pdf: Stretch words to fit in their boxes, for more perfect embedding

- Words are stretched to fit their boxes, which means the accuracy
  is now very high indeed. This was done by modifying gofpdf to add
  the SetCellStretchToFit function, which will hopefully be
  upstreamed in due course.
- Copy pasting from a PDF works well with lines rarely if ever being
  erroneously broken by the PDF reader. There was quite a bit of
  trial-and-error to improve this, and the stretched text plus a space
  being added after the word in CellFormat was the best (plus preserves
  accuracy of word and character locations).

1 files changed, 11 insertions, 4 deletions

diff --git a/pdf.go b/pdf.go
index be7f8a9..eb5f021 100644
--- a/pdf.go
+++ b/pdf.go
@@ -16,7 +16,8 @@ import (
 	"io/ioutil"
 	"os"
 
-	"github.com/phpdave11/gofpdf"
+	//"github.com/phpdave11/gofpdf"
+	"github.com/nickjwhite/gofpdf" // adds SetCellStretchToFit function
 	"golang.org/x/image/draw"
 	"rescribe.xyz/utils/pkg/hocr"
 )
@@ -112,7 +113,7 @@ func (p *Fpdf) AddPage(imgpath, hocrpath string, smaller bool) error {
 		if err != nil {
 			continue
 		}
-		lineheight := linecoords[3] - linecoords[1]
+		lineheight := pxToPt(linecoords[3] - linecoords[1])
 		for _, w := range l.Words {
 			coords, err := hocr.BoxCoords(w.Title)
 			if err != nil {
@@ -120,8 +121,14 @@ func (p *Fpdf) AddPage(imgpath, hocrpath string, smaller bool) error {
 			}
 			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, "")
+			p.fpdf.SetFontSize(lineheight)
+			cellW := pxToPt(coords[2] - coords[0])
+			cellText := html.UnescapeString(w.Text)
+			p.fpdf.SetCellStretchToFit(cellW, cellText)
+			// Adding a space after each word causes fewer line breaks to
+			// be erroneously inserted when copy pasting from the PDF, for
+			// some reason.
+			p.fpdf.CellFormat(cellW, lineheight, cellText + " ", "", 0, "T", false, 0, "")
 		}
 	}
 	return p.fpdf.Error()