Merge

Basic Merge

Combine two PDFs into one.

merged, _ := gpdf.Merge([]gpdf.Source{
    {Data: cover},
    {Data: body},
})

Page Range Extraction

Extract pages 2 through 4 from a 5-page document.

extracted, _ := gpdf.Merge([]gpdf.Source{
    {Data: full, Pages: gpdf.PageRange{From: 2, To: 4}},
})

With Metadata

Set title, author, and producer on the merged output.

merged, _ := gpdf.Merge(
    []gpdf.Source{
        {Data: cover},
        {Data: body},
        {Data: appendix},
    },
    gpdf.WithMergeMetadata("Policy Bundle", "Example Ltd", "gpdf"),
)

Merge + Page Numbers

Merge documents, then overlay page numbers on every page.

// Merge
merged, _ := gpdf.Merge([]gpdf.Source{
    {Data: cover},
    {Data: body},
})

// Open and add page numbers
doc, _ := gpdf.Open(merged)
count, _ := doc.PageCount()

doc.EachPage(func(i int, p *template.PageBuilder) {
    p.Absolute(document.Mm(170), document.Mm(285), func(c *template.ColBuilder) {
        c.Text(fmt.Sprintf("%d / %d", i+1, count),
            template.FontSize(10),
            template.AlignRight(),
        )
    }, template.AbsoluteWidth(document.Mm(20)))
})

result, _ := doc.Save()

Cover + Generated + Partial Attachment

A production scenario: combine a scanned cover page, a gpdf-generated body, and the first 3 pages of an attachment.

coverPage, _ := os.ReadFile("cover.pdf")
attachment, _ := os.ReadFile("attachment.pdf")

// Generate body with gpdf
doc := template.New(template.WithPageSize(document.A4))
page := doc.AddPage()
page.AutoRow(func(r *template.RowBuilder) {
    r.Col(12, func(c *template.ColBuilder) {
        c.Text("Generated Content", template.FontSize(20), template.Bold())
    })
})
generated, _ := doc.Generate()

// Merge all together
merged, _ := gpdf.Merge(
    []gpdf.Source{
        {Data: coverPage},
        {Data: generated},
        {Data: attachment, Pages: gpdf.PageRange{From: 1, To: 3}},
    },
    gpdf.WithMergeMetadata("Policy Bundle", "Example Ltd", ""),
)