to HTML with specifying a save format:

To convert a document to MHTML or EPUB, use SaveFormat.Mhtml or SaveFormat.Epub respectively.

Convert a Document with Round-trip Information

The HTML format does not support many Microsoft Word features, and if we need to restore a document model as close to the original as possible, we need to save some extra information within the HTML file. Such information is also called “round-trip information”. For this purpose, Aspose.Words provides an ability to export round-trip information when saving to HTML, MHTML, or EPUB using the ExportRoundtripInformation property. Saving the round-trip information allows restoring document properties such as tabs, comments, headers, and footers during the loading documents of the listed formats back into a Document object.

The default value is true for HTML and false for MHTML and EPUB:

  • When true, the round-trip information is exported as - aw - * CSS properties of the corresponding HTML elements
  • When false, there is no round-trip information to be output into produced files

The following code example shows how to export round-trip information when converting a document from DOCX into HTML:

Specify Save Options when Conversion to HTML

Aspose.Words allows converting a Word document to HTML using default or custom save options. Few examples of custom save options are described below.

Specify a Folder for Saving Resources

Using Aspose.Words we can specify a physical folder where all resources, such as images, fonts, and external CSS, are saved when a document is converted to HTML. By default, this is an empty string.

Specifying the ResourceFolder property is the simplest way to set the folder where all resources should be written. We can use individual properties, such as FontsFolder which saves fonts to the specified folder and ImagesFolder which saves images to a specified folder. When a relative path is specified, FontsFolder and ImagesFolder refer to the folder where the code assembly is located, ResourceFolder and CssStyleSheetFileName refer to the output folder where the HTML document is located.

In this example, ResourceFolder specifies the relative path. This path refers to the output folder where the HTML document is saved. The value of the ResourceFolderAlias property is used to create URLs for all resources.

The following code example shows how to work with these properties:

Using the ResourceFolderAlias property, we can also specify the name of the folder used to construct URIs of all resources written into an HTML document. This is the simplest way to specify how URIs should be generated for all resource files. The same information can be specified for images and fonts separately via ImagesFolderAlias and FontsFolderAlias properties, respectively.

However, there is no individual property for CSS. The behavior of the FontsFolderFontsFolderAliasImagesFolderImagesFolderAlias and CssStyleSheetFileName properties are not changed. Note that the CssStyleSheetFileName property is used both for specifying folder name and file name.

  • ResourceFolder has lower priority than folders specified via FontsFolder, ImagesFolder, and CssStyleSheetFileName. If the folder specified in the ResourceFolder does not exist, it will be created automatically.
  • ResourceFolderAlias has a lower priority than FontsFolderAlias and ImagesFolderAlias. If ResourceFolderAlias is empty, the value of the ResourceFolder property will be used to create resource URIs. If ResourceFolderAlias is set to “.” (dot), resource URIs will only contain file names without specifying a path.

Export Base64 Encoding Fonts Resources

Aspose.Words provides an ability to specify whether font resources should be embedded into HTML in Base64 encodings. To perform this, use the ExportFontsAsBase64 property – this is an extension of the ExportFontResources property. By default, its value is false, and fonts are written into separate files. But if this option is set to true, fonts will be embedded into the document’s CSS in Base64 encoding. The ExportFontsAsBase64 property only affects HTML format and does not affect EPUB and MHTML.

The following code example shows how to export Base64-encoded fonts to HTML:

Specify Save Options when Conversion to EPUB

Aspose.Words allows converting a Word document into EPUB format using default or custom save options. You can specify a number of options by passing an instance of HtmlSaveOptions to the Save method.

The following code example shows how to converts a Word document to EPUB with specifying some custom save options: