Make egui_wgpu::winit::Painter::set_window async (#2434)

* Make `egui_wgpu::winit::Painter::set_window` async

* Fix changelog link

crates/egui-wgpu/CHANGELOG.md

@@ -4,6 +4,7 @@ All notable changes to the `egui-wgpu` integration will be noted in this file.
 
 ## Unreleased
 * Return `Err` instead of panic if we can't find a device ([#2428](https://github.com/emilk/egui/pull/2428)).
+* `winit::Painter::set_window` is now `async` ([#2434](https://github.com/emilk/egui/pull/2434)).
 
 
 ## 0.20.0 - 2022-12-08 - web support

crates/egui-wgpu/Cargo.toml

@@ -32,7 +32,7 @@ all-features = true
 puffin = ["dep:puffin"]
 
 ## Enable [`winit`](https://docs.rs/winit) integration.
-winit = ["dep:pollster", "dep:winit"]
+winit = ["dep:winit"]
 
 
 [dependencies]
@@ -49,7 +49,6 @@ wgpu = "0.14"
 ## Enable this when generating docs.
 document-features = { version = "0.2", optional = true }
 
-pollster = { version = "0.2", optional = true }
 winit = { version = "0.27.2", optional = true }
 
 # Native:

crates/egui-wgpu/src/winit.rs

@@ -88,17 +88,19 @@ impl Painter {
     //
     // After we've initialized our render state once though we expect all future surfaces
     // will have the same format and so this render state will remain valid.
-    fn ensure_render_state_for_surface(
+    async fn ensure_render_state_for_surface(
         &mut self,
         surface: &Surface,
     ) -> Result<(), wgpu::RequestDeviceError> {
         if self.adapter.is_none() {
-            self.adapter =
-                pollster::block_on(self.instance.request_adapter(&wgpu::RequestAdapterOptions {
+            self.adapter = self
+                .instance
+                .request_adapter(&wgpu::RequestAdapterOptions {
                     power_preference: self.configuration.power_preference,
                     compatible_surface: Some(surface),
                     force_fallback_adapter: false,
-                }));
+                })
+                .await;
         }
         if self.render_state.is_none() {
             match &self.adapter {
@@ -106,7 +108,7 @@ impl Painter {
                     let swapchain_format = crate::preferred_framebuffer_format(
                         &surface.get_supported_formats(adapter),
                     );
-                    let rs = pollster::block_on(self.init_render_state(adapter, swapchain_format))?;
+                    let rs = self.init_render_state(adapter, swapchain_format).await?;
                     self.render_state = Some(rs);
                 }
                 None => return Err(wgpu::RequestDeviceError {}),
@@ -171,7 +173,7 @@ impl Painter {
     ///
     /// # Errors
     /// If the provided wgpu configuration does not match an available device.
-    pub unsafe fn set_window(
+    pub async unsafe fn set_window(
         &mut self,
         window: Option<&winit::window::Window>,
     ) -> Result<(), wgpu::RequestDeviceError> {
@@ -179,7 +181,7 @@ impl Painter {
             Some(window) => {
                 let surface = self.instance.create_surface(&window);
 
-                self.ensure_render_state_for_surface(&surface)?;
+                self.ensure_render_state_for_surface(&surface).await?;
 
                 let size = window.inner_size();
                 let width = size.width;