add auto split double page

README.md

@@ -80,6 +80,8 @@ Usage of go-comic-converter:
     	Author of the epub (default "GO Comic Converter")
   -autorotate
     	Auto Rotate page when width > height
+  -autosplitdoublepage
+    	Auto Split double page when width > height
   -brightness int
     	Brightness readjustement: between -100 and 100, > 0 lighter, < 0 darker
   -contrast int

internal/epub/core.go

@@ -21,6 +21,7 @@ type ImageOptions struct {
 	Brightness          int
 	Contrast            int
 	AutoRotate          bool
+	AutoSplitDoublePage bool
 	Workers             int
 }
 
@@ -184,7 +185,7 @@ func (e *ePub) Write() error {
 		wz.WriteImage(part.Cover.Data)
 
 		for _, img := range part.Images {
-			text := fmt.Sprintf("OEBPS/Text/%d.xhtml", img.Id)
+			text := fmt.Sprintf("OEBPS/Text/%d_p%d.xhtml", img.Id, img.Part)
 			if err := wz.WriteFile(text, e.render(textTmpl, img)); err != nil {
 				return err
 			}

internal/epub/filters/crop.go

@@ -0,0 +1,35 @@
+package filters
+
+import (
+	"image"
+	"image/draw"
+
+	"github.com/disintegration/gift"
+)
+
+func CropSplitDoublePage(right bool) *cropSplitDoublePage {
+	return &cropSplitDoublePage{right}
+}
+
+type cropSplitDoublePage struct {
+	right bool
+}
+
+func (p *cropSplitDoublePage) Bounds(srcBounds image.Rectangle) (dstBounds image.Rectangle) {
+	if p.right {
+		dstBounds = image.Rectangle{
+			Min: image.Point{srcBounds.Max.X / 2, srcBounds.Min.Y},
+			Max: srcBounds.Max,
+		}
+	} else {
+		dstBounds = image.Rectangle{
+			Min: srcBounds.Min,
+			Max: image.Point{srcBounds.Max.X / 2, srcBounds.Max.Y},
+		}
+	}
+	return
+}
+
+func (p *cropSplitDoublePage) Draw(dst draw.Image, src image.Image, options *gift.Options) {
+	gift.Crop(dst.Bounds()).Draw(dst, src, options)
+}

internal/epub/image_data.go

@@ -4,7 +4,10 @@ import (
 	"archive/zip"
 	"bytes"
 	"compress/flate"
+	"fmt"
 	"hash/crc32"
+	"image"
+	"image/jpeg"
 	"time"
 )
 
@@ -17,13 +20,23 @@ func (img *ImageData) CompressedSize() uint64 {
 	return img.Header.CompressedSize64 + 30 + uint64(len(img.Header.Name))
 }
 
-func newImageData(name string, data []byte) *ImageData {
+func newImageData(id int, part int, img image.Image, quality int) *ImageData {
+	name := fmt.Sprintf("OEBPS/Images/%d_p%d.jpg", id, part)
+	if id == 0 {
+		name = "OEBPS/Images/cover.jpg"
+	}
+
+	data := bytes.NewBuffer([]byte{})
+	if err := jpeg.Encode(data, img, &jpeg.Options{Quality: quality}); err != nil {
+		panic(err)
+	}
+
 	cdata := bytes.NewBuffer([]byte{})
 	wcdata, err := flate.NewWriter(cdata, flate.BestCompression)
 	if err != nil {
 		panic(err)
 	}
-	wcdata.Write(data)
+	wcdata.Write(data.Bytes())
 	wcdata.Close()
 	if err != nil {
 		panic(err)
@@ -33,8 +46,8 @@ func newImageData(name string, data []byte) *ImageData {
 		&zip.FileHeader{
 			Name:               name,
 			CompressedSize64:   uint64(cdata.Len()),
-			UncompressedSize64: uint64(len(data)),
+			UncompressedSize64: uint64(data.Len()),
-			CRC32:              crc32.Checksum(data, crc32.IEEETable),
+			CRC32:              crc32.Checksum(data.Bytes(), crc32.IEEETable),
 			Method:             zip.Deflate,
 			ModifiedTime:       uint16(t.Second()/2 + t.Minute()<<5 + t.Hour()<<11),
 			ModifiedDate:       uint16(t.Day() + int(t.Month())<<5 + (t.Year()-1980)<<9),

internal/epub/image_filters.go

@@ -23,3 +23,29 @@ func NewGift(options *ImageOptions) *gift.GIFT {
 	)
 	return g
 }
+
+func NewGiftSplitDoublePage(options *ImageOptions) []*gift.GIFT {
+	gifts := make([]*gift.GIFT, 2)
+
+	gifts[0] = gift.New(
+		filters.CropSplitDoublePage(false),
+	)
+
+	gifts[1] = gift.New(
+		filters.CropSplitDoublePage(true),
+	)
+
+	for _, g := range gifts {
+		if options.Contrast != 0 {
+			g.Add(gift.Contrast(float32(options.Contrast)))
+		}
+		if options.Brightness != 0 {
+			g.Add(gift.Brightness(float32(options.Brightness)))
+		}
+		g.Add(
+			gift.ResizeToFit(options.ViewWidth, options.ViewHeight, gift.LanczosResampling),
+		)
+	}
+
+	return gifts
+}

internal/epub/image_processing.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"image"
 	"image/color"
-	"image/jpeg"
 	"io"
 	"io/fs"
 	"os"
@@ -24,6 +23,7 @@ import (
 
 type Image struct {
 	Id     int
+	Part   int
 	Data   *ImageData
 	Width  int
 	Height int
@@ -154,23 +154,29 @@ func LoadImages(path string, options *ImageOptions) ([]*Image, error) {
 					g.Draw(dst, src)
 				}
 
-				// Encode image
-				b := bytes.NewBuffer([]byte{})
-				err = jpeg.Encode(b, dst, &jpeg.Options{Quality: options.Quality})
-				if err != nil {
-					panic(err)
-				}
-
-				name := fmt.Sprintf("OEBPS/Images/%d.jpg", img.Id)
-				if img.Id == 0 {
-					name = "OEBPS/Images/cover.jpg"
-				}
 				imageOutput <- &Image{
 					img.Id,
-					newImageData(name, b.Bytes()),
+					0,
+					newImageData(img.Id, 0, dst, options.Quality),
 					dst.Bounds().Dx(),
 					dst.Bounds().Dy(),
 				}
+
+				if options.AutoSplitDoublePage && src.Bounds().Dx() > src.Bounds().Dy() {
+					gifts := NewGiftSplitDoublePage(options)
+					for i, g := range gifts {
+						part := i + 1
+						dst := image.NewPaletted(g.Bounds(src.Bounds()), options.Palette)
+						g.Draw(dst, src)
+						imageOutput <- &Image{
+							img.Id,
+							part,
+							newImageData(img.Id, part, dst, options.Quality),
+							dst.Bounds().Dx(),
+							dst.Bounds().Dy(),
+						}
+					}
+				}
 			}
 		}()
 	}
@@ -183,8 +189,10 @@ func LoadImages(path string, options *ImageOptions) ([]*Image, error) {
 	bar := NewBar(imageCount, "Processing", 1, 2)
 	for image := range imageOutput {
 		images = append(images, image)
+		if image.Part == 0 {
 			bar.Add(1)
 		}
+	}
 	bar.Close()
 
 	if len(images) == 0 {
@@ -192,7 +200,12 @@ func LoadImages(path string, options *ImageOptions) ([]*Image, error) {
 	}
 
 	sort.Slice(images, func(i, j int) bool {
-		return images[i].Id < images[j].Id
+		if images[i].Id < images[j].Id {
+			return true
+		} else if images[i].Id == images[j].Id && images[i].Part < images[j].Part {
+			return true
+		}
+		return false
 	})
 
 	return images, nil

internal/epub/templates/content.opf.tmpl

@@ -26,18 +26,14 @@
 <item id="css" href="Text/style.css" media-type="text/css"/>
 <item id="page_part" href="Text/part.xhtml" media-type="application/xhtml+xml"/>
 {{ range .Images }}
-<item id="page_{{ .Id }}" href="Text/{{ .Id }}.xhtml" media-type="application/xhtml+xml"/>
+<item id="page_{{ .Id }}_p{{ .Part}}" href="Text/{{ .Id }}_p{{ .Part}}.xhtml" media-type="application/xhtml+xml"/>
-<item id="img_{{ .Id }}" href="Images/{{ .Id }}.jpg" media-type="image/jpeg"/>
+<item id="img_{{ .Id }}_p{{ .Part}}" href="Images/{{ .Id }}_p{{ .Part}}.jpg" media-type="image/jpeg"/>
 {{ end }}
 </manifest>
 <spine page-progression-direction="ltr" toc="ncx">
 <itemref idref="page_part" linear="yes" properties="page-spread-right"/>
 {{ range $idx, $ := .Images }}
-{{ if mod $idx 2 }}
+<itemref idref="page_{{ $.Id }}_p{{ $.Part }}" linear="yes" properties="page-spread-{{ if mod $idx 2 }}left{{ else }}right{{ end }}"/>
-<itemref idref="page_{{ $.Id }}" linear="yes" properties="page-spread-left"/>
-{{ else }}
-<itemref idref="page_{{ $.Id }}" linear="yes" properties="page-spread-right"/>
-{{ end }}
 {{ end }}
 </spine>
 </package>

internal/epub/templates/text.xhtml.tmpl

@@ -2,13 +2,13 @@
 <!DOCTYPE html>
 <html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
 <head>
-<title>Page {{ .Id }}</title>
+<title>Page {{ .Id }}_p{{ .Part}}</title>
 <link href="style.css" type="text/css" rel="stylesheet"/>
 <meta name="viewport" content="width={{ .Width }}, height={{ .Height }}"/>
 </head>
 <body style="">
 <div style="text-align:center;top:0.0%;">
-<img width="{{ .Width }}" height="{{ .Height }}" src="../Images/{{ .Id }}.jpg"/>
+<img width="{{ .Width }}" height="{{ .Height }}" src="../Images/{{ .Id }}_p{{ .Part}}.jpg"/>
 </div>
 <div id="PV">
 <div id="PV-TL">
@@ -25,16 +25,16 @@
 </div>
 </div>
 <div class="PV-P" id="PV-TL-P" style="">
-<img style="position:absolute;left:0;top:0;" src="../Images/{{ .Id }}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
+<img style="position:absolute;left:0;top:0;" src="../Images/{{ .Id }}_p{{ .Part}}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
 </div>
 <div class="PV-P" id="PV-TR-P" style="">
-<img style="position:absolute;right:0;top:0;" src="../Images/{{ .Id }}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
+<img style="position:absolute;right:0;top:0;" src="../Images/{{ .Id }}_p{{ .Part}}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
 </div>
 <div class="PV-P" id="PV-BL-P" style="">
-<img style="position:absolute;left:0;bottom:0;" src="../Images/{{ .Id }}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
+<img style="position:absolute;left:0;bottom:0;" src="../Images/{{ .Id }}_p{{ .Part}}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
 </div>
 <div class="PV-P" id="PV-BR-P" style="">
-<img style="position:absolute;right:0;bottom:0;" src="../Images/{{ .Id }}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
+<img style="position:absolute;right:0;bottom:0;" src="../Images/{{ .Id }}_p{{ .Part}}.jpg" width="{{ zoom .Width 1.5 }}" height="{{ zoom .Height 1.5 }}"/>
 </div>
 </body>
 </html>

main.go

@@ -67,6 +67,7 @@ type Option struct {
 	Brightness          int
 	Contrast            int
 	AutoRotate          bool
+	AutoSplitDoublePage bool
 	Workers             int
 	LimitMb             int
 }
@@ -99,6 +100,7 @@ Options:
     Brightness         : %d
     Contrast           : %d
     AutoRotate         : %v
+    AutoSplitDoublePage: %v
     LimitMb            : %s
     Workers            : %d
 `,
@@ -112,6 +114,7 @@ Options:
 		o.Brightness,
 		o.Contrast,
 		o.AutoRotate,
+		o.AutoSplitDoublePage,
 		limitmb,
 		o.Workers,
 	)
@@ -140,6 +143,7 @@ func main() {
 	flag.IntVar(&opt.Brightness, "brightness", 0, "Brightness readjustement: between -100 and 100, > 0 lighter, < 0 darker")
 	flag.IntVar(&opt.Contrast, "contrast", 0, "Contrast readjustement: between -100 and 100, > 0 more contrast, < 0 less contrast")
 	flag.BoolVar(&opt.AutoRotate, "autorotate", false, "Auto Rotate page when width > height")
+	flag.BoolVar(&opt.AutoSplitDoublePage, "autosplitdoublepage", false, "Auto Split double page when width > height")
 	flag.IntVar(&opt.LimitMb, "limitmb", 0, "Limit size of the ePub: Default nolimit (0), Minimum 20")
 	flag.IntVar(&opt.Workers, "workers", runtime.NumCPU(), "Number of workers")
 	flag.Usage = func() {
@@ -239,6 +243,7 @@ func main() {
 			Brightness:          opt.Brightness,
 			Contrast:            opt.Contrast,
 			AutoRotate:          opt.AutoRotate,
+			AutoSplitDoublePage: opt.AutoSplitDoublePage,
 			Workers:             opt.Workers,
 		},
 	}).Write(); err != nil {