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another-boids-in-rust/vendor/winit/examples/util/fill.rs

118 lines
4.1 KiB
Rust

//! 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.
#[allow(unused_imports)]
pub use platform::cleanup_window;
pub use platform::fill_window;
#[cfg(all(feature = "rwh_05", not(any(target_os = "android", target_os = "ios"))))]
mod platform {
use std::cell::RefCell;
use std::collections::HashMap;
use std::mem;
use std::mem::ManuallyDrop;
use std::num::NonZeroU32;
use softbuffer::{Context, Surface};
use winit::window::{Window, WindowId};
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.
//
// A static, thread-local map of graphics contexts to open windows.
static GC: ManuallyDrop<RefCell<Option<GraphicsContext>>> = const { ManuallyDrop::new(RefCell::new(None)) };
}
/// The graphics context used to draw to a window.
struct GraphicsContext {
/// The global softbuffer context.
context: RefCell<Context<&'static Window>>,
/// The hash map of window IDs to surfaces.
surfaces: HashMap<WindowId, Surface<&'static Window, &'static Window>>,
}
impl GraphicsContext {
fn new(w: &Window) -> Self {
Self {
context: RefCell::new(
Context::new(unsafe { mem::transmute::<&'_ Window, &'static Window>(w) })
.expect("Failed to create a softbuffer context"),
),
surfaces: HashMap::new(),
}
}
fn create_surface(
&mut self,
window: &Window,
) -> &mut Surface<&'static Window, &'static Window> {
self.surfaces.entry(window.id()).or_insert_with(|| {
Surface::new(&self.context.borrow(), unsafe {
mem::transmute::<&'_ Window, &'static Window>(window)
})
.expect("Failed to create a softbuffer surface")
})
}
fn destroy_surface(&mut self, window: &Window) {
self.surfaces.remove(&window.id());
}
}
pub fn fill_window(window: &Window) {
GC.with(|gc| {
let size = window.inner_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.
const DARK_GRAY: u32 = 0xff181818;
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(DARK_GRAY);
buffer.present().expect("Failed to present the softbuffer buffer");
})
}
#[allow(dead_code)]
pub fn cleanup_window(window: &Window) {
GC.with(|gc| {
let mut gc = gc.borrow_mut();
if let Some(context) = gc.as_mut() {
context.destroy_surface(window);
}
});
}
}
#[cfg(not(all(feature = "rwh_05", not(any(target_os = "android", target_os = "ios")))))]
mod platform {
pub fn fill_window(_window: &winit::window::Window) {
// No-op on mobile platforms.
}
#[allow(dead_code)]
pub fn cleanup_window(_window: &winit::window::Window) {
// No-op on mobile platforms.
}
}