Rust egui window size and dark mode - user-interface

Question

I'm tring to make a native gui app using egui.
After some time got the hello_world example to compile.Heres the code:
use eframe::{epi, egui};
struct MyEguiApp {
name: String,
age: u32,
}
impl Default for MyEguiApp {
fn default() -> Self {
Self {
name: "Arthur".to_owned(),
age: 42,
}
}
}
impl epi::App for MyEguiApp {
fn name(&self) -> &str {
"Test"
}
fn update(&mut self, ctx: &egui::Context, frame: &epi::Frame) {
egui::CentralPanel::default().show(ctx, |ui| {
ui.heading("My egui aplication");
ui.horizontal(|ui|{
ui.label("Your name: ");
ui.text_edit_singleline(&mut self.name);
});
ui.add(egui::Slider::new(&mut self.age,0..=120));
if ui.button("Click each year").clicked() {
self.age += 1;
}
ui.label(format!("Hello '{}', age {}", self.name, self.age));
});
frame.set_window_size(ctx.used_size());
}
}
fn main() {
let app = MyEguiApp::default();
let native_options = eframe::NativeOptions::default();
eframe::run_native(Box::new(app), native_options);
}
But i have 2 problems:
First: the window is always 800x600 unless i manually resize it
Second: i have no idea how to activate dark mode
I just started learning rust so if anyone could help that would be great.

Answer 1

Replace the "native_options" in the main method with this.
let options = eframe::NativeOptions {
always_on_top: false,
maximized: false,
decorated: true,
drag_and_drop_support: true,
icon_data: None,
initial_window_pos: None,
initial_window_size: Option::from(Vec2::new(PUT X SIZE HERE as f32, PUT Y SIZE HERE as f32)),
min_window_size: None,
max_window_size: None,
resizable: true,
transparent: true,
vsync: true,
multisampling: 0,
depth_buffer: 0,
stencil_buffer: 0,
};
To set to dark mode, you can use the built in dark mode buttons: egui::widgets::global_dark_light_mode_buttons(ui); or you can do cc.egui_ctx.set_visuals(egui::Visuals::dark()); in your eframe run native function.