257 lines
8.9 KiB
Swift
257 lines
8.9 KiB
Swift
//
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// UsbCameraEngine.swift
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// usb_camera_android
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//
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// iOS 端 UVC 外接摄像头引擎（iPadOS 17+）。
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// 通过 AVCaptureDevice.DiscoverySession 枚举外接摄像头，
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// 用 AVCaptureSession + AVCaptureVideoPreviewLayer 出画面。
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// 协议与 Android 端完全对齐：deviceId 使用 device.uniqueID。
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//
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// 兼容性：整个 Runner / pod 的最低系统版本仍为 iOS 12，
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// 因此对 iOS 17 才有的 API（.externalUnknown）一律用 #available 运行时保护，
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// iOS 17 以下枚举返回空、isSupported 返回 false，走优雅降级。
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//
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import AVFoundation
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import Flutter
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import UIKit
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final class UsbCameraEngine: NSObject, FlutterStreamHandler {
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/// 预览会话，供 PlatformView 绑定 layer。
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private(set) var captureSession: AVCaptureSession?
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private(set) var currentDevice: AVCaptureDevice?
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private var isRunning = false
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private var eventSink: FlutterEventSink?
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private let workQueue = DispatchQueue(label: "com.maibu.usb_camera.engine")
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// MARK: - 能力探测
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/// iPhone 无论系统版本都不支持外接摄像头输入；iPad 需 iPadOS 17+。
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func isSupported() -> Bool {
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if #available(iOS 17.0, *) {
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return UIDevice.current.userInterfaceIdiom != .phone
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}
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return false
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}
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// MARK: - 枚举
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private func discoverySession() -> AVCaptureDevice.DiscoverySession {
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if #available(iOS 17.0, *) {
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return AVCaptureDevice.DiscoverySession(
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deviceTypes: [.externalUnknown],
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mediaType: .video,
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position: .unspecified
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)
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}
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return AVCaptureDevice.DiscoverySession(
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deviceTypes: [],
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mediaType: .video,
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position: .unspecified
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)
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}
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/// 返回设备列表，字段与 Android 对齐：deviceId / vendorId / productId / productName。
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func getDeviceList() -> [[String: Any]] {
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return discoverySession().devices.map { device in
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return [
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"deviceId": device.uniqueID,
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"vendorId": 0,
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"productId": 0,
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"productName": device.localizedName,
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]
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}
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}
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// MARK: - 打开 / 关闭
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func open(deviceId: String?, resolution: String?, result: @escaping FlutterResult) {
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guard let deviceId = deviceId else {
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result(FlutterError(code: "INVALID_ARG", message: "deviceId 为空", details: nil))
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return
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}
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let handle = { [weak self] in
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guard let self = self else { return }
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switch AVCaptureDevice.authorizationStatus(for: .video) {
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case .authorized:
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self.doOpen(deviceId: deviceId, resolution: resolution, result: result)
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case .notDetermined:
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AVCaptureDevice.requestAccess(for: .video) { granted in
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DispatchQueue.main.async {
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if granted {
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self.doOpen(deviceId: deviceId, resolution: resolution, result: result)
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} else {
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result(FlutterError(code: "PERMISSION_DENIED",
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message: "用户拒绝了相机权限", details: nil))
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}
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}
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}
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default:
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result(FlutterError(code: "PERMISSION_DENIED",
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message: "相机权限未授权，请在系统设置中开启", details: nil))
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}
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}
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if Thread.isMainThread { handle() } else { DispatchQueue.main.async(execute: handle) }
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}
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private func doOpen(deviceId: String, resolution: String?, result: @escaping FlutterResult) {
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let candidates = discoverySession().devices
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guard let device = candidates.first(where: { $0.uniqueID == deviceId }) else {
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result(FlutterError(code: "DEVICE_NOT_FOUND",
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message: "USB 设备已拔出或未检测到，请重新插入后重试", details: nil))
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return
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}
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stopRunningIfNeeded()
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let session = AVCaptureSession()
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session.beginConfiguration()
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if let input = try? AVCaptureDeviceInput(device: device),
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session.canAddInput(input) {
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session.addInput(input)
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}
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if let resolution = resolution {
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applyResolution(resolution, to: device)
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}
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session.commitConfiguration()
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self.captureSession = session
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self.currentDevice = device
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workQueue.async {
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session.startRunning()
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}
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isRunning = true
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postEvent(type: "opened", deviceId: deviceId)
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result(nil)
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}
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func close(result: FlutterResult?) {
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stopRunningIfNeeded()
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captureSession = nil
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currentDevice = nil
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result?(nil)
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}
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private func stopRunningIfNeeded() {
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if isRunning, let session = captureSession {
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workQueue.async {
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if session.isRunning { session.stopRunning() }
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}
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}
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isRunning = false
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}
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// MARK: - 分辨率
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func getSupportedResolutions() -> [String] {
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guard let device = currentDevice else { return [] }
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var seen = Set<String>()
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var list: [String] = []
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for fmt in device.formats {
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let dims = CMFormatDescriptionGetDimensions(fmt.description)
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let key = "\(dims.width)x\(dims.height)"
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if seen.insert(key).inserted { list.append(key) }
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}
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return list
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}
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func getPreviewSize() -> [String: Any]? {
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guard isRunning, let device = currentDevice else { return nil }
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let dims = CMFormatDescriptionGetDimensions(device.activeFormat.description)
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return ["width": Int(dims.width), "height": Int(dims.height)]
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}
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func setResolution(_ resolution: String?, result: FlutterResult) {
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guard let resolution = resolution, let device = currentDevice else {
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result(FlutterError(code: "NO_DEVICE", message: "摄像头未打开", details: nil))
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return
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}
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if applyResolution(resolution, to: device) {
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postEvent(type: "opened", deviceId: device.uniqueID)
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result(nil)
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} else {
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result(FlutterError(code: "RESOLUTION_UNSUPPORTED",
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message: "不支持的分辨率 \(resolution)", details: nil))
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}
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}
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@discardableResult
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private func applyResolution(_ resolution: String, to device: AVCaptureDevice) -> Bool {
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let parts = resolution.lowercased().split(separator: "x")
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guard parts.count == 2, let w = Int(parts[0]), let h = Int(parts[1]) else { return false }
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do {
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try device.lockForConfiguration()
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for fmt in device.formats {
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let dims = CMFormatDescriptionGetDimensions(fmt.description)
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if Int(dims.width) == w && Int(dims.height) == h {
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device.activeFormat = fmt
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device.unlockForConfiguration()
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return true
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}
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}
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device.unlockForConfiguration()
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} catch {
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return false
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}
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return false
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}
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// MARK: - 插拔监听
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func startMonitoring() {
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let nc = NotificationCenter.default
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nc.addObserver(self, selector: #selector(deviceConnected(_:)),
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name: AVCaptureDevice.wasConnectedNotification, object: nil)
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nc.addObserver(self, selector: #selector(deviceDisconnected(_:)),
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name: AVCaptureDevice.wasDisconnectedNotification, object: nil)
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}
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@objc private func deviceConnected(_ note: Notification) {
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guard let device = note.object as? AVCaptureDevice else { return }
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postEvent(type: "attached", deviceId: device.uniqueID)
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}
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@objc private func deviceDisconnected(_ note: Notification) {
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guard let device = note.object as? AVCaptureDevice else { return }
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if device.uniqueID == currentDevice?.uniqueID {
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stopRunningIfNeeded()
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}
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postEvent(type: "detached", deviceId: device.uniqueID)
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}
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// MARK: - FlutterStreamHandler
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func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
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self.eventSink = events
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return nil
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}
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func onCancel(withArguments arguments: Any?) -> FlutterError? {
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self.eventSink = nil
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return nil
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}
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private func postEvent(type: String, deviceId: String?) {
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let payload: [String: Any] = [
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"type": type,
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"data": deviceId == nil ? [:] : ["deviceId": deviceId!],
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]
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DispatchQueue.main.async { [weak self] in
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self?.eventSink?(payload)
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}
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}
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func dispose() {
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NotificationCenter.default.removeObserver(self)
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stopRunningIfNeeded()
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captureSession = nil
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currentDevice = nil
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}
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}
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