photoview/api/scanner/encode_photo.go

package scanner

import (
	"image"
	"image/jpeg"
	"os"

	"github.com/disintegration/imaging"
	"github.com/photoview/photoview/api/graphql/models"
	"github.com/photoview/photoview/api/scanner/image_helpers"
	"github.com/photoview/photoview/api/utils"
	"github.com/pkg/errors"
	"gopkg.in/vansante/go-ffprobe.v2"
	"gorm.io/gorm"
)

func DecodeImage(imagePath string) (image.Image, error) {
	file, err := os.Open(imagePath)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to open file to decode image (%s)", imagePath)
	}
	defer file.Close()

	image, err := imaging.Decode(file, imaging.AutoOrientation(true))
	if err != nil {
		return nil, errors.Wrapf(err, "failed to decode image (%s)", imagePath)
	}

	return image, nil
}

// EncodeMediaData is used to easily decode media data, with a cache so expensive operations are not repeated
type EncodeMediaData struct {
	media           *models.Media
	_photoImage     image.Image
	_thumbnailImage image.Image
	_contentType    *MediaType
	_videoMetadata  *ffprobe.ProbeData
}

func EncodeImageJPEG(image image.Image, outputPath string, jpegQuality int) error {
	photo_file, err := os.Create(outputPath)
	if err != nil {
		return errors.Wrapf(err, "could not create file: %s", outputPath)
	}
	defer photo_file.Close()

	err = jpeg.Encode(photo_file, image, &jpeg.Options{Quality: jpegQuality})
	if err != nil {
		return err
	}

	return nil
}

// ContentType reads the image to determine its content type
func (img *EncodeMediaData) ContentType() (*MediaType, error) {
	if img._contentType != nil {
		return img._contentType, nil
	}

	imgType, err := getMediaType(img.media.Path)
	if err != nil {
		return nil, err
	}

	img._contentType = imgType
	return imgType, nil
}

func (img *EncodeMediaData) EncodeHighRes(tx *gorm.DB, outputPath string) error {
	contentType, err := img.ContentType()
	if err != nil {
		return err
	}

	if !contentType.isSupported() {
		return errors.New("could not convert photo as file format is not supported")
	}

	// Use darktable if there is no counterpart JPEG file to use instead
	if contentType.isRaw() && img.media.CounterpartPath == nil {
		if DarktableCli.IsInstalled() {
			err := DarktableCli.EncodeJpeg(img.media.Path, outputPath, 70)
			if err != nil {
				return err
			}
		} else {
			return errors.New("could not convert photo as no RAW converter was found")
		}
	} else {
		image, err := img.photoImage(tx)
		if err != nil {
			return err
		}

		EncodeImageJPEG(image, outputPath, 70)
	}

	return nil
}

func EncodeThumbnail(inputPath string, outputPath string) (*image_helpers.PhotoDimensions, error) {
	inputImage, err := DecodeImage(inputPath)
	if err != nil {
		return nil, err
	}

	dimensions := image_helpers.PhotoDimensionsFromRect(inputImage.Bounds())
	dimensions = dimensions.ThumbnailScale()

	thumbImage := imaging.Resize(inputImage, dimensions.Width, dimensions.Height, imaging.NearestNeighbor)
	if err = EncodeImageJPEG(thumbImage, outputPath, 60); err != nil {
		return nil, err
	}

	return &dimensions, nil
}

// PhotoImage reads and decodes the image file and saves it in a cache so the photo in only decoded once
func (img *EncodeMediaData) photoImage(tx *gorm.DB) (image.Image, error) {
	if img._photoImage != nil {
		return img._photoImage, nil
	}

	var photoPath string
	if img.media.CounterpartPath != nil {
		photoPath = *img.media.CounterpartPath
	} else {
		photoPath = img.media.Path
	}

	photoImg, err := DecodeImage(photoPath)
	if err != nil {
		return nil, utils.HandleError("image decoding", err)
	}

	img._photoImage = photoImg
	return img._photoImage, nil
}