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diff --git a/docs/content/en/templates/render-hooks.md b/docs/content/en/templates/render-hooks.md new file mode 100644 index 000000000..57c2efa06 --- /dev/null +++ b/docs/content/en/templates/render-hooks.md @@ -0,0 +1,172 @@ +--- +title: "Markdown Render Hooks" +linkTitle: "Render Hooks" +description: "Render Hooks allow custom templates to override markdown rendering functionality." +date: 2017-03-11 +categories: [templates] +keywords: [markdown] +toc: true +menu: + docs: + title: "Markdown Render Hooks" + parent: "templates" + weight: 20 +--- + +{{< new-in "0.62.0" >}} Note that this is only supported with the [Goldmark](#goldmark) renderer. + + +You can override certain parts of the default Markdown rendering to HTML by creating templates with base names `render-{kind}` in `layouts/_default/_markup`. + +You can also create type/section specific hooks in `layouts/[type/section]/_markup`, e.g.: `layouts/blog/_markup`.{{< new-in "0.71.0" >}} + +The hook kinds currently supported are: + +* `image` +* `link` +* `heading` {{< new-in "0.71.0" >}} +* `codeblock`{{< new-in "0.83.0" >}} + +You can define [Output-Format-](/templates/output-formats) and [language-](/content-management/multilingual/)specific templates if needed. Your `layouts` folder may look like this: + +```goat { class="black f7" } +layouts +└── _default + └── _markup + ├── render-image.html + ├── render-image.rss.xml + └── render-link.html + └── render-codeblock.html + └── render-codeblock-bash.html +``` + +Some use cases for the above: + +* Resolve link references using `.GetPage`. This would make links portable as you could translate `./my-post.md` (and similar constructs that would work on GitHub) into `/blog/2019/01/01/my-post/` etc. +* Add `target=_blank` to external links. +* Resolve and [process](/content-management/image-processing/) images. +* Add [header links](https://remysharp.com/2014/08/08/automatic-permalinks-for-blog-posts). + +## Render Hooks for Headings, Links and Images + +The `render-link` and `render-image` templates will receive this context: + +Page +: The [Page](/variables/page/) being rendered. + +Destination +: The URL. + +Title +: The title attribute. + +Text +: The rendered (HTML) link text. + +PlainText +: The plain variant of the above. + +The `render-heading` template will receive this context: + +Page +: The [Page](/variables/page/) being rendered. + +Level +: The header level (1--6) + +Anchor +: An auto-generated html id unique to the header within the page + +Text +: The rendered (HTML) text. + +PlainText +: The plain variant of the above. + +Attributes (map) {{< new-in "0.82.0" >}} +: A map of attributes (e.g. `id`, `class`) + +### Link with title Markdown example: + +```md +[Text](https://www.gohugo.io "Title") +``` + +Here is a code example for how the render-link.html template could look: + +{{< code file="layouts/_default/_markup/render-link.html" >}} +<a href="{{ .Destination | safeURL }}"{{ with .Title}} title="{{ . }}"{{ end }}{{ if strings.HasPrefix .Destination "http" }} target="_blank" rel="noopener"{{ end }}>{{ .Text | safeHTML }}</a> +{{< /code >}} + +### Image Markdown example: + +```md +![Text](https://d33wubrfki0l68.cloudfront.net/c38c7334cc3f23585738e40334284fddcaf03d5e/2e17c/images/hugo-logo-wide.svg "Title") +``` + +Here is a code example for how the render-image.html template could look: + +{{< code file="layouts/_default/_markup/render-image.html" >}} +<p class="md__image"> + <img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" {{ with .Title}} title="{{ . }}"{{ end }} /> +</p> +{{< /code >}} + +### Heading link example + +Given this template file + +{{< code file="layouts/_default/_markup/render-heading.html" >}} +<h{{ .Level }} id="{{ .Anchor | safeURL }}">{{ .Text | safeHTML }} <a href="#{{ .Anchor | safeURL }}">¶</a></h{{ .Level }}> +{{< /code >}} + +And this markdown + +```md +### Section A +``` + +The rendered html will be + +```html +<h3 id="section-a">Section A <a href="#section-a">¶</a></h3> +``` + +## Render Hooks for Code Blocks + +{{< new-in "0.93.0" >}} + +You can add a hook template for either all code blocks or for a specific type/language (`bash` in the example below): + +```goat { class="black f7" } +layouts +└── _default + └── _markup + └── render-codeblock.html + └── render-codeblock-bash.html +``` + +The default behaviour for these code blocks is to do [Code Highlighting](/content-management/syntax-highlighting/#highlighting-in-code-fences), but since you can pass attributes to these code blocks, they can be used for almost anything. One example would be the built-in [GoAT Diagrams](/content-management/diagrams/#goat-diagrams-ascii) or this [Mermaid Diagram Code Block Hook](/content-management/diagrams/#mermaid-diagrams) example. + +The context (the ".") you receive in a code block template contains: + +Type (string) +: The type of code block. This will be the programming language, e.g. `bash`, when doing code highlighting. + +Attributes (map) +: Attributes passed in from Markdown (e.g. `{ attrName1=attrValue1 attrName2="attr Value 2" }`). + +Options (map) +: Chroma highlighting processing options. This will only be filled if `Type` is a known [Chroma Lexer](/content-management/syntax-highlighting/#list-of-chroma-highlighting-languages). + +Inner (string) +: The text between the code fences. + +Ordinal (integer) +: Zero-based ordinal for all code blocks in the current document. + +Page +: The owning `Page`. + +Position +: Useful in error logging as it prints the filename and position (linenumber, column), e.g. `{{ errorf "error in code block: %s" .Position }}`. |