pdf

README

  

baseline-pdf is a low-level PDF writer for the Go language. It is used in the boxes and glue typesetting library but can be used in other projects as well.

This library has a godoc reference and a more verbose manual.

Status

Not yet used in production. Expect API changes.

License

BSD license - see License.md

Contact

Patrick Gundlach, gundlach@speedata.de

Documentation

Index

• Variables
• func FloatToPoint(in float64) string
• func Serialize(item any) string
• type Annotation
• type Array
• type Dict
• type Face
  • func (face *Face) Codepoint(r rune) int
  • func (face *Face) Codepoints(runes []rune) []int
  • func (face *Face) InternalName() string
  • func (face *Face) RegisterChar(codepoint int)
  • func (face *Face) RegisterChars(codepoints []int)
• type Imagefile
  • func (imgf *Imagefile) GetPDFBoxDimensions(p int, boxname string) (map[string]float64, error)
  • func (imgf *Imagefile) InternalName() string
• type Name
  • func (n Name) String() string
• type NameDest
• type Object
  • func (obj *Object) Dict(d Dict) *Object
  • func (obj *Object) Save() error
  • func (obj *Object) SetCompression(compresslevel uint)
• type Objectnumber
  • func (o Objectnumber) Ref() string
  • func (o Objectnumber) String() string
• type Outline
• type PDF
  • func NewPDFWriter(file io.Writer) *PDF
  • func (pw *PDF) AddPage(content *Object, page Objectnumber) *Page
  • func (pw *PDF) Finish() error
  • func (pw *PDF) LoadFace(filename string, idx int) (*Face, error)
  • func (pw *PDF) LoadImageFile(filename string) (*Imagefile, error)
  • func (pw *PDF) LoadImageFileWithBox(filename string, box string, pagenumber int) (*Imagefile, error)
  • func (pw *PDF) NewFaceFromData(data []byte, idx int) (*Face, error)
  • func (pw *PDF) NewObject() *Object
  • func (pw *PDF) NewObjectWithNumber(objnum Objectnumber) *Object
  • func (pw *PDF) NextObject() Objectnumber
  • func (pw *PDF) Print(s string) error
  • func (pw *PDF) Printf(format string, a ...any) error
  • func (pw *PDF) Println(s string) error
  • func (pw *PDF) Size() int64
• type Page
• type Pages
• type Separation
• type String

Variables

var (
	// Logger is initialized to write to io.Discard and the default log level is math.MaxInt, so it should never write anything.
	Logger *slog.Logger
)

Functions

func FloatToPoint

func FloatToPoint(in float64) string

FloatToPoint returns a string suitable as a PDF size value.

func Serialize

func Serialize(item any) string

Serialize returns a string representation of the item as it may appear in the PDF file. Arrays are written with square brackets, Dicts with double angle brackets, Strings (PDF strings) with parentheses or single angle brackets, depending on the contents and all other objects with their respective String() method.

Types

type Annotation

type Annotation struct {
	Subtype    Name
	Action     string
	Dictionary Dict
	Rect       [4]float64 // x1, y1, x2, y2
}

An Annotation is a PDF element that is additional to the text, such as a hyperlink or a note.

type Array

type Array []any

Array is a list of anything

type Dict

type Dict map[Name]any

Dict is a dictionary where each key begins with a slash (/). Each value can be a string, an array or another dictionary.

type Face

type Face struct {
	FaceID         int
	HarfbuzzFont   *harfbuzz.Font
	UnitsPerEM     int32
	Cmap           fonts.Cmap
	Filename       string
	PostscriptName string
	// contains filtered or unexported fields
}

Face represents a font structure with no specific size. To get the dimensions of a font, you need to create a Font object with a given size.

func (*Face) Codepoint

func (face *Face) Codepoint(r rune) int

Codepoint tries to find the code point for r. If none found, 0 is returned.

func (*Face) Codepoints

func (face *Face) Codepoints(runes []rune) []int

Codepoints returns the internal code points for the runes.

func (*Face) InternalName

func (face *Face) InternalName() string

InternalName returns a PDF usable name such as /F1

func (*Face) RegisterChar

func (face *Face) RegisterChar(codepoint int)

RegisterChar marks the codepoint as used on the page. For font subsetting.

func (*Face) RegisterChars

func (face *Face) RegisterChars(codepoints []int)

RegisterChars marks the codepoints as used on the page. For font subsetting.

type Imagefile

type Imagefile struct {
	Format        string
	NumberOfPages int
	PageSizes     map[int]map[string]map[string]float64
	Filename      string
	ScaleX        float64
	ScaleY        float64
	W             int
	H             int
	Box           string
	PageNumber    int
	// contains filtered or unexported fields
}

Imagefile represents a physical image file. Images to be place in the PDF must be derived from the image.

func (*Imagefile) GetPDFBoxDimensions

func (imgf *Imagefile) GetPDFBoxDimensions(p int, boxname string) (map[string]float64, error)

GetPDFBoxDimensions returns the dimensions for the given box. Box must be one of "/MediaBox", "/CropBox", "/BleedBox", "/TrimBox", "/ArtBox".

func (*Imagefile) InternalName

func (imgf *Imagefile) InternalName() string

InternalName returns a PDF usable name such as /F1

type Name

type Name string

Name represents a PDF name such as Adobe Green. The String() method prepends a / (slash) to the name if not present.

func (Name) String

func (n Name) String() string

type NameDest

type NameDest struct {
	PageObjectnumber Objectnumber
	Name             String
	X                float64
	Y                float64
	// contains filtered or unexported fields
}

NameDest represents a named PDF destination. The origin of X and Y are in the top left corner and expressed in DTP points.

type Object

type Object struct {
	ObjectNumber Objectnumber
	Data         *bytes.Buffer
	Dictionary   Dict
	Array        []any
	Raw          bool // Data holds everything between object number and endobj
	ForceStream  bool
	// contains filtered or unexported fields
}

Object has information about a specific PDF object

func (*Object) Dict

func (obj *Object) Dict(d Dict) *Object

Dict writes the dict d to a PDF object

func (*Object) Save

func (obj *Object) Save() error

Save adds the PDF object to the main PDF file.

func (*Object) SetCompression

func (obj *Object) SetCompression(compresslevel uint)

SetCompression turns on stream compression if compresslevel > 0

type Objectnumber

type Objectnumber int

Objectnumber represents a PDF object number

func (Objectnumber) Ref

func (o Objectnumber) Ref() string

Ref returns a reference to the object number

func (Objectnumber) String

func (o Objectnumber) String() string

String returns a reference to the object number

type Outline

type Outline struct {
	Children []*Outline
	Title    string
	Open     bool
	Dest     string
	// contains filtered or unexported fields
}

Outline represents PDF bookmarks. To create outlines, you need to assign previously created Dest items to the outline. When Open is true, the PDF viewer shows the child outlines.

type PDF

type PDF struct {
	Catalog           Dict
	InfoDict          Dict
	DefaultOffsetX    float64
	DefaultOffsetY    float64
	DefaultPageWidth  float64
	DefaultPageHeight float64
	Colorspaces       []*Separation
	NameDestinations  map[String]*NameDest
	Outlines          []*Outline
	Major             uint
	Minor             uint
	NoPages           int // set when PDF is finished
	// contains filtered or unexported fields
}

PDF is the central point of writing a PDF file.

func NewPDFWriter

func NewPDFWriter(file io.Writer) *PDF

NewPDFWriter creates a PDF file for writing to file

func (*PDF) AddPage

func (pw *PDF) AddPage(content *Object, page Objectnumber) *Page

AddPage adds a page to the PDF file. The content stream must a stream object (i.e. an object with data). Pass 0 for the page object number if you don't pre-allocate an object number for the page.

func (*PDF) Finish

func (pw *PDF) Finish() error

Finish writes the trailer and xref section but does not close the file.

func (*PDF) LoadFace

func (pw *PDF) LoadFace(filename string, idx int) (*Face, error)

LoadFace loads a font from the disc. The index specifies the sub font to be loaded.

func (*PDF) LoadImageFile

func (pw *PDF) LoadImageFile(filename string) (*Imagefile, error)

LoadImageFile loads an image from the disc. For PDF files it defaults to page 1 and the /MediaBox.

func (*PDF) LoadImageFileWithBox

func (pw *PDF) LoadImageFileWithBox(filename string, box string, pagenumber int) (*Imagefile, error)

LoadImageFileWithBox loads an image from the disc with the given box and page number.

func (*PDF) NewFaceFromData

func (pw *PDF) NewFaceFromData(data []byte, idx int) (*Face, error)

NewFaceFromData returns a Face object which is a representation of a font file. The first parameter (id) should be the file name of the font, but can be any string. This is to prevent duplicate font loading.

func (*PDF) NewObject

func (pw *PDF) NewObject() *Object

NewObject create a new PDF object and reserves an object number for it. The object is not written to the PDF until Save() is called.

func (*PDF) NewObjectWithNumber

func (pw *PDF) NewObjectWithNumber(objnum Objectnumber) *Object

NewObjectWithNumber create a new PDF object and reserves an object number for it. The object is not written to the PDF until Save() is called.

func (*PDF) NextObject

func (pw *PDF) NextObject() Objectnumber

NextObject returns the next free object number

func (*PDF) Print

func (pw *PDF) Print(s string) error

Print writes the string to the PDF file

func (*PDF) Printf

func (pw *PDF) Printf(format string, a ...any) error

Printf writes the formatted string to the PDF file.

func (*PDF) Println

func (pw *PDF) Println(s string) error

Println writes the string to the PDF file and adds a newline.

func (*PDF) Size

func (pw *PDF) Size() int64

Size returns the current size of the PDF file.

type Page

type Page struct {
	Objnum      Objectnumber // The "/Page" object
	Annotations []Annotation
	Faces       []*Face
	Images      []*Imagefile
	Width       float64
	Height      float64
	OffsetX     float64
	OffsetY     float64
	Dict        Dict // Additional dictionary entries such as "/Trimbox"
	// contains filtered or unexported fields
}

Page contains information about a single page.

type Pages

type Pages struct {
	Pages []*Page
	// contains filtered or unexported fields
}

Pages is the parent page structure

type Separation

type Separation struct {
	Obj        Objectnumber
	ID         string
	Name       string
	ICCProfile Objectnumber
	C          float64
	M          float64
	Y          float64
	K          float64
}

Separation represents a spot color

type String

type String string

String is a string that gets automatically converted to (...) or hexadecimal form when placed in the PDF.