remove invert argument and use colors in terminal instead

main.go

@@ -32,6 +32,7 @@ import (
 	mathrand "math/rand"
 	"net"
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -129,13 +130,13 @@ func secureRandBase64(length int) string {
 
 func main() {
 	var bind, certFile, keyFile, secret string
-	var showVersion, invert bool
+	var showVersion bool
 	flag.BoolVar(&showVersion, "version", false, "show program's version number and exit")
 	flag.StringVar(&bind, "bind", defaultBind, "bind server to [HOSTNAME]:PORT")
 	flag.StringVar(&secret, "secret", "", "shared secret for client authentication")
 	flag.StringVar(&certFile, "cert", "", "file containing TLS certificate")
 	flag.StringVar(&keyFile, "key", "", "file containing TLS private key")
-	flag.BoolVar(&invert, "invert", false, "use inverse colors for QR code")
+	flag.Bool("invert", false, "obsolete, not used anymore")
 	flag.Int("interval", 0, "obsolete, not used anymore")
 	flag.Parse()
 	if showVersion {
@@ -225,7 +226,7 @@ func main() {
 	}
 	url := fmt.Sprintf("%s://%s/#%s\n", scheme, domain, secret)
 	readyMsg := "ready: " + url
-	qrCode, _ := GenerateQRCode(url, invert)
+	qrCode, _ := GenerateQRCode(url, terminalSupportsColor(os.Stderr.Fd()))
 	readyMsg += qrCode
 	if !tls {
 		readyMsg += ("" +

qr.go

@@ -21,36 +21,42 @@ package main
 
 import qrcode "github.com/skip2/go-qrcode"
 
-func GenerateQRCode(message string, invert bool) (string, error) {
+func GenerateQRCode(message string, colorize bool) (string, error) {
 	q, err := qrcode.New(message, qrcode.Medium)
 	if err != nil {
 		return "", err
 	}
-	return qrCodeToString(q.Bitmap(), invert), nil
+	return qrCodeToString(q.Bitmap(), colorize), nil
 }
 
-func qrCodeToString(bits [][]bool, invert bool) string {
+func qrCodeToString(bits [][]bool, colorize bool) string {
 	s := ""
 	for y := -1; y < len(bits); y += 2 {
+		if colorize {
+			s += terminalForegroundWhite + terminalBackgroundBlack
+		}
 		for x := range bits[0] {
-			upper := !invert
+			upper := false
 			if 0 <= y && y < len(bits) {
 				upper = bits[y][x]
 			}
-			lower := !invert
+			lower := false
 			if 0 <= y+1 && y+1 < len(bits) {
 				lower = bits[y+1][x]
 			}
-			if upper != invert && lower != invert {
+			if upper && lower {
 				s += " "
-			} else if upper == invert && lower != invert {
+			} else if !upper && lower {
 				s += "▀"
-			} else if upper != invert && lower == invert {
+			} else if upper && !lower {
 				s += "▄"
 			} else {
 				s += "█"
 			}
 		}
+		if colorize {
+			s += terminalForegroundReset + terminalBackgroundReset
+		}
 		s += "\n"
 	}
 	return s

terminal_color.go

@@ -0,0 +1,27 @@
+/*
+ *    Copyright (c) 2018 Unrud<unrud@outlook.com>
+ *
+ *    This file is part of Remote-Touchpad.
+ *
+ *    Foobar is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    Remote-Touchpad is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+const (
+	terminalForegroundWhite string = "\033[37m"
+	terminalForegroundReset string = "\033[39m"
+	terminalBackgroundBlack string = "\033[40m"
+	terminalBackgroundReset string = "\033[49m"
+)

terminal_color_posix.go

@@ -0,0 +1,29 @@
+// +build !windows
+
+/*
+ *    Copyright (c) 2018 Unrud<unrud@outlook.com>
+ *
+ *    This file is part of Remote-Touchpad.
+ *
+ *    Foobar is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    Remote-Touchpad is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+// #include <unistd.h>
+import "C"
+
+func terminalSupportsColor(fd uintptr) bool {
+	return C.isatty(C.int(fd)) != 0
+}

terminal_color_windows.go

@@ -0,0 +1,39 @@
+/*
+ *    Copyright (c) 2018 Unrud<unrud@outlook.com>
+ *
+ *    This file is part of Remote-Touchpad.
+ *
+ *    Foobar is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    Remote-Touchpad is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+import "syscall"
+
+const (
+	enableProcessedOuput            uint32 = 0x1
+	enableWrapAtEolOutput           uint32 = 0x2
+	enableVirtualTerminalProcessing uint32 = 0x4
+)
+
+var (
+	kernel32DLL        = syscall.NewLazyDLL("kernel32.dll")
+	setConsoleModeProc = kernel32DLL.NewProc("SetConsoleMode")
+)
+
+func terminalSupportsColor(fd uintptr) bool {
+	r, _, _ := setConsoleModeProc.Call(fd, uintptr(enableProcessedOuput|
+		enableWrapAtEolOutput|enableVirtualTerminalProcessing))
+	return r != 0
+}