feat(desktop): add --list-gpu-adapters CLI flag

desktop/src/cli.rs

@@ -6,4 +6,7 @@ pub struct Cli {
 
 	#[arg(long, action = clap::ArgAction::SetTrue, help = "Disable hardware accelerated UI rendering")]
 	pub disable_ui_acceleration: bool,
+
+	#[arg(long, action = clap::ArgAction::SetTrue, help = "List available GPU adapters and exit")]
+	pub list_gpu_adapters: bool,
 }

desktop/src/gpu_context.rs

@@ -1,23 +1,39 @@
 use crate::wrapper::{WgpuContext, WgpuContextBuilder, WgpuFeatures};
 
+const ADAPTER_ENV_VAR: &str = "GRAPHITE_WGPU_ADAPTER";
+
+fn create_context_builder() -> WgpuContextBuilder {
+	WgpuContextBuilder::new().with_features(WgpuFeatures::PUSH_CONSTANTS)
+}
+
+/// Lists all available WGPU adapters to stdout.
+///
+/// This is intended for use with the `--list-gpu-adapters` CLI flag,
+/// allowing users to identify available GPU adapters before selecting one
+/// via the `GRAPHITE_WGPU_ADAPTER` environment variable.
+pub(super) async fn list_adapters() {
+	let builder = create_context_builder();
+	println!("\nAvailable WGPU adapters:\n{}", builder.available_adapters_fmt().await);
+	println!("\nTo select a specific adapter, set the {} environment variable to the adapter index.", ADAPTER_ENV_VAR);
+}
+
+/// Creates and initializes the WGPU context for GPU rendering.
+///
+/// Adapter selection can be overridden by setting the `GRAPHITE_WGPU_ADAPTER`
+/// environment variable to the desired adapter index.
 pub(super) async fn create_wgpu_context() -> WgpuContext {
-	let wgpu_context_builder = WgpuContextBuilder::new().with_features(WgpuFeatures::PUSH_CONSTANTS);
+	let builder = create_context_builder();
 
-	// TODO: add a cli flag to list adapters and exit instead of always printing
-	println!("\nAvailable WGPU adapters:\n{}", wgpu_context_builder.available_adapters_fmt().await);
+	let adapter_override = std::env::var(ADAPTER_ENV_VAR).ok().and_then(|s| s.parse().ok());
 
-	// TODO: make this configurable via cli flags instead
-	let wgpu_context = match std::env::var("GRAPHITE_WGPU_ADAPTER").ok().and_then(|s| s.parse().ok()) {
-		None => wgpu_context_builder.build().await,
+	let wgpu_context = match adapter_override {
+		None => builder.build().await,
 		Some(adapter_index) => {
 			tracing::info!("Overriding WGPU adapter selection with adapter index {adapter_index}");
-			wgpu_context_builder.build_with_adapter_selection(|_| Some(adapter_index)).await
+			builder.build_with_adapter_selection(|_| Some(adapter_index)).await
 		}
 	}
 	.expect("Failed to create WGPU context");
 
-	// TODO: add a cli flag to list adapters and exit instead of always printing
-	println!("Using WGPU adapter: {:?}", wgpu_context.adapter.get_info());
-
 	wgpu_context
 }

desktop/src/lib.rs

@@ -58,8 +58,12 @@ pub fn start() {
 
 	let cli = Cli::parse();
 
-	let wgpu_context = futures::executor::block_on(gpu_context::create_wgpu_context());
+	if cli.list_gpu_adapters {
+		futures::executor::block_on(gpu_context::list_adapters());
+		return;
+	}
 
+	let wgpu_context = futures::executor::block_on(gpu_context::create_wgpu_context());
 	let event_loop = EventLoop::new().unwrap();
 	let (app_event_sender, app_event_receiver) = std::sync::mpsc::channel();
 	let app_event_scheduler = event_loop.create_app_event_scheduler(app_event_sender);