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Further improve xterm mouse decoding #819

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Merged
lhecker merged 1 commit into from
Apr 27, 2026
Merged

Further improve xterm mouse decoding #819

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126 changes: 61 additions & 65 deletions crates/edit/src/input.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,8 @@ pub struct InputMouse {
pub position: Point,
/// Scroll delta.
pub scroll: Point,
/// Whether the mouse is being dragged with a button held down.
pub drag: bool,
}

/// Primary result type of the parser.
Expand Down Expand Up @@ -433,43 +435,10 @@ impl<'input> Iterator for Stream<'_, '_, 'input> {
}
}
'm' | 'M' if csi.private_byte == '<' => {
let btn = csi.params[0];
let mut mouse = InputMouse {
state: InputMouseState::None,
modifiers: kbmod::NONE,
position: Default::default(),
scroll: Default::default(),
};

mouse.state = InputMouseState::None;

match csi.params[0] {
btn @ 0..3 if csi.final_byte == 'M' => match btn {
0 => mouse.state = InputMouseState::Left,
1 => mouse.state = InputMouseState::Middle,
2 => mouse.state = InputMouseState::Right,
_ => {}
},
btn @ 64..68 => {
let delta = if (btn & 1) != 0 { 3 } else { -3 };
let idx = if (btn & 2) != 0 { 0 } else { 1 };
mouse.scroll.as_array()[idx] += delta;
mouse.state = InputMouseState::Scroll;
}
_ => {}
}

mouse.modifiers = kbmod::NONE;
mouse.modifiers |=
if (btn & 0x04) != 0 { kbmod::SHIFT } else { kbmod::NONE };
mouse.modifiers |=
if (btn & 0x08) != 0 { kbmod::ALT } else { kbmod::NONE };
mouse.modifiers |=
if (btn & 0x10) != 0 { kbmod::CTRL } else { kbmod::NONE };

mouse.position.x = csi.params[1] as CoordType - 1;
mouse.position.y = csi.params[2] as CoordType - 1;
return Some(Input::Mouse(mouse));
return Self::parse_xterm_mouse(
&csi.params[..csi.param_count],
csi.final_byte,
);
}
'M' if csi.param_count == 0 => {
self.parser.x10_mouse_want = true;
Expand Down Expand Up @@ -547,38 +516,14 @@ impl<'input> Stream<'_, '_, 'input> {
return None;
}

let b = self.parser.x10_mouse_buf[0] as u32;
let x = self.parser.x10_mouse_buf[1] as CoordType - 0x21;
let y = self.parser.x10_mouse_buf[2] as CoordType - 0x21;
let action = match b & 0b11 {
0 => InputMouseState::Left,
1 => InputMouseState::Middle,
2 => InputMouseState::Right,
_ => InputMouseState::None,
};
let modifiers = {
let mut m = kbmod::NONE;
if (b & 0b00100) != 0 {
m |= kbmod::SHIFT;
}
if (b & 0b01000) != 0 {
m |= kbmod::ALT;
}
if (b & 0b10000) != 0 {
m |= kbmod::CTRL;
}
m
};
let b = self.parser.x10_mouse_buf[0] as u16 - 0x20;
let x = self.parser.x10_mouse_buf[1] as u16 - 0x20;

@DHowett DHowett Apr 27, 2026

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i thought xterm mouse reports had a load-bearing offset of 1, and that's what this 0x21 was for?

@lhecker lhecker Apr 27, 2026

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We now subtract 1 in the unified parse_xterm_mouse function!

let y = self.parser.x10_mouse_buf[2] as u16 - 0x20;

self.parser.x10_mouse_want = false;
self.parser.x10_mouse_len = 0;

Some(Input::Mouse(InputMouse {
state: action,
modifiers,
position: Point { x, y },
scroll: Default::default(),
}))
Self::parse_xterm_mouse(&[b, x, y], 'M')
}

fn parse_modifiers(csi: &vt::Csi) -> InputKeyMod {
Expand All @@ -595,4 +540,55 @@ impl<'input> Stream<'_, '_, 'input> {
}
modifiers
}

fn parse_xterm_mouse(params: &[u16], final_byte: char) -> Option<Input<'input>> {
const SHIFT: u16 = 0x04;
const ALT: u16 = 0x08;
const CTRL: u16 = 0x10;
const MOTION: u16 = 0x20;
const WHEEL: u16 = 0x40;
const MODIFIERS: u16 = SHIFT | ALT | CTRL;
Comment on lines +545 to +550

@lhecker lhecker Apr 27, 2026

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The code here is almost identical to before with two changes:

  • Properly mask modifiers, etc., off of btn (now called kind)
  • Handle final_byte just in case


let &[btn, x, y, ..] = params else {
return None;
};

let kind = btn & !MODIFIERS;
let x = x as CoordType - 1;
let y = y as CoordType - 1;
let mut mouse = InputMouse {
state: InputMouseState::None,
modifiers: kbmod::NONE,
position: Point { x, y },
scroll: Default::default(),
drag: false,
};

if final_byte == 'm' {
// M = down, m = release.
// I know there's an InputMouseState::Release, but that's because the internals of tui.rs
// have leaked into intput.rs. input.rs indicates release by the absence of buttons being
// held, which is InputMouseState::None. This makes it more reliable in my opinion.
} else if (WHEEL..WHEEL + 4).contains(&kind) {
let delta = if (kind & 1) != 0 { 3 } else { -3 };
let idx = if (kind & 2) != 0 { 0 } else { 1 };
mouse.scroll.as_array()[idx] += delta;
mouse.state = InputMouseState::Scroll;
} else if (kind & !MOTION) < 3 {
match kind & 3 {
0 => mouse.state = InputMouseState::Left,
1 => mouse.state = InputMouseState::Middle,
2 => mouse.state = InputMouseState::Right,
_ => {}
}
mouse.drag = (kind & MOTION) != 0;
}

mouse.modifiers = kbmod::NONE;
mouse.modifiers |= if (btn & SHIFT) != 0 { kbmod::SHIFT } else { kbmod::NONE };
mouse.modifiers |= if (btn & ALT) != 0 { kbmod::ALT } else { kbmod::NONE };
mouse.modifiers |= if (btn & CTRL) != 0 { kbmod::CTRL } else { kbmod::NONE };

Some(Input::Mouse(mouse))
}
}
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