Fill the windows in the examples with a solid color

Fixes #776.

Cargo.toml

@@ -63,6 +63,9 @@ smol_str = "0.2.0"
 image = { version = "0.24.0", default-features = false, features = ["png"] }
 simple_logger = { version = "2.1.0", default_features = false }
 
+[target.'cfg(not(any(target_os = "android", target_os = "ios")))'.dev-dependencies]
+softbuffer = "0.3.0"
+
 [target.'cfg(target_os = "android")'.dependencies]
 # Coordinate the next winit release with android-ndk-rs: https://github.com/rust-windowing/winit/issues/1995
 android-activity = "0.4.0"

README.md

@@ -73,10 +73,6 @@ Winit provides the following features, which can be enabled in your `Cargo.toml`
 
 Note that windows don't appear on Wayland until you draw/present to them.
 
-`winit` doesn't do drawing, try the examples in [`glutin`] instead.
-
-[`glutin`]: https://github.com/rust-windowing/glutin
-
 #### WebAssembly
 
 To run the web example: `cargo run-wasm --example web`

deny.toml

@@ -34,6 +34,8 @@ skip = [
     { name = "bitflags" },      # the ecosystem is in the process of migrating.
     { name = "nix" },           # differing version - as of 2023-03-02 whis can be solved with `cargo update && cargo update -p calloop --precise 0.10.2`
     { name = "memoffset"},      # due to different nix versions.
+    { name = "memmap2" },       # sctk uses a different version until the next update
+    { name = "libloading" },    # x11rb uses a different version until the next update
     { name = "syn" },           # https://github.com/rust-mobile/ndk/issues/392 and https://github.com/rustwasm/wasm-bindgen/issues/3390
     { name = "miniz_oxide"},    # https://github.com/rust-lang/flate2-rs/issues/340
     { name = "redox_syscall" }, # https://gitlab.redox-os.org/redox-os/orbclient/-/issues/46

examples/child_window.rs

@@ -1,3 +1,7 @@
+#[cfg(any(x11_platform, macos_platform, windows_platform))]
+#[path = "util/fill.rs"]
+mod fill;
+
 #[cfg(any(x11_platform, macos_platform, windows_platform))]
 fn main() {
     use std::collections::HashMap;
@@ -70,6 +74,10 @@ fn main() {
                 }
                 _ => (),
             }
+        } else if let Event::RedrawRequested(wid) = event {
+            if let Some(window) = windows.get(&wid) {
+                fill::fill_window(window);
+            }
         }
     })
 }

examples/control_flow.rs

@@ -14,6 +14,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Mode {
     Wait,
@@ -100,7 +103,9 @@ fn main() {
                     control_flow.set_exit();
                 }
             }
-            Event::RedrawRequested(_window_id) => {}
+            Event::RedrawRequested(_window_id) => {
+                fill::fill_window(&window);
+            }
             Event::RedrawEventsCleared => {
                 match mode {
                     Mode::Wait => control_flow.set_wait(),

examples/cursor.rs

@@ -7,6 +7,9 @@ use winit::{
     window::{CursorIcon, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -46,6 +49,9 @@ fn main() {
             } => {
                 control_flow.set_exit();
             }
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/cursor_grab.rs

@@ -8,6 +8,9 @@ use winit::{
     window::{CursorGrabMode, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -67,6 +70,7 @@ fn main() {
                 },
                 _ => (),
             },
+            Event::RedrawRequested(_) => fill::fill_window(&window),
             _ => (),
         }
     });

examples/custom_events.rs

@@ -9,6 +9,9 @@ fn main() {
         window::WindowBuilder,
     };
 
+    #[path = "util/fill.rs"]
+    mod fill;
+
     #[derive(Debug, Clone, Copy)]
     enum CustomEvent {
         Timer,
@@ -17,7 +20,7 @@ fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoopBuilder::<CustomEvent>::with_user_event().build();
 
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_title("A fantastic window!")
         .build(&event_loop)
         .unwrap();
@@ -44,6 +47,9 @@ fn main() {
                 event: WindowEvent::CloseRequested,
                 ..
             } => control_flow.set_exit(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/drag_window.rs

@@ -8,6 +8,9 @@ use winit::{
     window::{Window, WindowBuilder, WindowId},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -58,6 +61,13 @@ fn main() {
             }
             _ => (),
         },
+        Event::RedrawRequested(wid) => {
+            if wid == window_1.id() {
+                fill::fill_window(&window_1);
+            } else if wid == window_2.id() {
+                fill::fill_window(&window_2);
+            }
+        }
         _ => (),
     });
 }

examples/fullscreen.rs

@@ -9,6 +9,9 @@ use winit::window::{Fullscreen, WindowBuilder};
 #[cfg(target_os = "macos")]
 use winit::platform::macos::WindowExtMacOS;
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -123,6 +126,9 @@ fn main() {
                 },
                 _ => (),
             },
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => {}
         }
     });

examples/handling_close.rs

@@ -8,11 +8,14 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_title("Your faithful window")
         .build(&event_loop)
         .unwrap();
@@ -79,6 +82,9 @@ fn main() {
                     _ => (),
                 }
             }
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/ime.rs

@@ -10,6 +10,9 @@ use winit::{
     window::{ImePurpose, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new()
         .with_level(LevelFilter::Trace)
@@ -97,6 +100,9 @@ fn main() {
                     println!("\nIME purpose: {ime_purpose:?}\n");
                 }
             }
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/key_binding.rs

@@ -18,10 +18,13 @@ fn main() {
 
 #[cfg(any(target_os = "macos", target_os = "windows", target_os = "linux"))]
 fn main() {
+    #[path = "util/fill.rs"]
+    mod fill;
+
     simple_logger::SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_inner_size(LogicalSize::new(400.0, 200.0))
         .build(&event_loop)
         .unwrap();
@@ -53,6 +56,9 @@ fn main() {
                 }
                 _ => (),
             },
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         };
     });

examples/mouse_wheel.rs

@@ -7,6 +7,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -56,6 +59,9 @@ In other words, the deltas indicate the direction in which to move the content (
                 },
                 _ => (),
             },
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/multiwindow.rs

@@ -10,6 +10,9 @@ use winit::{
     window::Window,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -56,6 +59,11 @@ fn main() {
                     _ => (),
                 }
             }
+            Event::RedrawRequested(window_id) => {
+                if let Some(window) = windows.get(&window_id) {
+                    fill::fill_window(window);
+                }
+            }
             _ => (),
         }
     })

examples/request_redraw.rs

@@ -7,6 +7,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -34,6 +37,7 @@ fn main() {
             },
             Event::RedrawRequested(_) => {
                 println!("\nredrawing!\n");
+                fill::fill_window(&window);
             }
             _ => (),
         }

examples/request_redraw_threaded.rs

@@ -2,7 +2,7 @@
 
 #[cfg(not(wasm_platform))]
 fn main() {
-    use std::{thread, time};
+    use std::{sync::Arc, thread, time};
 
     use simple_logger::SimpleLogger;
     use winit::{
@@ -11,17 +11,26 @@ fn main() {
         window::WindowBuilder,
     };
 
+    #[path = "util/fill.rs"]
+    mod fill;
+
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
+    let window = {
         let window = WindowBuilder::new()
             .with_title("A fantastic window!")
             .build(&event_loop)
             .unwrap();
+        Arc::new(window)
+    };
 
-    thread::spawn(move || loop {
+    thread::spawn({
+        let window = window.clone();
+        move || loop {
             thread::sleep(time::Duration::from_secs(1));
             window.request_redraw();
+        }
     });
 
     event_loop.run(move |event, _, control_flow| {
@@ -36,6 +45,7 @@ fn main() {
             } => control_flow.set_exit(),
             Event::RedrawRequested(_) => {
                 println!("\nredrawing!\n");
+                fill::fill_window(&window);
             }
             _ => (),
         }

examples/resizable.rs

@@ -9,6 +9,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -45,6 +48,9 @@ fn main() {
                 }
                 _ => (),
             },
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         };
     });

examples/theme.rs

@@ -8,6 +8,9 @@ use winit::{
     window::{Theme, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -66,6 +69,10 @@ fn main() {
                 }
                 _ => (),
             },
+            Event::RedrawRequested(_) => {
+                println!("\nredrawing!\n");
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/timer.rs

@@ -13,11 +13,14 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_title("A fantastic window!")
         .build(&event_loop)
         .unwrap();
@@ -39,6 +42,9 @@ fn main() {
                 event: WindowEvent::CloseRequested,
                 ..
             } => control_flow.set_exit(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/touchpad_gestures.rs

@@ -5,11 +5,14 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
 
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_title("Touchpad gestures")
         .build(&event_loop)
         .unwrap();
@@ -41,6 +44,8 @@ fn main() {
                 }
                 _ => (),
             }
+        } else if let Event::RedrawRequested(_) = event {
+            fill::fill_window(&window);
         }
     });
 }

examples/transparent.rs

@@ -7,6 +7,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -28,6 +31,9 @@ fn main() {
                 event: WindowEvent::CloseRequested,
                 ..
             } => control_flow.set_exit(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/util/fill.rs

@@ -0,0 +1,81 @@
+//! 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 winit::window::Window;
+
+#[cfg(not(any(target_os = "android", target_os = "ios")))]
+pub(super) fn fill_window(window: &Window) {
+    use softbuffer::{Context, Surface};
+    use std::cell::RefCell;
+    use std::collections::HashMap;
+    use std::num::NonZeroU32;
+    use winit::window::WindowId;
+
+    /// The graphics context used to draw to a window.
+    struct GraphicsContext {
+        /// The global softbuffer context.
+        context: Context,
+
+        /// The hash map of window IDs to surfaces.
+        surfaces: HashMap<WindowId, Surface>,
+    }
+
+    impl GraphicsContext {
+        fn new(w: &Window) -> Self {
+            Self {
+                context: unsafe { Context::new(w) }.expect("Failed to create a softbuffer context"),
+                surfaces: HashMap::new(),
+            }
+        }
+
+        fn surface(&mut self, w: &Window) -> &mut Surface {
+            self.surfaces.entry(w.id()).or_insert_with(|| {
+                unsafe { Surface::new(&self.context, w) }
+                    .expect("Failed to create a softbuffer surface")
+            })
+        }
+    }
+
+    thread_local! {
+        /// A static, thread-local map of graphics contexts to open windows.
+        static GC: RefCell<Option<GraphicsContext>> = RefCell::new(None);
+    }
+
+    GC.with(|gc| {
+        // 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))
+            .surface(window);
+
+        // Fill a buffer with a solid color.
+        const DARK_GRAY: u32 = 0xFF181818;
+        let size = window.inner_size();
+
+        surface
+            .resize(
+                NonZeroU32::new(size.width).expect("Width must be greater than zero"),
+                NonZeroU32::new(size.height).expect("Height must be greater than zero"),
+            )
+            .expect("Failed to resize the softbuffer surface");
+
+        let mut buffer = surface
+            .buffer_mut()
+            .expect("Failed to get the softbuffer buffer");
+        buffer.fill(DARK_GRAY);
+        buffer
+            .present()
+            .expect("Failed to present the softbuffer buffer");
+    })
+}
+
+#[cfg(any(target_os = "android", target_os = "ios"))]
+pub(super) fn fill_window(_window: &Window) {
+    // No-op on mobile platforms.
+}

examples/window.rs

@@ -7,6 +7,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -29,6 +32,9 @@ fn main() {
             Event::MainEventsCleared => {
                 window.request_redraw();
             }
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/window_buttons.rs

@@ -11,6 +11,9 @@ use winit::{
     window::{WindowBuilder, WindowButtons},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -63,6 +66,9 @@ fn main() {
                 event: WindowEvent::CloseRequested,
                 window_id,
             } if window_id == window.id() => control_flow.set_exit(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/window_debug.rs

@@ -11,6 +11,9 @@ use winit::{
     window::{Fullscreen, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -131,6 +134,9 @@ fn main() {
                 event: WindowEvent::CloseRequested,
                 window_id,
             } if window_id == window.id() => control_flow.set_exit(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/window_drag_resize.rs

@@ -10,6 +10,9 @@ use winit::{
 
 const BORDER: f64 = 8.0;
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -65,6 +68,9 @@ fn main() {
             }
             _ => (),
         },
+        Event::RedrawRequested(_) => {
+            fill::fill_window(&window);
+        }
         _ => (),
     });
 }

examples/window_icon.rs

@@ -9,6 +9,9 @@ use winit::{
     window::{Icon, WindowBuilder},
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
 
@@ -42,6 +45,8 @@ fn main() {
                 }
                 _ => (),
             }
+        } else if let Event::RedrawRequested(_) = event {
+            fill::fill_window(&window);
         }
     });
 }

examples/window_resize_increments.rs

@@ -8,6 +8,9 @@ use winit::{
     window::WindowBuilder,
 };
 
+#[path = "util/fill.rs"]
+mod fill;
+
 fn main() {
     SimpleLogger::new().init().unwrap();
     let event_loop = EventLoop::new();
@@ -52,6 +55,9 @@ fn main() {
                 window.set_resize_increments(new_increments);
             }
             Event::MainEventsCleared => window.request_redraw(),
+            Event::RedrawRequested(_) => {
+                fill::fill_window(&window);
+            }
             _ => (),
         }
     });

examples/window_run_return.rs

@@ -19,10 +19,14 @@ fn main() {
         platform::run_return::EventLoopExtRunReturn,
         window::WindowBuilder,
     };
+
+    #[path = "util/fill.rs"]
+    mod fill;
+
     let mut event_loop = EventLoop::new();
 
     SimpleLogger::new().init().unwrap();
-    let _window = WindowBuilder::new()
+    let window = WindowBuilder::new()
         .with_title("A fantastic window!")
         .build(&event_loop)
         .unwrap();
@@ -48,6 +52,9 @@ fn main() {
                 Event::MainEventsCleared => {
                     control_flow.set_exit();
                 }
+                Event::RedrawRequested(_) => {
+                    fill::fill_window(&window);
+                }
                 _ => (),
             }
         });