rafaelcaricio/lvgl-rs

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Button callbacks #5

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opened 2020-05-15 04:04:16 +00:00 by justinmoon · 9 comments

justinmoon commented

2020-05-15 04:04:16 +00:00

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How can I define a button "on-click" callback?

I'm trying to add a button example and I'm stuck trying to type the callback to lvgl_sys::lvgl_obj_set_event_cb

How can I define a button "on-click" callback? I'm trying to add a button example and [I'm stuck trying to type the callback to `lvgl_sys::lvgl_obj_set_event_cb`](https://github.com/justinmoon/lvgl-rs/blob/50105eb3dcb2cbcb8dfb4cf0427a199d861aa058/examples/button/src/main.rs#L42)

justinmoon commented

2020-05-15 04:45:22 +00:00

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It seems like lvgl_sys wants the callback to be an unsafe extern "C" function, which doesn't really make sense if I'm providing this callback from Rust ...

It seems like `lvgl_sys` wants the callback to be an `unsafe extern "C"` function, which doesn't really make sense if I'm providing this callback from Rust ...

rafaelcaricio commented

2020-05-15 10:51:25 +00:00

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Hi @justinmoon,

It is flattering that you have interest in using lvgl-rs. I just wanted to tell you that this project is in the very early stages of development. I would really appreciate help of others, like you, to push this project forward. Most things are still missing and I'm still pondering about how to handle the global state dependency in lvgl library rely.

Hi @justinmoon, It is flattering that you have interest in using lvgl-rs. I just wanted to tell you that this project is in the very early stages of development. I would really appreciate help of others, like you, to push this project forward. Most things are still missing and I'm still pondering about how to handle the global state dependency in lvgl library rely.

justinmoon commented

2020-05-15 19:52:04 +00:00

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No problem. I'll try to help out wherever I can.

rafaelcaricio commented

2020-05-15 21:06:30 +00:00

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In general, I'm trying to follow the recommendations from those articles:

In general, I'm trying to follow the recommendations from those articles: - http://adventures.michaelfbryan.com/posts/how-not-to-riir/ - https://kornel.ski/rust-sys-crate

justinmoon commented

2020-05-15 21:19:59 +00:00

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Thanks for sharing.

I'm trying to figure out how to get these event callbacks working. This post seems to explain roughly what is needed, but still working on it

Thanks for sharing. I'm trying to figure out how to get these event callbacks working. [This post](https://users.rust-lang.org/t/callback-based-c-ffi/26583/5) seems to explain roughly what is needed, but still working on it

justinmoon commented

2020-05-15 22:08:46 +00:00

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On a related note, how were you able to get a button to look like this?

Mine look like this

Might help if you could add whatever code produced your screenshot as an example.

On a related note, how were you able to get a button to look like this? ![image](https://user-images.githubusercontent.com/4335621/82100064-75ae2d80-96ce-11ea-8368-63404e453bf9.png) Mine look like this ![image](https://user-images.githubusercontent.com/4335621/82100169-b3ab5180-96ce-11ea-8711-665b46017fba.png) Might help if you could add whatever code produced your screenshot as an example.

rafaelcaricio commented

2020-05-27 20:04:09 +00:00

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@justinmoon that screenshot was in an earlier version of the demo app, 7bf1ac0cae/examples/demo/src/main.rs I was using SDL directly.

@justinmoon that screenshot was in an earlier version of the demo app, https://github.com/rafaelcaricio/lvgl-rs/blob/7bf1ac0cae3b1867b4687efaf1ccbd9e321df54b/examples/demo/src/main.rs I was using SDL directly.

rafaelcaricio commented

2020-05-31 17:28:24 +00:00

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Hey @justinmoon , I just implemented a way to add event callbacks. So you can do things when buttons are clicked, hovered, etc. Please look the example:

let mut button = Button::new(&mut screen);
button.on_event(|this, event| {
    if let lvgl::Event::Clicked = event {
        println!("Clicked!");
    }
});

https://github.com/rafaelcaricio/lvgl-rs/blob/master/examples/bar.rs#L48-L52

Hey @justinmoon , I just implemented a way to add event callbacks. So you can do things when buttons are clicked, hovered, etc. Please look the example: ```rust let mut button = Button::new(&mut screen); button.on_event(|this, event| { if let lvgl::Event::Clicked = event { println!("Clicked!"); } }); ``` https://github.com/rafaelcaricio/lvgl-rs/blob/master/examples/bar.rs#L48-L52

rafaelcaricio commented

2020-05-31 17:29:36 +00:00

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I will close this ticket now, as this is now supported. If you have other questions. Please open other issue.