First implementation

camera/camera.go

@@ -0,0 +1,81 @@
+package camera
+
+import (
+	"github.com/cyrilix/robocar-base/mqttdevice"
+	"gocv.io/x/gocv"
+	"io"
+	"log"
+	"sync"
+	"time"
+)
+
+type VideoSource interface {
+	Read(m *gocv.Mat) bool
+	io.Closer
+}
+
+type OpencvCameraPart struct {
+	vc               VideoSource
+	pub              mqttdevice.Publisher
+	topic            string
+	publishFrequency int
+	muImgBuffered    sync.Mutex
+	imgBuffered      *gocv.Mat
+}
+
+func New(topic string, publisher mqttdevice.Publisher, publishFrequency int, videoProperties map[gocv.VideoCaptureProperties]float64) *OpencvCameraPart {
+	log.Printf("Run camera part")
+
+	vc, err := gocv.OpenVideoCapture(0)
+	if err != nil {
+		log.Fatalf("unable to open video device: %v", err)
+	}
+	for k, v := range videoProperties {
+		vc.Set(k, v)
+	}
+
+	img := gocv.NewMat()
+	o := OpencvCameraPart{
+		vc:               vc,
+		pub:              publisher,
+		topic:            topic,
+		publishFrequency: publishFrequency,
+		imgBuffered:      &img,
+	}
+	return &o
+}
+
+func (o *OpencvCameraPart) Start() error {
+	log.Printf("start camera")
+	ticker := time.NewTicker(1 * time.Second / time.Duration(o.publishFrequency))
+	defer ticker.Stop()
+
+	for {
+		go o.publishFrame()
+		<-ticker.C
+	}
+}
+
+func (o *OpencvCameraPart) Stop() {
+	log.Print("close video device")
+	if err := o.vc.Close(); err != nil {
+		log.Printf("unexpected error while VideoCapture is closed: %v", err)
+	}
+	if err := o.imgBuffered.Close(); err != nil {
+		log.Printf("unexpected error while VideoCapture is closed: %v", err)
+	}
+}
+
+func (o *OpencvCameraPart) publishFrame() {
+	o.muImgBuffered.Lock()
+	defer o.muImgBuffered.Unlock()
+
+	o.vc.Read(o.imgBuffered)
+	img, err := gocv.IMEncode(gocv.JPEGFileExt, *o.imgBuffered)
+	if err != nil {
+		log.Printf("unable to convert image to jpeg: %v", err)
+		return
+	}
+
+	o.pub.Publish(o.topic, img)
+}

camera/camera_test.go

@@ -0,0 +1,57 @@
+package camera
+
+import (
+	"bytes"
+	"github.com/cyrilix/robocar-base/testtools"
+	"gocv.io/x/gocv"
+	"image/jpeg"
+	"io"
+	"log"
+	"testing"
+	"time"
+)
+
+type fakeVideoSource struct {
+	io.Closer
+}
+
+func (f fakeVideoSource) Read(dest *gocv.Mat) bool {
+	img := gocv.IMRead("testdata/img.jpg", gocv.IMReadUnchanged)
+	if img.Total() == 0 {
+		log.Print("image read is empty")
+		return false
+	}
+	img.CopyTo(dest)
+	return true
+}
+
+func TestOpencvCameraPart(t *testing.T) {
+	p := testtools.NewFakePublisher()
+	const topic = "topic/test/camera"
+	imgBuffer := gocv.NewMat()
+
+	part := OpencvCameraPart{
+		vc:               fakeVideoSource{},
+		pub:              p,
+		topic:            topic,
+		publishFrequency: 1000,
+		imgBuffered:      &imgBuffer,
+	}
+
+	go part.Start()
+	time.Sleep(1 * time.Millisecond)
+
+	img := p.PublishedEvent(topic)
+	if img == nil {
+		t.Fatalf("event %s has not been published", topic)
+	}
+	content, err := img.ByteSliceValue()
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	_, err = jpeg.Decode(bytes.NewReader(content))
+	if err != nil {
+		t.Errorf("image published can't be decoded: %v", err)
+	}
+}