feat(gui): host + viewer tabs driving the headless child

The GUI now does real work. Host tab: a config form (quality combo,
max-viewers, software-encode + single-window toggles) spawns
`pixelpass --host --output json …` via re-exec, then a background thread
parses the child's JSON events and the window shows live status — ticket
with a copy button, viewer count, streaming/waiting state, host_info
summary, and host-full refusals. Viewer tab: paste a code, pick mpv/VLC,
Connect spawns `pixelpass <ticket> --output json`, and on the connected
event the GUI launches the player (reusing interactive::Player).

ChildProc (gui/child.rs) owns the child: reads stdout events over a
channel, rings the last 60 stderr lines for failure display, and stops via
SIGINT (graceful host teardown) with a 2s grace before SIGKILL — Drop
ensures closing the window never orphans a live host. Five round-trip tests
lock the common::output::Event ↔ ChildEvent wire contract.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
2026-05-24 16:32:26 -04:00
parent 6f0fd088f6
commit 0be92f36a5
2 changed files with 750 additions and 20 deletions
+238
View File
@@ -0,0 +1,238 @@
//! Drives a headless `pixelpass` child process for the GUI.
//!
//! The GUI re-execs this same binary (via [`std::env::current_exe`]) in
//! headless mode with `--output json`, then reads the child's JSON event
//! stream on a background thread and forwards parsed events over a channel the
//! egui app drains each frame. stderr is captured into a small ring so a
//! failed launch (e.g. a missing gst plugin) can be surfaced in the window.
use std::io::{BufRead, BufReader};
use std::process::{Child, Command, Stdio};
use std::sync::mpsc::Receiver;
use std::sync::{Arc, Mutex};
use std::time::Duration;
use eframe::egui;
use nix::sys::signal::{Signal, kill};
use nix::unistd::Pid;
use serde::Deserialize;
/// One parsed event from the child's stdout. Owned mirror of
/// [`crate::common::output::Event`] (which borrows for emit); kept separate so
/// the wire format and the parser can evolve independently.
#[derive(Deserialize, Debug)]
#[serde(tag = "event", rename_all = "snake_case")]
pub enum ChildEvent {
Ticket {
value: String,
},
HostInfo {
display_server: String,
capture: String,
quality: String,
dimensions: String,
hw_encode: bool,
max_viewers: u32,
max_viewers_source: String,
},
ViewerCount {
active: u32,
max: u32,
},
Capture {
state: CaptureState,
},
ViewerRefused {
reason: String,
},
Connected {
url: String,
},
}
#[derive(Deserialize, Debug, Clone, Copy, PartialEq)]
#[serde(rename_all = "snake_case")]
pub enum CaptureState {
Started,
Stopped,
}
const STDERR_TAIL_MAX: usize = 60;
pub struct ChildProc {
child: Child,
pub rx: Receiver<ChildEvent>,
stderr_tail: Arc<Mutex<Vec<String>>>,
}
impl ChildProc {
/// Spawn `pixelpass <args>` as a child, wiring up the event reader. `ctx`
/// is repainted whenever an event arrives so the UI updates live.
pub fn spawn(args: &[String], ctx: egui::Context) -> std::io::Result<Self> {
let exe = std::env::current_exe()?;
let mut child = Command::new(exe)
.args(args)
.stdin(Stdio::null())
.stdout(Stdio::piped())
.stderr(Stdio::piped())
.spawn()?;
let (tx, rx) = std::sync::mpsc::channel();
let stdout = child.stdout.take().expect("stdout piped");
std::thread::spawn(move || {
let reader = BufReader::new(stdout);
for line in reader.lines().map_while(Result::ok) {
if line.trim().is_empty() {
continue;
}
// Ignore any non-event line rather than dropping the stream.
if let Ok(ev) = serde_json::from_str::<ChildEvent>(&line) {
if tx.send(ev).is_err() {
break; // app gone
}
ctx.request_repaint();
}
}
});
let stderr_tail = Arc::new(Mutex::new(Vec::<String>::new()));
let stderr = child.stderr.take().expect("stderr piped");
let tail = stderr_tail.clone();
std::thread::spawn(move || {
let reader = BufReader::new(stderr);
for line in reader.lines().map_while(Result::ok) {
let mut t = tail.lock().unwrap();
t.push(line);
let overflow = t.len().saturating_sub(STDERR_TAIL_MAX);
if overflow > 0 {
t.drain(0..overflow);
}
}
});
Ok(Self {
child,
rx,
stderr_tail,
})
}
/// Whether the child is still running.
pub fn is_alive(&mut self) -> bool {
matches!(self.child.try_wait(), Ok(None))
}
/// The last captured stderr lines, joined — for error display.
pub fn stderr_tail(&self) -> String {
self.stderr_tail.lock().unwrap().join("\n")
}
/// Gracefully stop the child: SIGINT (so the host runs its ctrl-c teardown
/// — tears down capture, closes the endpoint), with a ~2 s grace period
/// before a hard kill. Idempotent.
pub fn stop(&mut self) {
if matches!(self.child.try_wait(), Ok(Some(_))) {
return; // already exited
}
let _ = kill(Pid::from_raw(self.child.id() as i32), Signal::SIGINT);
for _ in 0..40 {
if matches!(self.child.try_wait(), Ok(Some(_))) {
return;
}
std::thread::sleep(Duration::from_millis(50));
}
let _ = self.child.kill();
let _ = self.child.wait();
}
}
impl Drop for ChildProc {
fn drop(&mut self) {
// Closing the window (dropping the app, hence the session) must not
// orphan a live host child streaming to viewers.
self.stop();
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::common::output::{CaptureState as EmitState, Event};
// The GUI parses what the headless child emits. These round-trip the
// emitter's own types (`common::output::Event`) through the parser
// (`ChildEvent`) so a rename on either side of the wire fails here rather
// than silently breaking the GUI at runtime.
fn parse(emit: Event) -> ChildEvent {
let line = serde_json::to_string(&emit).unwrap();
serde_json::from_str::<ChildEvent>(&line).unwrap()
}
#[test]
fn ticket_round_trips() {
assert!(matches!(
parse(Event::Ticket { value: "endpointXYZ" }),
ChildEvent::Ticket { value } if value == "endpointXYZ"
));
}
#[test]
fn host_info_round_trips() {
let ev = parse(Event::HostInfo {
display_server: "Wayland",
capture: "fullscreen + system-audio",
quality: "Medium",
dimensions: "≤720p / 2500 kbps / 30 fps",
hw_encode: true,
max_viewers: 3,
max_viewers_source: "user-specified",
});
match ev {
ChildEvent::HostInfo {
display_server,
quality,
hw_encode,
max_viewers,
..
} => {
assert_eq!(display_server, "Wayland");
assert_eq!(quality, "Medium");
assert!(hw_encode);
assert_eq!(max_viewers, 3);
}
other => panic!("expected HostInfo, got {other:?}"),
}
}
#[test]
fn viewer_count_round_trips() {
assert!(matches!(
parse(Event::ViewerCount { active: 2, max: 4 }),
ChildEvent::ViewerCount { active: 2, max: 4 }
));
}
#[test]
fn capture_state_round_trips() {
assert!(matches!(
parse(Event::Capture { state: EmitState::Started }),
ChildEvent::Capture { state: CaptureState::Started }
));
assert!(matches!(
parse(Event::Capture { state: EmitState::Stopped }),
ChildEvent::Capture { state: CaptureState::Stopped }
));
}
#[test]
fn refused_and_connected_round_trip() {
assert!(matches!(
parse(Event::ViewerRefused { reason: "host is full" }),
ChildEvent::ViewerRefused { reason } if reason == "host is full"
));
assert!(matches!(
parse(Event::Connected { url: "http://127.0.0.1:5000" }),
ChildEvent::Connected { url } if url == "http://127.0.0.1:5000"
));
}
}
+512 -20
View File
@@ -9,15 +9,19 @@
//! shows. That keeps the fragile capture stack sealed in a separate process:
//! the GUI can be closed or crash without taking a live stream down.
mod child;
use eframe::egui;
use self::child::{ChildEvent, ChildProc};
/// Launch the GUI event loop. Blocks until the window is closed. Runs on the
/// main thread (a winit requirement), which is where `main` calls it from.
pub fn run() -> anyhow::Result<()> {
let options = eframe::NativeOptions {
viewport: egui::ViewportBuilder::default()
.with_inner_size([520.0, 420.0])
.with_min_inner_size([420.0, 320.0])
.with_inner_size([520.0, 480.0])
.with_min_inner_size([460.0, 380.0])
.with_title("PixelPass"),
..Default::default()
};
@@ -39,15 +43,138 @@ enum Screen {
Viewer,
}
/// Quality preset choices, mirroring `cli::Quality`. Map to the `--quality`
/// argument value passed to the child.
#[derive(Default, PartialEq, Clone, Copy)]
enum QualitySel {
#[default]
Auto,
Source,
High,
Medium,
Low,
}
impl QualitySel {
fn as_arg(self) -> &'static str {
match self {
QualitySel::Auto => "auto",
QualitySel::Source => "source",
QualitySel::High => "high",
QualitySel::Medium => "medium",
QualitySel::Low => "low",
}
}
fn label(self) -> &'static str {
match self {
QualitySel::Auto => "Auto — pick from my upload speed",
QualitySel::Source => "Source — native resolution",
QualitySel::High => "High — up to 1080p",
QualitySel::Medium => "Medium — up to 720p",
QualitySel::Low => "Low — up to 480p",
}
}
const ALL: [QualitySel; 5] = [
QualitySel::Auto,
QualitySel::Source,
QualitySel::High,
QualitySel::Medium,
QualitySel::Low,
];
}
/// Player choices for the viewer screen.
#[derive(Default, PartialEq, Clone, Copy)]
enum PlayerSel {
#[default]
Mpv,
Vlc,
}
impl PlayerSel {
fn to_player(self) -> crate::interactive::Player {
match self {
PlayerSel::Mpv => crate::interactive::Player::Mpv,
PlayerSel::Vlc => crate::interactive::Player::Vlc,
}
}
}
/// Host-screen state: the config form fields plus, once started, the running
/// child and the latest values parsed from its event stream.
struct HostState {
// form
quality: QualitySel,
max_viewers: u32, // 0 = let the host auto-size from the bandwidth preflight
no_hwencode: bool,
window: bool,
// running session + accumulated live state
proc: Option<ChildProc>,
ticket: Option<String>,
info: Option<HostInfo>,
active: u32,
max: u32,
capturing: bool,
last_refusal: Option<String>,
error: Option<String>,
}
impl Default for HostState {
fn default() -> Self {
Self {
quality: QualitySel::default(),
max_viewers: 0,
no_hwencode: false,
window: false,
proc: None,
ticket: None,
info: None,
active: 0,
max: 0,
capturing: false,
last_refusal: None,
error: None,
}
}
}
/// The host config summary echoed back by the child's `host_info` event.
struct HostInfo {
display: String,
capture: String,
quality: String,
dimensions: String,
hw_encode: bool,
cap_source: String,
}
/// Viewer-screen state.
#[derive(Default)]
struct ViewerState {
ticket_input: String,
player: PlayerSel,
proc: Option<ChildProc>,
url: Option<String>,
launched: bool,
error: Option<String>,
}
#[derive(Default)]
struct PixelPassApp {
screen: Screen,
host: HostState,
viewer: ViewerState,
}
impl eframe::App for PixelPassApp {
// eframe 0.34 hands us the central-panel `ui` directly (it wraps this in a
// CentralPanel for us).
// eframe 0.34 hands us the central-panel `ui` directly.
fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
// Drain any pending child events before drawing this frame.
self.pump_host_events();
self.pump_viewer_events();
match self.screen {
Screen::Menu => self.menu(ui),
Screen::Host => self.host(ui),
@@ -64,7 +191,7 @@ impl PixelPassApp {
ui.label("P2P screen sharing");
ui.add_space(32.0);
if ui
.add_sized([240.0, 40.0], egui::Button::new("Host — share my screen"))
.add_sized([260.0, 40.0], egui::Button::new("Host — share my screen"))
.clicked()
{
self.screen = Screen::Host;
@@ -72,7 +199,7 @@ impl PixelPassApp {
ui.add_space(8.0);
if ui
.add_sized(
[240.0, 40.0],
[260.0, 40.0],
egui::Button::new("View — watch someone's screen"),
)
.clicked()
@@ -82,25 +209,390 @@ impl PixelPassApp {
});
}
// ── Host screen ──────────────────────────────────────────────────────
fn host(&mut self, ui: &mut egui::Ui) {
self.back_bar(ui, "Host");
ui.separator();
ui.label("Host controls land in the next step.");
}
fn viewer(&mut self, ui: &mut egui::Ui) {
self.back_bar(ui, "View");
ui.separator();
ui.label("Viewer controls land in a later step.");
}
/// Title row with a back-to-menu button, shared by the host/viewer screens.
fn back_bar(&mut self, ui: &mut egui::Ui, title: &str) {
let running = self.host.proc.is_some();
ui.horizontal(|ui| {
// Leaving the host screen stops the session (Drop on the child).
if ui.button("← Menu").clicked() {
self.stop_host();
self.screen = Screen::Menu;
}
ui.heading(title);
ui.heading("Host");
});
ui.separator();
if running {
self.host_running(ui);
} else {
self.host_form(ui);
}
}
fn host_form(&mut self, ui: &mut egui::Ui) {
if let Some(err) = &self.host.error {
ui.colored_label(egui::Color32::LIGHT_RED, err);
ui.add_space(8.0);
}
egui::Grid::new("host_form")
.num_columns(2)
.spacing([12.0, 10.0])
.show(ui, |ui| {
ui.label("Quality");
egui::ComboBox::from_id_salt("quality")
.selected_text(self.host.quality.label())
.show_ui(ui, |ui| {
for q in QualitySel::ALL {
ui.selectable_value(&mut self.host.quality, q, q.label());
}
});
ui.end_row();
ui.label("Max viewers");
ui.horizontal(|ui| {
ui.add(egui::DragValue::new(&mut self.host.max_viewers).range(0..=16));
if self.host.max_viewers == 0 {
ui.label("(auto from upload speed)");
}
});
ui.end_row();
ui.label("Options");
ui.vertical(|ui| {
ui.checkbox(&mut self.host.window, "Share a single window");
ui.checkbox(
&mut self.host.no_hwencode,
"Software encoding (no GPU / VAAPI)",
);
});
ui.end_row();
});
ui.add_space(16.0);
if ui
.add_sized([160.0, 36.0], egui::Button::new("Start hosting"))
.clicked()
{
self.start_host(ui.ctx().clone());
}
ui.add_space(8.0);
ui.label(
egui::RichText::new(
"On Wayland a \"Share Screen?\" dialog appears when the first \
viewer connects.",
)
.small()
.weak(),
);
}
fn host_running(&mut self, ui: &mut egui::Ui) {
if self.host.capturing {
ui.colored_label(egui::Color32::LIGHT_GREEN, "● Streaming");
} else if self.host.ticket.is_some() {
ui.colored_label(egui::Color32::YELLOW, "● Waiting for viewers…");
} else {
ui.label("Starting…");
}
ui.add_space(6.0);
ui.label(format!("Viewers: {} / {}", self.host.active, self.host.max));
if let Some(info) = &self.host.info {
ui.label(
egui::RichText::new(format!("{} · {}", info.display, info.capture))
.small()
.weak(),
);
ui.label(
egui::RichText::new(format!(
"{} · {} · {} · cap {}",
info.quality,
info.dimensions,
if info.hw_encode {
"HW encode"
} else {
"software encode"
},
info.cap_source
))
.small()
.weak(),
);
}
ui.add_space(12.0);
if let Some(ticket) = self.host.ticket.clone() {
ui.label("Share this code with your viewer(s):");
ui.add_space(4.0);
egui::Frame::group(ui.style()).show(ui, |ui| {
ui.add(egui::Label::new(egui::RichText::new(&ticket).monospace().small()).wrap());
});
ui.add_space(4.0);
if ui.button("📋 Copy code").clicked() {
self.copy_to_clipboard(&ticket);
}
}
if let Some(reason) = &self.host.last_refusal {
ui.add_space(8.0);
ui.colored_label(
egui::Color32::from_rgb(220, 160, 60),
format!("{reason}"),
);
}
ui.add_space(16.0);
if ui
.add_sized([140.0, 36.0], egui::Button::new("Stop hosting"))
.clicked()
{
self.stop_host();
}
}
fn start_host(&mut self, ctx: egui::Context) {
self.host.error = None;
self.host.last_refusal = None;
self.host.ticket = None;
self.host.info = None;
self.host.active = 0;
self.host.max = 0;
self.host.capturing = false;
let mut args = vec![
"--host".to_string(),
"--output".to_string(),
"json".to_string(),
"--quality".to_string(),
self.host.quality.as_arg().to_string(),
];
if self.host.max_viewers > 0 {
args.push("--max-viewers".to_string());
args.push(self.host.max_viewers.to_string());
}
if self.host.no_hwencode {
args.push("--no-hwencode".to_string());
}
if self.host.window {
args.push("--window".to_string());
}
match ChildProc::spawn(&args, ctx) {
Ok(p) => self.host.proc = Some(p),
Err(e) => self.host.error = Some(format!("Couldn't start host: {e}")),
}
}
fn stop_host(&mut self) {
// Dropping the ChildProc SIGINTs the child and reaps it.
self.host.proc = None;
self.host.capturing = false;
self.host.ticket = None;
}
/// Drain the host child's event channel into state, and detect an
/// unexpected child exit (e.g. a failed dependency check) so it surfaces
/// in the form instead of leaving a dead "running" view.
fn pump_host_events(&mut self) {
let events: Vec<ChildEvent> = match &self.host.proc {
Some(p) => std::iter::from_fn(|| p.rx.try_recv().ok()).collect(),
None => return,
};
for ev in events {
self.apply_host_event(ev);
}
if let Some(p) = &mut self.host.proc
&& !p.is_alive()
{
if self.host.ticket.is_none() {
let tail = p.stderr_tail();
self.host.error = Some(if tail.trim().is_empty() {
"Host exited before it could start.".to_string()
} else {
format!("Host exited before it could start:\n{tail}")
});
}
self.host.proc = None;
self.host.capturing = false;
}
}
fn apply_host_event(&mut self, ev: ChildEvent) {
match ev {
ChildEvent::Ticket { value } => self.host.ticket = Some(value),
ChildEvent::HostInfo {
display_server,
capture,
quality,
dimensions,
hw_encode,
max_viewers,
max_viewers_source,
} => {
self.host.max = max_viewers;
self.host.info = Some(HostInfo {
display: display_server,
capture,
quality,
dimensions,
hw_encode,
cap_source: max_viewers_source,
});
}
ChildEvent::ViewerCount { active, max } => {
self.host.active = active;
self.host.max = max;
}
ChildEvent::Capture { state } => {
self.host.capturing = matches!(state, child::CaptureState::Started);
}
ChildEvent::ViewerRefused { reason } => self.host.last_refusal = Some(reason),
ChildEvent::Connected { .. } => {} // viewer-side; not used on the host screen
}
}
fn copy_to_clipboard(&mut self, text: &str) {
if let Err(e) = arboard::Clipboard::new().and_then(|mut cb| cb.set_text(text.to_owned())) {
self.host.error = Some(format!("Clipboard copy failed: {e}"));
}
}
// ── Viewer screen ─────────────────────────────────────────────────────
fn viewer(&mut self, ui: &mut egui::Ui) {
let running = self.viewer.proc.is_some();
ui.horizontal(|ui| {
if ui.button("← Menu").clicked() {
self.stop_viewer();
self.screen = Screen::Menu;
}
ui.heading("View");
});
ui.separator();
if running {
self.viewer_running(ui);
} else {
self.viewer_form(ui);
}
}
fn viewer_form(&mut self, ui: &mut egui::Ui) {
if let Some(err) = &self.viewer.error {
ui.colored_label(egui::Color32::LIGHT_RED, err);
ui.add_space(8.0);
}
ui.label("Paste the share code you received:");
ui.add_space(4.0);
ui.add(
egui::TextEdit::singleline(&mut self.viewer.ticket_input)
.desired_width(f32::INFINITY)
.hint_text("endpoint…"),
);
ui.add_space(10.0);
ui.horizontal(|ui| {
ui.label("Player");
egui::ComboBox::from_id_salt("player")
.selected_text(match self.viewer.player {
PlayerSel::Mpv => "mpv",
PlayerSel::Vlc => "VLC",
})
.show_ui(ui, |ui| {
ui.selectable_value(&mut self.viewer.player, PlayerSel::Mpv, "mpv");
ui.selectable_value(&mut self.viewer.player, PlayerSel::Vlc, "VLC");
});
});
ui.add_space(16.0);
let can_connect = !self.viewer.ticket_input.trim().is_empty();
if ui
.add_enabled(
can_connect,
egui::Button::new("Connect").min_size(egui::vec2(140.0, 36.0)),
)
.clicked()
{
self.start_viewer(ui.ctx().clone());
}
}
fn viewer_running(&mut self, ui: &mut egui::Ui) {
if self.viewer.launched {
ui.colored_label(egui::Color32::LIGHT_GREEN, "● Streaming");
ui.label("Player launched. Close it or disconnect to stop.");
} else if self.viewer.url.is_some() {
ui.label("Connected — launching player…");
} else {
ui.colored_label(egui::Color32::YELLOW, "● Connecting…");
}
ui.add_space(16.0);
if ui
.add_sized([140.0, 36.0], egui::Button::new("Disconnect"))
.clicked()
{
self.stop_viewer();
}
}
fn start_viewer(&mut self, ctx: egui::Context) {
self.viewer.error = None;
self.viewer.url = None;
self.viewer.launched = false;
let ticket = self.viewer.ticket_input.trim().to_string();
let args = vec![ticket, "--output".to_string(), "json".to_string()];
match ChildProc::spawn(&args, ctx) {
Ok(p) => self.viewer.proc = Some(p),
Err(e) => self.viewer.error = Some(format!("Couldn't connect: {e}")),
}
}
fn stop_viewer(&mut self) {
self.viewer.proc = None;
self.viewer.url = None;
self.viewer.launched = false;
}
fn pump_viewer_events(&mut self) {
let events: Vec<ChildEvent> = match &self.viewer.proc {
Some(p) => std::iter::from_fn(|| p.rx.try_recv().ok()).collect(),
None => return,
};
for ev in events {
if let ChildEvent::Connected { url } = ev {
self.viewer.url = Some(url.clone());
if !self.viewer.launched {
match self.viewer.player.to_player().spawn(&url) {
Ok(()) => self.viewer.launched = true,
Err(e) => self.viewer.error = Some(format!("Couldn't launch player: {e}")),
}
}
}
}
if let Some(p) = &mut self.viewer.proc
&& !p.is_alive()
{
// Bridge ended (player closed) or the connection failed.
if self.viewer.url.is_none() {
let tail = p.stderr_tail();
self.viewer.error = Some(if tail.trim().is_empty() {
"Couldn't connect to the host (check the code).".to_string()
} else {
format!("Connection ended:\n{tail}")
});
}
self.viewer.proc = None;
self.viewer.launched = false;
self.viewer.url = None;
}
}
}