A Simple GUI Library

트레이트와 트레이트 객체 지식을 활용하여 고전적인 GUI 라이브러리를 설계합니다. 라이브러리에는 몇가지 위젯이 있습니다:

• Window: title 속성과 다른 위젯이 포함됩니다.
• Button: label위젯과 버튼이 눌렸을때 실행되는 콜백 함수가 있습니다.
• Label: label 위젯 입니다. 위젯은 Widget 트레이트를 구현합니다. 아래 코드를 참조하세요

아래 코드를 https://play.rust-lang.org/에 복사하고 누락된 draw_into메서드를 채워 넣어 Widget 트레이트를 완성해봅시다:

Let us design a classical GUI library using our new knowledge of traits and trait objects. We will have a number of widgets in our library:

• Window: has a title and contains other widgets.
• Button: has a label and a callback function which is invoked when the button is pressed.
• Label: has a label.

The widgets will implement a Widget trait, see below.
Copy the code below to https://play.rust-lang.org/, fill in the missing draw_into methods so that you implement the Widget trait:

// TODO: remove this when you're done with your implementation.
#![allow(unused_imports, unused_variables, dead_code)]

pub trait Widget {
    /// Natural width of `self`.
    fn width(&self) -> usize;

    /// Draw the widget into a buffer.
    fn draw_into(&self, buffer: &mut dyn std::fmt::Write);

    /// Draw the widget on standard output.
    fn draw(&self) {
        let mut buffer = String::new();
        self.draw_into(&mut buffer);
        println!("{}", &buffer);
    }
}

pub struct Label {
    label: String,
}

impl Label {
    fn new(label: &str) -> Label {
        Label {
            label: label.to_owned(),
        }
    }
}

pub struct Button {
    label: Label,
    callback: Box<dyn FnMut()>,
}

impl Button {
    fn new(label: &str, callback: Box<dyn FnMut()>) -> Button {
        Button {
            label: Label::new(label),
            callback,
        }
    }
}

pub struct Window {
    title: String,
    widgets: Vec<Box<dyn Widget>>,
}

impl Window {
    fn new(title: &str) -> Window {
        Window {
            title: title.to_owned(),
            widgets: Vec::new(),
        }
    }

    fn add_widget(&mut self, widget: Box<dyn Widget>) {
        self.widgets.push(widget);
    }
}


impl Widget for Label {
    fn width(&self) -> usize {
        unimplemented!()
    }

    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
        unimplemented!()
    }
}

impl Widget for Button {
    fn width(&self) -> usize {
        unimplemented!()
    }

    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
        unimplemented!()
    }
}

impl Widget for Window {
    fn width(&self) -> usize {
        unimplemented!()
    }

    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
        unimplemented!()
    }
}

fn main() {
    let mut window = Window::new("Rust GUI Demo 1.23");
    window.add_widget(Box::new(Label::new("This is a small text GUI demo.")));
    window.add_widget(Box::new(Button::new(
        "Click me!",
        Box::new(|| println!("You clicked the button!")),
    )));
    window.draw();
}

위 프로그램의 출력은 아래와 같습니다:

The output of the above program can be something simple like this:

========
Rust GUI Demo 1.23
========

This is a small text GUI demo.

| Click me! |

정력된 글자를 그리기 위해서는 fill/alignment 를 참조하시기 바랍니다. 특수 문자(여기서는 ‘/’)로 패딩을 주는 방법과 정렬을 제어하는 방법을 확인하시기 바랍니다.

If you want to draw aligned text, you can use the fill/alignment formatting operators. In particular, notice how you can pad with different characters (here a '/') and how you can control alignment:

fn main() {
    let width = 10;
    println!("left aligned:  |{:/<width$}|", "foo");
    println!("centered:      |{:/^width$}|", "foo");
    println!("right aligned: |{:/>width$}|", "foo");
}

위의 정렬 트릭을 사용하여 다음과 같은 출력을 생성할 수 있습니다.

Using such alignment tricks, you can for example produce output like this:

+--------------------------------+
|       Rust GUI Demo 1.23       |
+================================+
| This is a small text GUI demo. |
| +-----------+                  |
| | Click me! |                  |
| +-----------+                  |
+--------------------------------+

역주

• 추가 구현할 함수는 없고 impl Widget for ~ 의 두 메서드들만 구현하면 됩니다.
• label에 줄바꿈(개행)문자도 포함될 수 있습니다.\n