Subclassing GstSystemClock in Rust

[Rodrigo Santos]

Hey folks, I'm trying to create a CustomClock implementation in Rust that is a subclass of GstSystemClock. I found some examples of how one can create GstElements in Rust but none explaining how to subclass a GstSystemClock. 



Is it possible to create a custom clock implementation purely in Rust? 



The code below is the boilerplate I implemented so far. This code doesn't compiler, one of the error messages says: 



type ParentType = gst_sys::GstSystemClock; 

    |                       ^^^^^^^^^^^^^^^^^^^^^^^ the trait `FromGlibPtrNone<*mut _>` is not implemented for `GstSystemClock`



I'm fairly new to create new GLib types and Gstreamer plugins in Rust, what am I missing? 



PS: a while ago I've done a similar implementation in C (https://github.com/TeleMidia/LibPlay/blob/master/lib/lp-clock.c) and now I'm trying to do it purely in Rust.



use gstreamer as gst; 

use gst::glib;

use gst::prelude::*;

use gst::subclass::prelude::*;

use gstreamer_sys as gst_sys;



pub struct CustomClock {

    current_time_in_ns: gst::ClockTime,

    internal_clock: gst::Clock,

}



impl CustomClock {

    pub fn new() -> Self {

        let sys_clock = gst::SystemClock::obtain();

        let now = sys_clock.internal_time();



        Self {

            current_time_in_ns: now,

            internal_clock: sys_clock

        }

    }



    pub fn advance_time(self: &mut Self, time_in_ns: gst::ClockTime) {

        self.current_time_in_ns += time_in_ns;

    }

}



#[glib::object_subclass]

impl ObjectSubclass for CustomClock {

    const NAME: &'static str = "CustomClock";

    type Type = CustomClock;

    type ParentType = gst_sys::GstSystemClock;

}



// Implementation of glib::Object virtual methods

impl ObjectImpl for CustomClock {}



impl GstObjectImpl for CustomClock {}



impl ClockImpl for CustomClock {

    fn internal_time(&self, clock: &Self::Type) -> gst::ClockTime {

        self.current_time_in_ns

    }

}



Rodrigo Santos
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