Add a simple wgpu benchmark using criterion

Cargo.toml

@@ -164,3 +164,12 @@ wgpu = "0.19"
 winapi = "0.3"
 window_clipboard = "0.4.1"
 winit = { git = "https://github.com/iced-rs/winit.git", rev = "592bd152f6d5786fae7d918532d7db752c0d164f" }
+
+[dev-dependencies]
+criterion = "0.5"
+iced_wgpu.workspace = true
+
+[[bench]]
+name = "wgpu"
+harness = false
+required-features = ["canvas"]

benches/wgpu.rs

@@ -0,0 +1,182 @@
+use criterion::{criterion_group, criterion_main, Bencher, Criterion};
+
+use iced::alignment;
+use iced::mouse;
+use iced::widget::{canvas, text};
+use iced::{
+    Color, Element, Font, Length, Pixels, Point, Rectangle, Size, Theme,
+};
+use iced_wgpu::Renderer;
+
+criterion_main!(benches);
+criterion_group!(benches, wgpu_benchmark);
+
+pub fn wgpu_benchmark(c: &mut Criterion) {
+    c.bench_function("wgpu — canvas (light)", |b| benchmark(b, scene(10)));
+    c.bench_function("wgpu — canvas (heavy)", |b| benchmark(b, scene(1_000)));
+}
+
+fn benchmark<'a>(
+    bencher: &mut Bencher<'_>,
+    widget: Element<'a, (), Theme, Renderer>,
+) {
+    use iced_futures::futures::executor;
+    use iced_wgpu::graphics;
+    use iced_wgpu::graphics::Antialiasing;
+    use iced_wgpu::wgpu;
+    use iced_winit::core;
+    use iced_winit::runtime;
+
+    let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
+        backends: wgpu::Backends::all(),
+        ..Default::default()
+    });
+
+    let adapter = executor::block_on(instance.request_adapter(
+        &wgpu::RequestAdapterOptions {
+            power_preference: wgpu::PowerPreference::HighPerformance,
+            compatible_surface: None,
+            force_fallback_adapter: false,
+        },
+    ))
+    .expect("request adapter");
+
+    let (device, queue) = executor::block_on(adapter.request_device(
+        &wgpu::DeviceDescriptor {
+            label: None,
+            required_features: wgpu::Features::empty(),
+            required_limits: wgpu::Limits::default(),
+        },
+        None,
+    ))
+    .expect("request device");
+
+    let format = wgpu::TextureFormat::Bgra8UnormSrgb;
+
+    let mut engine = iced_wgpu::Engine::new(
+        &adapter,
+        &device,
+        &queue,
+        format,
+        Some(Antialiasing::MSAAx4),
+    );
+
+    let mut renderer = Renderer::new(
+        iced_wgpu::Settings {
+            present_mode: wgpu::PresentMode::Immediate,
+            backends: wgpu::Backends::all(),
+            default_font: Font::DEFAULT,
+            default_text_size: Pixels::from(16),
+            antialiasing: Some(Antialiasing::MSAAx4),
+        },
+        &engine,
+    );
+
+    let viewport =
+        graphics::Viewport::with_physical_size(Size::new(3840, 2160), 2.0);
+
+    let texture = device.create_texture(&wgpu::TextureDescriptor {
+        label: None,
+        size: wgpu::Extent3d {
+            width: 3840,
+            height: 2160,
+            depth_or_array_layers: 1,
+        },
+        mip_level_count: 1,
+        sample_count: 1,
+        dimension: wgpu::TextureDimension::D2,
+        format,
+        usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
+        view_formats: &[],
+    });
+
+    let texture_view =
+        texture.create_view(&wgpu::TextureViewDescriptor::default());
+
+    let mut user_interface = runtime::UserInterface::build(
+        widget,
+        viewport.logical_size(),
+        runtime::user_interface::Cache::default(),
+        &mut renderer,
+    );
+
+    bencher.iter(|| {
+        user_interface.draw(
+            &mut renderer,
+            &Theme::Dark,
+            &core::renderer::Style {
+                text_color: Color::WHITE,
+            },
+            mouse::Cursor::Unavailable,
+        );
+
+        let mut encoder =
+            device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
+                label: None,
+            });
+
+        renderer.present::<&str>(
+            &mut engine,
+            &device,
+            &queue,
+            &mut encoder,
+            Some(Color::BLACK),
+            format,
+            &texture_view,
+            &viewport,
+            &[],
+        );
+
+        engine.submit(&queue, encoder);
+    });
+}
+
+fn scene<'a, Message: 'a, Theme: 'a>(
+    n: usize,
+) -> Element<'a, Message, Theme, Renderer> {
+    canvas(Scene { n })
+        .width(Length::Fill)
+        .height(Length::Fill)
+        .into()
+}
+
+struct Scene {
+    n: usize,
+}
+
+impl<Message, Theme> canvas::Program<Message, Theme, Renderer> for Scene {
+    type State = canvas::Cache<Renderer>;
+
+    fn draw(
+        &self,
+        cache: &Self::State,
+        renderer: &Renderer,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: mouse::Cursor,
+    ) -> Vec<canvas::Geometry<Renderer>> {
+        vec![cache.draw(renderer, bounds.size(), |frame| {
+            for i in 0..self.n {
+                frame.fill_rectangle(
+                    Point::new(0.0, i as f32),
+                    Size::new(10.0, 10.0),
+                    Color::WHITE,
+                );
+            }
+
+            for i in 0..self.n {
+                frame.fill_text(canvas::Text {
+                    content: i.to_string(),
+                    position: Point::new(0.0, i as f32),
+                    color: Color::BLACK,
+                    size: Pixels::from(16),
+                    line_height: text::LineHeight::default(),
+                    font: Font::DEFAULT,
+                    horizontal_alignment: alignment::Horizontal::Left,
+                    vertical_alignment: alignment::Vertical::Top,
+                    shaping: text::Shaping::Basic,
+                });
+            }
+        })]
+    }
+}