TextEditor use 2gb memory for rendering a 10mb file

[lost22git]

code for reproduce

use eframe::egui::{
    self,
    CentralPanel,
    TextEdit,
};

fn main() -> Result<(), eframe::Error,> {
    let options = eframe::NativeOptions {
        ..Default::default()
    };

    eframe::run_native(
        "editor big file test",
        options,
        Box::new(|_cc| Box::<MyApp,>::new(MyApp::new(),),),
    )
}

struct MyApp {
    text: String,
}

impl MyApp {
    fn new() -> Self {
        let bytes = include_bytes!("../10mb.png"); // a 10mb png file
        let encoding = detect_encoding(bytes,);
        let (str, _, _,) = encoding.decode(bytes,);
        let string: String = str.into();
        MyApp {
            text: string,
        }
    }
}

pub fn detect_encoding(text: &[u8],) -> &'static encoding_rs::Encoding {
    let len = text.len();
    let to = std::cmp::min(1000, len,);
    let mut encoding_detector = chardetng::EncodingDetector::new();
    encoding_detector.feed(&text[0..to], to == len,);
    encoding_detector.guess(None, true,)
}

impl eframe::App for MyApp {
    fn update(
        &mut self,
        ctx: &egui::Context,
        _frame: &mut eframe::Frame,
    ) {
        CentralPanel::default().show(ctx, |ui| {
            let code_editor = TextEdit::multiline(&mut self.text,)
                .code_editor()
                .frame(true,)
                .lock_focus(true,)
                .desired_width(f32::INFINITY,)
                .desired_rows(40,);
            let _output = code_editor.show(ui,);
        },);
    }
}

[YgorSouza]

Here is a version of the new method that generates a big string without any dependencies, so it is easier to test:

    fn new() -> Self {
        let bytes = (0..1_000_000).flat_map(|_| (0u8..10));
        let string: String = bytes.map(|b| format!(" {b:02x}")).collect();
        MyApp { text: string }
    }

Anyway, I don't think this is a "bug". The file is just too big for an immediate UI to handle. It is trying to render the entire string as an image because it doesn't know where to start or stop, so the buffer ends up being huge. There would have to be an equivalent to the show_rows method for the text editor, so I guess this is more of a feature request?

[lost22git]

@YgorSouza I see, thanks for your explaination ;-)