Working implementation of #73

Author: jessp01

cmd/md2pdf/md2pdf.go

@@ -29,6 +29,7 @@ var fontName = flag.String("font-name", "", "Font name ID; e.g 'Helvetica-1251'"
 var themeArg = flag.String("theme", "light", "[light | dark | /path/to/custom/theme.json]")
 var hrAsNewPage = flag.Bool("new-page-on-hr", false, "Interpret HR as a new page; useful for presentations")
 var printFooter = flag.Bool("with-footer", false, "Print doc footer (<author>  <title>  <page number>)")
+var generateTOC = flag.Bool("generate-toc", false, "Auto Generate TOC")
 var pageSize = flag.String("page-size", "A4", "[A3 | A4 | A5]")
 var orientation = flag.String("orientation", "portrait", "[portrait | landscape]")
 var logFile = flag.String("log-file", "", "Path to log file")
@@ -174,6 +175,42 @@ func main() {
 	}
 
 	pf := mdtopdf.NewPdfRenderer(params)
+
+	if *generateTOC == true {
+		// we need to generate the TOC for `content`
+		headers, err := mdtopdf.GetTOCEntries(content)
+		if err != nil {
+			log.Fatal(err)
+		}
+		headerLinks := make(map[string]*int)
+		for _, header := range headers {
+			linkID := pf.Pdf.AddLink()
+			headerLinks[header.Title] = &linkID
+
+			// debug
+			// log.Printf("Header: '%s' (Level %d) -> Link ID: %d\n",
+			// header.Title, header.Level, linkID)
+		}
+
+		pf.SetTOCLinks(headerLinks)
+		pf.Pdf.SetFont("Arial", "B", 24)
+
+		// Add a table of contents with clickable links
+		pf.Pdf.Cell(40, 10, "Table of Contents")
+		pf.Pdf.Ln(30)
+
+		for _, header := range headers {
+			if linkPtr, exists := headerLinks[header.Title]; exists {
+				link := *linkPtr
+				pf.Pdf.SetFont("Arial", "", 12)
+				tr := pf.Pdf.UnicodeTranslatorFromDescriptor("")
+				pf.Pdf.WriteLinkID(8, fmt.Sprintf("%s %s", tr("•"), header.Title), link)
+				pf.Pdf.Ln(15)
+			}
+		}
+		pf.Pdf.AddPage()
+	}
+
 	if inputBaseURL != "" {
 		pf.InputBaseURL = inputBaseURL
 	}

mdtopdf.go

@@ -129,6 +129,8 @@ type PdfRenderer struct {
 	documentMatter            ast.DocumentMatters // keep track of front/main/back matter.
 	Extensions                parser.Extensions
 	ColumnWidths              map[ast.Node][]float64
+
+	tocLinks map[string]*int
 }
 
 // TOCEntry represents a table of contents entry
@@ -140,7 +142,7 @@ type TOCEntry struct {
 
 // TOCVisitor implements ast.NodeVisitor to collect headers
 type TOCVisitor struct {
-	entries []TOCEntry
+	Entries []TOCEntry
 }
 
 // Visit implements the ast.NodeVisitor interface
@@ -167,7 +169,7 @@ func (v *TOCVisitor) Visit(node ast.Node, entering bool) ast.WalkStatus {
 				Title: title,
 				ID:    id,
 			}
-			v.entries = append(v.entries, entry)
+			v.Entries = append(v.Entries, entry)
 		}
 	}
 
@@ -209,7 +211,13 @@ func GetTOCEntries(content []byte) ([]TOCEntry, error) {
 	// Walk the AST and collect headers
 	ast.Walk(doc, visitor)
 
-	return visitor.entries, nil
+	return visitor.Entries, nil
+}
+
+// SetTOCLinks these will be used in `nodeProcessing.go:processText()` if the header is encoutered
+// as we need to call `r.Pdf.SetLink()` if that's the case
+func (r *PdfRenderer) SetTOCLinks(tocHeaders map[string]*int) {
+	r.tocLinks = tocHeaders
 }
 
 // SetLightTheme sets theme to 'light'

nodeProcessing.go

@@ -59,6 +59,16 @@ func (r *PdfRenderer) processText(node *ast.Text) {
 	case *ast.Link:
 		r.writeLink(currentStyle, s, r.cs.peek().destination)
 	case *ast.Heading:
+		if len(r.tocLinks) > 0 {
+			if linkPtr, exists := r.tocLinks[s]; exists {
+				// Dereference the pointer to get the actual link ID
+				link := *linkPtr
+				r.Pdf.SetLink(link, -1, -1)
+				r.tracer("Text Heading", fmt.Sprintf("Set link for header '%s' with link ID: %d\n", s, link))
+			} else {
+				r.tracer("Text Heading", fmt.Sprintf("Header '%s' not found in links map\n", s))
+			}
+		}
 		r.write(currentStyle, s)
 	case *ast.BlockQuote:
 		if r.NeedBlockquoteStyleUpdate {