From 6e7769b65dfda1ab748eb26f8832fd32714f6fc1 Mon Sep 17 00:00:00 2001
From: Rob Ede <robjtede@icloud.com>
Date: Wed, 8 Apr 2020 23:07:42 +0100
Subject: [PATCH] impl default for canvas cache

---
 examples/clock/src/main.rs            |  2 +-
 examples/solar_system/src/main.rs     |  2 +-
 wgpu/src/widget/canvas/layer/cache.rs | 31 +++++++++++++++++++++------
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/examples/clock/src/main.rs b/examples/clock/src/main.rs
index 88f8322c..a85a964c 100644
--- a/examples/clock/src/main.rs
+++ b/examples/clock/src/main.rs
@@ -29,7 +29,7 @@ impl Application for Clock {
         (
             Clock {
                 now: chrono::Local::now().into(),
-                clock: canvas::layer::Cache::new(),
+                clock: Default::default(),
             },
             Command::none(),
         )
diff --git a/examples/solar_system/src/main.rs b/examples/solar_system/src/main.rs
index 1967b7c5..963f047b 100644
--- a/examples/solar_system/src/main.rs
+++ b/examples/solar_system/src/main.rs
@@ -39,7 +39,7 @@ impl Application for SolarSystem {
         (
             SolarSystem {
                 state: State::new(),
-                solar_system: canvas::layer::Cache::new(),
+                solar_system: Default::default(),
             },
             Command::none(),
         )
diff --git a/wgpu/src/widget/canvas/layer/cache.rs b/wgpu/src/widget/canvas/layer/cache.rs
index 20a095bd..4f8c2bec 100644
--- a/wgpu/src/widget/canvas/layer/cache.rs
+++ b/wgpu/src/widget/canvas/layer/cache.rs
@@ -6,6 +6,19 @@ use crate::{
 use iced_native::Size;
 use std::{cell::RefCell, marker::PhantomData, sync::Arc};
 
+enum State {
+    Empty,
+    Filled {
+        bounds: Size,
+        primitive: Arc<Primitive>,
+    },
+}
+
+impl Default for State {
+    fn default() -> Self {
+        State::Empty
+    }
+}
 /// A simple cache that stores generated geometry to avoid recomputation.
 ///
 /// A [`Cache`] will not redraw its geometry unless the dimensions of its layer
@@ -19,12 +32,16 @@ pub struct Cache<T: Drawable> {
     state: RefCell<State>,
 }
 
-enum State {
-    Empty,
-    Filled {
-        bounds: Size,
-        primitive: Arc<Primitive>,
-    },
+impl<T> Default for Cache<T>
+where
+    T: Drawable,
+{
+    fn default() -> Self {
+        Self {
+            input: PhantomData,
+            state: Default::default(),
+        }
+    }
 }
 
 impl<T> Cache<T>
@@ -37,7 +54,7 @@ where
     pub fn new() -> Self {
         Cache {
             input: PhantomData,
-            state: RefCell::new(State::Empty),
+            state: Default::default(),
         }
     }