Struct HeadlessRenderer 

pub struct HeadlessRenderer { /* private fields */ }

A deterministic, non-interactive Tessera renderer session.

Frames advance on a virtual clock, so a fixed input script always produces the same output regardless of wall-clock timing.

Implementations

impl HeadlessRenderer

pub fn gpu_instance(&self) -> &Instance

Returns the GPU instance for resource observations across renderer lifetimes.

pub fn resource_snapshot(&self) -> Result<Value, PollError>

Waits for GPU completion and reports held resource handles and allocator usage.

Allocator reservations include unused capacity and are not resident VRAM. Unsupported byte counters and allocator reports are null.

pub fn graphics_work(&self) -> GraphicsWorkDiagnostics

Captures cumulative resource creation and uploads performed by pipelines.

pub fn frame_graphics_work(&self) -> &GraphicsWorkDiagnostics

Returns actual resource operations performed in the last completed frame.

pub fn session_id(&self) -> RuntimeSessionId

Returns the runtime identity shared by this session’s snapshots and diagnostics.

pub fn run<R>(&self, work: impl FnOnce() -> R) -> R

Runs state or controller operations in this renderer’s session.

pub fn new<Output: 'static>( entry: Box<dyn Fn() -> Output>, modules: Vec<Box<dyn RenderModule>>, config: HeadlessConfig, ) -> Result<Self, HeadlessError>

Creates a headless renderer for the given entry point and render modules.

pub fn physical_size(&self) -> PhysicalSize<u32>

Returns the current offscreen size in physical pixels.

pub fn frame_index(&self) -> u64

Returns the number of frames rendered so far.

pub fn diagnostics(&self) -> LayoutFrameDiagnostics

Returns the work performed by the most recently rendered frame.

pub fn inject_pointer(&mut self, change: PointerChange)

Queues a synthetic pointer change.

Movement changes also update the tracked cursor position so hit testing observes the new location on the next frame.

pub fn pointer_move(&mut self, pointer_id: PointerId, position: PxPosition)

Moves the given pointer to position.

pub fn pointer_press( &mut self, pointer_id: PointerId, position: PxPosition, button: PressKeyEventType, )

Presses a pointer button at position.

pub fn pointer_release( &mut self, pointer_id: PointerId, position: PxPosition, button: PressKeyEventType, )

Releases a pointer button at position.

pub fn pointer_scroll( &mut self, pointer_id: PointerId, position: PxPosition, delta_x: f32, delta_y: f32, )

Queues a mouse-wheel scroll at position.

pub fn touch_start(&mut self, touch_id: u64, position: PxPosition)

Starts a touch contact at the given window position.

pub fn touch_move(&mut self, touch_id: u64, position: PxPosition)

Moves a touch contact, generating scrolling after touch slop is crossed.

pub fn touch_end(&mut self, touch_id: u64)

Releases a touch contact and completes its gesture.

pub fn touch_cancel(&mut self, touch_id: u64)

Cancels a touch contact without producing a tap or fling.

pub fn inject_key_event(&mut self, event: impl Into<KeyboardEvent>)

Queues a native or owned keyboard sample for the next frame.

pub fn press_key(&mut self, key: NamedKey)

Queues a non-repeating press of a named key for the next frame.

pub fn set_key_modifiers(&mut self, modifiers: ModifiersState)

Sets the modifier state captured by subsequent keyboard events.

pub fn inject_ime_event(&mut self, event: Ime)

Queues an IME event, used for synthetic text entry.

pub fn inject_text(&mut self, text: &str)

Commits text as IME input for the next frame.

pub fn step_frame(&mut self)

Advances the virtual clock by one frame and renders it.

pub fn render_frames(&mut self, frames: u32)

Renders exactly frames frames (at least one).

pub fn render_for_duration(&mut self, duration: Duration)

Renders frames until at least duration of virtual time has elapsed.

pub fn read_pixels(&self) -> Result<Vec<u8>, HeadlessError>

Reads the last rendered frame back as tightly packed RGBA8 pixels.

pub fn resize(&mut self, width: u32, height: u32)

Resizes the offscreen target and updates the runtime window size.

pub fn work(&self) -> &FrameWork

Returns actual component, layout, and paint work in the last frame.

pub fn work_totals(&self) -> &WorkTotals

Returns cumulative work for this fixture’s lifetime.

pub fn frame_clock_diagnostics(&self) -> &FrameClockDiagnostics

Returns frame-clock work and remaining subscriptions for the last frame.

pub fn snapshot(&self) -> Value

Captures a semantic snapshot of the component tree as JSON.

Each node reports its component function name, role, absolute bounds and accessibility metadata (role, label, value, key and state flags), which is what an automated agent needs to locate and target widgets.

pub fn accessibility_snapshot(&self) -> Option<TreeUpdate>

Returns the accessibility tree published to assistive technologies.

Use this after rendering a frame to verify semantic roles, reading order, visibility, actions, and focus independently of layout snapshots.

pub fn dispatch_accessibility_action(&mut self, request: ActionRequest) -> bool

Dispatches an assistive-technology action to a published node.

Returns whether a focus target or action handler received the request. Render another frame to publish resulting state and focus changes.