wgpu/src/widget/canvas/layer.rs


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//! Produce, store, and reuse geometry.
mod cache;

pub use cache::Cache;

use crate::Primitive;
use iced_native::Size;

use std::sync::Arc;

/// A layer that can be presented at a [`Canvas`].
///
/// [`Canvas`]: ../struct.Canvas.html
pub trait Layer: std::fmt::Debug {
    /// Draws the [`Layer`] in the given bounds and produces a [`Primitive`] as
    /// a result.
    ///
    /// The [`Layer`] may choose to store the produced [`Primitive`] locally and
    /// only recompute it when the bounds change, its contents change, or is
    /// otherwise explicitly cleared by other means.
    ///
    /// [`Layer`]: trait.Layer.html
    /// [`Primitive`]: ../../../enum.Primitive.html
    fn draw(&self, bounds: Size) -> Arc<Primitive>;
}