latchshot 0.2.0

A lightweight yet intelligent window-aware screenshot tool
Documentation 
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// FIXME: Keep the local wire types aligned with the custom Niri IPC fork.
use std::collections::HashMap;

use anyhow::{Context, Result};
use log::warn;

use self::ipc::{Request, Response, Socket, Transform};
use super::SceneReader;
use super::generic::Generic;
use crate::{Output, OutputId, OutputTransform, Rect, Scene, Size, Window};

mod ipc;

/// [niri](https://github.com/niri-wm/niri) window discovery
pub(super) struct Niri {
    socket: Socket,
}

impl Niri {
    pub(super) fn connect() -> Result<Self> {
        let socket = Socket::connect().context("failed to connect to the Niri IPC socket")?;

        Ok(Self { socket })
    }

    fn request_raw(&mut self, request: Request) -> Result<Result<Response, String>> {
        self.socket
            .send(request)
            .context("failed to communicate with Niri")
    }

    fn request(&mut self, request: Request) -> Result<Response> {
        self.request_raw(request)?.map_err(anyhow::Error::msg)
    }
}

impl SceneReader for Niri {
    fn scene(&mut self) -> Result<Scene> {
        let geometries = match self.request_raw(Request::WindowGeometries)? {
            Ok(Response::WindowGeometries(geometries)) => geometries,
            Ok(_) => panic!("Niri returned an unexpected response to WindowGeometries"),
            Err(error)
                if error.contains("error parsing request")
                    && error.contains("unknown variant `WindowGeometries`") =>
            {
                warn!("Niri does not support WindowGeometries; using generic Wayland discovery");

                // FIXME: Remove this compatibility fallback as soon as upstream Niri supports
                // the WindowGeometries IPC request.
                return Generic::connect()?.scene();
            }
            Err(error) => return Err(anyhow::Error::msg(error)),
        };
        let Response::Outputs(outputs) = self.request(Request::Outputs)? else {
            panic!("Niri returned an unexpected response to Outputs");
        };
        let Response::Windows(windows) = self.request(Request::Windows)? else {
            panic!("Niri returned an unexpected response to Windows");
        };

        let mut outputs: Vec<Output> = outputs
            .into_values()
            .filter_map(|output| output.logical.map(|logical| (output, logical)))
            .map(|(output, logical)| {
                // Current-mode metadata is required by the Niri IPC.
                let mode = &output.modes[output.current_mode.unwrap()];
                let (transform, swaps_axes) = match logical.transform {
                    Transform::Normal => (OutputTransform::Normal, false),
                    Transform::_90 => (OutputTransform::Rotate90, true),
                    Transform::_180 => (OutputTransform::Rotate180, false),
                    Transform::_270 => (OutputTransform::Rotate270, true),
                    Transform::Flipped => (OutputTransform::Flipped, false),
                    Transform::Flipped90 => (OutputTransform::Flipped90, true),
                    Transform::Flipped180 => (OutputTransform::Flipped180, false),
                    Transform::Flipped270 => (OutputTransform::Flipped270, true),
                };
                let pixel_size = if swaps_axes {
                    Size::new(mode.height as f64, mode.width as f64)
                } else {
                    Size::new(mode.width as f64, mode.height as f64)
                };

                Output {
                    id: OutputId::new(output.name),
                    logical_geometry: Rect::new(
                        f64::from(logical.x),
                        f64::from(logical.y),
                        pixel_size.width / logical.scale,
                        pixel_size.height / logical.scale,
                    ),
                    pixel_size,
                    scale: logical.scale,
                    transform,
                }
            })
            .collect();
        // Stabilize scene output
        outputs.sort_by(|a, b| a.id.as_str().cmp(b.id.as_str()));

        let output_by_name = outputs
            .iter()
            .map(|output| (output.id.as_str(), output))
            .collect::<HashMap<_, _>>();
        let geometries = geometries
            .into_iter()
            .map(|geometry| (geometry.id, geometry))
            .collect::<HashMap<_, _>>();

        // Preserve stacking order; skip entries lost between IPC snapshots.
        let windows = windows
            .into_iter()
            .filter_map(|window| {
                let geometry = geometries.get(&window.id)?;
                let output = output_by_name.get(geometry.output.as_str())?;

                let geometry = Rect::new(
                    output.logical_geometry.left() + geometry.x,
                    output.logical_geometry.top() + geometry.y,
                    geometry.width,
                    geometry.height,
                );
                let geometry = geometry.intersection(output.logical_geometry)?;

                Some(Window { geometry })
            })
            .collect();

        Ok(Scene { outputs, windows })
    }
}