https://ugjka.net/webcam/

termux-webcam.go

package main

import (
	"bytes"
	_ "embed"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"net/textproto"
	"os"
	"os/exec"
	"os/signal"
	"sync"
	"syscall"
	"time"
	_ "time/tzdata"
)

//go:embed loading.jpg
var loading []byte

func main() {
	logf, err := os.OpenFile(
		"cam.log",
		os.O_CREATE|os.O_RDWR|os.O_APPEND|os.O_SYNC,
		0644,
	)
	if err != nil {
		log.Fatal(err)
	}
	log.SetOutput(logf)

	loc, err := time.LoadLocation("Europe/Riga")
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		log.Fatal(err)
	}
	time.Local = loc

	exes := []string{
		"mogrify",
		"termux-camera-photo",
		"pidof",
	}
	for _, exe := range exes {
		_, err := exec.LookPath(exe)
		if err != nil {
			fmt.Fprintln(os.Stderr, "dependency:", err)
			log.Println("dependency:", err)
			log.Fatal("cam: exited")
		}
	}

	out, err := exec.Command("pidof", os.Args[0]).CombinedOutput()
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		log.Fatalf("pidof: %v, %s\n", err, out)
	}
	arr := bytes.Split(out, []byte(" "))
	if len(arr) > 1 {
		log.Fatal("cam: already running")
	}

	log.Println("cam: launched")

	cleanup := func() {
		os.Remove("cam.jpg")
	}

	sig := make(chan os.Signal, 1)
	signal.Notify(
		sig, syscall.SIGINT, syscall.SIGTERM, //syscall.SIGHUP,
	)
	go func() {
		s := <-sig
		cleanup()
		log.Println("cam:", s)
		os.Exit(0)
	}()

	var c cam
	go func() {
		var err error
		var now time.Time
		for {
			if !c.ready() {
				time.Sleep(time.Millisecond * 100)
				continue
			}
			now = time.Now()
			err = c.get()
			if err != nil {
				log.Println("termux:", err)
			}
			time.Sleep(time.Second*5 - time.Since(now))
		}
	}()
	mux := http.NewServeMux()
	mux.Handle("/live", &c)
	err = http.ListenAndServe(":9999", mux)
	log.Println(err)
	cleanup()
	log.Fatal("cam: exited")
}

type cam struct {
	currentimg []byte
	timestamp  int64
	clients    int
	mu         sync.RWMutex
}

func (c *cam) ready() bool {
	c.mu.Lock()
	if c.clients == 0 {
		c.currentimg = nil
		c.mu.Unlock()
		return false
	}
	c.mu.Unlock()
	return true
}

func (c *cam) get() error {
	f := "cam.jpg"
	out, err := exec.Command("termux-camera-photo", f).CombinedOutput()
	if err != nil {
		return fmt.Errorf("%v, %s", err, out)
	}
	now := time.Now()
	cmd := exec.Command(
		"mogrify",
		"-strip",
		"-quality", "70",
		"-resize", "900x900",
		"-rotate", "-90",
		"-pointsize", "20",
		"-font", "Droid-Sans-Mono",
		"-undercolor", "White",
		"-annotate", "+10+30", now.Format(time.TimeOnly),
		f,
	)
	out, err = cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("%v, %s", err, out)
	}
	data, err := os.ReadFile(f)
	if err != nil {
		return err
	}
	c.mu.Lock()
	c.currentimg = data
	c.timestamp = time.Now().UnixNano()
	c.mu.Unlock()
	os.Remove(f)
	return nil
}

func (c *cam) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	mw := multipart.NewWriter(w)

	ct := fmt.Sprintf(
		"multipart/x-mixed-replace;boundary=%s", mw.Boundary(),
	)
	w.Header().Add("Content-Type", ct)
	w.Header().Set("Cache-Control", "no-cache")

	if r.Method == http.MethodHead {
		w.WriteHeader(http.StatusOK)
		return
	}
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	c.mu.Lock()
	c.clients++
	c.mu.Unlock()

	defer func() {
		c.mu.Lock()
		c.clients--
		c.mu.Unlock()
	}()

	ip := r.Header.Get("X-Real-IP")
	log.Printf("cam: accessd (%s)", ip)
	now := time.Now()
	defer func() {
		log.Printf("cam: watched [%s] (%s)", time.Since(now), ip)
	}()

	var img []byte
	var err error
	var writer io.Writer

	header := make(textproto.MIMEHeader)
	header.Add("Content-Type", "image/jpeg")
	c.mu.RLock()
	if c.currentimg == nil {
		c.mu.RUnlock()
		for range 3 {
			writer, err = mw.CreatePart(header)
			if err != nil {
				return
			}
			_, err = writer.Write(loading)
			if err != nil {
				return
			}
		}
	} else {
		c.mu.RUnlock()
	}
	for {
		c.mu.RLock()
		if c.currentimg != nil {
			c.mu.RUnlock()
			break
		}
		c.mu.RUnlock()
		time.Sleep(time.Millisecond * 100)
	}
	var previous int64
	for {
		c.mu.RLock()
		if previous == c.timestamp {
			c.mu.RUnlock()
			time.Sleep(time.Millisecond * 100)
			continue
		}
		previous = c.timestamp
		img = c.currentimg
		c.mu.RUnlock()

		for range 3 {
			writer, err = mw.CreatePart(header)
			if err != nil {
				return
			}
			_, err = writer.Write(img)
			if err != nil {
				return
			}
		}
	}
}