Method preview

src-tauri/src/recorder.rs:122–203

Return PNG encoded screen preview

(&self)

    /// Return PNG encoded screen preview
    pub fn preview(&self) -> anyhow::Result<Vec<u8>> {
        use gst::prelude::*;
        use scrap::Capturer;

        let mut capturer = Capturer::new(self.display.clone_device()).unwrap();

        let width;
        let height;
        let data;
        
        loop {
            let frame = match capturer.frame(std::time::Duration::ZERO) {
                Ok(frame) => frame,
                Err(err) if err.kind() == std::io::ErrorKind::WouldBlock => continue,
                Err(err) if err.kind() == std::io::ErrorKind::InvalidData => {
                    eprintln!("Received invalid data, skipping");
                    continue
                },
                Err(err) => panic!("{err}"),
            };

            let scrap::Frame::PixelBuffer(pixel_buffer) = frame else {
                eprintln!("Received frame is not PixelBuffer, skipping");
                continue
            };

            width = pixel_buffer.width();
            height = pixel_buffer.height();
            data = pixel_buffer.data().to_vec();

            break;
        };

        let pipeline =
            gst::parse::launch("appsrc name=input ! videoconvert ! pngenc ! appsink name=output").unwrap()
                .dynamic_cast::<gst::Pipeline>().unwrap();

        pipeline.by_name("input").unwrap().dynamic_cast::<gst_app::AppSrc>().unwrap()
            .set_callbacks(gst_app::AppSrcCallbacks::builder()
                .need_data(move |source, _| {
                    let caps = gst::Caps::builder("video/x-raw")
                        .field("format", "BGRx")
                        .field("width", width as i32)
                        .field("height", height as i32)
                        .build();

                    source.set_caps(Some(&caps));

                    let buffer = gst::Buffer::from_slice(data.clone());

                    let _ = source.push_buffer(buffer);

                    source.end_of_stream().unwrap();
                }).build());

        let preview = Arc::new(Mutex::new(None));

        pipeline.by_name("output").unwrap().dynamic_cast::<gst_app::AppSink>().unwrap()