Add 'thumbnails/' from commit '2ebf7b2f23af96b3b499c401fe5498a9349403d8'

git-subtree-dir: thumbnails
git-subtree-mainline: ccc651a11e
git-subtree-split: 2ebf7b2f23

thumbnails/pkg/thumbnail/encoding.go

@@ -0,0 +1,70 @@
+package thumbnail
+
+import (
+	"image"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"strings"
+)
+
+// Encoder encodes the thumbnail to a specific format.
+type Encoder interface {
+	// Encode encodes the image to a format.
+	Encode(io.Writer, image.Image) error
+	// Types returns the formats suffixes.
+	Types() []string
+	// MimeType returns the mimetype used by the encoder.
+	MimeType() string
+}
+
+// PngEncoder encodes to png
+type PngEncoder struct{}
+
+// Encode encodes to png format
+func (e PngEncoder) Encode(w io.Writer, i image.Image) error {
+	return png.Encode(w, i)
+}
+
+// Types returns the png suffix
+func (e PngEncoder) Types() []string {
+	return []string{"png"}
+}
+
+// MimeType returns the mimetype for png files.
+func (e PngEncoder) MimeType() string {
+	return "image/png"
+}
+
+// JpegEncoder encodes to jpg.
+type JpegEncoder struct{}
+
+// Encode encodes to jpg
+func (e JpegEncoder) Encode(w io.Writer, i image.Image) error {
+	return jpeg.Encode(w, i, nil)
+}
+
+// Types returns the jpg suffixes.
+func (e JpegEncoder) Types() []string {
+	return []string{"jpeg", "jpg"}
+}
+
+// MimeType returns the mimetype for jpg files.
+func (e JpegEncoder) MimeType() string {
+	return "image/jpeg"
+}
+
+// EncoderForType returns the encoder for a given file type
+// or nil if the type is not supported.
+func EncoderForType(fileType string) Encoder {
+	switch strings.ToLower(fileType) {
+	case "png":
+		return PngEncoder{}
+	case "jpg":
+		fallthrough
+	case "jpeg":
+		return JpegEncoder{}
+	default:
+		return nil
+	}
+}