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Settings

Updated on Jun 16, 2026

HtmlFormatProvider allows you to import HTML documents and export a RadFlowDocument to HTML. The import and export settings let you modify the provider behavior. This article outlines the available settings.

Import Settings
UriImageSource Class
Export Settings

Import Settings

The HtmlImportSettings class represents the import settings. You can specify the following options:

DefaultStyleSheet

The property specifies the default stylesheet that the provider uses. This is equivalent to the browser's "user agent stylesheet" and specifies the formatting that applies by default to the elements (before all styles that the document explicitly defines).

The default value, for example, specifies that b elements are imported with font-weight: bold.

You can set the value of the property to any valid CSS document. Example 1 shows how you can add styling besides the default styles.

Example 1: Add CSS to the DefaultStyleSheet

HtmlFormatProvider html_provider = new HtmlFormatProvider();
html_provider.ImportSettings.DefaultStyleSheet = provider.ImportSettings.DefaultStyleSheet + @" p {color: #ff99ac;}";

GenericFonts

The property contains an instance of the GenericHtmlFonts class, which specifies the ThemableFontFamily objects to use when importing the five generic CSS font families: serif, sans-serif, monospace, cursive, and fantasy. By default, these fonts are Times New Roman, Arial, Courier New, Comic Sans MS, and Algerian, respectively.

LoadImageFromUri and LoadStyleSheetFromUri Events

These events allow you to load external resources (images and CSS files) that the HTML does not include. To use these events, load the data from the URI in the event arguments and return it.

The LoadFromUri event is obsolete starting with R1 2021. Use LoadImageFromUri or LoadStyleSheetFromUri instead. Starting with Q3 2015, the library introduced the UriImageSource class. This class automatically downloads the images. But because such an approach poses a security risk, it is obsolete starting with R1 2021.

The LoadImageFromUri event uses the LoadImageFromUriEventArgs object which exposes the following properties:

Uri: The URI originally specified in the imported HTML file.
SetImageInfo: Passes the image data and image format (extension).

Example 2 shows how to use the LoadImageFromUri event to download an image.

Example 2: Use the LoadImageFromUri

HtmlFormatProvider provider = new HtmlFormatProvider();
HtmlImportSettings importSettings = new HtmlImportSettings();

importSettings.LoadImageFromUri += (s, e) =>
{
    // Load the data representing the resource  
    System.Net.WebClient webClient = new System.Net.WebClient();
    byte[] data = webClient.DownloadData(e.Uri);

    // Pass the loaded data to the arguments 
    string extension = System.IO.Path.GetExtension(e.Uri).Substring(1); // Get the extension without the dot 
    e.SetImageInfo(data, extension);
};

provider.ImportSettings = importSettings;

The LoadStyleSheetFromUri event uses the LoadStyleSheetFromUriEventArgs object which exposes the following properties:

Uri: The URI originally specified in the imported HTML file.
SetStyleSheetContent: Passes the styles as a string.

Example 3 shows how to use the LoadStyleSheetFromUri event.

Example 3: Use the LoadStyleSheetFromUri event

HtmlFormatProvider provider = new HtmlFormatProvider();
HtmlImportSettings importSettings = new HtmlImportSettings();

importSettings.LoadStyleSheetFromUri += (s, e) =>
{
    string styles = File.ReadAllText(@"Data\" + e.Uri);
    e.SetStyleSheetContent(styles);
};

provider.ImportSettings = importSettings;

UriImageSource Class

When importing HTML that contains images with URI source, the HtmlFormatProvider creates a UriImageSource object for each of these images. UriImageSource downloads the image data on demand and exposes the following properties:

Uri: Gets the URI of the image.
Data: Gets a byte array that represents the image data. When you access this property, the class downloads the image data.
Extension: Gets the extension. When you access this property, the class downloads the image data only if the extension is not predefined.

The UriImageSource class and the LoadFromUri event make HTTP requests and download the respective resources. Consider this if your application must not freely access remote resources.

When you export a UriImageSource object to other supported formats, the provider downloads the image and saves it according to the target format specification.

Converting UriImageSource to ImageSource

The provider always exports UriImageSource objects as images with URI as their source, regardless of the export settings. If you need to export this object as an embedded or external image, convert the UriImageSource to an ImageSource object.

Example 4: Convert UriImageSource to ImageSource

UriImageSource uriImageSource = imageInline.Image.ImageSource as UriImageSource;
if (uriImageSource != null)
{
    imageInline.Image.ImageSource = new ImageSource(uriImageSource.Data, uriImageSource.Extension);
}

Export Settings

The HtmlExportSettings class represents the export settings. You can specify the following settings:

BordersMinimalThickness

Specifies the minimal exported thickness of the borders of tables and table cells. This can be useful because some browsers cannot render thin borders properly (below 1px or similar). The default value is 0, which means the provider exports all borders with their actual thickness.

DocumentExportLevel

Specifies the export level of the document through the DocumentExportLevel enumeration:

Document: Exports a full HTML document. This is the default value of the property.
Fragment: Exports a fragment of the HTML document—only the body tag.

IndentDocument

Specifies whether the exported document is indented (formatted with spaces). The default value is false, as this ensures minimum size rather than human-readability.

ImagesExportMode

This property controls how the provider exports images. The available options are external file and embedded image.

When you import an image with URI source, the ImageSource property of the Image contains an object of type UriImageSource. As a result, the provider always exports the image with URI and does not respect the ImagesExportMode property. If you need the provider to respect this property, convert the UriImageSource object to ImageSource.

When you work with relative URIs, the import and export features only preserve the path to the image and do not change it.

ImagesFolderPath

This property specifies the folder path where the provider exports external images. This property applies only when ImageExportMode is set to External.

ImagesSourceBasePath

Specifies the base path for the src attribute of the exported image tags. This property applies only when the ImageExportMode is set to External.

ImageExporting

The provider raises this event for every image in the document. The event argument exposes the following options:

Title: Allows you to set the title attribute of the image element.
AlternativeText: Can be used to specify the content of the alt attribute of the image. It is null by default and the attribute is not exported.
Handled: Marks the event as handled. If ImagesExportMode is set to External and the event is marked as handled, the format provider does not attempt to export the image to an external image file.
Image: Can be used to get the original Image object, from where you can access image name, image data, and image extension.
Source: Can be used to specify the value of the src attribute of the image element. If ImagesExportMode is set to External, the source can be set to absolute or to a relative path pointing to the image file.
ExportSize: Use this property to specify whether the width and height attributes of an image element are exported. The default value is true.

StylesExportMode

Specifies the export mode for the styles in the RadFlowDocument StyleRepository, through the StylesExportMode enumeration:

Embedded: RadFlowDocument styles are exported as internal CSS—selectors embedded into the HTML in style element in the head section. This is the default value of the property.
External: RadFlowDocument styles are exported as CSS selectors in external CSS file. You have two options:
- Set StylesFilePath and StylesSourcePath properties, which are used to export the external file.
- Handle ExportStylesToExternalSource event, specifying the output stream and reference URI to be exported.
Inline: RadFlowDocument styles are exported as CSS properties in the style attribute of the HTML elements. This ensures maximum compatibility with some applications that don't support external or embedded CSS, for example, some email clients.
None: RadFlowDocument styles are not exported. The local values of style properties of the DocumentElements are still exported as CSS properties in the style attribute of the HTML elements.

Css: String that contains the actual CSS that is exported.
Handled: Marks the event as handled. If the event is marked as handled, the format provider does not attempt to export the CSS file.
Reference: The value that is set to the href attribute of the link element tag. In general, this is set to the absolute or relative path pointing to the file that contains the CSS styles.

Example 5 shows how to create export settings.

Example 5: Create HtmlExportSettings

HtmlFormatProvider html_provider = new HtmlFormatProvider();
HtmlExportSettings exportSettings = new HtmlExportSettings();

byte[] data = null;
exportSettings.BordersMinimalThickness = 1;
exportSettings.DocumentExportLevel = DocumentExportLevel.Fragment;
exportSettings.IndentDocument = true;
exportSettings.ImageExporting += (s, e) =>
{
    e.Source = "test.jpg";
    data = e.Image.ImageSource.Data;
    e.Handled = true;
    e.Title = "Test image";
    e.ExportSize = true;
    e.AlternativeText = "You will see this text if the image is not loaded";
};

html_provider.ExportSettings = exportSettings;