The backend library#

The backend layer is right above the PDF layer and contains low-level stuff like node lists, font and image loading and putting objects into a PDF file. With this library, you have complete control over the output you need but also have a few helper functions like a line breaking algorithm, hyphenation and color management.

Installation#

The installation is very simple by importing the package into your code. First initialize a module and get the library:

go mod init mymodule
go get github.com/boxesandglue/boxesandglue@latest

and use the library:

package main

import (
    "os"

    "github.com/boxesandglue/boxesandglue/backend/document"
)

func main() {
    w, _ := os.Create("out.pdf")
    doc := document.NewDocument(w)
    ...
}

Getting started#

The starting point is the PDFDocument:

func NewDocument(w io.Writer) *PDFDocument

With this document, you can load fonts and images, create pages and shipout pages, define colors and much more. Since the API is a bit extensive, it is covered in different chapters:

Core units: The basic definition of units and conversion between basic unit “scaled point” and other units.
Document level methods and settings: All building blocks around document structure, pages and output debugging.
Color spaces: Color spaces such as RGB, CMYK, spot colors and the PDF accessors.
Font handling: Loading fonts and turning text into font specific code points.
Image loading: Image loading.
Languages and hyphenation: Loading languages and hyphenation handling.
Nodes and node list manipulation: Nodes are the basic building blocks of all pages.
Interactive features: PDF has lots of interactive features such as hyperlinks and bookmarks.

Logging

Breaking paragraphs into lines