Fix build issues, update go version, add a simple HTTP webserver that is able to render image in browser

go.mod

@@ -1,14 +1,25 @@
 module github.com/rs/jplot
 
-go 1.14
+go 1.17
 
 require (
 	github.com/dustin/go-humanize v1.0.0
 	github.com/elgs/gojq v0.0.0-20160421194050-81fa9a608a13
+	github.com/mattn/go-isatty v0.0.14
+	github.com/mattn/go-sixel v0.0.1
+	github.com/monochromegane/terminal v0.0.0-20161222050454-9bc47e2707d9
+	github.com/wcharczuk/go-chart/v2 v2.1.0
+	golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c
+)
+
+require (
+	github.com/blend/go-sdk v1.20211204.3 // indirect
 	github.com/elgs/gosplitargs v0.0.0-20161028071935-a491c5eeb3c8 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
-	github.com/monochromegane/terminal v0.0.0-20161222050454-9bc47e2707d9
-	github.com/wcharczuk/go-chart v2.0.1+incompatible
-	golang.org/x/crypto v0.0.0-20200414173820-0848c9571904
-	golang.org/x/image v0.0.0-20200119044424-58c23975cae1 // indirect
+	github.com/soniakeys/quant v1.0.0 // indirect
+	github.com/stretchr/testify v1.7.0 // indirect
+	github.com/wcharczuk/go-chart v2.0.1+incompatible // indirect
+	golang.org/x/image v0.0.0-20200927104501-e162460cd6b5 // indirect
+	golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c // indirect
+	golang.org/x/term v0.0.0-20201117132131-f5c789dd3221 // indirect
 )

graph/dash.go

@@ -7,7 +7,7 @@ import (
 	"io"
 
 	"github.com/rs/jplot/data"
-	chart "github.com/wcharczuk/go-chart"
+	chart "github.com/wcharczuk/go-chart/v2"
 )
 
 type Dash struct {

graph/graph.go

@@ -6,8 +6,8 @@ import (
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/rs/jplot/data"
-	chart "github.com/wcharczuk/go-chart"
-	"github.com/wcharczuk/go-chart/drawing"
+	chart "github.com/wcharczuk/go-chart/v2"
+	"github.com/wcharczuk/go-chart/v2/drawing"
 )
 
 func init() {

graph/legend.go

@@ -3,8 +3,8 @@ package graph
 import (
 	"math"
 
-	chart "github.com/wcharczuk/go-chart"
-	"github.com/wcharczuk/go-chart/drawing"
+	chart "github.com/wcharczuk/go-chart/v2"
+	"github.com/wcharczuk/go-chart/v2/drawing"
 )
 
 // custom version of chart.Legend

main.go

@@ -3,6 +3,7 @@ package main // import "github.com/rs/jplot"
 import (
 	"flag"
 	"fmt"
+	"github.com/rs/jplot/streamer"
 	"os"
 	"os/signal"
 	"strings"
@@ -28,6 +29,10 @@ func main() {
 		fmt.Fprintln(out, "  option:")
 		fmt.Fprintln(out, "    - counter: Computes the difference with the last value. The value must increase monotonically.")
 		fmt.Fprintln(out, "    - marker: When the value is none-zero, a vertical line is drawn.")
+		fmt.Fprintln(out, "    - port: launches a web-server that will be drawing images. This disables drawing in terminal")
+		fmt.Fprintln(out, "    - hiw (http image width): defines web server's image width")
+		fmt.Fprintln(out, "    - hih (http image height): defines web server's image width")
+		fmt.Fprintln(out, "    - hirr (http image refresh rate): how often image will be refreshed (milliseconds)")
 		fmt.Fprintln(out, "  path:")
 		fmt.Fprintln(out, "    JSON field path (eg: field.sub-field).")
 	}
@@ -36,15 +41,12 @@ func main() {
 		" Note that counter fields are computed based on this interval.")
 	steps := flag.Int("steps", 100, "Number of values to plot.")
 	rows := flag.Int("rows", 0, "Limits the height of the graph output.")
+	port := flag.Int("port", 0, "web server port")
+	hiw := flag.Int("hiw", 500, "web server image height")
+	hih := flag.Int("hih", 500, "web server  image width")
+	hirr := flag.Int("hirr", 1000, "web server refresh rate (milliseconds)")
 	flag.Parse()
 
-	if !term.HasGraphicsSupport() {
-		fatal("iTerm2 or DRCS Sixel graphics required")
-	}
-	if os.Getenv("TERM") == "screen" {
-		fatal("screen and tmux not supported")
-	}
-
 	if len(flag.Args()) == 0 {
 		flag.Usage()
 		os.Exit(1)
@@ -66,6 +68,25 @@ func main() {
 		Specs: specs,
 		Data:  dp,
 	}
+	go func() {
+		if er := dp.Run(specs); er != nil {
+			fatal("Data source error: ", er)
+		}
+	}()
+
+	if *port != 0 {
+		err := streamer.Start(*port, &dash, *hiw, *hih, *hirr)
+		if err != nil {
+			fatal("cannot start server: %s", err.Error())
+		}
+	}
+
+	if !term.HasGraphicsSupport() {
+		fatal("iTerm2 or DRCS Sixel graphics required")
+	}
+	if os.Getenv("TERM") == "screen" {
+		fatal("screen and tmux not supported")
+	}
 
 	wg := &sync.WaitGroup{}
 	wg.Add(1)
@@ -106,9 +127,6 @@ func main() {
 		}
 	}()
 
-	if err := dp.Run(specs); err != nil {
-		fatal("Data source error: ", err)
-	}
 }
 
 func fatal(a ...interface{}) {
@@ -149,9 +167,9 @@ func render(dash graph.Dash, rows int) {
 		rows = size.Row
 	}
 	// Use iTerm2 image display feature.
-	term := term.NewImageWriter(width, height)
-	defer term.Close()
-	if err := dash.Render(term, width, height); err != nil {
+	tm := term.NewImageWriter(width, height)
+	defer tm.Close()
+	if err := dash.Render(tm, width, height); err != nil {
 		fatal(fmt.Sprintf("cannot render graph: %v", err.Error()))
 	}
 }

streamer/start.go

@@ -0,0 +1,31 @@
+package streamer
+
+import (
+	"fmt"
+	"github.com/rs/jplot/graph"
+	"log"
+	"net"
+	"net/http"
+)
+
+func Start(port int, dash *graph.Dash, width, height, refreshRate int) error {
+	listener, err := net.Listen("tcp", fmt.Sprintf("0.0.0.0:%d", port))
+	if err != nil {
+		return err
+	}
+
+	stream := &Streamer{
+		dash:        dash,
+		width:       width,
+		height:      height,
+		refreshRate: refreshRate,
+	}
+
+	log.Println("starting server on ", port)
+	er := http.Serve(listener, stream)
+	if er != nil {
+		return er
+	}
+
+	return nil
+}

streamer/streamer.go

@@ -0,0 +1,62 @@
+package streamer
+
+import (
+	"errors"
+	"fmt"
+	"github.com/rs/jplot/graph"
+	"net/http"
+	"syscall"
+)
+
+type Streamer struct {
+	dash *graph.Dash
+
+	width, height, refreshRate int
+}
+
+func (s *Streamer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+	if req.URL.String() == "/" {
+		err := s.serveStatic(resp)
+		if err != nil {
+			resp.WriteHeader(http.StatusInternalServerError)
+			fmt.Println("error on serving static: ", err)
+		}
+		return
+	}
+
+	resp.Header().Add("Content-Type", "image/png")
+	err := s.dash.Render(resp, s.width, s.height)
+	if err == nil {
+		return
+	}
+
+	if errors.Is(err, syscall.EPIPE) {
+		return
+	}
+
+	fmt.Println("error on render: ", err)
+}
+
+func (s *Streamer) serveStatic(resp http.ResponseWriter) error {
+	resp.Header().Add("Content-Type", "text/html")
+	_, err := resp.Write([]byte(fmt.Sprintf(`
+<html>
+<head>
+</head>
+<body>
+<img id="data" src="data.png">
+</body>
+
+<script>
+
+var i = 0
+setInterval( () => {
+	i++
+	document.getElementById("data").src = "data.png" + "?q=" + i
+}, %d)
+</script>
+</html>
+`, s.refreshRate)))
+
+	return err
+}