chore: avoid unsafe in examples

By using `OwnedDisplayHandle`, which uses reference-counting, instead of
`DisplayHandle<'static>` (where the user has to guarantee that the
Application doesn't outlive the event loop).

winit/examples/util/fill.rs

@@ -1,115 +1,43 @@
-//! Fill the window buffer with a solid color.
-//!
-//! Launching a window without drawing to it has unpredictable results varying from platform to
-//! platform. In order to have well-defined examples, this module provides an easy way to
-//! fill the window buffer with a solid color.
-//!
-//! The `softbuffer` crate is used, largely because of its ease of use. `glutin` or `wgpu` could
-//! also be used to fill the window buffer, but they are more complicated to use.
-
-use std::cell::RefCell;
-use std::collections::HashMap;
-use std::mem;
-use std::mem::ManuallyDrop;
 use std::num::NonZeroU32;
-#[cfg(not(web_platform))]
-use std::time::Instant;
 
-use softbuffer::{Context, Surface};
-#[cfg(web_platform)]
-use web_time::Instant;
-use winit::window::{Window, WindowId};
+use rwh_06::{HasDisplayHandle, HasWindowHandle};
+use softbuffer::Surface;
+use winit::window::Window;
 
-thread_local! {
-    // NOTE: You should never do things like that, create context and drop it before
-    // you drop the event loop. We do this for brevity to not blow up examples. We use
-    // ManuallyDrop to prevent destructors from running.
+/// Resize the surface.
+pub fn resize(
+    surface: &mut Surface<impl HasDisplayHandle, impl HasWindowHandle>,
+    surface_size: dpi::PhysicalSize<u32>,
+) {
+    // Handle zero-sized buffers.
     //
-    // A static, thread-local map of graphics contexts to open windows.
-    static GC: ManuallyDrop<RefCell<Option<GraphicsContext>>> = const { ManuallyDrop::new(RefCell::new(None)) };
+    // FIXME(madsmtm): This should be done by softbuffer internally in the future:
+    // https://github.com/rust-windowing/softbuffer/issues/238
+    let (Some(width), Some(height)) =
+        (NonZeroU32::new(surface_size.width), NonZeroU32::new(surface_size.height))
+    else {
+        return;
+    };
+
+    surface.resize(width, height).expect("Failed to resize the softbuffer surface");
 }
 
-/// The graphics context used to draw to a window.
-struct GraphicsContext {
-    /// The global softbuffer context.
-    context: RefCell<Context<&'static dyn Window>>,
+/// Fill the window buffer with a solid color.
+pub fn fill_with_color(
+    surface: &mut Surface<impl HasDisplayHandle, impl HasWindowHandle + AsRef<dyn Window>>,
+    color: u32,
+) {
+    let surface_size = surface.window().as_ref().surface_size();
+    resize(surface, surface_size);
 
-    /// The hash map of window IDs to surfaces.
-    surfaces: HashMap<WindowId, Surface<&'static dyn Window, &'static dyn Window>>,
-}
-
-impl GraphicsContext {
-    fn new(w: &dyn Window) -> Self {
-        Self {
-            context: RefCell::new(
-                Context::new(unsafe { mem::transmute::<&'_ dyn Window, &'static dyn Window>(w) })
-                    .expect("Failed to create a softbuffer context"),
-            ),
-            surfaces: HashMap::new(),
-        }
-    }
-
-    fn create_surface(
-        &mut self,
-        window: &dyn Window,
-    ) -> &mut Surface<&'static dyn Window, &'static dyn Window> {
-        self.surfaces.entry(window.id()).or_insert_with(|| {
-            Surface::new(&self.context.borrow(), unsafe {
-                mem::transmute::<&'_ dyn Window, &'static dyn Window>(window)
-            })
-            .expect("Failed to create a softbuffer surface")
-        })
-    }
-
-    fn destroy_surface(&mut self, window: &dyn Window) {
-        self.surfaces.remove(&window.id());
-    }
-}
-
-pub fn fill_window_with_color(window: &dyn Window, color: u32) {
-    GC.with(|gc| {
-        let size = window.surface_size();
-        let (Some(width), Some(height)) =
-            (NonZeroU32::new(size.width), NonZeroU32::new(size.height))
-        else {
-            return;
-        };
-
-        // Either get the last context used or create a new one.
-        let mut gc = gc.borrow_mut();
-        let surface = gc.get_or_insert_with(|| GraphicsContext::new(window)).create_surface(window);
-
-        // Fill a buffer with a solid color
-
-        surface.resize(width, height).expect("Failed to resize the softbuffer surface");
-
-        let mut buffer = surface.buffer_mut().expect("Failed to get the softbuffer buffer");
-        buffer.fill(color);
-        buffer.present().expect("Failed to present the softbuffer buffer");
-    })
+    let mut buffer = surface.buffer_mut().expect("Failed to get the softbuffer buffer");
+    buffer.fill(color);
+    buffer.present().expect("Failed to present the softbuffer buffer");
 }
 
 #[allow(dead_code)]
-pub fn fill_window(window: &dyn Window) {
-    fill_window_with_color(window, 0xff181818);
-}
-
-#[allow(dead_code)]
-pub fn fill_window_with_animated_color(window: &dyn Window, start: Instant) {
-    let time = start.elapsed().as_secs_f32() * 1.5;
-    let blue = (time.sin() * 255.0) as u32;
-    let green = ((time.cos() * 255.0) as u32) << 8;
-    let red = ((1.0 - time.sin() * 255.0) as u32) << 16;
-    let color = red | green | blue;
-    fill_window_with_color(window, color);
-}
-
-#[allow(dead_code)]
-pub fn cleanup_window(window: &dyn Window) {
-    GC.with(|gc| {
-        let mut gc = gc.borrow_mut();
-        if let Some(context) = gc.as_mut() {
-            context.destroy_surface(window);
-        }
-    });
+pub fn fill(
+    surface: &mut Surface<impl HasDisplayHandle, impl HasWindowHandle + AsRef<dyn Window>>,
+) {
+    fill_with_color(surface, 0xff181818);
 }