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// Copyright 2021 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.
package bookpipeline
import (
"bytes"
"compress/zlib"
"errors"
"fmt"
"html"
"image"
"image/jpeg"
"image/png"
"io/ioutil"
"os"
"github.com/phpdave11/gofpdf"
"golang.org/x/image/draw"
"rescribe.xyz/utils/pkg/hocr"
)
// TODO: maybe set this in Fpdf struct
const pageWidth = 5.8 // pageWidth in inches - 5.8" is A5
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
func pxToPt(i int) float64 {
return float64(i) / pageWidth
}
// Fpdf abstracts the gofpdf.Fpdf adding some useful methods
type Fpdf struct {
fpdf *gofpdf.Fpdf
}
// Setup creates a new PDF with appropriate settings and fonts
func (p *Fpdf) Setup() error {
p.fpdf = gofpdf.New("P", "pt", "A5", "")
// Even though it's invisible, we need to add a font which can do
// UTF-8 so that text renders correctly.
// We embed the font directly in the binary, compressed with zlib
c := bytes.NewBuffer(dejavucondensed)
r, err := zlib.NewReader(c)
defer r.Close()
if err != nil {
return errors.New(fmt.Sprintf("Could not open compressed font: %v", err))
}
var b bytes.Buffer
_, err = b.ReadFrom(r)
if err != nil {
return errors.New(fmt.Sprintf("Could not read compressed font: %v", err))
}
p.fpdf.AddUTF8FontFromBytes("dejavu", "", b.Bytes())
p.fpdf.SetFont("dejavu", "", 10)
p.fpdf.SetAutoPageBreak(false, float64(0))
return p.fpdf.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, smaller bool) error {
file, err := ioutil.ReadFile(hocrpath)
if err != nil {
return errors.New(fmt.Sprintf("Could not read file %s: %v", hocrpath, err))
}
h, err := hocr.Parse(file)
if err != nil {
return errors.New(fmt.Sprintf("Could not parse hocr in file %s: %v", hocrpath, err))
}
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, 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.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)
for _, l := range h.Lines {
linecoords, err := hocr.BoxCoords(l.Title)
if err != nil {
continue
}
lineheight := linecoords[3] - linecoords[1]
for _, w := range l.Words {
coords, err := hocr.BoxCoords(w.Title)
if err != nil {
continue
}
p.fpdf.SetXY(pxToPt(coords[0]), pxToPt(linecoords[1]))
p.fpdf.SetCellMargin(0)
p.fpdf.SetFontSize(pxToPt(lineheight))
p.fpdf.CellFormat(pxToPt(coords[2] - coords[0]), pxToPt(lineheight), html.UnescapeString(w.Text)+" ", "", 0, "T", false, 0, "")
}
}
return p.fpdf.Error()
}
// Save saves the PDF to the file at path
func (p *Fpdf) Save(path string) error {
return p.fpdf.OutputFileAndClose(path)
}
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