generate animated thumbnails for animated gifs

protogen/gen/ocis/services/thumbnails/v0/thumbnails.swagger.json

@@ -34,7 +34,8 @@
       "type": "string",
       "enum": [
         "PNG",
-        "JPG"
+        "JPG",
+        "GIF"
       ],
       "default": "PNG",
       "description": "The file types to which the thumbnail can get encoded to."

protogen/proto/ocis/services/thumbnails/v0/thumbnails.proto

@@ -45,6 +45,7 @@ message GetThumbnailRequest {
     enum ThumbnailType {
         PNG = 0; // Represents PNG type
         JPG = 1; // Represents JPG type
+        GIF = 2; // Represents GIF type
     }
     // The type to which the thumbnail should get encoded to.
     ThumbnailType thumbnail_type = 2;

thumbnails/pkg/preprocessor/preprocessor.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"image"
 	"image/draw"
+	"image/gif"
 	"io"
 	"math"
 	"mime"
@@ -16,24 +17,34 @@ import (
 )
 
 type FileConverter interface {
-	Convert(r io.Reader) (image.Image, error)
+	Convert(r io.Reader) (interface{}, error)
 }
 
 type ImageDecoder struct{}
 
-func (i ImageDecoder) Convert(r io.Reader) (image.Image, error) {
+func (i ImageDecoder) Convert(r io.Reader) (interface{}, error) {
 	img, _, err := image.Decode(r)
 	if err != nil {
 		return nil, errors.Wrap(err, `could not decode the image`)
 	}
 	return img, nil
 }
 
+type GifDecoder struct{}
+
+func (i GifDecoder) Convert(r io.Reader) (interface{}, error) {
+	img, err := gif.DecodeAll(r)
+	if err != nil {
+		return nil, errors.Wrap(err, `could not decode the image`)
+	}
+	return img, nil
+}
+
 type TxtToImageConverter struct {
 	fontLoader *FontLoader
 }
 
-func (t TxtToImageConverter) Convert(r io.Reader) (image.Image, error) {
+func (t TxtToImageConverter) Convert(r io.Reader) (interface{}, error) {
 	img := image.NewRGBA(image.Rect(0, 0, 640, 480))
 
 	imgBounds := img.Bounds()
@@ -183,6 +194,8 @@ func ForType(mimeType string, opts map[string]interface{}) FileConverter {
 		return TxtToImageConverter{
 			fontLoader: fontLoader,
 		}
+	case "image/gif":
+		return GifDecoder{}
 	default:
 		return ImageDecoder{}
 	}

thumbnails/pkg/service/v0/service.go

@@ -71,19 +71,23 @@ func (g Thumbnail) GetThumbnail(ctx context.Context, req *thumbnailssvc.GetThumb
 		g.logger.Debug().Str("thumbnail_type", req.ThumbnailType.String()).Msg("unsupported thumbnail type")
 		return nil
 	}
-	encoder := thumbnail.EncoderForType(req.ThumbnailType.String())
-	if encoder == nil {
+	generator, err := thumbnail.GeneratorForType(req.ThumbnailType.String())
+	if err != nil {
+		g.logger.Debug().Str("thumbnail_type", req.ThumbnailType.String()).Msg("unsupported thumbnail type")
+		return nil
+	}
+	encoder, err := thumbnail.EncoderForType(req.ThumbnailType.String())
+	if err != nil {
 		g.logger.Debug().Str("thumbnail_type", req.ThumbnailType.String()).Msg("unsupported thumbnail type")
 		return nil
 	}
 
 	var thumb []byte
-	var err error
 	switch {
 	case req.GetWebdavSource() != nil:
-		thumb, err = g.handleWebdavSource(ctx, req, encoder)
+		thumb, err = g.handleWebdavSource(ctx, req, generator, encoder)
 	case req.GetCs3Source() != nil:
-		thumb, err = g.handleCS3Source(ctx, req, encoder)
+		thumb, err = g.handleCS3Source(ctx, req, generator, encoder)
 	default:
 		g.logger.Error().Msg("no image source provided")
 		return merrors.BadRequest(g.serviceID, "image source is missing")
@@ -97,7 +101,7 @@ func (g Thumbnail) GetThumbnail(ctx context.Context, req *thumbnailssvc.GetThumb
 	return nil
 }
 
-func (g Thumbnail) handleCS3Source(ctx context.Context, req *thumbnailssvc.GetThumbnailRequest, encoder thumbnail.Encoder) ([]byte, error) {
+func (g Thumbnail) handleCS3Source(ctx context.Context, req *thumbnailssvc.GetThumbnailRequest, generator thumbnail.Generator, encoder thumbnail.Encoder) ([]byte, error) {
 	src := req.GetCs3Source()
 	sRes, err := g.stat(src.Path, src.Authorization)
 	if err != nil {
@@ -106,6 +110,7 @@ func (g Thumbnail) handleCS3Source(ctx context.Context, req *thumbnailssvc.GetTh
 
 	tr := thumbnail.Request{
 		Resolution: image.Rect(0, 0, int(req.Width), int(req.Height)),
+		Generator:  generator,
 		Encoder:    encoder,
 		Checksum:   sRes.GetInfo().GetChecksum().GetSum(),
 	}
@@ -136,7 +141,7 @@ func (g Thumbnail) handleCS3Source(ctx context.Context, req *thumbnailssvc.GetTh
 	return thumb, nil
 }
 
-func (g Thumbnail) handleWebdavSource(ctx context.Context, req *thumbnailssvc.GetThumbnailRequest, encoder thumbnail.Encoder) ([]byte, error) {
+func (g Thumbnail) handleWebdavSource(ctx context.Context, req *thumbnailssvc.GetThumbnailRequest, generator thumbnail.Generator, encoder thumbnail.Encoder) ([]byte, error) {
 	src := req.GetWebdavSource()
 	imgURL, err := url.Parse(src.Url)
 	if err != nil {
@@ -182,6 +187,7 @@ func (g Thumbnail) handleWebdavSource(ctx context.Context, req *thumbnailssvc.Ge
 	}
 	tr := thumbnail.Request{
 		Resolution: image.Rect(0, 0, int(req.Width), int(req.Height)),
+		Generator:  generator,
 		Encoder:    encoder,
 		Checksum:   sRes.GetInfo().GetChecksum().GetSum(),
 	}

thumbnails/pkg/thumbnail/encoding.go

@@ -1,17 +1,33 @@
 package thumbnail
 
 import (
+	"errors"
 	"image"
+	"image/gif"
 	"image/jpeg"
 	"image/png"
 	"io"
 	"strings"
 )
 
+const (
+	typePng  = "png"
+	typeJpg  = "jpg"
+	typeJpeg = "jpeg"
+	typeGif  = "gif"
+)
+
+var (
+	// ErrInvalidType represents the error when a type can't be encoded.
+	ErrInvalidType = errors.New("can't encode this type")
+	// ErrNoEncoderForType represents the error when an encoder couldn't be found for a type.
+	ErrNoEncoderForType = errors.New("no encoder for this type found")
+)
+
 // Encoder encodes the thumbnail to a specific format.
 type Encoder interface {
 	// Encode encodes the image to a format.
-	Encode(io.Writer, image.Image) error
+	Encode(io.Writer, interface{}) error
 	// Types returns the formats suffixes.
 	Types() []string
 	// MimeType returns the mimetype used by the encoder.
@@ -22,13 +38,17 @@ type Encoder interface {
 type PngEncoder struct{}
 
 // Encode encodes to png format
-func (e PngEncoder) Encode(w io.Writer, i image.Image) error {
-	return png.Encode(w, i)
+func (e PngEncoder) Encode(w io.Writer, img interface{}) error {
+	m, ok := img.(image.Image)
+	if !ok {
+		return ErrInvalidType
+	}
+	return png.Encode(w, m)
 }
 
 // Types returns the png suffix
 func (e PngEncoder) Types() []string {
-	return []string{"png"}
+	return []string{typePng}
 }
 
 // MimeType returns the mimetype for png files.
@@ -40,29 +60,53 @@ func (e PngEncoder) MimeType() string {
 type JpegEncoder struct{}
 
 // Encode encodes to jpg
-func (e JpegEncoder) Encode(w io.Writer, i image.Image) error {
-	return jpeg.Encode(w, i, nil)
+func (e JpegEncoder) Encode(w io.Writer, img interface{}) error {
+	m, ok := img.(image.Image)
+	if !ok {
+		return ErrInvalidType
+	}
+	return jpeg.Encode(w, m, nil)
 }
 
 // Types returns the jpg suffixes.
 func (e JpegEncoder) Types() []string {
-	return []string{"jpeg", "jpg"}
+	return []string{typeJpeg, typeJpg}
 }
 
 // MimeType returns the mimetype for jpg files.
 func (e JpegEncoder) MimeType() string {
 	return "image/jpeg"
 }
 
+type GifEncoder struct{}
+
+func (e GifEncoder) Encode(w io.Writer, img interface{}) error {
+	g, ok := img.(*gif.GIF)
+	if !ok {
+		return ErrInvalidType
+	}
+	return gif.EncodeAll(w, g)
+}
+
+func (e GifEncoder) Types() []string {
+	return []string{typeGif}
+}
+
+func (e GifEncoder) MimeType() string {
+	return "image/gif"
+}
+
 // EncoderForType returns the encoder for a given file type
 // or nil if the type is not supported.
-func EncoderForType(fileType string) Encoder {
+func EncoderForType(fileType string) (Encoder, error) {
 	switch strings.ToLower(fileType) {
-	case "png":
-		return PngEncoder{}
-	case "jpg", "jpeg":
-		return JpegEncoder{}
+	case typePng:
+		return PngEncoder{}, nil
+	case typeJpg, typeJpeg:
+		return JpegEncoder{}, nil
+	case typeGif:
+		return GifEncoder{}, nil
 	default:
-		return nil
+		return nil, ErrNoEncoderForType
 	}
 }

thumbnails/pkg/thumbnail/encoding_test.go

@@ -14,7 +14,7 @@ func TestEncoderForType(t *testing.T) {
 	}
 
 	for k, v := range table {
-		e := EncoderForType(k)
+		e, _ := EncoderForType(k)
 		if e != v {
 			t.Fail()
 		}