Printing formatted text in an Iced window

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1

My goal is to print a simple math problem in a window. This is easy enough to do when working in the terminal. This code works fine:

fn main() {
    let num1 = 4;
    let num2 = 3;
    
    println!("\n{} x {} = ", num1, num2);
}

However, so far my attempts at printing that same line in an Iced window have failed. Here’s the code I’m using:

use iced::widget::text;
use iced::window;
use iced::{Element, Sandbox, Settings};

const PROGRAM_TITLE: &str = "Math Drill";
const VERSION: &str = "0.0.1";

struct Mathfact {
    num1: i32,
    num2: i32,
}

#[derive(Debug)]
enum Message {}

impl Sandbox for Mathfact {
    type Message = Message;

    fn new() -> Mathfact {
        let fact1 = Mathfact { num1: 4, num2: 3 };
        fact1
    }

    fn title(&self) -> String {
        String::from(PROGRAM_TITLE)
    }

    fn update(&mut self, _message: Self::Message) {
        // No interactions yet, so nothing to do here.
    }

    fn view(&self) -> Element<Self::Message> {
        //println!("\n{} x {} = ", self.num1, self.num2);
        "\n\nHello, world!".into()
    }
} // End Mathfact/Sandbox impl

pub fn main() -> iced::Result {
    Mathfact::run(Settings::default())
}

The problem, of course, is in the view() function. The formatted output with println() printed just fine – in the terminal, not the window. I had to include the

"\n\nHello, world!".into()

line to satisfy the return type of Element<Self::Message>. Admittedly, I don’t have a good understanding of what that return value is doing and, eventually, I need to get that figured out, but my goal is to get this text printed in the Iced window. How do I do that?

2

It turns out that return value is the mystery you need to solve. What do you see inside the window when you run your app?

3

“Hello, world!” in the upper left corner. My math problem shows up in the terminal.

The code is mostly the “Simplest Example” we were talking about in this thread.

4

Right, and what does your view code say?

5

I actually tried to find a way to insert the variables into the "Hello, world!" string, but finding a way to insert the variable values has me stumped. I’m also having trouble wrapping my brain around into(). I know it’s basically from() in reverse, but it’s still somewhat mysterious. (I think you talked a little about it in your video, but I’m kind of dense. :>)

Just tried this:

"\n{self.num1} x {self.num2} = ".into()

                       and

let output = format!("\n{} x {} = ", self.num1, self.num2);
output.into()

and of course, neither worked.

6

Great! Almost there! Try:

text(format!("{} x {} = ", self.num1, self.num2)).into()

into is used in this case to convert a specific type into a generic Element.

"Hello, world!" is a &'static str and can be turned into an Element with just into, which is convenient for cases such as button("Some text").

However, format! creates a String; therefore, into cannot be used directly. However, you can use the text helper to create a Text widget from any impl ToString. A Text widget can always be turned into an Element.

7

Awesome! That worked. Thank you.

Now I can start playing around with it. Tried to learn more about text(). Found Text in iced::advanced::widget - Rust but not text().