winit-sonoma-fix/examples/mouse_wheel.rs
Robert Bragg 0d366ffbda Re-work event loop run() API so it can return a Result
This re-works the portable `run()` API that consumes the `EventLoop` and
runs the loop on the calling thread until the app exits.

This can be supported across _all_ platforms and compared to the
previous `run() -> !` API is now able to return a `Result` status on all
platforms except iOS and Web. Fixes: #2709

By moving away from `run() -> !` we stop calling `std::process::exit()`
internally as a means to kill the process without returning which means
it's possible to return an exit status and applications can return from
their `main()` function normally.

This also fixes Android support where an Activity runs in a thread but
we can't assume to have full ownership of the process (other services
could be running in separate threads).

Additionally all examples have generally been updated so that `main()`
returns a `Result` from `run()`

Fixes: #2709
2023-07-28 03:04:32 +04:00

69 lines
2.5 KiB
Rust

#![allow(clippy::single_match)]
use simple_logger::SimpleLogger;
use winit::{
event::{Event, WindowEvent},
event_loop::EventLoop,
window::WindowBuilder,
};
#[path = "util/fill.rs"]
mod fill;
fn main() -> Result<(), impl std::error::Error> {
SimpleLogger::new().init().unwrap();
let event_loop = EventLoop::new();
let window = WindowBuilder::new()
.with_title("Mouse Wheel events")
.build(&event_loop)
.unwrap();
println!(
r"
When using so called 'natural scrolling' (scrolling that acts like on a touch screen), this is what to expect:
Moving your finger downwards on a scroll wheel should make the window move down, and you should see a positive Y scroll value.
When moving fingers on a trackpad down and to the right, you should see positive X and Y deltas, and the window should move down and to the right.
With reverse scrolling, you should see the inverse behavior.
In both cases the example window should move like the content of a scroll area in any other application.
In other words, the deltas indicate the direction in which to move the content (in this case the window)."
);
event_loop.run(move |event, _, control_flow| {
control_flow.set_wait();
match event {
Event::WindowEvent { event, .. } => match event {
WindowEvent::CloseRequested => control_flow.set_exit(),
WindowEvent::MouseWheel { delta, .. } => match delta {
winit::event::MouseScrollDelta::LineDelta(x, y) => {
println!("mouse wheel Line Delta: ({x},{y})");
let pixels_per_line = 120.0;
let mut pos = window.outer_position().unwrap();
pos.x += (x * pixels_per_line) as i32;
pos.y += (y * pixels_per_line) as i32;
window.set_outer_position(pos)
}
winit::event::MouseScrollDelta::PixelDelta(p) => {
println!("mouse wheel Pixel Delta: ({},{})", p.x, p.y);
let mut pos = window.outer_position().unwrap();
pos.x += p.x as i32;
pos.y += p.y as i32;
window.set_outer_position(pos)
}
},
_ => (),
},
Event::RedrawRequested(_) => {
fill::fill_window(&window);
}
_ => (),
}
})
}