[BUG] Page break between subchapters

[ricardogama]

Description

I'm trying to use chapters and subchapters to include them in the TOC, and I need each subchapter to start in a new page.

Expected Behavior

By using c.NewPage() or c.Draw(c.NewPageBreak()), I expect to have a new page, and in this case right before a new subchapter.

Actual Behavior

The page break only seems to work on a new chapter, but not on a new subchapter.

I tried having the page breaks before and after creating the subchapter, but neither seems to work.

Steps to reproduce the behavior:

1. go run main.go
2. open result.pdf
3. See both subchapters 2 and 3 are on the same page (page 13)

Attachments

main.go

package main

import (
	"bytes"
	"fmt"
	"os"

	"github.com/unidoc/unipdf/v3/common/license"
	"github.com/unidoc/unipdf/v3/creator"
	"github.com/unidoc/unipdf/v3/model"
)

var (
	regularFont *model.PdfFont
	boldFont    *model.PdfFont
)

func main() {
	if err := license.SetMeteredKey(os.Getenv("UNIDOC_KEY")); err != nil {
		panic(err)
	}

	var err error
	regularFont, err = model.NewStandard14Font("Helvetica")
	if err != nil {
		panic(err)
	}

	boldFont, err = model.NewStandard14Font("Helvetica-Bold")
	if err != nil {
		panic(err)
	}

	c := creator.New()
	c.SetPageMargins(30, 30, 30, 30)

	c.DrawFooter(func(block *creator.Block, args creator.FooterFunctionArgs) {
		p := c.NewStyledParagraph()
		p.SetTextAlignment(creator.TextAlignmentCenter)

		chunk := p.Append(fmt.Sprintf("Page %d of %d", args.PageNum, args.TotalPages))
		chunk.Style.Font = regularFont
		chunk.Style.FontSize = 8
		chunk.Style.Color = creator.ColorBlack

		if err := block.Draw(p); err != nil {
			panic(err)
		}
	})

	chapters := map[string][]string{
		"chapter 1": {
			"subchapter 1",
		},
		"chapter 2": {
			"subchapter 2",
			"subchapter 3",
		},
	}

	c.AddTOC = true
	toc := c.TOC()

	hstyle := c.NewTextStyle()
	hstyle.Color = creator.ColorRGBFromArithmetic(0.2, 0.2, 0.2)
	hstyle.Font = boldFont
	hstyle.FontSize = 21
	toc.SetHeading("Index", hstyle)

	lstyle := c.NewTextStyle()
	lstyle.Font = regularFont
	toc.SetLineStyle(lstyle)
	toc.SetLineMargins(0, 0, 10, 0)

	for chapter, subchapters := range chapters {
		ch := newChapter(c, chapter)
		
                 for _, subchapter := range subchapters {
			c.NewPage()
			c.Draw(c.NewPageBreak())

			sc := newSubchapter(ch, subchapter)
			p := newParagraph(c, regularFont, creator.ColorBlack, subchapter)

			c.NewPage()
			c.Draw(c.NewPageBreak())

			sc.Add(p)
		}

		c.Draw(ch)
	}

	var content bytes.Buffer
	if err := c.Write(&content); err != nil {
		panic(err)
	}

	f, err := os.Create("./result.pdf")
	if err != nil {
		panic(err)
	}
	_, err = f.Write(content.Bytes())
	if err != nil {
		panic(err)
	}
	err = f.Close()
	if err != nil {
		panic(err)
	}

	fmt.Println("result.pdf created")
}

func newChapter(c *creator.Creator, title string) *creator.Chapter {
	ch := c.NewChapter(title)
	ch.GetHeading().SetFontSize(0)
	return ch
}

func newSubchapter(ch *creator.Chapter, title string) *creator.Chapter {
	sc := ch.NewSubchapter(title)
	sc.GetHeading().SetFontSize(0)
	return sc
}

func newParagraph(c *creator.Creator, font *model.PdfFont, color creator.Color, text string) *creator.StyledParagraph {
	p := c.NewStyledParagraph()
	p.SetMargins(2, 2, 5, 5)
	chunk := p.Append(text)
	chunk.Style.Font = font
	chunk.Style.Color = color
	return p
}

result.pdf

[ricardogama]

Adding the line break to the chapter instead of *Creator fixed it:

chapter.Add(c.NewPageBreak())