Struct LayerPresenter 

pub struct LayerPresenter { /* private fields */ }

The layer textures of one output and what they hold.

Implementations

impl LayerPresenter

pub fn can_present(cache: &FrameCache, size: (u32, u32)) -> bool

Whether cache can be presented on an output of size: it has strips, one drawing for each, on a canvas at least as wide.

pub fn present<R>( &mut self, raster: &mut R, cache: &FrameCache, revision: u64, holds: Option<u64>, ) -> Result<(), <R as LayerRaster>::Error>

where R: LayerRaster,

Composite cache, frame revision, into the output: a strip pan copies what stays on screen and rasterises only what it uncovered. holds is the frame the output target holds now, when it holds a complete one; only what changed since is composited when that is the frame last composited from the layers.

Errors

As the raster’s; a failure forgets what the layers hold, so the next frame rasterises them whole.

pub fn warm<R>( &mut self, raster: &mut R, cache: &FrameCache, keep_going: &dyn Fn() -> bool, ) -> Result<u64, <R as LayerRaster>::Error>

where R: LayerRaster,

Bring the layer textures up to cache without compositing it: the content at rest drawn as layers, so that the first frame of the next pan copies and composites instead of rasterising every layer. Rasterises only the layers that differ from what the textures hold, a whole one in bands (warm_bands), and stops between two renders as soon as keep_going says a frame waits, keeping what it finished. The output is left alone. Returns the pixels rasterised.

Errors

As the raster’s; a failure forgets what the layers hold.

pub fn kept(&mut self, previous: u64, revision: u64)

The output went from previous to revision without a pixel changing: layers it was composited from as previous are still what it shows, so the next pan composites only what moves.

pub fn forget(&mut self)

What the layer textures hold is no longer known (the colour the backdrop is rasterised over changed, or the renderer lost geometry): the next frame rasterises every layer.

pub fn holds_layers(&self) -> bool

Whether the layer textures hold every layer of some frame: then a frame drawn as layers composites from them, rasterising only what changed.

pub fn last_work(&self) -> Option<&LayerWork>

The work the latest Self::present planned.

pub fn last_pixels(&self, size: (u32, u32)) -> Option<(u64, u64)>

The pixels the latest Self::present rasterised and composited, on an output of size, for counters.

Trait Implementations

impl Default for LayerPresenter

fn default() -> LayerPresenter

Returns the “default value” for a type.