Implement image resizing option into PDF generation, so that smaller PDFs to be generated

2 files changed, 41 insertions, 22 deletions

diff --git a/cmd/pdfbook/main.go b/cmd/pdfbook/main.go
index 79db353..3fdcc67 100644
--- a/cmd/pdfbook/main.go
+++ b/cmd/pdfbook/main.go
@@ -16,7 +16,7 @@ import (
 
 type Pdfer interface {
 	Setup() error
-	AddPage(imgpath, hocrpath string) error
+	AddPage(imgpath, hocrpath string, smaller bool) error
 	Save(path string) error
 }
 
@@ -49,7 +49,7 @@ func imgPath(hocrpath string, colour bool) string {
 }
 
 // addBest adds the pages in dir/best to a PDF
-func addBest(dir string, pdf Pdfer, colour bool) error {
+func addBest(dir string, pdf Pdfer, colour, smaller bool) error {
 	f, err := os.Open(path.Join(dir, "best"))
 	if err != nil {
 		log.Fatalln("Failed to open best file", err)
@@ -70,7 +70,7 @@ func addBest(dir string, pdf Pdfer, colour bool) error {
 	for _, f := range files {
 		hocrpath := path.Join(dir, f)
 		img := imgPath(hocrpath, colour)
-		err := pdf.AddPage(img, hocrpath)
+		err := pdf.AddPage(img, hocrpath, smaller)
 		if err != nil {
 			return err
 		}
@@ -80,7 +80,7 @@ func addBest(dir string, pdf Pdfer, colour bool) error {
 
 // walker walks each hocr file in a directory and adds a page to
 // the pdf for each one.
-func walker(pdf Pdfer, colour bool) filepath.WalkFunc {
+func walker(pdf Pdfer, colour, smaller bool) filepath.WalkFunc {
 	return func(fpath string, info os.FileInfo, err error) error {
 		if info.IsDir() {
 			return nil
@@ -88,15 +88,15 @@ func walker(pdf Pdfer, colour bool) filepath.WalkFunc {
 		if path.Ext(fpath) != ".hocr" {
 			return nil
 		}
-		return pdf.AddPage(imgPath(fpath, colour), fpath)
+		return pdf.AddPage(imgPath(fpath, colour), fpath, smaller)
 	}
 }
 
 func main() {
-	// TODO: probably take flags to resize / change quality in due course
 	colour := flag.Bool("c", false, "colour")
+	smaller := flag.Bool("s", false, "smaller")
 	flag.Usage = func() {
-		fmt.Fprintln(flag.CommandLine.Output(), "Usage: pdfbook [-c] hocrdir out.pdf")
+		fmt.Fprintln(flag.CommandLine.Output(), "Usage: pdfbook [-c] [-s] hocrdir out.pdf")
 		flag.PrintDefaults()
 	}
 	flag.Parse()
@@ -106,24 +106,24 @@ func main() {
 		return
 	}
 
-	_, err := os.Stat(path.Join(flag.Arg(0), "best"))
-	if err != nil && !os.IsNotExist(err) {
-		log.Fatalln("Failed to stat best", err)
-	}
-
 	pdf := new(bookpipeline.Fpdf)
-	err = pdf.Setup()
+	err := pdf.Setup()
 	if err != nil {
 		log.Fatalln("Failed to set up PDF", err)
 	}
 
+	_, err = os.Stat(path.Join(flag.Arg(0), "best"))
+	if err != nil && !os.IsNotExist(err) {
+		log.Fatalln("Failed to stat best", err)
+	}
+
 	if os.IsNotExist(err) {
-		err = filepath.Walk(flag.Arg(0), walker(pdf, *colour))
+		err = filepath.Walk(flag.Arg(0), walker(pdf, *colour, *smaller))
 		if err != nil {
 			log.Fatalln("Failed to walk", flag.Arg(0), err)
 		}
 	} else {
-		err = addBest(flag.Arg(0), pdf, *colour)
+		err = addBest(flag.Arg(0), pdf, *colour, *smaller)
 		if err != nil {
 			log.Fatalln("Failed to add best pages", err)
 		}
diff --git a/pdf.go b/pdf.go
index 9fa52f3..79d2b8c 100644
--- a/pdf.go
+++ b/pdf.go
@@ -7,17 +7,19 @@ import (
 	"fmt"
 	"html"
 	"image"
-	_ "image/jpeg"
-	_ "image/png"
+	"image/jpeg"
+	"image/png"
 	"io/ioutil"
 	"os"
 
 	"github.com/jung-kurt/gofpdf"
+	"golang.org/x/image/draw"
 	"rescribe.xyz/utils/pkg/hocr"
 )
 
 // TODO: maybe set this in Fpdf struct
 const pageWidth = 5 // pageWidth in inches
+const scaleSmaller = 3 // amount the width and height are divided by
 
 // pxToPt converts a pixel value into a pt value (72 pts per inch)
 // This uses pageWidth to determine the appropriate value
@@ -56,7 +58,7 @@ func (p *Fpdf) Setup() error {
 
 // AddPage adds a page to the pdf with an image and (invisible)
 // text from an hocr file
-func (p *Fpdf) AddPage(imgpath, hocrpath string) error {
+func (p *Fpdf) AddPage(imgpath, hocrpath string, smaller bool) error {
 	file, err := ioutil.ReadFile(hocrpath)
 	if err != nil {
 		return errors.New(fmt.Sprintf("Could not read file %s: %v", hocrpath, err))
@@ -66,19 +68,36 @@ func (p *Fpdf) AddPage(imgpath, hocrpath string) error {
 		return errors.New(fmt.Sprintf("Could not parse hocr in file %s: %v", hocrpath, err))
 	}
 
-	f, err := os.Open(imgpath)
-	defer f.Close()
+	imgf, err := os.Open(imgpath)
+	defer imgf.Close()
 	if err != nil {
 		return errors.New(fmt.Sprintf("Could not open file %s: %v", imgpath, err))
 	}
-	img, _, err := image.Decode(f)
+	img, imgtype, err := image.Decode(imgf)
 	if err != nil {
 		return errors.New(fmt.Sprintf("Could not decode image: %v", err))
 	}
 	b := img.Bounds()
+	if smaller {
+		r := image.Rect(0, 0, b.Max.X/scaleSmaller, b.Max.Y/scaleSmaller)
+		smimg := image.NewRGBA(r)
+		draw.ApproxBiLinear.Scale(smimg, r, img, b, draw.Over, nil)
+		img = smimg
+	}
+
+	var buf bytes.Buffer
+	if imgtype == "jpeg" {
+		err = jpeg.Encode(&buf, img, &jpeg.Options{Quality: jpeg.DefaultQuality})
+	} else {
+		err = png.Encode(&buf, img)
+	}
+	if err != nil {
+		return err
+	}
+
 	p.fpdf.AddPageFormat("P", gofpdf.SizeType{Wd: pxToPt(b.Dx()), Ht: pxToPt(b.Dy())})
 
-	_ = p.fpdf.RegisterImageOptions(imgpath, gofpdf.ImageOptions{})
+	_ = p.fpdf.RegisterImageOptionsReader(imgpath, gofpdf.ImageOptions{ImageType: imgtype}, &buf)
 	p.fpdf.ImageOptions(imgpath, 0, 0, pxToPt(b.Dx()), pxToPt(b.Dy()), false, gofpdf.ImageOptions{}, 0, "")
 
 	p.fpdf.SetTextRenderingMode(3)