feat: detect image protocol

examples/img2term/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"flag"
+	"fmt"
 	"image"
 	"io"
 	"log"
@@ -13,10 +14,16 @@ import (
 
 	"github.com/charmbracelet/x/ansi"
 	"github.com/charmbracelet/x/ansi/sixel"
+	"github.com/charmbracelet/x/graphics"
 )
 
 // $ go run . ./../../ansi/fixtures/graphics/JigokudaniMonkeyPark.png
 func main() {
+	imageProtocols := graphics.DetectImageProtocols()
+	fmt.Println("sixel  supported:", imageProtocols.Sixel)
+	fmt.Println("iTerm2 supported:", imageProtocols.ITerm2)
+	fmt.Println("kitty  supported", imageProtocols.Kitty)
+
 	flag.Parse()
 	args := flag.Args()
 	if len(args) == 0 {

go.work

@@ -17,6 +17,7 @@ use (
 	./exp/strings
 	./exp/teatest
 	./exp/teatest/v2
+	./graphics
 	./input
 	./json
 	./mosaic

graphics/detect.go

@@ -0,0 +1,111 @@
+package graphics
+
+import (
+	"bytes"
+	"os"
+	"time"
+
+	"github.com/charmbracelet/x/term"
+)
+
+// TODO: Verify if it's running with tmux for Kitty and ITerm2
+// TODO: Write a func for preferred protocol for the terminal
+// TODO: Additional check if the terminal supports cell-size by `[16t` or `[14t`
+// TODO: Write tests by mocking a terminal context ?
+
+const (
+	termProgramVariable = "TERM_PROGRAM"
+	lcTerminalVariable  = "LC_TERMINAL"
+)
+
+// Returns the availability of each image protocol.
+type ImageProtocols struct {
+	Sixel  bool
+	ITerm2 bool
+	Kitty  bool
+	// Mosaic (Halfblocks) should work in all terminals,
+	// even if the font size could not be detected, with a 4:8 pixel ratio.
+	Mosaic bool
+}
+
+// Detect all availables image protocols and return as [ImageProtocols].
+func DetectImageProtocols() ImageProtocols {
+	return ImageProtocols{
+		Sixel: detectSixel(),
+		// TODO: `_Gi=...`: Kitty graphics support.
+		Kitty: detectKitty(),
+		// TODO: `[1337n`: iTerm2 (some terminals implement the protocol but sadly not this custom CSI)
+		ITerm2: detectIterm2() || detectIterm2FromEnv(),
+		Mosaic: true,
+	}
+}
+
+func detectKitty() bool {
+	return false
+}
+
+func detectIterm2() bool {
+	return false
+}
+
+// This function detects iTerm2 protocol from environment variable.
+func detectIterm2FromEnv() bool {
+	termProgram := os.Getenv(termProgramVariable)
+	if termProgram == "iTerm" ||
+		termProgram == "WezTerm" ||
+		termProgram == "mintty" ||
+		termProgram == "vscode" ||
+		termProgram == "Tabby" ||
+		termProgram == "Hyper" ||
+		termProgram == "rio" {
+		return true
+	}
+
+	lcTerminal := os.Getenv(lcTerminalVariable)
+	return lcTerminal == "iTerm"
+}
+
+func detectSixel() bool {
+	sixelSupportedTerminals := []string{
+		"\x1b[?62;", // VT240
+		"\x1b[?63;", // wsltty
+		"\x1b[?64;", // mintty
+		"\x1b[?65;", // RLogin
+		// NOTE: tmux does not return VT name.
+		"\x1b[?1;2;4c", // Tmux
+	}
+
+	if term.IsTerminal(os.Stdout.Fd()) {
+		return true
+	}
+	s, err := term.MakeRaw(1)
+	if err == nil {
+		defer term.Restore(1, s) // nolint:errcheck
+	}
+	_, err = os.Stdout.Write([]byte("\x1b[c"))
+	if err != nil {
+		return false
+	}
+	defer os.Stdout.SetReadDeadline(time.Time{}) // nolint:errcheck
+
+	var b [100]byte
+	n, err := os.Stdout.Read(b[:])
+	if err != nil {
+		return false
+	}
+
+	for _, t := range bytes.Split(b[6:n], []byte(";")) {
+		// Check if 4 is present in terminal capabilities.
+		if len(t) == 1 && t[0] == '4' {
+			return true
+		}
+	}
+
+	for _, supportedTerminal := range sixelSupportedTerminals {
+		if bytes.HasPrefix(b[:n], []byte(supportedTerminal)) {
+			return true
+		}
+	}
+
+	return false
+}

graphics/go.mod

@@ -0,0 +1,7 @@
+module github.com/charmbracelet/x/graphics
+
+go 1.21
+
+require github.com/charmbracelet/x/term v0.2.1
+
+require golang.org/x/sys v0.26.0 // indirect

graphics/go.sum

@@ -0,0 +1,4 @@
+github.com/charmbracelet/x/term v0.2.1 h1:AQeHeLZ1OqSXhrAWpYUtZyX1T3zVxfpZuEQMIQaGIAQ=
+github.com/charmbracelet/x/term v0.2.1/go.mod h1:oQ4enTYFV7QN4m0i9mzHrViD7TQKvNEEkHUMCmsxdUg=
+golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
+golang.org/x/sys v0.26.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=