Add RTL rendering support to Markdown

Author: silverwind

modules/markup/markdown/goldmark.go

@@ -69,6 +69,9 @@ func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc pa
 				header.ID = util.BytesToReadOnlyString(id.([]byte))
 			}
 			tocList = append(tocList, header)
+			v.SetAttributeString("dir", []byte("auto"))
+		case *ast.Paragraph:
+			v.SetAttributeString("dir", []byte("auto"))
 		case *ast.Image:
 			// Images need two things:
 			//
@@ -171,6 +174,7 @@ func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc pa
 					v.AppendChild(v, newChild)
 				}
 			}
+			v.SetAttributeString("dir", []byte("auto"))
 		case *ast.Text:
 			if v.SoftLineBreak() && !v.HardLineBreak() {
 				renderMetas := pc.Get(renderMetasKey).(map[string]string)

modules/markup/sanitizer.go

@@ -102,6 +102,9 @@ func createDefaultPolicy() *bluemonday.Policy {
 	// Allow 'style' attribute on text elements.
 	policy.AllowAttrs("style").OnElements("span", "p")
 
+	// Allow 'dir' attribute on elements that may contain rtl content.
+	policy.AllowAttrs("dir").OnElements("span", "div", "p", "ul", "ol", "h1", "h2", "h3", "h4", "h5", "h6")
+
 	// Allow 'color' and 'background-color' properties for the style attribute on text elements.
 	policy.AllowStyles("color", "background-color").OnElements("span", "p")