term.ui: approximate colors into ansi if rgb isn't supported (#6951)

examples/term.ui/term_drawing.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module main
 
 import term.ui as tui

vlib/term/ui/color.v

@@ -0,0 +1,88 @@
+// radare - LGPL - Copyright 2013-2020 - pancake, xarkes
+// ansi 256 color extension for r_cons
+// https://en.wikipedia.org/wiki/ANSI_color
+
+module ui
+
+const (
+	value_range = [0x00, 0x5f, 0x87, 0xaf, 0xd7, 0xff]!!
+	color_table = init_color_table()
+)
+
+[direct_array_access]
+fn init_color_table() []int {
+	mut color_table := []int{len: 256}
+	// ansi colors
+	color_table[0] = 0x000000
+	color_table[1] = 0x800000
+	color_table[2] = 0x008000
+	color_table[3] = 0x808000
+	color_table[4] = 0x000080
+	color_table[5] = 0x800080
+	color_table[6] = 0x008080
+	color_table[7] = 0xc0c0c0
+	color_table[8] = 0x808080
+	color_table[9] = 0xff0000
+	color_table[10] = 0x00ff00
+	color_table[11] = 0xffff00
+	color_table[12] = 0x0000ff
+	color_table[13] = 0xff00ff
+	color_table[14] = 0x00ffff
+	color_table[15] = 0xffffff
+	// color palette
+	for i in 0 .. 216 {
+		r := value_range[(i / 36) % 6]
+		g := value_range[(i / 6) % 6]
+		b := value_range[i % 6]
+		color_table[i + 16] = ((r << 16) & 0xffffff) + ((g << 8) & 0xffff) + (b & 0xff)
+	}
+	// grayscale
+	for i in 0 .. 24 {
+		r := 8 + (i * 10)
+		color_table[i + 232] = ((r << 16) & 0xffffff) + ((r << 8) & 0xffff) + (r & 0xff)
+	}
+	return color_table
+}
+
+fn clamp(x int, y int, z int) int {
+	if x < y {
+		return y
+	}
+	if x > z {
+		return z
+	}
+	return x
+}
+
+fn approximate_rgb(r int, g int, b int) int {
+	grey := r > 0 && r < 255 && r == g && r == b
+	if grey {
+		return 232 + int(f64(r) / (255 / 24.1))
+	}
+	k := int(256.0 / 6)
+	r2 := clamp(r / k, 0, 5)
+	g2 := clamp(g / k, 0, 5)
+	b2 := clamp(b / k, 0, 5)
+	return 16 + (r2 * 36) + (g2 * 6) + b2
+}
+
+fn lookup_rgb(r int, g int, b int) int {
+	color := (r << 16) + (g << 8) + b
+	// lookup extended colors only, coz non-extended can be changed by users.
+	for i in 16 .. 256 {
+		if color_table[i] == color {
+			return i
+		}
+	}
+	return -1
+}
+
+// converts an RGB color to an ANSI 256-color, approximating it to the nearest available color
+// if an exact match is not found
+fn rgb2ansi(r int, g int, b int) int {
+	c := lookup_rgb(r, g, b)
+	if c == -1 {
+		return approximate_rgb(r, g, b)
+	}
+	return c
+}

vlib/term/ui/input.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module ui
 
 pub enum KeyCode {
@@ -164,11 +167,11 @@ pub struct Context {
 pub:
 	cfg 		  Config
 mut:
-	termios       C.termios
 	read_buf      []byte
 	print_buf     []byte
 	paused        bool
 	enable_su     bool
+	enable_rgb    bool
 pub mut:
 	frame_count   u64
 	window_width  int
@@ -176,21 +179,22 @@ pub mut:
 }
 
 pub struct Config {
-	user_data      voidptr
+	user_data            voidptr
-	init_fn        fn(voidptr)
+	init_fn              fn(voidptr)
-	frame_fn       fn(voidptr)
+	frame_fn             fn(voidptr)
-	cleanup_fn     fn(voidptr)
+	cleanup_fn           fn(voidptr)
-	event_fn       fn(&Event, voidptr)
+	event_fn             fn(&Event, voidptr)
-	fail_fn        fn(string)
+	fail_fn              fn(string)
 
-	buffer_size    int = 256
+	buffer_size          int = 256
-	frame_rate     int = 30
+	frame_rate           int = 30
-	use_x11        bool
+	use_x11              bool
 
-	window_title   string
+	window_title         string
-	hide_cursor    bool
+	hide_cursor          bool
-	capture_events bool
+	capture_events       bool
 	use_alternate_buffer bool = true
-	// All kill signals
+	skip_init_checks     bool
-	reset          []int = [1, 2, 3, 4, 6, 7, 8, 9, 11, 13, 14, 15, 19]
+	// All kill signals to set up exit listeners on
+	reset                []int = [1, 2, 3, 4, 6, 7, 8, 9, 11, 13, 14, 15, 19]
 }

vlib/term/ui/input_nix.c.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module ui
 
 const (
@@ -28,12 +31,12 @@ pub fn (mut ctx Context) load_title() {
     print('\x1b[23;0t')
 }
 
-pub fn (mut ctx Context) run() {
+pub fn (mut ctx Context) run() ? {
 	if ctx.cfg.use_x11 {
 		ctx.fail('error: x11 backend not implemented yet')
 		exit(1)
 	} else {
-		ctx.termios_setup()
+		ctx.termios_setup()?
 		ctx.termios_loop()
 	}
 }

vlib/term/ui/input_windows.c.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module ui
 
 const (

vlib/term/ui/termios_nix.c.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module ui
 
 import os
@@ -51,10 +54,14 @@ fn restore_terminal_state() {
 	os.flush()
 }
 
-fn (mut ctx Context) termios_setup() {
+fn (mut ctx Context) termios_setup() ? {
 	// store the current title, so restore_terminal_state can get it back
 	ctx.save_title()
 
+	if !ctx.cfg.skip_init_checks && !(is_atty(C.STDIN_FILENO) != 0 && is_atty(C.STDOUT_FILENO) != 0) {
+		return error('not running under a TTY')
+	}
+
 	mut termios := get_termios()
 
 	if ctx.cfg.capture_events {
@@ -75,20 +82,28 @@ fn (mut ctx Context) termios_setup() {
 		print('\x1b]0;$ctx.cfg.window_title\x07')
 	}
 
-	C.tcsetattr(C.STDIN_FILENO, C.TCSAFLUSH, &termios)
+	if !ctx.cfg.skip_init_checks {
-	// feature-test the SU spec
+		// prevent blocking during the feature detections, but allow enough time for the terminal
-	sx, sy := get_cursor_position()
+		// to send back the relevant input data
-	print('$bsu$esu')
+		termios.c_cc[C.VTIME] = 1
-	ex, ey := get_cursor_position()
+		termios.c_cc[C.VMIN] = 0
-
+		C.tcsetattr(C.STDIN_FILENO, C.TCSAFLUSH, &termios)
-	if sx == ex && sy == ey {
+		// feature-test the SU spec
-		// the terminal either ignored or handled the sequence properly, enable SU
+		sx, sy := get_cursor_position()
-		ctx.enable_su = true
+		print('$bsu$esu')
-	} else {
+		ex, ey := get_cursor_position()
-		ctx.draw_line(sx, sy, ex, ey)
+		if sx == ex && sy == ey {
-		ctx.set_cursor_position(sx, sy)
+			// the terminal either ignored or handled the sequence properly, enable SU
-		ctx.flush()
+			ctx.enable_su = true
+		} else {
+			ctx.draw_line(sx, sy, ex, ey)
+			ctx.set_cursor_position(sx, sy)
+			ctx.flush()
+		}
+		// feature-test rgb (truecolor) support
+		ctx.enable_rgb = supports_truecolor()
 	}
+
 	// Prevent stdin from blocking by making its read time 0
 	termios.c_cc[C.VTIME] = 0
 	termios.c_cc[C.VMIN] = 0
@@ -101,7 +116,6 @@ fn (mut ctx Context) termios_setup() {
 		// clear the terminal and set the cursor to the origin
 		print('\x1b[2J\x1b[3J\x1b[1;1H')
 	}
-	ctx.termios = termios
 	ctx.window_height, ctx.window_width = get_terminal_size()
 
 	// Reset console on exit
@@ -179,6 +193,61 @@ fn get_cursor_position() (int, int) {
 	return x, y
 }
 
+fn supports_truecolor() bool {
+	// set the bg color to some arbirtrary value (#010203), assumed not to be the default
+	print('\x1b[48:2:1:2:3m')
+
+	sx, sy := get_cursor_position()
+	// sequence to query the current cursor position
+	print('\x1bP\$qm\x1b\\')
+	color := get_current_bg_color()
+	ex, ey := get_cursor_position()
+	// if the terminal doesn't understand the "get current color",
+	// assume it doesn't support truecolor either
+	if !(sx == ex && sy == ey) {
+		println('>>> different pos: ($sx, $sy) -> ($ex, $ey)')
+		return false
+	}
+	// TODO: iTerm emits a different sequence, but it's compatible anyways, so
+	if color !in [0x010203, 0x01010203] {
+		println('>>> no match: $color')
+		return false
+	}
+	return true
+}
+
+fn get_current_bg_color() int {
+	mut res := 0
+	mut colon_cnt := 0
+	mut cur_val := 0
+
+	for i := 0; i < 50 ; i++ {
+		ch := int(C.getchar())
+		b := byte(ch)
+
+		if b in [0, 255] {
+			return -1
+		} else if b == `m` {
+			if colon_cnt > 1 {
+				res = (res << 8) | cur_val
+				cur_val = 0
+			}
+			break
+		} else if b in [`:`, `;`] {
+			if colon_cnt > 1 {
+				res = (res << 8) | cur_val
+				cur_val = 0
+			}
+			colon_cnt++
+		} else if b.is_digit() {
+			if colon_cnt > 1 {
+				cur_val = cur_val * 10 + b - byte(`0`)
+			}
+		}
+	}
+	return res
+}
+
 fn termios_reset() {
 	C.tcsetattr(C.STDIN_FILENO, C.TCSAFLUSH /* C.TCSANOW ?? */, &termios_at_startup)
 	print('\x1b[?1003l\x1b[?1006l\x1b[?25h')

vlib/term/ui/ui.v

@@ -1,3 +1,6 @@
+// Copyright (c) 2020 Raúl Hernández. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
 module ui
 
 import strings
@@ -57,12 +60,20 @@ pub fn (mut ctx Context) set_cursor_position(x int, y int) {
 
 [inline]
 pub fn (mut ctx Context) set_color(c Color) {
-	ctx.write('\x1b[38;2;${int(c.r)};${int(c.g)};${int(c.b)}m')
+	if ctx.enable_rgb {
+		ctx.write('\x1b[38;2;${int(c.r)};${int(c.g)};${int(c.b)}m')
+	} else {
+		ctx.write('\x1b[38;5;${rgb2ansi(c.r, c.g, c.b)}m')
+	}
 }
 
 [inline]
 pub fn (mut ctx Context) set_bg_color(c Color) {
-	ctx.write('\x1b[48;2;${int(c.r)};${int(c.g)};${int(c.b)}m')
+	if ctx.enable_rgb {
+		ctx.write('\x1b[48;2;${int(c.r)};${int(c.g)};${int(c.b)}m')
+	} else {
+		ctx.write('\x1b[48;5;${rgb2ansi(c.r, c.g, c.b)}m')
+	}
 }
 
 [inline]