feat: generate a BlurHash when uploading a new image

pkg/models/list.go

@@ -640,7 +640,7 @@ func UpdateList(s *xorm.Session, list *List, auth web.Auth, updateListBackground
 	}
 
 	if updateListBackground {
-		colsToUpdate = append(colsToUpdate, "background_file_id")
+		colsToUpdate = append(colsToUpdate, "background_file_id", "background_blur_hash")
 	}
 
 	wasFavorite, err := isFavorite(s, list.ID, auth, FavoriteKindList)
@@ -801,14 +801,15 @@ func (l *List) Delete(s *xorm.Session, a web.Auth) (err error) {
 }
 
 // SetListBackground sets a background file as list background in the db
-func SetListBackground(s *xorm.Session, listID int64, background *files.File) (err error) {
+func SetListBackground(s *xorm.Session, listID int64, background *files.File, blurHash string) (err error) {
 	l := &List{
-		ID:               listID,
-		BackgroundFileID: background.ID,
+		ID:                 listID,
+		BackgroundFileID:   background.ID,
+		BackgroundBlurHash: blurHash,
 	}
 	_, err = s.
 		Where("id = ?", l.ID).
-		Cols("background_file_id").
+		Cols("background_file_id", "background_blur_hash").
 		Update(l)
 	return
 }

pkg/models/list_duplicate.go

@@ -144,7 +144,7 @@ func (ld *ListDuplicate) Create(s *xorm.Session, doer web.Auth) (err error) {
 			}
 		}
 
-		if err := SetListBackground(s, ld.List.ID, file); err != nil {
+		if err := SetListBackground(s, ld.List.ID, file, ld.List.BackgroundBlurHash); err != nil {
 			return err
 		}
 

pkg/modules/background/handler/background.go

@@ -17,6 +17,9 @@
 package handler
 
 import (
+	"github.com/bbrks/go-blurhash"
+	"golang.org/x/image/draw"
+	"image"
 	"io"
 	"net/http"
 	"strconv"
@@ -134,6 +137,18 @@ func (bp *BackgroundProvider) SetBackground(c echo.Context) error {
 	return c.JSON(http.StatusOK, list)
 }
 
+func CreateBlurHash(srcf io.Reader) (hash string, err error) {
+	src, _, err := image.Decode(srcf)
+	if err != nil {
+		return "", err
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, 32, 32))
+	draw.NearestNeighbor.Scale(dst, dst.Rect, src, src.Bounds(), draw.Over, nil)
+
+	return blurhash.Encode(4, 3, dst)
+}
+
 // UploadBackground uploads a background and passes the id of the uploaded file as an Image to the Set function of the BackgroundProvider.
 func (bp *BackgroundProvider) UploadBackground(c echo.Context) error {
 	s := db.NewSession()
@@ -153,15 +168,15 @@ func (bp *BackgroundProvider) UploadBackground(c echo.Context) error {
 		_ = s.Rollback()
 		return err
 	}
-	src, err := file.Open()
+	srcf, err := file.Open()
 	if err != nil {
 		_ = s.Rollback()
 		return err
 	}
-	defer src.Close()
+	defer srcf.Close()
 
 	// Validate we're dealing with an image
-	mime, err := mimetype.DetectReader(src)
+	mime, err := mimetype.DetectReader(srcf)
 	if err != nil {
 		_ = s.Rollback()
 		return handler.HandleHTTPError(err, c)
@@ -170,10 +185,10 @@ func (bp *BackgroundProvider) UploadBackground(c echo.Context) error {
 		_ = s.Rollback()
 		return c.JSON(http.StatusBadRequest, models.Message{Message: "Uploaded file is no image."})
 	}
-	_, _ = src.Seek(0, io.SeekStart)
+	_, _ = srcf.Seek(0, io.SeekStart)
 
 	// Save the file
-	f, err := files.CreateWithMime(src, file.Filename, uint64(file.Size), auth, mime.String())
+	f, err := files.CreateWithMime(srcf, file.Filename, uint64(file.Size), auth, mime.String())
 	if err != nil {
 		_ = s.Rollback()
 		if files.IsErrFileIsTooLarge(err) {
@@ -183,9 +198,16 @@ func (bp *BackgroundProvider) UploadBackground(c echo.Context) error {
 		return handler.HandleHTTPError(err, c)
 	}
 
-	image := &background.Image{ID: strconv.FormatInt(f.ID, 10)}
+	// Generate a blurHash
+	_, _ = srcf.Seek(0, io.SeekStart)
+	list.BackgroundBlurHash, err = CreateBlurHash(srcf)
+	if err != nil {
+		return handler.HandleHTTPError(err, c)
+	}
 
-	err = p.Set(s, image, list, auth)
+	// Save it
+	img := &background.Image{ID: strconv.FormatInt(f.ID, 10)}
+	err = p.Set(s, img, list, auth)
 	if err != nil {
 		_ = s.Rollback()
 		return handler.HandleHTTPError(err, c)
@@ -300,6 +322,7 @@ func RemoveListBackground(c echo.Context) error {
 
 	list.BackgroundFileID = 0
 	list.BackgroundInformation = nil
+	list.BackgroundBlurHash = ""
 	err = models.UpdateList(s, list, auth, true)
 	if err != nil {
 		return err

pkg/modules/background/upload/upload.go

@@ -52,7 +52,7 @@ func (p *Provider) Search(s *xorm.Session, search string, page int64) (result []
 // @Failure 404 {object} models.Message "The list does not exist."
 // @Failure 500 {object} models.Message "Internal error"
 // @Router /lists/{id}/backgrounds/upload [put]
-func (p *Provider) Set(s *xorm.Session, image *background.Image, list *models.List, auth web.Auth) (err error) {
+func (p *Provider) Set(s *xorm.Session, img *background.Image, list *models.List, auth web.Auth) (err error) {
 	// Remove the old background if one exists
 	if list.BackgroundFileID != 0 {
 		file := files.File{ID: list.BackgroundFileID}
@@ -62,12 +62,12 @@ func (p *Provider) Set(s *xorm.Session, image *background.Image, list *models.Li
 	}
 
 	file := &files.File{}
-	file.ID, err = strconv.ParseInt(image.ID, 10, 64)
+	file.ID, err = strconv.ParseInt(img.ID, 10, 64)
 	if err != nil {
 		return
 	}
 
 	list.BackgroundInformation = &models.ListBackgroundType{Type: models.ListBackgroundUpload}
 
-	return models.SetListBackground(s, list.ID, file)
+	return models.SetListBackground(s, list.ID, file, list.BackgroundBlurHash)
 }

pkg/modules/migration/create_from_structure.go

@@ -18,6 +18,7 @@ package migration
 
 import (
 	"bytes"
+	"code.vikunja.io/api/pkg/modules/background/handler"
 	"io/ioutil"
 
 	"xorm.io/xorm"
@@ -115,7 +116,12 @@ func insertFromStructure(s *xorm.Session, str []*models.NamespaceWithListsAndTas
 					return err
 				}
 
-				err = models.SetListBackground(s, l.ID, file)
+				hash, err := handler.CreateBlurHash(backgroundFile)
+				if err != nil {
+					return err
+				}
+
+				err = models.SetListBackground(s, l.ID, file, hash)
 				if err != nil {
 					return err
 				}