Method new

rustcv/src/videoio/mod.rs:44–166

(index: u32)

impl VideoCapture {
    pub fn new(index: u32) -> Result<Self> {
        // 1. 创建驱动 (移动到后台线程前先创建)
        let driver = backend::create_driver()?;

        // 2. 查找设备 ID
        let device_id = Self::resolve_device_id(&*driver, index)?;

        // 3. 创建通道
        let (cmd_tx, cmd_rx) = bounded::<Command>(1);
        let (res_tx, res_rx) = bounded::<Response>(1);

        // 4. 【升级】启动后台任务
        // 我们将 driver 和 device_id 移动到后台，让后台全权管理生命周期
        runtime::get_runtime().spawn(async move {
            // 初始配置 (默认)
            let mut current_config = CameraConfig::new();
            // 当前流 (Option，允许为空以便重启)
            let mut current_stream: Option<Box<dyn Stream>> = None;

            // 内部辅助：尝试打开流
            // 这是一个闭包无法捕获 async 引用，所以我们用 macro 或者简单的代码块复用逻辑
            // 这里为了简单，直接在循环外先尝试打开一次
            match driver.open(&device_id, current_config.clone()) {
                Ok((s, _)) => {
                    // 启动流
                    let mut s = s;
                    if let Err(e) = s.start().await {
                        let _ = res_tx.send(Response::Error(format!("Stream start failed: {}", e)));
                        return;
                    }
                    current_stream = Some(s);
                }
                Err(e) => {
                    // 初始打开失败不要紧，后续 NextFrame 会报错，或者允许 SetResolution 修复
                    eprintln!("Warning: Initial open failed: {}", e);
                }
            }

            // 循环处理指令
            while let Ok(cmd) = cmd_rx.recv() {
                match cmd {
                    Command::NextFrame => {
                        if let Some(stream) = current_stream.as_mut() {
                            match stream.next_frame().await {
                                Ok(frame) => {
                                    let data_vec = frame.data.to_vec();
                                    let w = frame.width;
                                    let h = frame.height;
                                    // 提取 FourCC
                                    let fourcc_val: u32 = match frame.format {
                                        PixelFormat::Known(fcc) => fcc.0,
                                        PixelFormat::Unknown(val) => val,
                                    };

                                    let _ = res_tx.send(Response::FrameData {
                                        width: w,
                                        height: h,
                                        data: data_vec,