Can't seem to make Button fire when clicked

[Isaac-Leonard]

I just got started with cacao today so am probably missing something but I can't seem to get the button to fire when clicked. Here is my code:

use cacao::appkit::window::Window;
use cacao::appkit::{App, AppDelegate};
use cacao::filesystem::FileSelectPanel;
use cacao::layout::Layout;
use cacao::notification_center::Dispatcher;
use cacao::text::{Font, Label};
use cacao::view::{View, ViewController, ViewDelegate};
use cacao::{button, view};

struct BasicApp {
    window: Window,
    content_view: ViewController<ContentView>,
}

impl Default for BasicApp {
    fn default() -> Self {
        Self {
            window: Window::default(),
            content_view: ViewController::new(ContentView::default()),
        }
    }
}

impl Dispatcher for BasicApp {
    type Message = Message;

    /// Handles a message that came over on the main (UI) thread.
    fn on_ui_message(&self, message: Self::Message) {
        eprint!("Got message");
        if let Some(delegate) = &self.content_view.view.delegate {
            delegate.on_ui_message(message);
        }
    }
}

impl AppDelegate for BasicApp {
    fn did_finish_launching(&self) {
        App::activate();
        self.window.set_minimum_content_size(400., 400.);
        self.window.set_title("Hello World!");
        self.window.set_movable_by_background(true);
        self.window.set_content_view_controller(&self.content_view);
        self.window.show();
        //        FileSelectPanel::new().show(|_| {});
    }

    fn should_terminate_after_last_window_closed(&self) -> bool {
        true
    }
}

#[derive(Default)]
struct ContentView {
    content: view::View,
    label: Label,
}

impl ViewDelegate for ContentView {
    const NAME: &'static str = "SafeAreaView";

    fn did_load(&mut self, view: View) {
        let font = Font::system(30.);
        self.label.set_font(&font);
        self.label.set_text("Hello World");
        self.label
            .set_text_color(cacao::color::Color::rgb(255, 255, 255));

        self.content.add_subview(&self.label);
        let mut btn = button::Button::new("Click me");
        btn.set_action(|| dispatch_ui(Message::ChangeText));
        btn.set_key_equivalent("c");
        self.content.add_subview(&btn);
        view.add_subview(&self.content);

        // Add layout constraints to be 100% excluding the safe area
        // Do last because it will crash because the view needs to be inside the hierarchy
        cacao::layout::LayoutConstraint::activate(&[
            self.content
                .top
                .constraint_equal_to(&view.safe_layout_guide.top),
            self.content
                .leading
                .constraint_equal_to(&view.safe_layout_guide.leading),
            self.content
                .trailing
                .constraint_equal_to(&view.safe_layout_guide.trailing),
            self.content
                .bottom
                .constraint_equal_to(&view.safe_layout_guide.bottom),
        ])
    }
}

impl Dispatcher for ContentView {
    type Message = Message;

    /// Handles a message that came over on the main (UI) thread.
    fn on_ui_message(&self, message: Self::Message) {
        self.label.set_text("Changed text")
    }
}

/// Dispatch a message on a background thread.
fn dispatch_ui(message: Message) {
    println!("Dispatching UI message: {:?}", message);
    App::<BasicApp, Message>::dispatch_main(message);
}

#[derive(Clone, Debug)]
enum Message {
    ChangeText,
}
fn main() {
    App::new("com.hello.world", BasicApp::default()).run();
}

No matter what I do the button refuses to call the action when I click on it, is this a bug or have I missed something? It may be relevant that I am using VoiceOver, the macOS screen reader, but have tested without it and still have the same issue so don't think its related.

[Isaac-Leonard]

Okay, I've fixed it, I wasn't storing the button anywhere so it was getting dropped Is there any way to enforce in the type system that it can't be dropped if its being displayed?

[ryanmcgrath]

Unfortunately no, at least not without some significant creative solution that I've not thought of yet (e.g effectively some form of a virtual DOM that's managed for you). It's due to having to work between Rust's lifetime model and the ObjC model.

I would be open to reviewing and considering a solution for this as a feature of the library, provided it's not invalidating the Rust ownership model - but I unfortunately don't have time to work on it myself.

Going to close this issue but feel free to open other ones as you hit issues, always happy to weigh in.

[Isaac-Leonard]

Makes sense I'd love to try implement some sort of framework on top of all this to manage everything like that if I get time.

[ryanmcgrath]

You're always welcome to pick up and revive Alchemy. ;)