[US-118] The new example for creating outlines

outlines/pdf_create_outlines.go

@@ -0,0 +1,86 @@
+/*
+ * Creates outlines for a PDF file.
+ *
+ * Run as: go run pdf_create_outlines.go input.pdf output.pdf
+ */
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/unidoc/unipdf/v3/common/license"
+	"github.com/unidoc/unipdf/v3/model"
+)
+
+func init() {
+	// Make sure to load your metered License API key prior to using the library.
+	// If you need a key, you can sign up and create a free one at https://cloud.unidoc.io
+	err := license.SetMeteredKey(os.Getenv(`UNIDOC_LICENSE_API_KEY`))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Printf("Usage: go run pdf_create_outlines.go input.pdf output.pdf\n")
+		os.Exit(1)
+	}
+
+	inputPath := os.Args[1]
+	outPath := os.Args[2]
+
+	fmt.Printf("Input file: %s\n", inputPath)
+	fmt.Printf("Output file: %s\n", outPath)
+
+	pdfReader, f, err := model.NewPdfReaderFromFile(inputPath, nil)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+	defer f.Close()
+
+	// Check number of PDF pages.
+	numPages, err := pdfReader.GetNumPages()
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	if numPages < 3 {
+		fmt.Printf("Too short PDF file. At least 3 pages are needed for this outline example.")
+		os.Exit(1)
+	}
+
+	// Don't copy document outlines.
+	opt := &model.ReaderToWriterOpts{
+		SkipOutlines: true,
+	}
+
+	// Generate a PdfWriter instance from existing PdfReader.
+	pdfWriter, err := pdfReader.ToWriter(opt)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Add the new document outlines.
+	outline := model.NewOutline()
+	for i := 0; i < 3; i++ {
+		page, _ := pdfReader.GetPage(i + 1)
+		_, y, _ := page.Size()
+		// Create outline for the top left corner of each page. Note that PDF y coordinate goes from bottom to top.
+		outline.Add(model.NewOutlineItem(fmt.Sprintf("page%d", i+1), model.NewOutlineDest(int64(i), 0, y)))
+	}
+
+	pdfWriter.AddOutlineTree(outline.ToOutlineTree())
+
+	// Write output file.
+	err = pdfWriter.WriteToFile(outPath)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+}