imaging

Documentation

Overview

Package imaging decodes images for PDF embedding. JPEG is embedded losslessly via DCTDecode (original bytes passed through); PNG is decoded and re-encoded with FlateDecode, its alpha channel becoming a soft-mask (SMask). The result is ready to write as an image XObject.

Index

• type Image
  • func Decode(data []byte) (*Image, error)
  • func DecodeDataURI(s string) (*Image, error)
  • func Load(src string) (*Image, error)
  • func LoadFile(path string) (*Image, error)
  • func LoadURL(url string) (*Image, error)

Types

type Image

type Image struct {
	Width, Height    int
	ColorSpace       string // "DeviceRGB", "DeviceGray", or "DeviceCMYK"
	BitsPerComponent int
	Filter           string // "DCTDecode" or "FlateDecode"
	Data             []byte // XObject stream data (already filtered)
	SMask            []byte // optional 8-bit gray alpha, FlateDecode-compressed
	Format           string // "jpeg" or "png"
}

Image is a decoded image ready to embed as a PDF XObject.

func Decode

func Decode(data []byte) (*Image, error)

Decode sniffs the image format and decodes it.

func DecodeDataURI

func DecodeDataURI(s string) (*Image, error)

DecodeDataURI decodes a data: URI (base64 or raw payload).

func Load

func Load(src string) (*Image, error)

Load resolves an image source and decodes it. The source may be a data: URI, an http:// or https:// URL, or a local file path; any other URI scheme is rejected with a descriptive error.

func LoadFile

func LoadFile(path string) (*Image, error)

LoadFile reads an image from the local filesystem and decodes it.

func LoadURL

func LoadURL(url string) (*Image, error)

LoadURL fetches an image over HTTP(S) and decodes it.