Add blurhash generation

api/scanner/thumbnail_blurhash.go

@@ -0,0 +1,98 @@
+package scanner
+
+import (
+	"fmt"
+	"image"
+	"log"
+	"os"
+
+	"github.com/buckket/go-blurhash"
+	"github.com/photoview/photoview/api/graphql/models"
+	"gorm.io/gorm"
+)
+
+// GenerateBlurhashes queries the database for media that are missing a blurhash and computes one for them.
+// This function blocks until all hashes have been computed
+func GenerateBlurhashes(db *gorm.DB) error {
+	var results []*models.Media
+
+	processErrors := make([]error, 0)
+
+	query := db.Model(&models.Media{}).
+		Preload("MediaURL").
+		Joins("INNER JOIN media_urls ON media.id = media_urls.media_id").
+		Where("blurhash IS NULL").
+		Where("media_urls.purpose = 'thumbnail' OR media_urls.purpose = 'video-thumbnail'")
+
+	err := query.FindInBatches(&results, 100, func(tx *gorm.DB, batch int) error {
+		log.Printf("generating %d blurhashes", len(results))
+
+		hashes := make([]*string, len(results))
+
+		for i, row := range results {
+
+			thumbnail, err := row.Thumbnail()
+			if err != nil {
+				log.Printf("failed to get thumbnail for media to generate blurhash (%d): %v", row.ID, err)
+				processErrors = append(processErrors, err)
+				continue
+			}
+
+			hashStr, err := GenerateBlurhashFromThumbnail(thumbnail)
+			if err != nil {
+				log.Printf("failed to generate blurhash for media (%d): %v", row.ID, err)
+				processErrors = append(processErrors, err)
+				continue
+			}
+
+			hashes[i] = &hashStr
+			results[i].Blurhash = &hashStr
+		}
+
+		tx.Save(results)
+		// if err := db.Update("blurhash", hashes).Error; err != nil {
+		// 	return err
+		// }
+
+		return nil
+	}).Error
+
+	if err != nil {
+		return err
+	}
+
+	if len(processErrors) == 0 {
+		return nil
+	} else {
+		return fmt.Errorf("failed to generate %d blurhashes", len(processErrors))
+	}
+}
+
+// GenerateBlurhashFromThumbnail generates a blurhash for a single media and stores it in the database
+func GenerateBlurhashFromThumbnail(thumbnail *models.MediaURL) (string, error) {
+	thumbnail_path, err := thumbnail.CachedPath()
+	if err != nil {
+		return "", err
+	}
+
+	imageFile, err := os.Open(thumbnail_path)
+	if err != nil {
+		return "", err
+	}
+
+	imageData, _, err := image.Decode(imageFile)
+	if err != nil {
+		return "", err
+	}
+
+	hashStr, err := blurhash.Encode(4, 3, imageData)
+	if err != nil {
+		return "", err
+	}
+
+	// if err := db.Model(&models.Media{}).Where("id = ?", thumbnail.MediaID).Update("blurhash", hashStr).Error; err != nil {
+	// 	return "", err
+	// }
+
+	return hashStr, nil
+}