Add Servo sidecar snapshot command

2026-05-08 12:17:41 -04:00
parent 5f0773a043
commit fcdc2de076
6 changed files with 318 additions and 1 deletions
@@ -0,0 +1,247 @@
+use std::{env, num::ParseIntError, path::PathBuf, thread, time::Duration};
+
+use ely_domain::{ProfileId, TabId, UrlText};
+use ely_servo_host::{
+    NavigationRequest, RenderedFrame, ServoHost, ServoHostError, ServoSurfaceSize,
+    SoftwareServoHost, WebViewSnapshot, WebViewState,
+};
+use serde::Serialize;
+use thiserror::Error;
+
+const WAIT_ITERATIONS: usize = 5_000;
+const WAIT_INTERVAL: Duration = Duration::from_millis(2);
+
+fn main() -> Result<(), SidecarError> {
+    match parse_command(env::args())? {
+        SidecarCommand::Snapshot(args) => run_snapshot(args),
+    }
+}
+
+enum SidecarCommand {
+    Snapshot(SnapshotArgs),
+}
+
+struct SnapshotArgs {
+    url: UrlText,
+    rgba_out: PathBuf,
+    width: u32,
+    height: u32,
+}
+
+#[derive(Debug, Error)]
+enum SidecarError {
+    #[error("missing sidecar command")]
+    MissingCommand,
+
+    #[error("unknown sidecar command: {value}")]
+    UnknownCommand { value: String },
+
+    #[error("missing argument value for {name}")]
+    MissingArgumentValue { name: &'static str },
+
+    #[error("missing required argument: {name}")]
+    MissingRequiredArgument { name: &'static str },
+
+    #[error("unknown argument: {value}")]
+    UnknownArgument { value: String },
+
+    #[error("{name} must be a positive integer: {value}")]
+    InvalidInteger {
+        name: &'static str,
+        value: String,
+        #[source]
+        source: ParseIntError,
+    },
+
+    #[error("{name} must be greater than zero")]
+    ZeroDimension { name: &'static str },
+
+    #[error("rgba output path is empty")]
+    EmptyRgbaOutputPath,
+
+    #[error("timed out rendering {url}: {snapshot:?}")]
+    RenderTimeout { url: String, snapshot: Box<WebViewSnapshot> },
+
+    #[error(transparent)]
+    Domain(#[from] ely_domain::DomainError),
+
+    #[error(transparent)]
+    Host(#[from] ServoHostError),
+
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+
+    #[error(transparent)]
+    Json(#[from] serde_json::Error),
+}
+
+fn parse_command(args: impl IntoIterator<Item = String>) -> Result<SidecarCommand, SidecarError> {
+    let mut args = args.into_iter();
+    let _program_name = args.next();
+    let command = args.next().ok_or(SidecarError::MissingCommand)?;
+
+    match command.as_str() {
+        "snapshot" => parse_snapshot_args(args).map(SidecarCommand::Snapshot),
+        _ => Err(SidecarError::UnknownCommand { value: command }),
+    }
+}
+
+fn parse_snapshot_args(
+    args: impl IntoIterator<Item = String>,
+) -> Result<SnapshotArgs, SidecarError> {
+    let mut args = args.into_iter();
+    let mut url = None;
+    let mut rgba_out = None;
+    let mut width = None;
+    let mut height = None;
+
+    while let Some(name) = args.next() {
+        match name.as_str() {
+            "--url" => url = Some(UrlText::parse(next_argument(&mut args, "--url")?)?),
+            "--rgba-out" => {
+                rgba_out = Some(parse_output_path(next_argument(&mut args, "--rgba-out")?)?)
+            }
+            "--width" => {
+                width = Some(parse_dimension("--width", next_argument(&mut args, "--width")?)?)
+            }
+            "--height" => {
+                height = Some(parse_dimension("--height", next_argument(&mut args, "--height")?)?)
+            }
+            _ => return Err(SidecarError::UnknownArgument { value: name }),
+        }
+    }
+
+    Ok(SnapshotArgs {
+        url: url.ok_or(SidecarError::MissingRequiredArgument { name: "--url" })?,
+        rgba_out: rgba_out.ok_or(SidecarError::MissingRequiredArgument { name: "--rgba-out" })?,
+        width: width.ok_or(SidecarError::MissingRequiredArgument { name: "--width" })?,
+        height: height.ok_or(SidecarError::MissingRequiredArgument { name: "--height" })?,
+    })
+}
+
+fn next_argument(
+    args: &mut impl Iterator<Item = String>,
+    name: &'static str,
+) -> Result<String, SidecarError> {
+    args.next().ok_or(SidecarError::MissingArgumentValue { name })
+}
+
+fn parse_dimension(name: &'static str, value: String) -> Result<u32, SidecarError> {
+    let dimension = value.parse::<u32>().map_err(|source| SidecarError::InvalidInteger {
+        name,
+        value,
+        source,
+    })?;
+    if dimension == 0 {
+        return Err(SidecarError::ZeroDimension { name });
+    }
+
+    Ok(dimension)
+}
+
+fn parse_output_path(value: String) -> Result<PathBuf, SidecarError> {
+    if value.trim().is_empty() {
+        return Err(SidecarError::EmptyRgbaOutputPath);
+    }
+
+    Ok(PathBuf::from(value))
+}
+
+fn run_snapshot(args: SnapshotArgs) -> Result<(), SidecarError> {
+    let mut host = SoftwareServoHost::new(ServoSurfaceSize::new(args.width, args.height))?;
+    let tab_id = TabId::new();
+    let profile_id = ProfileId::new();
+    let webview_id = host.create_webview(tab_id.clone(), profile_id)?;
+
+    host.navigate(NavigationRequest {
+        webview_id: webview_id.clone(),
+        tab_id,
+        url: args.url.clone(),
+    })?;
+
+    let snapshot = wait_for_frame(&mut host, &webview_id, args.url.as_str())?;
+    let frame = host.last_rendered_frame()?;
+    std::fs::write(&args.rgba_out, frame.rgba_bytes())?;
+
+    serde_json::to_writer(
+        std::io::stdout().lock(),
+        &SnapshotReport::new(args.url.as_str(), &args.rgba_out, &snapshot, &frame),
+    )?;
+    Ok(())
+}
+
+fn wait_for_frame(
+    host: &mut SoftwareServoHost,
+    webview_id: &ely_domain::WebViewId,
+    url: &str,
+) -> Result<WebViewSnapshot, SidecarError> {
+    for _ in 0..WAIT_ITERATIONS {
+        host.tick();
+        let snapshot = host.snapshot(webview_id)?;
+        if snapshot.has_pending_frame() {
+            host.paint(webview_id)?;
+        }
+
+        let snapshot = host.snapshot(webview_id)?;
+        let has_rendered_frame =
+            host.last_rendered_frame().is_ok_and(|frame| frame.non_white_pixel_count() > 0);
+        if snapshot.state() == &WebViewState::Complete && has_rendered_frame {
+            return Ok(snapshot);
+        }
+
+        thread::sleep(WAIT_INTERVAL);
+    }
+
+    Err(SidecarError::RenderTimeout {
+        url: url.to_string(),
+        snapshot: Box::new(host.snapshot(webview_id)?),
+    })
+}
+
+#[derive(Serialize)]
+struct SnapshotReport {
+    requested_url: String,
+    loaded_url: Option<String>,
+    title: Option<String>,
+    rgba_path: String,
+    state: &'static str,
+    width: u32,
+    height: u32,
+    rgba_byte_count: usize,
+    opaque_pixel_count: u64,
+    non_white_pixel_count: u64,
+    sample_hash: u64,
+}
+
+impl SnapshotReport {
+    fn new(
+        requested_url: &str,
+        rgba_path: &std::path::Path,
+        snapshot: &WebViewSnapshot,
+        frame: &RenderedFrame,
+    ) -> Self {
+        Self {
+            requested_url: requested_url.to_string(),
+            loaded_url: snapshot.url().map(str::to_string),
+            title: snapshot.title().map(str::to_string),
+            rgba_path: rgba_path.display().to_string(),
+            state: state_label(snapshot.state()),
+            width: frame.width(),
+            height: frame.height(),
+            rgba_byte_count: frame.rgba_bytes().len(),
+            opaque_pixel_count: frame.opaque_pixel_count(),
+            non_white_pixel_count: frame.non_white_pixel_count(),
+            sample_hash: frame.sample_hash(),
+        }
+    }
+}
+
+fn state_label(state: &WebViewState) -> &'static str {
+    match state {
+        WebViewState::Created => "created",
+        WebViewState::Loading => "loading",
+        WebViewState::Complete => "complete",
+        WebViewState::Sleeping => "sleeping",
+        WebViewState::Crashed => "crashed",
+    }
+}