markup/goldmark: Add removeSurroundingParagraph for Markdown images

This both:

* Removes any surrounding paragraph nodes
* And transfers any attributes from the surrounding paragraph down to the image node

Closes gohugoio#8362
Fixes gohugoio#10492

markup/goldmark/convert.go

@@ -17,12 +17,12 @@ package goldmark
 import (
 	"bytes"
 
+	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/markup/goldmark/codeblocks"
+	"github.com/gohugoio/hugo/markup/goldmark/images"
 	"github.com/gohugoio/hugo/markup/goldmark/internal/extensions/attributes"
 	"github.com/gohugoio/hugo/markup/goldmark/internal/render"
 
-	"github.com/gohugoio/hugo/identity"
-
 	"github.com/gohugoio/hugo/markup/converter"
 	"github.com/gohugoio/hugo/markup/tableofcontents"
 	"github.com/yuin/goldmark"
@@ -131,11 +131,14 @@ func newMarkdown(pcfg converter.ProviderConfig) goldmark.Markdown {
 	if cfg.Parser.Attribute.Title {
 		parserOptions = append(parserOptions, parser.WithAttribute())
 	}
-
 	if cfg.Parser.Attribute.Block {
 		extensions = append(extensions, attributes.New())
 	}
 
+	if cfg.Parser.Image.RemoveSurroundingParagraph {
+		extensions = append(extensions, images.New())
+	}
+
 	md := goldmark.New(
 		goldmark.WithExtensions(
 			extensions...,

markup/goldmark/goldmark_config/config.go

@@ -88,6 +88,9 @@ type Parser struct {
 
 	// Enables custom attributes.
 	Attribute ParserAttribute
+
+	// Parsing configuration for images.
+	Image ParserImage
 }
 
 type ParserAttribute struct {
@@ -96,3 +99,9 @@ type ParserAttribute struct {
 	// Enables custom attributeds for blocks.
 	Block bool
 }
+
+type ParserImage struct {
+	// Remove any surrounding <p> tags around images.
+	// Also copies any attributes from the <p> tag to the <img> tag.
+	RemoveSurroundingParagraph bool
+}

markup/goldmark/images/integration_test.go

@@ -0,0 +1,63 @@
+package images_test
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestRemoveSurroundingParagraph(t *testing.T) {
+	t.Parallel()
+
+	filesTemplate := `
+-- config.toml --
+[markup.goldmark.renderer]
+	unsafe = false
+[markup.goldmark.parser]
+[markup.goldmark.parser.image]
+removeSurroundingParagraph = true
+[markup.goldmark.parser.attribute]
+	block = true
+	title = true
+-- content/p1.md --
+---
+title: "p1"
+---
+
+![Image](/img.jpg)
+{.b}
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	t.Run("With Hook", func(t *testing.T) {
+		files := filesTemplate + `-- layouts/_default/_markup/render-image.html --
+<figure class="{{ .Attributes.class }}">
+	<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" />
+</figure>
+`
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: files,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html", "<figure class=\"b\">\n  <img src=\"/img.jpg\" alt=\"Image\" />\n</figure>")
+	})
+
+	t.Run("No Hook", func(t *testing.T) {
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: filesTemplate,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html", `<img src="/img.jpg" alt="Image" class="b">`)
+	})
+
+}

markup/goldmark/images/transform.go

@@ -0,0 +1,56 @@
+package images
+
+import (
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type (
+	imagesExtension struct{}
+)
+
+func New() goldmark.Extender {
+	return &imagesExtension{}
+}
+
+func (e *imagesExtension) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithASTTransformers(
+			util.Prioritized(&Transformer{}, 300),
+		),
+	)
+}
+
+type Transformer struct {
+}
+
+// Transform transforms the provided Markdown AST.
+func (t *Transformer) Transform(doc *ast.Document, reader text.Reader, pctx parser.Context) {
+	ast.Walk(doc, func(node ast.Node, enter bool) (ast.WalkStatus, error) {
+		if !enter {
+			return ast.WalkContinue, nil
+		}
+
+		if n, ok := node.(*ast.Image); ok {
+			if p := n.Parent(); p != nil {
+				if p.Kind() == ast.KindParagraph {
+					for _, attr := range p.Attributes() {
+						// Transfer any attribute set down to the image.
+						// Image elements does not support attributes on its own,
+						// so it's safe to just set without checking first.
+						n.SetAttribute(attr.Name, attr.Value)
+					}
+					grandParent := p.Parent()
+					grandParent.ReplaceChild(grandParent, p, n)
+				}
+			}
+		}
+
+		return ast.WalkContinue, nil
+
+	})
+
+}

markup/goldmark/render_hooks.go

@@ -52,6 +52,7 @@ type linkContext struct {
 	title       string
 	text        hstring.RenderedString
 	plainText   string
+	*attributes.AttributesHolder
 }
 
 func (ctx linkContext) Destination() string {
@@ -154,11 +155,12 @@ func (r *hookedRenderer) renderImage(w util.BufWriter, source []byte, node ast.N
 	err := lr.RenderLink(
 		w,
 		linkContext{
-			page:        ctx.DocumentContext().Document,
-			destination: string(n.Destination),
-			title:       string(n.Title),
-			text:        hstring.RenderedString(text),
-			plainText:   string(n.Text(source)),
+			page:             ctx.DocumentContext().Document,
+			destination:      string(n.Destination),
+			title:            string(n.Title),
+			text:             hstring.RenderedString(text),
+			plainText:        string(n.Text(source)),
+			AttributesHolder: attributes.New(n.Attributes(), attributes.AttributesOwnerGeneral),
 		},
 	)
 
@@ -186,6 +188,9 @@ func (r *hookedRenderer) renderImageDefault(w util.BufWriter, source []byte, nod
 		r.Writer.Write(w, n.Title)
 		_ = w.WriteByte('"')
 	}
+	if n.Attributes() != nil {
+		attributes.RenderASTAttributes(w, node.Attributes()...)
+	}
 	if r.XHTML {
 		_, _ = w.WriteString(" />")
 	} else {
@@ -224,11 +229,12 @@ func (r *hookedRenderer) renderLink(w util.BufWriter, source []byte, node ast.No
 	err := lr.RenderLink(
 		w,
 		linkContext{
-			page:        ctx.DocumentContext().Document,
-			destination: string(n.Destination),
-			title:       string(n.Title),
-			text:        hstring.RenderedString(text),
-			plainText:   string(n.Text(source)),
+			page:             ctx.DocumentContext().Document,
+			destination:      string(n.Destination),
+			title:            string(n.Title),
+			text:             hstring.RenderedString(text),
+			plainText:        string(n.Text(source)),
+			AttributesHolder: attributes.Empty,
 		},
 	)
 
@@ -292,10 +298,11 @@ func (r *hookedRenderer) renderAutoLink(w util.BufWriter, source []byte, node as
 	err := lr.RenderLink(
 		w,
 		linkContext{
-			page:        ctx.DocumentContext().Document,
-			destination: url,
-			text:        hstring.RenderedString(label),
-			plainText:   label,
+			page:             ctx.DocumentContext().Document,
+			destination:      url,
+			text:             hstring.RenderedString(label),
+			plainText:        label,
+			AttributesHolder: attributes.Empty,
 		},
 	)
 

markup/internal/attributes/attributes.go

@@ -126,6 +126,9 @@ func (a Attribute) ValueString() string {
 	return cast.ToString(a.Value)
 }
 
+// Empty holds no attributes.
+var Empty = &AttributesHolder{}
+
 type AttributesHolder struct {
 	// What we get from Goldmark.
 	attributes []Attribute