Struct WgpuRenderer 

pub struct WgpuRenderer { /* private fields */ }

WGPU-based renderer for GPU-accelerated 2D rendering.

This renderer supports:

• GPU-accelerated shape rendering (rectangles, rounded rectangles)
• Gradients (solid, linear, radial)
• GPU text rendering via retained raster image batches
• Cross-platform support (Desktop, Web, Android)

Implementations

impl WgpuRenderer

pub fn new(fonts: &[&[u8]]) -> Self

Create a new WGPU renderer.

• fonts – font bytes to load, ordered by priority (first = highest priority). Pass &[] to load no fonts; text will not render until fonts are provided.

Call init_gpu before rendering.

pub fn with_font_set(fonts: SoftwareTextFontSet) -> Self

Create a renderer over an already-parsed font set.

Measurement and rasterization both take clones of this one set, so an app-supplied family resolves identically on both sides.

pub fn with_text_system(text_system: WgpuTextSystem) -> Self

pub fn init_gpu( &mut self, device: Arc<Device>, queue: Arc<Queue>, surface_format: TextureFormat, adapter_backend: Backend, adapter_downlevel: DownlevelFlags, )

Initialize GPU resources with a WGPU device and queue.

Replacing a live renderer (Android surface recreation, device loss) bumps the renderer epoch, so a packet built against the previous renderer is cancelled instead of drawn.

pub fn init_gpu_threaded( &mut self, device: Arc<Device>, queue: Arc<Queue>, surface_format: TextureFormat, adapter_backend: Backend, adapter_downlevel: DownlevelFlags, waker: Arc<dyn Fn() + Send + Sync>, clock: Option<Arc<dyn Fn() -> i64 + Send + Sync>>, observer: Option<Box<dyn PresentObserver>>, ) -> Result<(), WgpuRendererError>

init_gpu for the threaded present runtime (Android): the same epoch bump and planner replacement hygiene, but instead of constructing a GpuRenderer here, everything it needs — all owned, all Send — crosses to a spawned present thread that constructs its own (its Rc caches are thread-confined). Frames then flow through publish_frame / drain_present_returns under the depth-one credit protocol instead of render.

• waker — wakes the producer’s event loop after every returns send (the Android frame waker).
• clock — producer’s monotonic nanosecond clock, so present-side PresentTimings share the producer telemetry’s clock domain; None leaves timings at zero.
• observer — runs on the present thread around every present to the surface.

pub fn note_surface_reconfigured(&mut self)

Record that the surface was reconfigured (resize, format change, swapchain recreation): bumps the surface epoch stamped into every subsequent packet, so a packet built against the previous configuration is cancelled by the present stage instead of drawn.

pub fn set_root_scale(&mut self, scale: f32)

Set root scale factor for text rendering (e.g., density scaling on Android)

pub fn set_transparent_background(&mut self, transparent: bool)

Clears each frame to nothing instead of the framework’s background, for a window whose surface composites with the desktop behind it. A renderer starts opaque; false puts the background back. Takes effect from the next frame, on either present backend.

pub fn root_scale(&self) -> f32

pub fn render( &mut self, texture: &Texture, view: &TextureView, width: u32, height: u32, ) -> Result<(), WgpuRendererError>

Render the scene to a texture view.

Producer first, present second: the frontend collects the frame into a frame_packet::FramePacket (root and dev overlay alike), the GPU renderer consumes it, and the present stage’s returns fold back into the frontend afterwards.

pub fn render_surface_texture( &mut self, texture: &Texture, view: &TextureView, width: u32, height: u32, ) -> Result<(), WgpuRendererError>

Renders the frame into a presentable image. When the image carries the composition format and the capture usages, the scene renders into it directly and no output conversion pass runs.

pub fn present(&self, frame: SurfaceTexture)

Presents a surface image this renderer drew with render_surface_texture, on the queue that recorded it.

Before init_gpu there is no queue, and the image is released without being shown.

pub fn capture_frame( &mut self, width: u32, height: u32, ) -> Result<CapturedFrame, WgpuRendererError>

Render the current scene into an RGBA pixel buffer for robot tests.

Uses the renderer’s configured root scale.

pub fn capture_frame_with_scale( &mut self, width: u32, height: u32, root_scale: f32, ) -> Result<CapturedFrame, WgpuRendererError>

Render the current scene into an RGBA pixel buffer with an explicit scale.

pub fn has_frame_credit(&self) -> bool

Threaded mode: whether the depth-one slot has room for a packet. The Android loop checks this BEFORE shell.update() so backpressure lands before the expensive update/lowering work. Always true on the sync path, which has no slot to fill.

pub fn publish_frame(&mut self, width: u32, height: u32) -> PublishOutcome

Threaded mode: lower the current scene into a packet and hand it to the present runtime. Credit is checked FIRST — a NoCredit return means no packet was built at all (frame_sequence does not advance). Returns NoCredit (with an error log) when the renderer is not in threaded mode.

pub fn drain_present_returns(&mut self) -> usize

Threaded mode: fold every pending RenderReturns back into producer state and free the publish credit. Returns how many were drained. No-op outside threaded mode.

pub fn drain_present_returns_with( &mut self, on_return: &mut dyn FnMut(u64, PresentOutcome, PresentTimings), ) -> usize

drain_present_returns, reporting each drained frame’s id, outcome and present-thread timings — the Android loop feeds its frame telemetry from this.

pub fn present_replace_surface( &mut self, surface: Surface<'static>, config: SurfaceConfiguration, ) -> bool

Threaded mode: install a (re)created surface on the present thread and wait for the acknowledgement. The caller must have bumped the surface epoch first (note_surface_reconfigured Self::note_surface_reconfigured) when the message invalidates in-flight packets; the message carries the current epoch.

pub fn present_reconfigure(&mut self, config: SurfaceConfiguration) -> bool

Threaded mode: reconfigure the present thread’s surface (resize) and wait for the acknowledgement. Same epoch contract as present_replace_surface.

pub fn present_drop_surface(&mut self) -> bool

Threaded mode: drop the present thread’s surface (the window died; the renderer survives for the next one) and wait for the acknowledgement. Bump the epoch first so in-flight packets cancel.

pub fn shutdown_present_runtime(&mut self)

Threaded mode: drain outstanding returns, stop the present thread and join it. The renderer returns to the uninitialized state.

pub fn present_thread_id(&self) -> Option<i32>

The OS id of the thread that presents frames, once that thread has started, on systems whose scheduler hints name threads by one. None when frames present on the calling thread.

pub fn last_published_frame_id(&self) -> u64

The producer’s monotone packet sequence: the frame_id stamped on the most recently lowered packet. After a Published outcome this is the published frame’s id (the Android loop keys its telemetry on it); it also proves a NoCredit publish never lowered a frame.

pub fn last_frame_stats(&self) -> Option<RenderStatsSnapshot>

pub fn gpu_pass_timings(&self) -> GpuPassTimingReport

GPU milliseconds by pass label, aggregated since the last [GPU-PASS] print. Empty unless CRANPOSE_GPU_PASS_TIMING armed pass timing on a device with wgpu::Features::TIMESTAMP_QUERY.

pub fn debug_cpu_allocation_stats(&self) -> DebugCpuAllocationStats

pub fn try_device(&self) -> Option<&Device>

Return the WGPU device when GPU resources are initialized. Sync backend only (desktop/web reconfigure paths); the threaded runtime owns its device on the present thread.

Trait Implementations

impl Default for WgpuRenderer

fn default() -> Self

Returns the “default value” for a type.

impl Renderer for WgpuRenderer

type Scene = Scene

type Error = WgpuRendererError

fn attach_app_context_services(&mut self, app_context: &AppContext)

Installs renderer-provided app services into the target AppContext.

fn scene(&self) -> &Self::Scene

fn scene_mut(&mut self) -> &mut Self::Scene

fn rebuild_scene( &mut self, layout_tree: &LayoutTree, _viewport: Size, ) -> Result<(), Self::Error>

fn rebuild_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, _viewport: Size, ) -> Result<(), Self::Error>

Rebuilds the scene by traversing the LayoutNode tree directly via Applier.

fn update_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, viewport: Size, dirty_nodes: &[NodeId], ) -> Result<(), Self::Error>

fn update_visual_scene_from_applier( &mut self, applier: &mut MemoryApplier, root: NodeId, viewport: Size, dirty_nodes: &[NodeId], ) -> Result<(), Self::Error>

fn draw_dev_overlay(&mut self, text: &str, viewport: Size)

Draw a development overlay (e.g., FPS counter) on top of the scene.

fn set_inspector_overlay(&mut self, graph: Option<RenderGraph>)

Replaces the developer inspector graph outside the application scene.

fn needs_frame_warmup(&self) -> bool

Returns whether renderer-side cache materialization needs a visible follow-up frame.