badterm_core/
export.rs

1//! Turning screen contents back into files or clipboard text: plain text,
2//! and ANSI as BBS art viewers and editors expect it (CP437 bytes for `.ans`
3//! files, or Unicode for pasting).
4
5use crate::cp437;
6use crate::palette::ANSI_TO_VGA;
7use crate::screen::{Cell, Color, DEFAULT_BG, DEFAULT_FG, flags};
8
9/// Plain text, one line per row, trailing blanks and blank lines trimmed.
10pub fn text(lines: &[&[Cell]]) -> String {
11    let mut out: Vec<String> =
12        lines.iter().map(|row| row.iter().map(|c| glyph(c.ch)).collect::<String>().trim_end().to_string()).collect();
13    while out.last().is_some_and(String::is_empty) {
14        out.pop();
15    }
16    let mut s = out.join("\n");
17    if !s.is_empty() {
18        s.push('\n');
19    }
20    s
21}
22
23/// Options for [`ansi`].
24#[derive(Clone, Copy, Debug, Default)]
25pub struct AnsiOptions {
26    /// The art uses iCE colors (blink means bright background): start with
27    /// `CSI ?33h` so viewers that know it switch modes.
28    pub ice: bool,
29    /// Write glyphs as UTF-8 instead of CP437 bytes (for the clipboard).
30    pub unicode: bool,
31}
32
33/// ANSI with SGR attributes, one CRLF-terminated line per row. Trailing
34/// blanks on each line and trailing blank lines are left out.
35pub fn ansi(lines: &[&[Cell]], opts: AnsiOptions) -> Vec<u8> {
36    let mut out = Vec::new();
37    if opts.ice {
38        out.extend_from_slice(b"\x1b[?33h");
39    }
40    out.extend_from_slice(b"\x1b[0m");
41    let last = lines.iter().rposition(|row| row.iter().any(|c| !blank(c))).map_or(0, |i| i + 1);
42    let default = Cell::default();
43    for row in &lines[..last] {
44        let end = row.iter().rposition(|c| !blank(c)).map_or(0, |i| i + 1);
45        let mut pen = default;
46        for c in &row[..end] {
47            if !same_attrs(c, &pen) {
48                sgr(c, &mut out);
49                pen = *c;
50            }
51            if opts.unicode {
52                let mut buf = [0; 4];
53                out.extend_from_slice(glyph(c.ch).encode_utf8(&mut buf).as_bytes());
54            } else {
55                out.push(safe_byte(c.ch));
56            }
57        }
58        if !same_attrs(&pen, &default) {
59            out.extend_from_slice(b"\x1b[0m");
60        }
61        out.extend_from_slice(b"\r\n");
62    }
63    out
64}
65
66fn glyph(ch: u8) -> char {
67    if ch == 0 { ' ' } else { cp437::to_unicode(ch) }
68}
69
70/// CP437 glyphs that would act as control codes in a file are written as
71/// spaces: NUL, BEL, BS, TAB, LF, FF, CR, SUB (end of file before a SAUCE
72/// record) and ESC.
73fn safe_byte(ch: u8) -> u8 {
74    match ch {
75        0 | 7 | 8 | 9 | 10 | 12 | 13 | 26 | 27 => b' ',
76        c => c,
77    }
78}
79
80fn blank(c: &Cell) -> bool {
81    c.is_blank() && c.flags & (flags::UNDERLINE | flags::BLINK) == 0
82}
83
84fn same_attrs(a: &Cell, b: &Cell) -> bool {
85    a.fg == b.fg && a.bg == b.bg && a.flags == b.flags
86}
87
88/// Write the attributes of `c` from scratch (`CSI 0;...m`).
89fn sgr(c: &Cell, out: &mut Vec<u8>) {
90    let mut p: Vec<String> = vec!["0".into()];
91    let f = c.flags;
92    // Bright PC colors are written the classic way, as bold, since that is
93    // what BBS art viewers understand.
94    let bright_fg = matches!(c.fg, Color::Pc(i) if i >= 8);
95    for (bit, code) in
96        [(flags::BOLD, "1"), (flags::FAINT, "2"), (flags::UNDERLINE, "4"), (flags::BLINK, "5"), (flags::REVERSE, "7")]
97    {
98        if f & bit != 0 || bit == flags::BOLD && bright_fg {
99            p.push(code.into());
100        }
101    }
102    if f & flags::CONCEAL != 0 {
103        p.push("8".into());
104    }
105    match c.fg {
106        DEFAULT_FG => {}
107        Color::Pc(i) => p.push(format!("{}", 30 + vga_to_ansi(i & 7))),
108        Color::Xterm(i) => p.push(format!("38;5;{i}")),
109        Color::Rgb(rgb) => p.push(format!("38;2;{};{};{}", rgb >> 16 & 0xFF, rgb >> 8 & 0xFF, rgb & 0xFF)),
110    }
111    match c.bg {
112        DEFAULT_BG => {}
113        Color::Pc(i) if i >= 8 => p.push(format!("{}", 100 + vga_to_ansi(i & 7))),
114        Color::Pc(i) => p.push(format!("{}", 40 + vga_to_ansi(i))),
115        Color::Xterm(i) => p.push(format!("48;5;{i}")),
116        Color::Rgb(rgb) => p.push(format!("48;2;{};{};{}", rgb >> 16 & 0xFF, rgb >> 8 & 0xFF, rgb & 0xFF)),
117    }
118    out.extend_from_slice(format!("\x1b[{}m", p.join(";")).as_bytes());
119}
120
121fn vga_to_ansi(i: u8) -> u8 {
122    // The mapping swaps red and blue (and cyan and brown), so it is its own
123    // inverse.
124    ANSI_TO_VGA[i as usize & 7]
125}
126
127#[cfg(test)]
128mod tests {
129    use super::*;
130    use crate::ansi::Terminal;
131
132    fn rows(t: &Terminal) -> Vec<&[Cell]> {
133        (0..t.screen.rows()).map(|y| t.screen.row(y)).collect()
134    }
135
136    #[test]
137    fn plain_text() {
138        let mut t = Terminal::new(20, 5, 0);
139        t.feed(b"\x1b[1;31mHello\x1b[0m  \r\n\r\n\xc9\xcd\xbb\r\n");
140        assert_eq!(text(&rows(&t)), "Hello\n\n\u{2554}\u{2550}\u{2557}\n");
141    }
142
143    #[test]
144    fn ansi_round_trips_through_the_terminal() {
145        let mut t = Terminal::new(40, 6, 0);
146        t.feed(b"\x1b[1;33;44mBold yellow on blue\x1b[0m plain\r\n");
147        t.feed(b"\x1b[5;31;47mblink\x1b[0m \x1b[38;5;196mxterm\x1b[38;2;1;2;3m rgb\x1b[0m\r\n");
148        t.feed(b"\x1b[92mbright\x1b[0m \x1b[104mbg\x1b[0m \x1b[4munder\x1b[7mrev\x1b[0m\r\n");
149        t.feed(b"\x1b[41m  \x1b[0m\x1b[30C\xdb\x1b[K");
150        let data = ansi(&rows(&t), AnsiOptions::default());
151
152        let mut back = Terminal::new(40, 6, 0);
153        back.feed(&data);
154        for y in 0..6 {
155            for x in 0..40 {
156                let (a, b) = (t.screen.row(y)[x], back.screen.row(y)[x]);
157                assert_eq!(a.ch, b.ch, "glyph at {x},{y}");
158                assert_eq!(a.resolve(false), b.resolve(false), "colors at {x},{y}");
159            }
160        }
161    }
162
163    #[test]
164    fn options_and_safety() {
165        let mut t = Terminal::new(10, 2, 0);
166        t.screen.put(0x1B);
167        t.screen.put(0x01);
168        let raw = ansi(&rows(&t), AnsiOptions { ice: true, unicode: false });
169        assert_eq!(raw, b"\x1b[?33h\x1b[0m \x01\r\n");
170        let uni = ansi(&rows(&t), AnsiOptions { ice: false, unicode: true });
171        assert_eq!(String::from_utf8(uni).unwrap(), "\x1b[0m\u{2190}\u{263A}\r\n");
172        // Nothing at all.
173        assert_eq!(ansi(&rows(&Terminal::new(10, 2, 0)), AnsiOptions::default()), b"\x1b[0m");
174    }
175}
badterm_core/export.rs

badterm_core/
export.rs
