change image library and refactor thumbnails service

thumbnails/pkg/thumbnail/thumbnail.go

@@ -0,0 +1,87 @@
+package thumbnail
+
+import (
+	"bytes"
+	"image"
+
+	"github.com/owncloud/ocis/ocis-pkg/log"
+	"github.com/owncloud/ocis/thumbnails/pkg/thumbnail/storage"
+	"golang.org/x/image/draw"
+)
+
+// Request bundles information needed to generate a thumbnail for afile
+type Request struct {
+	Resolution image.Rectangle
+	Encoder    Encoder
+	ETag       string
+	Username   string
+}
+
+// Manager is responsible for generating thumbnails
+type Manager interface {
+	// Get will return a thumbnail for a file
+	Get(Request, image.Image) ([]byte, error)
+	// GetStored loads the thumbnail from the storage.
+	// It will return nil if no image is stored for the given context.
+	GetStored(Request) []byte
+}
+
+// NewSimpleManager creates a new instance of SimpleManager
+func NewSimpleManager(resolutions Resolutions, storage storage.Storage, logger log.Logger) SimpleManager {
+	return SimpleManager{
+		storage:     storage,
+		logger:      logger,
+		resolutions: resolutions,
+	}
+}
+
+// SimpleManager is a simple implementation of Manager
+type SimpleManager struct {
+	storage     storage.Storage
+	logger      log.Logger
+	resolutions Resolutions
+}
+
+// Get implements the Get Method of Manager
+func (s SimpleManager) Get(r Request, img image.Image) ([]byte, error) {
+	match := s.resolutions.ClosestMatch(r.Resolution, img.Bounds())
+	thumbnail := s.generate(match, img)
+
+	key := s.storage.BuildKey(mapToStorageRequest(r))
+
+	buf := new(bytes.Buffer)
+	err := r.Encoder.Encode(buf, thumbnail)
+	if err != nil {
+		return nil, err
+	}
+	bytes := buf.Bytes()
+	err = s.storage.Set(r.Username, key, bytes)
+	if err != nil {
+		s.logger.Warn().Err(err).Msg("could not store thumbnail")
+	}
+	return bytes, nil
+}
+
+// GetStored tries to get the stored thumbnail and return it.
+// If there is no cached thumbnail it will return nil
+func (s SimpleManager) GetStored(r Request) []byte {
+	key := s.storage.BuildKey(mapToStorageRequest(r))
+	stored := s.storage.Get(r.Username, key)
+	return stored
+}
+
+func (s SimpleManager) generate(r image.Rectangle, img image.Image) image.Image {
+	targetResolution := mapRatio(img.Bounds(), r)
+	thumbnail := image.NewRGBA(targetResolution)
+	draw.ApproxBiLinear.Scale(thumbnail, targetResolution, img, img.Bounds(), draw.Over, nil)
+	return thumbnail
+}
+
+func mapToStorageRequest(r Request) storage.Request {
+	sR := storage.Request{
+		ETag:       r.ETag,
+		Resolution: r.Resolution,
+		Types:      r.Encoder.Types(),
+	}
+	return sR
+}