gstreamer-rs/gstreamer/src/pad.rs

// Copyright (C) 2017 Sebastian Dröge <sebastian@centricular.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use Pad;
use PadProbeType;
use PadProbeReturn;

use std::cell::RefCell;
use std::mem::transmute;

use glib::IsA;
use glib::translate::{ToGlib, from_glib, from_glib_none};
use glib::source::CallbackGuard;
use glib_ffi::gpointer;

use libc;

use ffi;

pub struct PadProbeId(libc::c_ulong);

pub struct PadProbeInfo {
    pub mask: PadProbeType,
    pub id: PadProbeId,
    pub offset: u64,
    pub size: u32,
    pub data: Option<PadProbeData>,
}

pub enum PadProbeData {
    // Buffer(&Buffer),
    // BufferList(&BufferList),
    // Query(&Query),
    // Event(&Event),
    Unknown,
}

pub trait PadExtManual {
    fn add_probe<F>(&self, mask: PadProbeType, func: F) -> PadProbeId
    where
        F: FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static;
    fn remove_probe(&self, id: PadProbeId);
}

impl<O: IsA<Pad>> PadExtManual for O {
    fn add_probe<F>(&self, mask: PadProbeType, func: F) -> PadProbeId
    where
        F: FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static,
    {
        unsafe {
            let id = ffi::gst_pad_add_probe(
                self.to_glib_none().0,
                mask.to_glib(),
                Some(trampoline_pad_probe),
                into_raw_pad_probe(func),
                Some(destroy_closure_pad_probe),
            );

            PadProbeId(id)
        }
    }

    fn remove_probe(&self, id: PadProbeId) {
        unsafe {
            ffi::gst_pad_remove_probe(self.to_glib_none().0, id.0 as libc::c_ulong);
        }
    }
}

unsafe extern "C" fn trampoline_pad_probe(
    pad: *mut ffi::GstPad,
    info: *mut ffi::GstPadProbeInfo,
    func: gpointer,
) -> ffi::GstPadProbeReturn {
    let _guard = CallbackGuard::new();
    let func: &RefCell<
        Box<FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static>,
    > = transmute(func);

    let mut probe_info = PadProbeInfo {
        mask: from_glib((*info).type_),
        id: PadProbeId((*info).id),
        offset: (*info).offset,
        size: (*info).size,
        data: if (*info).data.is_null() {
            None
        } else {
            Some(PadProbeData::Unknown)
        },
    };

    let ret = (&mut *func.borrow_mut())(&from_glib_none(pad), &mut probe_info).to_glib();

    // TODO: Possibly replace info.data

    ret
}

unsafe extern "C" fn destroy_closure_pad_probe(ptr: gpointer) {
    let _guard = CallbackGuard::new();
    Box::<RefCell<Box<FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static>>>::from_raw(ptr as *mut _);
}

fn into_raw_pad_probe<
    F: FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static,
>(
    func: F,
) -> gpointer {
    let func: Box<
        RefCell<Box<FnMut(&Pad, &mut PadProbeInfo) -> PadProbeReturn + Send + Sync + 'static>>,
    > = Box::new(RefCell::new(Box::new(func)));
    Box::into_raw(func) as gpointer
}