Present Servo BGRA hardware surfaces

crates/ely_app/src/services/servo_sidecar_command.rs

@@ -7,6 +7,9 @@ use std::{
 use thiserror::Error;
 
 const SIDECAR_PATH_ENV: &str = "ELY_SERVO_SIDECAR";
+const RENDERING_CONTEXT_ENV: &str = "ELY_SERVO_RENDERING_CONTEXT";
+const SOFTWARE_SIDECAR_FEATURES: &str = "servo-engine";
+const HARDWARE_SIDECAR_FEATURES: &str = "servo-engine,hardware-render";
 
 #[derive(Clone, Debug)]
 pub(super) enum SidecarCommandTarget {
@@ -28,7 +31,7 @@ impl SidecarCommandTarget {
                     .arg("-p")
                     .arg("ely_servo_host")
                     .arg("--features")
-                    .arg("servo-engine")
+                    .arg(sidecar_features_from_env())
                     .arg("--bin")
                     .arg("ely_servo_sidecar")
                     .arg("--");
@@ -64,13 +67,17 @@ pub(super) fn default_sidecar_command() -> Result<SidecarCommandTarget, SidecarC
         SidecarCommandError::CurrentExecutableDirectoryUnavailable { path: current_exe.clone() }
     })?;
     let adjacent_sidecar = exe_dir.join(sidecar_binary_name());
-    if adjacent_sidecar.is_file() {
+    let workspace_manifest = workspace_manifest_path();
+    let prefer_cargo_hardware_sidecar = hardware_rendering_context_requested()
+        && workspace_manifest.as_ref().is_some_and(|path| path.is_file());
+    if adjacent_sidecar.is_file() && !prefer_cargo_hardware_sidecar {
         return Ok(SidecarCommandTarget::Binary(adjacent_sidecar));
     }
 
-    if let Some(manifest_path) = workspace_manifest_path() {
+    if let Some(manifest_path) = workspace_manifest {
         if let Some(target_sidecar) = workspace_target_sidecar_path(&manifest_path)
             && target_sidecar.is_file()
+            && !prefer_cargo_hardware_sidecar
         {
             return Ok(SidecarCommandTarget::Binary(target_sidecar));
         }
@@ -86,6 +93,30 @@ fn workspace_manifest_path() -> Option<PathBuf> {
     option_env!("ELY_WORKSPACE_MANIFEST").map(PathBuf::from)
 }
 
+fn hardware_rendering_context_requested() -> bool {
+    env::var(RENDERING_CONTEXT_ENV).ok().as_deref().is_some_and(rendering_context_requests_hardware)
+}
+
+fn sidecar_features_from_env() -> &'static str {
+    env::var(RENDERING_CONTEXT_ENV)
+        .ok()
+        .as_deref()
+        .map(sidecar_features_for_rendering_context)
+        .unwrap_or(SOFTWARE_SIDECAR_FEATURES)
+}
+
+fn sidecar_features_for_rendering_context(raw: &str) -> &'static str {
+    if rendering_context_requests_hardware(raw) {
+        HARDWARE_SIDECAR_FEATURES
+    } else {
+        SOFTWARE_SIDECAR_FEATURES
+    }
+}
+
+fn rendering_context_requests_hardware(raw: &str) -> bool {
+    raw.eq_ignore_ascii_case("hardware")
+}
+
 fn workspace_target_sidecar_path(manifest_path: &Path) -> Option<PathBuf> {
     let profile = if cfg!(debug_assertions) { "debug" } else { "release" };
     Some(manifest_path.parent()?.join("target").join(profile).join(sidecar_binary_name()))
@@ -94,3 +125,23 @@ fn workspace_target_sidecar_path(manifest_path: &Path) -> Option<PathBuf> {
 fn sidecar_binary_name() -> String {
     format!("ely_servo_sidecar{}", env::consts::EXE_SUFFIX)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        HARDWARE_SIDECAR_FEATURES, SOFTWARE_SIDECAR_FEATURES,
+        sidecar_features_for_rendering_context,
+    };
+
+    #[test]
+    fn hardware_rendering_context_enables_hardware_sidecar_feature() {
+        assert_eq!(sidecar_features_for_rendering_context("hardware"), HARDWARE_SIDECAR_FEATURES);
+        assert_eq!(sidecar_features_for_rendering_context("HARDWARE"), HARDWARE_SIDECAR_FEATURES);
+    }
+
+    #[test]
+    fn software_and_unknown_contexts_use_software_sidecar_feature() {
+        assert_eq!(sidecar_features_for_rendering_context("software"), SOFTWARE_SIDECAR_FEATURES);
+        assert_eq!(sidecar_features_for_rendering_context("garbage"), SOFTWARE_SIDECAR_FEATURES);
+    }
+}