1 files changed, 25 insertions, 0 deletions
diff --git a/wgpu/src/widget/canvas/layer.rs b/wgpu/src/widget/canvas/layer.rs
new file mode 100644
index 00000000..82d647bb
--- /dev/null
+++ b/wgpu/src/widget/canvas/layer.rs
@@ -0,0 +1,25 @@
+//! Produce, store, and reuse geometry.
+mod cache;
+
+pub use cache::Cache;
+
+use crate::triangle;
+
+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 [`Mesh2D`] as a
+    /// result.
+    ///
+    /// The [`Layer`] may choose to store the produced [`Mesh2D`] locally and
+    /// only recompute it when the bounds change, its contents change, or is
+    /// otherwise explicitly cleared by other means.
+    ///
+    /// [`Layer`]: trait.Layer.html
+    /// [`Mesh2D`]: ../../../triangle/struct.Mesh2D.html
+    fn draw(&self, bounds: Size) -> Arc<triangle::Mesh2D>;
+}