Added support for JPEG encoding/decoding in utio.

utio/imager.go

@@ -0,0 +1,18 @@
+package utio
+
+import "image"
+
+// Imager describes a image encoder/decoder.
+type Imager interface {
+	Encoder
+	Decoder
+	Image() image.Image
+}
+
+type imager struct {
+	m image.Image
+}
+
+func (i *imager) Image() image.Image {
+	return i.m
+}

utio/jpeg.go

@@ -0,0 +1,50 @@
+package utio
+
+import (
+	"image"
+	"image/jpeg"
+	"io"
+)
+
+// JPEG creates a JPEG encoder/decoder for m, m is only required for encoding.
+func JPEG(m image.Image) Imager {
+	return JPEGOpts(m, 95)
+}
+
+func JPEGOpts(m image.Image, quality int) Imager {
+	return &jpeger{imager{m}, quality}
+}
+
+type jpeger struct {
+	imager
+
+	quality int
+}
+
+func (j *jpeger) Encode(w io.Writer) error {
+	return jpeg.Encode(w, j.m, &jpeg.Options{Quality: j.quality})
+}
+
+func (j *jpeger) Decode(r io.Reader) error {
+	var m, err = jpeg.Decode(r)
+	if nil != err {
+		return err
+	}
+	j.m = m
+	return nil
+}
+
+// LoadJPEG loads a JPEG image from the supplied path.
+func LoadJPEG(path string) (image.Image, error) {
+	var j = JPEG(nil)
+	var err = DecodeFile(path, j)
+	if nil != err {
+		return nil, err
+	}
+	return j.Image(), nil
+}
+
+// SaveJPEG writes an image as JPEG to the supplied path.
+func SaveJPEG(path string, m image.Image) error {
+	return EncodeFile(path, JPEG(m))
+}

utio/png.go

@@ -7,19 +7,15 @@ import (
 )
 
 // PNGer describes a PNG encoder/decoder.
-type PNGer interface {
-	Encoder
-	Decoder
-	Image() image.Image
-}
+type PNGer Imager
 
 // PNG creates a PNG encoder/decoder for m, m is only required for encoding.
 func PNG(m image.Image) PNGer {
-	return &pnger{m}
+	return &pnger{imager{m}}
 }
 
 type pnger struct {
-	m image.Image
+	imager
 }
 
 func (p *pnger) Encode(w io.Writer) error {
@@ -35,10 +31,6 @@ func (p *pnger) Decode(r io.Reader) error {
 	return nil
 }
 
-func (p *pnger) Image() image.Image {
-	return p.m
-}
-
 // LoadPNG loads a PNG image from the supplied path.
 func LoadPNG(path string) (image.Image, error) {
 	var p = PNG(nil)