markup/goldmark: Add removeSurroundingParagraph for Markdown images

* Removes any surrounding paragraph nodes
* And transfers any attributes from the surrounding paragraph down to the image node
* Adds IsBlock and Ordinal (zero based) field to the image context passed to the image render hooks

IsBlock is set to true if `wrapStandAloneImageWithinParagraph = false` and  the image's parent node has only one child.

Closes #8362
Fixes #10492
Fixes #10494
Fixes #10501

markup/goldmark/images/integration_test.go

@@ -0,0 +1,113 @@
+package images_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestDisableWrapStandAloneImageWithinParagraph(t *testing.T) {
+	t.Parallel()
+
+	filesTemplate := `
+-- config.toml --
+[markup.goldmark.renderer]
+	unsafe = false
+[markup.goldmark.parser]
+wrapStandAloneImageWithinParagraph = CONFIG_VALUE
+[markup.goldmark.parser.attribute]
+	block = true
+	title = true
+-- content/p1.md --
+---
+title: "p1"
+---
+
+This is an inline image: ![Inline Image](/inline.jpg). Some more text.
+
+![Block Image](/block.jpg)
+{.b}
+
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	t.Run("With Hook, no wrap", func(t *testing.T) {
+		files := strings.ReplaceAll(filesTemplate, "CONFIG_VALUE", "false")
+		files = files + `-- layouts/_default/_markup/render-image.html --
+{{ if .IsBlock }}
+<figure class="{{ .Attributes.class }}">
+	<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" />
+</figure>
+{{ else }}
+	<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" />
+{{ end }}
+`
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: files,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html",
+			"This is an inline image: \n\t<img src=\"/inline.jpg\" alt=\"Inline Image\" />\n. Some more text.</p>",
+			"<figure class=\"b\">\n\t<img src=\"/block.jpg\" alt=\"Block Image\" />",
+		)
+	})
+
+	t.Run("With Hook, wrap", func(t *testing.T) {
+		files := strings.ReplaceAll(filesTemplate, "CONFIG_VALUE", "true")
+		files = files + `-- layouts/_default/_markup/render-image.html --
+{{ if .IsBlock }}
+<figure class="{{ .Attributes.class }}">
+	<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" />
+</figure>
+{{ else }}
+	<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" />
+{{ end }}
+`
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: files,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html",
+			"This is an inline image: \n\t<img src=\"/inline.jpg\" alt=\"Inline Image\" />\n. Some more text.</p>",
+			"<p class=\"b\">\n\t<img src=\"/block.jpg\" alt=\"Block Image\" />\n</p>",
+		)
+	})
+
+	t.Run("No Hook, no wrap", func(t *testing.T) {
+		files := strings.ReplaceAll(filesTemplate, "CONFIG_VALUE", "false")
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: files,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html", "<p>This is an inline image: <img src=\"/inline.jpg\" alt=\"Inline Image\">. Some more text.</p>\n<img src=\"/block.jpg\" alt=\"Block Image\" class=\"b\">")
+	})
+
+	t.Run("No Hook, wrap", func(t *testing.T) {
+		files := strings.ReplaceAll(filesTemplate, "CONFIG_VALUE", "true")
+		b := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           t,
+				TxtarString: files,
+				NeedsOsFS:   false,
+			},
+		).Build()
+
+		b.AssertFileContent("public/p1/index.html", "<p class=\"b\"><img src=\"/block.jpg\" alt=\"Block Image\"></p>")
+	})
+
+}

markup/goldmark/images/transform.go

@@ -0,0 +1,77 @@
+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 {
+		wrapStandAloneImageWithinParagraph bool
+	}
+)
+
+const (
+	// Used to signal to the rendering step that an image is used in a block context.
+	// Dont's change this; the prefix must match the internalAttrPrefix in the root goldmark package.
+	AttrIsBlock = "_h__isBlock"
+	AttrOrdinal = "_h__ordinal"
+)
+
+func New(wrapStandAloneImageWithinParagraph bool) goldmark.Extender {
+	return &imagesExtension{wrapStandAloneImageWithinParagraph: wrapStandAloneImageWithinParagraph}
+}
+
+func (e *imagesExtension) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithASTTransformers(
+			util.Prioritized(&Transformer{wrapStandAloneImageWithinParagraph: e.wrapStandAloneImageWithinParagraph}, 300),
+		),
+	)
+}
+
+type Transformer struct {
+	wrapStandAloneImageWithinParagraph bool
+}
+
+// Transform transforms the provided Markdown AST.
+func (t *Transformer) Transform(doc *ast.Document, reader text.Reader, pctx parser.Context) {
+	var ordinal int
+	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 {
+			parent := n.Parent()
+			n.SetAttributeString(AttrOrdinal, ordinal)
+			ordinal++
+
+			if !t.wrapStandAloneImageWithinParagraph {
+				isBlock := parent.ChildCount() == 1
+				if isBlock {
+					n.SetAttributeString(AttrIsBlock, true)
+				}
+
+				if isBlock && parent.Kind() == ast.KindParagraph {
+					for _, attr := range parent.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 := parent.Parent()
+					grandParent.ReplaceChild(grandParent, parent, n)
+				}
+			}
+
+		}
+
+		return ast.WalkContinue, nil
+
+	})
+
+}