set static naive JFIF headers for compatibility with kindle

go.mod

@@ -23,7 +23,6 @@ require (
 	github.com/mitchellh/colorstring v0.0.0-20190213212951-d06e56a500db // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/stretchr/testify v1.9.0 // indirect
-	github.com/viam-labs/go-libjpeg v0.3.1 // indirect
 	golang.org/x/net v0.25.0 // indirect
 	golang.org/x/sys v0.20.0 // indirect
 	golang.org/x/term v0.20.0 // indirect

go.sum

@@ -39,8 +39,6 @@ github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsT
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/tcnksm/go-latest v0.0.0-20170313132115-e3007ae9052e h1:IWllFTiDjjLIf2oeKxpIUmtiDV5sn71VgeQgg6vcE7k=
 github.com/tcnksm/go-latest v0.0.0-20170313132115-e3007ae9052e/go.mod h1:d7u6HkTYKSv5m6MCKkOQlHwaShTMl3HjqSGW3XtVhXM=
-github.com/viam-labs/go-libjpeg v0.3.1 h1:J/byavXHFqRI1PFPrnPbP+wFCr1y+Cn1CwKXrORCPD0=
-github.com/viam-labs/go-libjpeg v0.3.1/go.mod h1:b0ISpf9lJv9MO1h1gXAmSA/osG19cKGYjfYc6aeEjqs=
 golang.org/x/image v0.16.0 h1:9kloLAKhUufZhA12l5fwnx2NZW39/we1UhBesW433jw=
 golang.org/x/image v0.16.0/go.mod h1:ugSZItdV4nOxyqp56HmXwH0Ry0nBCpjnZdpDaIHdoPs=
 golang.org/x/net v0.25.0 h1:d/OCCoBEUq33pjydKrGQhw7IlUPI2Oylr+8qLx49kac=

internal/pkg/converter/options.go

@@ -1,4 +1,4 @@
-// Package converter options manage options with default value from config.
+// Package options manage options with default value from config.
 package converter
 
 import (

internal/pkg/converter/profiles.go

@@ -1,4 +1,4 @@
-// Package converter profiles manage supported profiles for go-comic-converter.
+// Package profiles manage supported profiles for go-comic-converter.
 package converter
 
 import (

internal/pkg/epub/epub.go

@@ -312,10 +312,9 @@ func (e EPUB) computeAspectRatio(epubParts []epubPart) float64 {
 	return bestAspectRatio
 }
 
-func (e EPUB) computeViewPort(epubParts []epubPart) (int, int) {
+func (e EPUB) computeViewPort(epubParts []epubPart) {
 	if e.Image.View.AspectRatio == -1 {
-		//keep device size
-		return e.Image.View.Width, e.Image.View.Height
+		return //keep device size
 	}
 
 	// readjusting view port
@@ -326,9 +325,9 @@ func (e EPUB) computeViewPort(epubParts []epubPart) (int, int) {
 
 	viewWidth, viewHeight := int(float64(e.Image.View.Height)/bestAspectRatio), int(float64(e.Image.View.Width)*bestAspectRatio)
 	if viewWidth > e.Image.View.Width {
-		return e.Image.View.Width, viewHeight
+		e.Image.View.Height = viewHeight
 	} else {
-		return viewWidth, e.Image.View.Height
+		e.Image.View.Width = viewWidth
 	}
 }
 
@@ -446,7 +445,7 @@ func (e EPUB) Write() error {
 		Json:        e.Json,
 	})
 
-	e.Image.View.Width, e.Image.View.Height = e.computeViewPort(epubParts)
+	e.computeViewPort(epubParts)
 	for i, part := range epubParts {
 		ext := filepath.Ext(e.Output)
 		suffix := ""

internal/pkg/epuboptions/epub_options.go

@@ -1,4 +1,4 @@
-// Package epuboptions for EPUB creation.
+// Package epuboptions EPUBOptions for EPUB creation.
 package epuboptions
 
 type EPUBOptions struct {

internal/pkg/epubtemplates/content.go

@@ -227,7 +227,7 @@ func (o Content) getSpineAuto() []tag {
 			)
 		}
 	}
-	for i, img := range o.Images {
+	for _, img := range o.Images {
 		if (img.DoublePage || img.Part == 1) && o.ImageOptions.Manga == isOnTheRight {
 			spine = append(spine, tag{
 				"itemref",
@@ -242,8 +242,6 @@ func (o Content) getSpineAuto() []tag {
 			tagAttrs{"idref": img.PageKey(), "properties": img.Position},
 			"",
 		})
-		// save position, img is a value type
-		o.Images[i] = img
 	}
 	if o.ImageOptions.Manga == isOnTheRight {
 		spine = append(spine, tag{

internal/pkg/epubzip/image.go

@@ -10,8 +10,6 @@ import (
 	"image/jpeg"
 	"image/png"
 	"time"
-
-	mozJpeg "github.com/viam-labs/go-libjpeg/jpeg"
 )
 
 type Image struct {
@@ -19,6 +17,18 @@ type Image struct {
 	Data   []byte
 }
 
+var naiveJFIFHeader = []byte{
+	0xFF, 0xD8, // SOI
+	0xFF, 0xE0, // APP0 Marker
+	0x00, 0x10, // Length
+	0x4A, 0x46, 0x49, 0x46, 0x00, // JFIF\0
+	0x01, 0x02, // 1.02
+	0x00,       // Density type
+	0x00, 0x01, // X Density
+	0x00, 0x01, // Y Density
+	0x00, 0x00, // No Thumbnail
+}
+
 // CompressImage create gzip encoded jpeg
 func CompressImage(filename string, format string, img image.Image, quality int) (Image, error) {
 	var (
@@ -30,15 +40,11 @@ func CompressImage(filename string, format string, img image.Image, quality int)
 	case "png":
 		err = png.Encode(&data, img)
 	case "jpeg":
-		err = mozJpeg.Encode(&data, img, &mozJpeg.EncoderOptions{
-			Quality:         quality,
-			OptimizeCoding:  true,
-			ProgressiveMode: true,
-			DCTMethod:       mozJpeg.DCTFloat,
-		})
-		if err != nil && err.Error() == "unsupported image type" {
-			err = jpeg.Encode(&data, img, &jpeg.Options{Quality: quality})
-		}
+		// static JFIF header for better compatibility with Kindle devices
+		var b bytes.Buffer
+		err = jpeg.Encode(&b, img, &jpeg.Options{Quality: quality})
+		data.Write(naiveJFIFHeader)
+		data.Write(b.Bytes()[2:])
 	default:
 		err = fmt.Errorf("unknown format %q", format)
 	}