AddWatermark returns error on PDF with empty page #843
Description
The function github.com/pdfcpu/pdfcpu/pkg/api.AddWatermarks returns pdfcpu: page without content.
The pdf file, which is being added as watermark, contains pdf pages with no content at all.
Expected behavior
The pdf is successfully being added as watermark, including empty pages. The empty pages might be placed in the beginning, in the middle or in the end of the pdf file.
Actual behavior
The function returns an error.
Environment
- OS: macOS Sonoma 14.3
- Go: 1.21.5
Code to reproduce
go.mod
go 1.21.5
require github.com/pdfcpu/pdfcpu v0.7.0
require (
github.com/hhrutter/lzw v1.0.0 // indirect
github.com/hhrutter/tiff v1.0.1 // indirect
github.com/mattn/go-runewidth v0.0.15 // indirect
github.com/pkg/errors v0.9.1 // indirect
github.com/rivo/uniseg v0.4.4 // indirect
golang.org/x/image v0.12.0 // indirect
golang.org/x/text v0.13.0 // indirect
gopkg.in/yaml.v2 v2.4.0 // indirect
)
main.go
package main
import (
"bytes"
_ "embed"
"log"
"github.com/pdfcpu/pdfcpu/pkg/api"
"github.com/pdfcpu/pdfcpu/pkg/pdfcpu"
"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/model"
"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/types"
)
var (
//go:embed blank.pdf
blankBytes []byte
//go:embed empty_page.pdf
pdfBytes []byte
)
func main() {
var (
buf bytes.Buffer
desc = "offset: 10 0 ,rot:0, scale:0.8 rel"
fileName = "test.pdf"
selectedPages = "1-2"
)
wm, err := pdfcpu.ParsePDFWatermarkDetails(fileName, desc, false, types.POINTS)
if err != nil {
log.Fatalf("error on pdfcpu.ParsePDFWatermarkDetails: %v", err)
}
wm.PDF = bytes.NewReader(pdfBytes)
// here returns error:
// pdfcpu: page without content
if err := api.AddWatermarks(
bytes.NewReader(blankBytes),
&buf,
[]string{selectedPages},
wm,
model.NewDefaultConfiguration(),
); err != nil {
log.Fatalf("error on api.AddWatermarks: %v", err)
}
}PDF files:
- blank.pdf
- empty_page.pdf <- this file triggers the error
Possible solution
The actual error is being returned from this line - pkg/pdfcpu/model/xreftable.go:1783:
if len(bb) == 0 {
return nil, ErrNoContent
}I tried to remove these lines and the function AddWatermarks works as expected.