feat: added QR code functionality

go.mod

@@ -0,0 +1,15 @@
+module p2p.org/dc4bc
+
+go 1.13
+
+require (
+	github.com/makiuchi-d/gozxing v0.0.0-20190830103442-eaff64b1ceb7
+	github.com/mattn/go-gtk v0.0.0-20191030024613-af2e013261f5
+	github.com/mattn/go-pointer v0.0.0-20190911064623-a0a44394634f // indirect
+	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
+	github.com/stretchr/testify v1.6.1 // indirect
+	gocv.io/x/gocv v0.23.0
+	golang.org/x/image v0.0.0-20200618115811-c13761719519
+	golang.org/x/text v0.3.3 // indirect
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect
+)

main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	_ "image/jpeg"
+	"log"
+	"os"
+	"os/exec"
+
+	"p2p.org/dc4bc/qr"
+
+	_ "image/gif"
+	_ "image/png"
+
+	_ "golang.org/x/image/bmp"
+	_ "golang.org/x/image/tiff"
+	_ "golang.org/x/image/webp"
+)
+
+func main() {
+	clearTerminal()
+	var data = "Hello, world!"
+
+	log.Println("A QR code will be shown on your screen.")
+	log.Println("Please take a photo of the QR code with your smartphone.")
+	log.Println("When you close the image, you will have 5 seconds to" +
+		"scan the QR code with your laptop's camera.")
+	err := qr.ShowQR(data)
+	if err != nil {
+		log.Fatalf("Failed to show QR code: %v", err)
+	}
+
+	var scannedData string
+	for {
+		clearTerminal()
+		if err != nil {
+			log.Printf("Failed to scan QR code: %v\n", err)
+		}
+
+		log.Println("Please center the photo of the QR-code in front" +
+			"of your web-camera...")
+
+		scannedData, err = qr.ReadQRFromCamera()
+		if err == nil {
+			break
+		}
+	}
+
+	clearTerminal()
+	log.Printf("QR code successfully scanned; the data is: %s\n", scannedData)
+}
+
+func clearTerminal() {
+	c := exec.Command("clear")
+	c.Stdout = os.Stdout
+	_ = c.Run()
+}

qr/qr_read.go

@@ -0,0 +1,59 @@
+package qr
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/makiuchi-d/gozxing"
+	"github.com/makiuchi-d/gozxing/qrcode"
+	"gocv.io/x/gocv"
+)
+
+const timeToScan = time.Second * 5
+
+func ReadQRFromCamera() (string, error) {
+	webcam, err := gocv.OpenVideoCapture(0)
+	if err != nil {
+		return "", fmt.Errorf("failed to OpenVideoCapture: %w", err)
+	}
+	window := gocv.NewWindow("Hello")
+
+	defer webcam.Close()
+	defer window.Close()
+
+	img := gocv.NewMat()
+	tk := time.NewTimer(timeToScan)
+
+	// This loop reads an image from the webcam every millisecond
+	// for 5 seconds. The last image taken will be used as the final
+	//one.
+loop:
+	for {
+		select {
+		case <-tk.C:
+			break loop
+		default:
+			webcam.Read(&img)
+			window.IMShow(img)
+			window.WaitKey(1)
+		}
+	}
+
+	imgObject, err := img.ToImage()
+	if err != nil {
+		return "", fmt.Errorf("failed to get image object: %w", err)
+	}
+
+	bmp, err := gozxing.NewBinaryBitmapFromImage(imgObject)
+	if err != nil {
+		return "", fmt.Errorf("failed to get NewBinaryBitmapFromImage: %w", err)
+	}
+
+	qrReader := qrcode.NewQRCodeReader()
+	result, err := qrReader.Decode(bmp, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode the QR-code contents: %w", err)
+	}
+
+	return result.String(), err
+}

qr/qr_show.go

@@ -0,0 +1,58 @@
+package qr
+
+import (
+	"fmt"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+
+	"github.com/mattn/go-gtk/glib"
+	"github.com/mattn/go-gtk/gtk"
+
+	encoder "github.com/skip2/go-qrcode"
+
+	_ "golang.org/x/image/bmp"
+	_ "golang.org/x/image/tiff"
+)
+
+const tmpImageFile = "/tmp/qr.png"
+
+func ShowQR(data string) error {
+	err := encoder.WriteFile(data, encoder.Medium, 512, tmpImageFile)
+	if err != nil {
+		return fmt.Errorf("failed to encode the data: %w", err)
+	}
+
+	showImage(tmpImageFile)
+
+	return nil
+}
+
+func showImage(imageFile string) {
+	gtk.Init(nil)
+	window := gtk.NewWindow(gtk.WINDOW_TOPLEVEL)
+	window.SetPosition(gtk.WIN_POS_CENTER)
+	window.SetTitle("p2p.org QR Viewer")
+	window.SetIconName("p2p.org QR Viewer")
+	window.Connect("destroy", func(ctx *glib.CallbackContext) {
+		gtk.MainQuit()
+	})
+
+	hbox := gtk.NewHBox(false, 1)
+	hpaned := gtk.NewHPaned()
+	hbox.Add(hpaned)
+	frame1 := gtk.NewFrame("QR Code")
+	framebox1 := gtk.NewHBox(false, 1)
+	frame1.Add(framebox1)
+	hpaned.Pack1(frame1, false, false)
+	image := gtk.NewImageFromFile(imageFile)
+	framebox1.Add(image)
+	window.Add(hbox)
+	imagePixBuffer := image.GetPixbuf()
+	horizontalSize := imagePixBuffer.GetWidth()
+	verticalSize := imagePixBuffer.GetHeight()
+
+	window.SetSizeRequest(horizontalSize, verticalSize)
+	window.ShowAll()
+	gtk.Main()
+}