Start to abstract

main.go

@@ -2,35 +2,60 @@ package main
 
 import (
 	"fmt"
+	"io"
 	"log/slog"
+	"os"
 
 	"codeberg.org/go-pdf/fpdf"
 	"github.com/yeqown/go-qrcode/v2"
 	"github.com/yeqown/go-qrcode/writer/standard"
 )
 
-var cols = 4
-var rows = 4
-var qrSize = 48.0
-var fontSize = 25.0 // pts
-var fontSizeMM = fontSize / 72 * 25.4
-var text = "Á[Hjqy]|"
-var font = "Courier"
-
-var textTopPadding = 0.0 // typically none is required
-var qrTopPadding = 5.0   // below the baseline of the text, remember the descenders like 'y', 'q'
-
+var textTopPadding = 0.0      // typically none is required
+var qrTopPadding = 5.0        // below the baseline of the text, remember the descenders like 'y', 'q'
 var requiredCellPadding = 3.0 // half on each side, effectively
 
-// var probably some padding instead of offsets for qr/font placement
-
 func main() {
+	f, _ := os.Create("hello.pdf")
+	err := generatePage(f, PageOptions{
+		qrURL:   "https://nanocat.net/dom/sdfih/dsifj/sidhof/sdifho/sdfiuoh/safiuho",
+		qrLabel: "Á[Hjqy]|",
+		qrSize:  54,
 
-	qrc, err := qrcode.New("https://nanocat.net/dom/sdfih/dsifj/sidhof/sdifho/sdfiuoh/safiuho")
+		font:      "Helvetica",
+		fontStyle: "B",
+		fontSize:  34.0,
+		rows:      4,
+		cols:      3,
+		borders:   true,
+	})
+	if err != nil {
+		slog.Error("could not generate pdf", "error", err)
+		os.Exit(1)
+	}
+
+}
+
+type PageOptions struct {
+	qrURL     string
+	qrLabel   string
+	qrSize    float64
+	font      string
+	fontStyle string
+	fontSize  float64
+	rows      int
+	cols      int
+	borders   bool
+}
+
+func generatePage(w io.Writer, po PageOptions) error {
+
+	fontSizeMM := po.fontSize / 72 * 25.4
+
+	qrc, err := qrcode.New(po.qrURL)
 
 	if err != nil {
-		fmt.Printf("could not generate QRCode: %v", err)
-		return
+		return fmt.Errorf("could not generate QRCode: %v", err)
 	}
 
 	b := newBWC()
@@ -78,65 +103,66 @@ func main() {
 		AllowNegativePosition: false,
 	}, b)
 
-	// info := pdf.GetImageInfo("qr")
-	// panic(info.Height())
-
 	pdf.AddPage()
-	pdf.SetFont(font, "B", float64(fontSize))
+	pdf.SetFont(po.font, po.fontStyle, float64(po.fontSize))
 
-	textWidth := pdf.GetStringWidth(text)
+	textWidth := pdf.GetStringWidth(po.qrLabel)
 
-	colWidth := pageWidth / float64(cols)
-	rowHeight := pageHeight / float64(rows)
+	colWidth := pageWidth / float64(po.cols)
+	rowHeight := pageHeight / float64(po.rows)
 
-	cellHeight := textTopPadding + fontSizeMM + qrTopPadding + qrSize
-	cellWidth := qrSize
+	cellHeight := textTopPadding + fontSizeMM + qrTopPadding + po.qrSize
+	cellWidth := po.qrSize
 
 	if cellHeight > rowHeight-requiredCellPadding {
-
 		slog.Warn("qr is too big for row", "cell_height", cellHeight, "row_height", rowHeight)
+		return fmt.Errorf("qr is too big for row size")
 	}
 
-	slog.Info("check width", "cell_width", cellWidth, "col_width", colWidth)
+	//	slog.Info("check width", "cell_width", cellWidth, "col_width", colWidth)
 
 	if cellWidth > colWidth-requiredCellPadding {
 		slog.Warn("qr is too big for column", "cell_width", cellWidth, "col_width", colWidth)
+		return fmt.Errorf("qr is too big for col size")
 	}
 
 	if textWidth > colWidth {
 		slog.Warn("text probably too wide")
+		return fmt.Errorf("text is too wide for col size")
 	}
 
-	for rowIdx := range rows {
-		for colIdx := range cols {
+	for rowIdx := range po.rows {
+		for colIdx := range po.cols {
 			topLeftX := colWidth * float64(colIdx)
 			topLeftY := rowHeight * float64(rowIdx)
 
 			// draw box
-			pdf.SetDashPattern([]float64{1, 1}, 0)
-			pdf.Rect(topLeftX, topLeftY, colWidth, rowHeight, "D")
-			pdf.SetDashPattern([]float64{}, 0)
+			if po.borders {
+				pdf.SetDashPattern([]float64{1, 1}, 0)
+				pdf.Rect(topLeftX, topLeftY, colWidth, rowHeight, "D")
+				pdf.SetDashPattern([]float64{}, 0)
+			}
 
 			// label at the top
 			pdf.Text(
 				topLeftX+colWidth/2-textWidth/2,
 				topLeftY+fontSizeMM+textTopPadding,
-				text, // +fmt.Sprintf("%d/%d", rowIdx, colIdx)
+				po.qrLabel, // +fmt.Sprintf("%d/%d", rowIdx, colIdx)
 			)
 
 			// qr at the bottom
 			pdf.ImageOptions("qr",
-				topLeftX+colWidth/2-qrSize/2,
+				topLeftX+colWidth/2-po.qrSize/2,
 				topLeftY+textTopPadding+fontSizeMM+qrTopPadding,
-				qrSize, qrSize,
+				po.qrSize, po.qrSize,
 				false,
 				fpdf.ImageOptions{AllowNegativePosition: true}, 0, "")
 		}
 	}
 
-	err = pdf.OutputFileAndClose("hello.pdf")
+	err = pdf.Output(w)
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("could not output PDF: %w", err)
 	}
-	fmt.Println(pageWidth, pageHeight)
+	return nil
 }