You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: pipewire.rs
    path of file: ./repos/Weylus/src/capturable
    
    the code of the file until where you have to start completion: use std::collections::HashMap;
use std::error::Error;
use std::os::unix::io::AsRawFd;
use std::sync::{atomic::AtomicBool, Arc, Mutex};
use std::time::Duration;
use tracing::{debug, trace, warn};

use dbus::{
    arg::{OwnedFd, PropMap, RefArg, Variant},
    blocking::{Proxy, SyncConnection},
    message::{MatchRule, MessageType},
    Message,
};

use gstreamer as gst;
use gstreamer::prelude::*;
use gstreamer_app::AppSink;

use crate::capturable::{Capturable, Recorder};
use crate::video::PixelProvider;

use crate::capturable::pipewire_dbus::{
    OrgFreedesktopPortalRequestResponse, OrgFreedesktopPortalScreenCast,
};

#[derive(Debug, Clone, Copy)]
struct PwStreamInfo {
    path: u64,
    source_type: u64,
}

#[derive(Debug)]
pub struct DBusError(String);

impl std::fmt::Display for DBusError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self(s) = self;
        write!(f, "{}", s)
    }
}

impl Error for DBusError {}

#[derive(Debug)]
pub struct GStreamerError(String);

impl std::fmt::Display for GStreamerError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self(s) = self;
        write!(f, "{}", s)
    }
}

impl Error for GStreamerError {}

#[derive(Clone)]
pub struct PipeWireCapturable {
    // connection needs to be kept alive for recording
    dbus_conn: Arc<SyncConnection>,
    fd: OwnedFd,
    path: u64,
    source_type: u64,
}

impl
    
    fn capture(&mut self) -> Result<PixelProvider, Box<dyn Error>> {
        if let Some(sample) = self
            .appsink
            .try_pull_sample(gst::ClockTime::from_mseconds(33))
        {
            let cap = sample.caps().unwrap().structure(0).unwrap();
            let w: i32 = cap.value("width")?.get()?;
            let h: i32 = cap.value("height")?.get()?;
            self.pix_fmt = cap.value("format")?.get()?;
            let w = w as usize;
            let h = h as usize;
            let buf = sample
                .buffer_owned()
                .ok_or_else(|| GStreamerError("Failed to get owned buffer.".into()))?;
            let mut crop = buf
                .meta::<gstreamer_video::VideoCropMeta>()
                .map(|m| m.rect());
            // only crop if necessary
            if Some((0, 0, w as u32, h as u32)) == crop {
                crop = None;
            }
            let buf = buf
                .into_mapped_buffer_readable()
                .map_err(|_| GStreamerError("Failed to map buffer.".into()))?;
            let buf_size = buf.size();
            // BGRx is 4 bytes per pixel
            if buf_size != (w * h * 4) {
                // for some reason the width and height of the caps do not guarantee correct buffer
                // size, so ignore those buffers, see:
                // https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/985
                trace!(
                    "Size of mapped buffer: {} does NOT match size of capturable {}x{}@BGRx, \
                    dropping it!",
                    buf_size,
                    w,
                    h
                );
            } else {
                // Copy region specified by crop into self.buffer_cropped
                // TODO: Figure out if ffmpeg provides a zero copy alternative
                if let Some((x_off, y_off, w_crop, h_crop)) = crop {
                    let x_off = x_off as usize;
                    let y_off = y_off as usize;
                    let w_crop = w_crop as usize;
                    let h_crop = h_crop as usize;
                    self.buffer_cropped.clear();
                    let data = buf.as_slice();
                    // BGRx is 4 bytes per pixel
                    self.buffer_cropped.reserve(w_crop * h_crop * 4);
                    for y in y_off..(y_off + h_crop) {
                        let i = 4 * (w * y + x_off);
                        self.buffer_cropped.extend(&data[i..i + 4 * w_crop]);
                    }
                    self.width = w_crop;
                    self.height = h_crop;
                } else {
                    self.width = w;
                    self.height = h;
                }
                self.is_cropped = crop.is_some();
                self.buffer = Some(buf);
            }
        } else {
            trace!("No new buffer available, falling back to previous one.");
        }
        if self.buffer.is_none() {
            return Err(Box::new(GStreamerError("No buffer available!".into())));
        }
        let buf = if self.is_cropped {
            self.buffer_cropped.as_slice()
        } else {
            self.buffer.as_ref().unwrap().as_slice()
        };
        match self.pix_fmt.as_str() {
            "BGRx" => Ok(PixelProvider::BGR0(self.width, self.height, buf)),
            "RGBx" => Ok(PixelProvider::RGB0(self.width, self.height, buf)),
            _ => unreachable!(),
        }
    }