Struct Gpu 

pub struct Gpu { /* private fields */ }

A device, a queue, and the one pipeline every frame is drawn with.

Built once per device and kept; Gpu::painter hands out a painter per frame.

Implementations

impl Gpu

pub fn new(device: Device, queue: Queue, format: TextureFormat) -> Self

Wraps a device the caller already has, drawing into textures of format.

format is what GpuPainter::finish will be handed views of — a swapchain’s, typically. Prefer a non-sRGB format: Denise’s colours are bytes meant for the screen, and an sRGB target forces a conversion that the software rasteriser never does.

pub fn headless() -> Result<Self, Error>

Any adapter wgpu can find, drawing into Rgba8Unorm.

For tests, tools and --snapshot paths: no window, no surface. Fails with Error::NoAdapter where there is nothing to draw with, which a test should treat as “skip”, not “fail”.

pub fn device(&self) -> &Device

The device frames are drawn with.

pub fn queue(&self) -> &Queue

The queue frames are submitted to.

pub fn read_texture(&self, texture: &Texture) -> Result<Vec<u32>, Error>

Reads a texture back as 0xAARRGGBB words, row after row with no padding — the layout a denise::Frame uses.

The texture must carry COPY_SRC and this device’s format. Blocks until the GPU is done; for tests, snapshots and tools.

pub fn page_uploads(&self) -> u64

How many glyph atlas pages this device has uploaded, in total.

A page is uploaded once per AtlasPage::version, so for a text engine whose glyphs have all been seen this stops moving; a number that keeps climbing means an atlas too small for its working set, which the engine’s own resets will confirm.

pub fn image_uploads(&self) -> u64

How many images this device has uploaded, in total.

An image is uploaded once per ImageRef::version: a picture that has been drawn before costs a quad, and only replacing its pixels costs an upload.

pub fn format(&self) -> TextureFormat

The texture format GpuPainter::finish expects its target to have.

pub fn painter(&self, size: Size) -> GpuPainter<'_>

A painter for one frame of size pixels.