bimg/metadata.go

package bimg

/*
#cgo pkg-config: vips
#include "vips/vips.h"
*/
import "C"

// Common EXIF fields for data extraction
const (
	Make                    = "exif-ifd0-Make"
	Model                   = "exif-ifd0-Model"
	Orientation             = "exif-ifd0-Orientation"
	XResolution             = "exif-ifd0-XResolution"
	YResolution             = "exif-ifd0-YResolution"
	ResolutionUnit          = "exif-ifd0-ResolutionUnit"
	Software                = "exif-ifd0-Software"
	Datetime                = "exif-ifd0-DateTime"
	YCbCrPositioning        = "exif-ifd0-YCbCrPositioning"
	Compression             = "exif-ifd1-Compression"
	ExposureTime            = "exif-ifd2-ExposureTime"
	FNumber                 = "exif-ifd2-FNumber"
	ExposureProgram         = "exif-ifd2-ExposureProgram"
	ISOSpeedRatings         = "exif-ifd2-ISOSpeedRatings"
	ExifVersion             = "exif-ifd2-ExifVersion"
	DateTimeOriginal        = "exif-ifd2-DateTimeOriginal"
	DateTimeDigitized       = "exif-ifd2-DateTimeDigitized"
	ComponentsConfiguration = "exif-ifd2-ComponentsConfiguration"
	ShutterSpeedValue       = "exif-ifd2-ShutterSpeedValue"
	ApertureValue           = "exif-ifd2-ApertureValue"
	BrightnessValue         = "exif-ifd2-BrightnessValue"
	ExposureBiasValue       = "exif-ifd2-ExposureBiasValue"
	MeteringMode            = "exif-ifd2-MeteringMode"
	Flash                   = "exif-ifd2-Flash"
	FocalLength             = "exif-ifd2-FocalLength"
	SubjectArea             = "exif-ifd2-SubjectArea"
	MakerNote               = "exif-ifd2-MakerNote"
	SubSecTimeOriginal      = "exif-ifd2-SubSecTimeOriginal"
	SubSecTimeDigitized     = "exif-ifd2-SubSecTimeDigitized"
	ColorSpace              = "exif-ifd2-ColorSpace"
	PixelXDimension         = "exif-ifd2-PixelXDimension"
	PixelYDimension         = "exif-ifd2-PixelYDimension"
	SensingMethod           = "exif-ifd2-SensingMethod"
	SceneType               = "exif-ifd2-SceneType"
	ExposureMode            = "exif-ifd2-ExposureMode"
	WhiteBalance            = "exif-ifd2-WhiteBalance"
	FocalLengthIn35mmFilm   = "exif-ifd2-FocalLengthIn35mmFilm"
	SceneCaptureType        = "exif-ifd2-SceneCaptureType"
	GPSLatitudeRef          = "exif-ifd3-GPSLatitudeRef"
	GPSLatitude             = "exif-ifd3-GPSLatitude"
	GPSLongitudeRef         = "exif-ifd3-GPSLongitudeRef"
	GPSLongitude            = "exif-ifd3-GPSLongitude"
	GPSAltitudeRef          = "exif-ifd3-GPSAltitudeRef"
	GPSAltitude             = "exif-ifd3-GPSAltitude"
	GPSSpeedRef             = "exif-ifd3-GPSSpeedRef"
	GPSSpeed                = "exif-ifd3-GPSSpeed"
	GPSImgDirectionRef      = "exif-ifd3-GPSImgDirectionRef"
	GPSImgDirection         = "exif-ifd3-GPSImgDirection"
	GPSDestBearingRef       = "exif-ifd3-GPSDestBearingRef"
	GPSDestBearing          = "exif-ifd3-GPSDestBearing"
	GPSDateStamp            = "exif-ifd3-GPSDateStamp"
)

// ImageSize represents the image width and height values
type ImageSize struct {
	Width  int
	Height int
}

// ImageMetadata represents the basic metadata fields
type ImageMetadata struct {
	Orientation int
	Channels    int
	Alpha       bool
	Profile     bool
	Type        string
	Space       string
	Colourspace string
	Size        ImageSize
	EXIF        EXIF
}

// EXIF image metadata
type EXIF struct {
	Make                    string
	Model                   string
	Orientation             int
	XResolution             string
	YResolution             string
	ResolutionUnit          int
	Software                string
	Datetime                string
	YCbCrPositioning        int
	Compression             int
	ExposureTime            string
	FNumber                 string
	ExposureProgram         int
	ISOSpeedRatings         int
	ExifVersion             string
	DateTimeOriginal        string
	DateTimeDigitized       string
	ComponentsConfiguration string
	ShutterSpeedValue       string
	ApertureValue           string
	BrightnessValue         string
	ExposureBiasValue       string
	MeteringMode            int
	Flash                   int
	FocalLength             string
	SubjectArea             string
	MakerNote               string
	SubSecTimeOriginal      string
	SubSecTimeDigitized     string
	ColorSpace              int
	PixelXDimension         int
	PixelYDimension         int
	SensingMethod           int
	SceneType               string
	ExposureMode            int
	WhiteBalance            int
	FocalLengthIn35mmFilm   int
	SceneCaptureType        int
	GPSLatitudeRef          string
	GPSLatitude             string
	GPSLongitudeRef         string
	GPSLongitude            string
	GPSAltitudeRef          string
	GPSAltitude             string
	GPSSpeedRef             string
	GPSSpeed                string
	GPSImgDirectionRef      string
	GPSImgDirection         string
	GPSDestBearingRef       string
	GPSDestBearing          string
	GPSDateStamp            string
}

// Size returns the image size by width and height pixels.
func Size(buf []byte) (ImageSize, error) {
	metadata, err := Metadata(buf)
	if err != nil {
		return ImageSize{}, err
	}

	return ImageSize{
		Width:  int(metadata.Size.Width),
		Height: int(metadata.Size.Height),
	}, nil
}

// ColourspaceIsSupported checks if the image colourspace is supported by libvips.
func ColourspaceIsSupported(buf []byte) (bool, error) {
	return vipsColourspaceIsSupportedBuffer(buf)
}

// ImageInterpretation returns the image interpretation type.
// See: https://libvips.github.io/libvips/API/current/VipsImage.html#VipsInterpretation
func ImageInterpretation(buf []byte) (Interpretation, error) {
	return vipsInterpretationBuffer(buf)
}

// Metadata returns the image metadata (size, type, alpha channel, profile, EXIF orientation...).
func Metadata(buf []byte) (ImageMetadata, error) {
	defer C.vips_thread_shutdown()

	image, imageType, err := vipsRead(buf)
	if err != nil {
		return ImageMetadata{}, err
	}
	defer C.g_object_unref(C.gpointer(image))

	size := ImageSize{
		Width:  int(image.Xsize),
		Height: int(image.Ysize),
	}

	orientation := vipsExifIntTag(image, Orientation)

	metadata := ImageMetadata{
		Size:        size,
		Channels:    int(image.Bands),
		Orientation: orientation,
		Alpha:       vipsHasAlpha(image),
		Profile:     vipsHasProfile(image),
		Space:       vipsSpace(image),
		Type:        ImageTypeName(imageType),
		EXIF: EXIF{
			Make:                    vipsExifStringTag(image, Make),
			Model:                   vipsExifStringTag(image, Model),
			Orientation:             orientation,
			XResolution:             vipsExifStringTag(image, XResolution),
			YResolution:             vipsExifStringTag(image, YResolution),
			ResolutionUnit:          vipsExifIntTag(image, ResolutionUnit),
			Software:                vipsExifStringTag(image, Software),
			Datetime:                vipsExifStringTag(image, Datetime),
			YCbCrPositioning:        vipsExifIntTag(image, YCbCrPositioning),
			Compression:             vipsExifIntTag(image, Compression),
			ExposureTime:            vipsExifStringTag(image, ExposureTime),
			FNumber:                 vipsExifStringTag(image, FNumber),
			ExposureProgram:         vipsExifIntTag(image, ExposureProgram),
			ISOSpeedRatings:         vipsExifIntTag(image, ISOSpeedRatings),
			ExifVersion:             vipsExifStringTag(image, ExifVersion),
			DateTimeOriginal:        vipsExifStringTag(image, DateTimeOriginal),
			DateTimeDigitized:       vipsExifStringTag(image, DateTimeDigitized),
			ComponentsConfiguration: vipsExifStringTag(image, ComponentsConfiguration),
			ShutterSpeedValue:       vipsExifStringTag(image, ShutterSpeedValue),
			ApertureValue:           vipsExifStringTag(image, ApertureValue),
			BrightnessValue:         vipsExifStringTag(image, BrightnessValue),
			ExposureBiasValue:       vipsExifStringTag(image, ExposureBiasValue),
			MeteringMode:            vipsExifIntTag(image, MeteringMode),
			Flash:                   vipsExifIntTag(image, Flash),
			FocalLength:             vipsExifStringTag(image, FocalLength),
			SubjectArea:             vipsExifStringTag(image, SubjectArea),
			MakerNote:               vipsExifStringTag(image, MakerNote),
			SubSecTimeOriginal:      vipsExifStringTag(image, SubSecTimeOriginal),
			SubSecTimeDigitized:     vipsExifStringTag(image, SubSecTimeDigitized),
			ColorSpace:              vipsExifIntTag(image, ColorSpace),
			PixelXDimension:         vipsExifIntTag(image, PixelXDimension),
			PixelYDimension:         vipsExifIntTag(image, PixelYDimension),
			SensingMethod:           vipsExifIntTag(image, SensingMethod),
			SceneType:               vipsExifStringTag(image, SceneType),
			ExposureMode:            vipsExifIntTag(image, ExposureMode),
			WhiteBalance:            vipsExifIntTag(image, WhiteBalance),
			FocalLengthIn35mmFilm:   vipsExifIntTag(image, FocalLengthIn35mmFilm),
			SceneCaptureType:        vipsExifIntTag(image, SceneCaptureType),
			GPSLatitudeRef:          vipsExifStringTag(image, GPSLatitudeRef),
			GPSLatitude:             vipsExifStringTag(image, GPSLatitude),
			GPSLongitudeRef:         vipsExifStringTag(image, GPSLongitudeRef),
			GPSLongitude:            vipsExifStringTag(image, GPSLongitude),
			GPSAltitudeRef:          vipsExifStringTag(image, GPSAltitudeRef),
			GPSAltitude:             vipsExifStringTag(image, GPSAltitude),
			GPSSpeedRef:             vipsExifStringTag(image, GPSSpeedRef),
			GPSSpeed:                vipsExifStringTag(image, GPSSpeed),
			GPSImgDirectionRef:      vipsExifStringTag(image, GPSImgDirectionRef),
			GPSImgDirection:         vipsExifStringTag(image, GPSImgDirection),
			GPSDestBearingRef:       vipsExifStringTag(image, GPSDestBearingRef),
			GPSDestBearing:          vipsExifStringTag(image, GPSDestBearing),
			GPSDateStamp:            vipsExifStringTag(image, GPSDateStamp),
		},
	}

	return metadata, nil
}