How to set the outer window size?

[bratish]

Hi, thanks for this amazing library. I'm am new to Rust and egui too. I am trying to make a small widget for Linux. The app is combination of a couple of sliders. I am done with the functionalities, but I am kind of stuck with the look of the app. Here's how it looks as of now:

I am trying to:

1. Fix the outer window size and make it much smaller (like the red rectangle).
2. Trying to put the slider between A and a.

The code is totally derived from the awesome starter guide egui_template. I am using only CentralPanel to display the content.

use eframe::{egui, epi};

#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
#[cfg_attr(feature = "persistence", serde(default))] // if we add new fields, give them default values when deserializing old state
pub struct GuiApp {
    label: String,
   #[cfg_attr(feature = "persistence", serde(skip))]
    value: f32,
}

impl Default for GuiApp {
    fn default() -> Self {
        Self {
            label: "Hello World!".to_owned(),
            value: 2.7,
        }
    }
}

impl epi::App for GuiApp {
    
    fn name(&self) -> &str {
        "Adjust Brightness"
    }

    #[cfg(feature = "persistence")]
    fn load(&mut self, storage: &dyn epi::Storage) {
        *self = epi::get_value(storage, epi::APP_KEY).unwrap_or_default()
    }

    #[cfg(feature = "persistence")]
    fn save(&mut self, storage: &mut dyn epi::Storage) {
        epi::set_value(storage, epi::APP_KEY, self);
    }
    
    fn update(&mut self, ctx: &egui::CtxRef, frame: &mut epi::Frame<'_>) {
        let Self { label, value } = self;

        egui::CentralPanel::default().show(ctx, |ui| {
            let highest_val = 1.0;
            let response = ui.add(
                egui::Slider::new(
                    value, 0.0..=highest_val
                ).text("A a").clamp_to_range(true).show_value(false)
            );
            // to mark the area during development. Will be removed later
            ui.painter().rect_stroke(response.rect, 0.0, (1.0, egui::Color32::WHITE));
            
            if response.changed(){
                println!(">>>{:?}", value);
                // the actions are taken here
            }
        });

        if false {
            egui::Window::new("Window").show(ctx, |ui| {
                ui.label("Windows can be moved by dragging them.");
                ui.label("They are automatically sized based on contents.");
                ui.label("You can turn on resizing and scrolling if you like.");
                ui.label("You would normally chose either panels OR windows.");
            });
        }
    }
}

Thank you!

[parasyte]

You can set the window size in eframe::NativeOptions: https://docs.rs/eframe/0.12.0/eframe/struct.NativeOptions.html#structfield.initial_window_size

If you want to put the slider between the two letters, you need to move one to the left side. Probably something like this:

ui.horizontal(|ui| {
    ui.label("A");
    let response = ui.add(
        egui::Slider::new(
            value, 0.0..=highest_val
        ).text("a").clamp_to_range(true).show_value(false)
    );

    // etc.
});

[bratish]

Thank you! Both of your answers worked for me. Really appreciate your help.