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Integrating Chroma syntax highlighter as a Blackfriday renderer
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depado/bfchroma
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IntegratingChroma syntax highlighter asaBlackfriday renderer.
This project requires and uses thev2 version ofBlackfriday.
$ go get github.com/Depado/bfchroma/v2This renderer integrates chroma to highlight code with triple backtick notation.It will try to use the given language when available otherwise it will try todetect the language. If none of these two method works it will fallback to sanedefaults.
bfchroma uses the functional options approach so you can customize the behaviorof the renderer. It uses sane defaults when no option is passed so you can usethe renderer simply by doing so :
html:=bf.Run([]byte(md),bf.WithRenderer(bfchroma.NewRenderer()))
Style(s string)Define the style used by chroma for the rendering. The full list can be foundhereChromaStyle(*chroma.Style)This option can be used to passe directly a*chroma.Styleinstead of thestring representing the style as with theStyle(string)option.WithoutAutodetect()By default when no language information is written in the code block, thisrenderer will try to auto-detect the used language. This option disablesthis behavior and will fallback to a sane default when no languageinformation is available.EmbedCSS()This option will embed CSS needed for chroma'shtml.WithClasses()at the beginning of blackfriday document.CSS can also be extracted separately by callingRenderer's.ChromaCSS(w)method, which will return styleshet for currently set styleExtend(bf.Renderer)This option allows to define the base blackfriday that will be extended.ChromaOptions(...html.Option)This option allows you to pass Chroma's html options in the renderer. Suchoptions can be foundhere.
Disabling language auto-detection and displaying line numbers
r:=bfchroma.NewRenderer(bfchroma.WithoutAutodetect(),bfchroma.ChromaOptions(html.WithLineNumbers()),)
Extend a blackfriday renderer
b:=bf.NewHTMLRenderer(bf.HTMLRendererParameters{Flags:bf.CommonHTMLFlags,})r:=bfchroma.NewRenderer(bfchroma.Extend(b))
Use a different style
r:=bfchroma.NewRenderer(bfchroma.Style("dracula"))// Orr=bfchroma.NewRenderer(bfchroma.ChromaStyle(styles.Dracula))
package mainimport ("fmt""github.com/Depado/bfchroma/v2"bf"github.com/russross/blackfriday/v2")varmd="This is some sample code.\n\n```go\n"+`func main() {fmt.Println("Hi")}`+"```"funcmain() {html:=bf.Run([]byte(md),bf.WithRenderer(bfchroma.NewRenderer()))fmt.Println(string(html))}
Will output :
<p>This is some sample code.</p><prestyle="color:#f8f8f2;background-color:#272822"><spanstyle="color:#66d9ef">func</span><spanstyle="color:#a6e22e">main</span>() {<spanstyle="color:#a6e22e">fmt</span>.<spanstyle="color:#a6e22e">Println</span>(<spanstyle="color:#e6db74">"Hi"</span>)}</pre>
Insmallblog I'm using bfchroma to rendermy articles. It's using a combination of both bfchroma's options and blackfridayextensions and flags.
package mainimport ("github.com/Depado/bfchroma/v2""github.com/alecthomas/chroma/v2/formatters/html"bf"github.com/russross/blackfriday/v2")// Defines the extensions that are usedvarexts=bf.NoIntraEmphasis|bf.Tables|bf.FencedCode|bf.Autolink|bf.Strikethrough|bf.SpaceHeadings|bf.BackslashLineBreak|bf.DefinitionLists|bf.Footnotes// Defines the HTML rendering flags that are usedvarflags=bf.UseXHTML|bf.Smartypants|bf.SmartypantsFractions|bf.SmartypantsDashes|bf.SmartypantsLatexDashes|bf.TOC// render will take a []byte input and will render it using a new renderer each// time because reusing the same can mess with TOC and header IDsfuncrender(input []byte) []byte {returnbf.Run(input,bf.WithRenderer(bfchroma.NewRenderer(bfchroma.WithoutAutodetect(),bfchroma.ChromaOptions(html.WithLineNumbers(),),bfchroma.Extend(bf.NewHTMLRenderer(bf.HTMLRendererParameters{Flags:flags,}),),),),bf.WithExtensions(exts),)}
If you have loads of code in your markdown, you might want to consider usinghtml.WithClasses() in yourbfchroma.ChromaOptions(). The CSS of the styleyou chose can then be accessed like this :
r:=bfchroma.NewRenderer(bfchroma.WithoutAutodetect(),bfchroma.Extend(bf.NewHTMLRenderer(bf.HTMLRendererParameters{Flags:flags}),),bfchroma.Style("monokai"),bfchroma.ChromaOptions(html.WithClasses()),)varcss template.CSSb:=new(bytes.Buffer)iferr:=r.ChromaCSS(b);err!=nil {logrus.WithError(err).Warning("Couldn't write CSS")}css=template.CSS(b.String())bf.Run(input,bf.WithRenderer(r),bf.WithExtensions(exts))
This way, you can pass yourcss var to any template and render it along therendered markdown.
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Integrating Chroma syntax highlighter as a Blackfriday renderer