pdftopswazero

README

Pstopdf tool from xpdfreader, converted to wasm, run with WASM+wazero+fake memory FS.

It's one part of PDF-to-PDF/A conversion. (We use this on some weird PDFs that refuse to be converted just with ghostscript; most are happy with ghostscript, some are not.)

We are actually building all xpdfreader tools to wasm; but we then use just pdftops.

How to use

See example_test.go

package main

import (
    "context"
    "fmt"

    pdftops "github.com/karelbilek/pdftops-wazero"
)

func main() {
	g, err = pdftops.New(context.Background())
	if err != nil {
		panic(err)
	}

	in, err := os.ReadFile("some.pdf")
	if err != nil {
		panic(err)
	}

	out, err := g.ConvertPDFToPS(context.Background(), in)
	if err != nil {
		panic(err)
	}

	err = os.WriteFile("someout.ps", out, 0o666)
	if err != nil {
		panic(err)
	}
}

Copyright

(C) 2023 Karel Bilek, Jeroen Bobbeldijk (https://github.com/jerbob92)

xpdfreader (C) 1996-2022 Glyph & Cog, LLC. (from https://www.xpdfreader.com/download.html )

ghostscript fonts Copyright (c) 2001- Valek Filippov (from https://packages.ubuntu.com/focal/gsfonts)

The whole code is GPLv2.

How to build the WASM

• git submodule update --init
• install docker
• cd build && ./build.sh on a Unix-like environment (WSL might work too if it has access to the Docker)
  • note - it might take a bit of time on the CMake step
• in build/out/pdftops.wasm there is the compiled wasm file

Documentation

Overview

Example (ConvertPDFToPS)

package main

import (
	"context"
	"fmt"
	"os"

	pdftops "github.com/karelbilek/pdftopswazero"
)

func main() {
	g, err := pdftops.New(context.Background())
	if err != nil {
		panic(err)
	}
	in, err := os.ReadFile("some.pdf")
	if err != nil {
		panic(err)
	}

	out, err := g.ConvertPDFToPS(context.Background(), in)
	if err != nil {
		panic(err)
	}

	err = os.WriteFile("someout.ps", out, 0o666)
	if err != nil {
		panic(err)
	}

	fmt.Println("success")
}

Output:
success

Index

• type PdfToPs
  • func New(ctx context.Context) (*PdfToPs, error)
  • func (p *PdfToPs) ConvertPDFToPS(ctx context.Context, in []byte) ([]byte, error)

Examples

• Package (ConvertPDFToPS)

Types

type PdfToPs

type PdfToPs struct {
	// contains filtered or unexported fields
}

func New

func New(ctx context.Context) (*PdfToPs, error)

DoInit inits; it is safe to call concurrently; only first will init

func (*PdfToPs) ConvertPDFToPS

func (p *PdfToPs) ConvertPDFToPS(ctx context.Context, in []byte) ([]byte, error)