SVG Images

Both block and inline image macros have built-in support for scalable vector graphics (SVGs). But there’s more than one way to include an SVG into a web page, and the strategy used can affect how the SVG behaves (or misbehaves). Therefore, these macros provide additional options to control how the SVG is included (i.e., referenced).

Options for SVG images

When the image target is an SVG, the options attribute on the macro accepts one of three values:

none (default)
interactive
inline

The following table demonstrates the impact these options have.

Demonstration of option values for SVG images
image::sample.svg[Static,300]
image::sample.svg[Interactive,300,opts=interactive]	Observe that the color changes when hovering over the SVG.
image::sample.svg[Embedded,300,opts=inline]	Observe that the color changes when hovering over the SVG. The SVG also inherits CSS from the document stylesheets.

How the options value works and when it should be used is described below:

Option values for SVG images (HTML output)
Option	HTML Element Used	Effect	When To Use
none (default)	`<img>`	Image is rasterized	Static image, no interactivity, no custom fonts
`interactive`	`<object>`	Image embedded as a live, interactive object	For using CSS animations, scripting, webfonts
`inline`	`<svg>`	The SVG is embedded directly into the HTML itself	For using CSS animations, scripting, webfonts, when you require search engines to search the SVG content To allow SVG content reachable by JavaScript in the main DOM or to inherit styles from the main DOM

When using the inline or interactive options, the viewBox attribute must be defined on the root <svg> element in order for scaling to work properly.

When using the inline option, if you specify a width or height on the image macro in AsciiDoc, the width, height and style attributes on the <svg> element will be removed. Additionally, when using inline the primary SVG elements (e.g., <svg>) cannot have a namespace.

If using the interactive option, you must link to the CSS that declares the fonts in the SVG file using an XML stylesheet declaration.

If you’re inserting an SVG using either the inline or interactive options, we strongly recommend you optimize your SVG using a tool like svgo or SVG Editor.

As you work with SVG, you’ll become more comfortable making the decision about which method to employ given the circumstances. It’s only confusing when you first encounter the choice. To learn more about using SVG on the web, consult the online book SVG on the Web: A Practical Guide as well as these articles about SVG.