changing_the_window_dynamically.md

Changing The Window Dynamically

We can use functions provided in window module to change the window after it is initialized.

For example, the resize function of the window returns a task that can be used as the return value in the update method. There are many other functions that return tasks in the window module.

The resize function needs an ID of the window we are going to resize. To do that, the window module has a get_latest function. This function also returns a task that needs to be resolved to the Id of the latest window. In our case, since we have a single window, it will always return the Id of the main window.

use iced::{
    Element, Result, Size, Task,
    widget::{button, row, text_input},
    window,
};

fn main() -> Result {
    iced::application("My App", MyApp::update, MyApp::view).run_with(MyApp::new)
}

#[derive(Debug, Clone)]
enum Message {
    UpdateWidth(String),
    UpdateHeight(String),
    ResizeWindow,
}

struct MyApp {
    width: String,
    height: String,
}

impl MyApp {
    fn new() -> (Self, Task<Message>) {
        (
            Self {
                width: "1024".into(),
                height: "768".into(),
            },
            Task::none(),
        )
    }

    fn resize_window(width: f32, height: f32) -> impl Fn(window::Id) -> Task<Message> {
        move |window_id: window::Id| {
            println!("Calling resize_window");
            window::resize::<Message>(window_id, Size::new(width, height))
        }
    }

    fn update(&mut self, message: Message) -> Task<Message> {
        match message {
            Message::UpdateWidth(w) => self.width = w,
            Message::UpdateHeight(h) => self.height = h,
            Message::ResizeWindow => {
                let width = self.width.parse::<f32>().unwrap_or(1024.0);
                let height = self.height.parse::<f32>().unwrap_or(768.0);
                println!("Resizing window to {}x{}", width, height);
                return window::get_latest().and_then(Self::resize_window(width, height));
            }
        }
        Task::none()
    }

    fn view(&self) -> Element<Message> {
        row![
            text_input("Width", &self.width).on_input(Message::UpdateWidth),
            text_input("Height", &self.height).on_input(Message::UpdateHeight),
            button("Resize window").on_press(Message::ResizeWindow),
        ]
        .into()
    }
}

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