Refactor OSC commands

Author: rs

main.go

@@ -1,16 +1,17 @@
 package main // import "github.com/rs/jplot"
 
 import (
-	"bytes"
-	"encoding/base64"
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/rs/jplot/data"
 	"github.com/rs/jplot/graph"
+	"github.com/rs/jplot/osc"
 	"github.com/rs/jplot/window"
 )
 
@@ -51,9 +52,13 @@ func main() {
 	defer close(exit)
 	go func() {
 		defer wg.Done()
-		clear()
+		osc.Clear()
+		osc.HideCursor()
+		defer osc.ShowCursor()
 		t := time.NewTicker(time.Second)
 		defer t.Stop()
+		c := make(chan os.Signal, 2)
+		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
 		i := 0
 		for {
 			width, height, err := window.Size()
@@ -65,12 +70,15 @@ func main() {
 				i++
 				if i%120 == 0 {
 					// Clear scrollback to avoid iTerm from eating all the memory.
-					cleanup()
+					osc.ClearScrollback()
 				}
 				render(dash, width, height)
 			case <-exit:
 				render(dash, width, height)
 				return
+			case <-c:
+				osc.ShowCursor()
+				os.Exit(0)
 			}
 		}
 	}()
@@ -86,24 +94,9 @@ func fatal(a ...interface{}) {
 }
 
 func render(dash graph.Dash, width, height int) {
-	var b bytes.Buffer
-	enc := base64.NewEncoder(base64.StdEncoding, &b)
-	defer enc.Close()
-	dash.Render(enc, width, height)
-	reset()
+	osc.CursorPosition(0, 0)
 	// Use iTerm2 image display feature.
-	fmt.Printf("\033]1337;File=preserveAspectRatio=1;inline=1:%s\007", b.Bytes())
-}
-
-func clear() {
-	print("\033\133\110\033\133\062\112") // clear screen
-	print("\033]1337;CursorShape=1\007")  // set cursor to vertical bar
-}
-
-func reset() {
-	print("\033\133\061\073\061\110") // move cursor to 0x0
-}
-
-func cleanup() {
-	print("\033]1337;ClearScrollback\007")
+	term := &osc.ImageWriter{}
+	defer term.Close()
+	dash.Render(term, width, height)
 }

osc/iterm2.go

@@ -0,0 +1,40 @@
+package osc
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"sync"
+)
+
+// ClearScrollback clears iTerm2 scrollback.
+func ClearScrollback() {
+	print("\033]1337;ClearScrollback\007")
+}
+
+// ImageWriter is a writer that write into iTerm2 terminal the PNG data written
+// to it.
+type ImageWriter struct {
+	Name string
+
+	once   sync.Once
+	b66enc io.WriteCloser
+	buf    *bytes.Buffer
+}
+
+func (w *ImageWriter) init() {
+	w.buf = &bytes.Buffer{}
+	w.b66enc = base64.NewEncoder(base64.StdEncoding, w.buf)
+}
+
+func (w *ImageWriter) Write(p []byte) (n int, err error) {
+	w.once.Do(w.init)
+	return w.b66enc.Write(p)
+}
+
+func (w *ImageWriter) Close() error {
+	w.once.Do(w.init)
+	fmt.Printf("\033]1337;File=preserveAspectRatio=1;inline=1:%s\007", w.buf.Bytes())
+	return w.b66enc.Close()
+}

osc/std.go

@@ -0,0 +1,49 @@
+package osc
+
+import "fmt"
+
+type Direction string
+
+const (
+	// Up moves the cursor up.
+	Up Direction = "A"
+	// Down moves the cursor down.
+	Down Direction = "B"
+	// Forward moves the cursor foward.
+	Forward Direction = "C"
+	// Backward moves the cursor backward.
+	Backward Direction = "D"
+	// NextLine cursor to beginning of the line next line.
+	NextLine Direction = "E"
+	// PreviousLine cursor to beginning of the line previous line.
+	PreviousLine Direction = "F"
+	// HorizontalAbsolute the cursor to the specified column.
+	HorizontalAbsolute Direction = "G"
+)
+
+const csi = "\033["
+
+// HideCursor hides cursor.
+func HideCursor() {
+	print(csi + "?25l")
+}
+
+// ShowCursor shows cursor.
+func ShowCursor() {
+	print(csi + "?25h")
+}
+
+// Clear clears the screen.
+func Clear() {
+	print(csi + "H\033[2J")
+}
+
+// CursorPosition moves cursor to row, col.
+func CursorPosition(row, col int) {
+	fmt.Printf("%s%d;%dH", csi, row, col)
+}
+
+// CursorMove moves the cursor n times in the direction d.
+func CursorMove(d Direction, n uint) {
+	fmt.Printf("%s%d%s", csi, n, d)
+}