[cscore] Add USB camera change event (#3123)

cscore/src/main/java/edu/wpi/cscore/VideoEvent.java

@@ -26,7 +26,8 @@ public class VideoEvent {
     kTelemetryUpdated(0x8000),
     kSinkPropertyCreated(0x10000),
     kSinkPropertyValueUpdated(0x20000),
-    kSinkPropertyChoicesUpdated(0x40000);
+    kSinkPropertyChoicesUpdated(0x40000),
+    kUsbCamerasChanged(0x80000);
 
     private final int value;
 
@@ -84,6 +85,8 @@ public class VideoEvent {
         return Kind.kSinkPropertyValueUpdated;
       case 0x40000:
         return Kind.kSinkPropertyChoicesUpdated;
+      case 0x80000:
+        return Kind.kUsbCamerasChanged;
       default:
         return Kind.kUnknown;
     }

cscore/src/main/native/cpp/Instance.cpp

@@ -36,7 +36,10 @@ static void def_log_func(unsigned int level, const char* file,
   wpi::errs() << oss.str();
 }
 
-Instance::Instance() : telemetry(notifier), networkListener(logger, notifier) {
+Instance::Instance()
+    : telemetry(notifier),
+      networkListener(logger, notifier),
+      usbCameraListener(logger, notifier) {
   SetDefaultLogger();
 }
 
@@ -52,6 +55,7 @@ void Instance::Shutdown() {
   m_sinks.FreeAll();
   m_sources.FreeAll();
   networkListener.Stop();
+  usbCameraListener.Stop();
   telemetry.Stop();
   notifier.Stop();
 }

cscore/src/main/native/cpp/Instance.h

@@ -18,6 +18,7 @@
 #include "SourceImpl.h"
 #include "Telemetry.h"
 #include "UnlimitedHandleResource.h"
+#include "UsbCameraListener.h"
 
 namespace cs {
 
@@ -54,6 +55,7 @@ class Instance {
   Notifier notifier;
   Telemetry telemetry;
   NetworkListener networkListener;
+  UsbCameraListener usbCameraListener;
 
  private:
   UnlimitedHandleResource<Handle, SourceData, Handle::kSource> m_sources;

cscore/src/main/native/cpp/Notifier.cpp

@@ -94,3 +94,7 @@ void Notifier::NotifyNetworkInterfacesChanged() {
 void Notifier::NotifyTelemetryUpdated() {
   Send(UINT_MAX, RawEvent::kTelemetryUpdated);
 }
+
+void Notifier::NotifyUsbCamerasChanged() {
+  Send(UINT_MAX, RawEvent::kUsbCamerasChanged);
+}

cscore/src/main/native/cpp/Notifier.h

@@ -83,6 +83,7 @@ class Notifier : public wpi::CallbackManager<Notifier, impl::NotifierThread> {
                           const wpi::Twine& valueStr);
   void NotifyNetworkInterfacesChanged();
   void NotifyTelemetryUpdated();
+  void NotifyUsbCamerasChanged();
 };
 
 }  // namespace cs

cscore/src/main/native/cpp/UsbCameraListener.h

@@ -0,0 +1,31 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#ifndef CSCORE_USBCAMERALISTENER_H_
+#define CSCORE_USBCAMERALISTENER_H_
+
+#include <memory>
+
+#include <wpi/Logger.h>
+
+namespace cs {
+
+class Notifier;
+
+class UsbCameraListener {
+ public:
+  UsbCameraListener(wpi::Logger& logger, Notifier& notifier);
+  ~UsbCameraListener();
+
+  void Start();
+  void Stop();
+
+ private:
+  class Impl;
+  std::unique_ptr<Impl> m_impl;
+};
+
+}  // namespace cs
+
+#endif  // CSCORE_USBCAMERALISTENER_H_

cscore/src/main/native/cpp/cscore_cpp.cpp

@@ -718,6 +718,13 @@ static void StartBackground(int eventMask, bool immediateNotify) {
       inst.notifier.NotifyNetworkInterfacesChanged();
     }
   }
+  if ((eventMask & CS_USB_CAMERAS_CHANGED) != 0) {
+    // start network interface event listener
+    inst.usbCameraListener.Start();
+    if (immediateNotify) {
+      inst.notifier.NotifyUsbCamerasChanged();
+    }
+  }
 }
 
 CS_Listener AddListener(std::function<void(const RawEvent& event)> callback,

cscore/src/main/native/include/cscore_c.h

@@ -170,7 +170,8 @@ enum CS_EventKind {
   CS_TELEMETRY_UPDATED = 0x8000,
   CS_SINK_PROPERTY_CREATED = 0x10000,
   CS_SINK_PROPERTY_VALUE_UPDATED = 0x20000,
-  CS_SINK_PROPERTY_CHOICES_UPDATED = 0x40000
+  CS_SINK_PROPERTY_CHOICES_UPDATED = 0x40000,
+  CS_USB_CAMERAS_CHANGED = 0x80000
 };
 
 /**

cscore/src/main/native/include/cscore_cpp.h

@@ -116,7 +116,8 @@ struct RawEvent {
     kTelemetryUpdated = CS_TELEMETRY_UPDATED,
     kSinkPropertyCreated = CS_SINK_PROPERTY_CREATED,
     kSinkPropertyValueUpdated = CS_SINK_PROPERTY_VALUE_UPDATED,
-    kSinkPropertyChoicesUpdated = CS_SINK_PROPERTY_CHOICES_UPDATED
+    kSinkPropertyChoicesUpdated = CS_SINK_PROPERTY_CHOICES_UPDATED,
+    kUsbCamerasChanged = CS_USB_CAMERAS_CHANGED
   };
 
   RawEvent() = default;

cscore/src/main/native/linux/UsbCameraListener.cpp

@@ -0,0 +1,55 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "UsbCameraListener.h"
+
+#include <wpi/EventLoopRunner.h>
+#include <wpi/uv/FsEvent.h>
+#include <wpi/uv/Timer.h>
+
+#include "Notifier.h"
+
+using namespace cs;
+
+class UsbCameraListener::Impl {
+ public:
+  explicit Impl(Notifier& notifier) : m_notifier(notifier) {}
+
+  Notifier& m_notifier;
+
+  std::unique_ptr<wpi::EventLoopRunner> m_runner;
+};
+
+UsbCameraListener::UsbCameraListener(wpi::Logger& logger, Notifier& notifier)
+    : m_impl(std::make_unique<Impl>(notifier)) {}
+
+UsbCameraListener::~UsbCameraListener() = default;
+
+void UsbCameraListener::Start() {
+  if (!m_impl->m_runner) {
+    m_impl->m_runner = std::make_unique<wpi::EventLoopRunner>();
+    m_impl->m_runner->ExecAsync([impl = m_impl.get()](wpi::uv::Loop& loop) {
+      auto refreshTimer = wpi::uv::Timer::Create(loop);
+      refreshTimer->timeout.connect([notifier = &impl->m_notifier] {
+        notifier->NotifyUsbCamerasChanged();
+      });
+      refreshTimer->Unreference();
+
+      auto devEvents = wpi::uv::FsEvent::Create(loop);
+      devEvents->fsEvent.connect([refreshTimer](const char* fn, int flags) {
+        if (wpi::StringRef(fn).startswith("video")) {
+          refreshTimer->Start(wpi::uv::Timer::Time(200));
+        }
+      });
+      devEvents->Start("/dev");
+      devEvents->Unreference();
+    });
+  }
+}
+
+void UsbCameraListener::Stop() {
+  if (m_impl->m_runner) {
+    m_impl->m_runner.reset();
+  }
+}

cscore/src/main/native/osx/UsbCameraListener.cpp

@@ -0,0 +1,17 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "UsbCameraListener.h"
+
+using namespace cs;
+
+class UsbCameraListener::Impl {};
+
+UsbCameraListener::UsbCameraListener(wpi::Logger& logger, Notifier& notifier) {}
+
+UsbCameraListener::~UsbCameraListener() = default;
+
+void UsbCameraListener::Start() {}
+
+void UsbCameraListener::Stop() {}

cscore/src/main/native/windows/UsbCameraListener.cpp

@@ -0,0 +1,72 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "UsbCameraListener.h"
+
+#include "Notifier.h"
+#include "WindowsMessagePump.h"
+
+#include <dbt.h>  // NOLINT(build/include_order)
+
+#define IDT_TIMER1 1001
+
+using namespace cs;
+
+class UsbCameraListener::Impl {
+ public:
+  explicit Impl(Notifier& notifier) : m_notifier{notifier} {}
+
+  void Start() {
+    m_messagePump = std::make_unique<WindowsMessagePump>(
+        [this](HWND hwnd, UINT uiMsg, WPARAM wParam, LPARAM lParam) {
+          return this->PumpMain(hwnd, uiMsg, wParam, lParam);
+        });
+  }
+
+  void Stop() { m_messagePump = nullptr; }
+
+  LRESULT PumpMain(HWND hwnd, UINT uiMsg, WPARAM wParam, LPARAM lParam) {
+    switch (uiMsg) {
+      case WM_CLOSE:
+        KillTimer(hwnd, IDT_TIMER1);
+        break;
+      case WM_TIMER:
+        if (wParam == IDT_TIMER1) {
+          KillTimer(hwnd, IDT_TIMER1);
+          m_notifier.NotifyUsbCamerasChanged();
+        }
+        break;
+      case WM_DEVICECHANGE:
+        PDEV_BROADCAST_HDR parameter =
+            reinterpret_cast<PDEV_BROADCAST_HDR>(lParam);
+        if (wParam == DBT_DEVICEARRIVAL &&
+            parameter->dbch_devicetype == DBT_DEVTYP_DEVICEINTERFACE) {
+          SetTimer(hwnd, IDT_TIMER1, 200, nullptr);
+        } else if (wParam == DBT_DEVICEREMOVECOMPLETE &&
+                   parameter->dbch_devicetype == DBT_DEVTYP_DEVICEINTERFACE) {
+          SetTimer(hwnd, IDT_TIMER1, 200, nullptr);
+        }
+        break;
+    }
+    return 0;
+  }
+
+  Notifier& m_notifier;
+  std::unique_ptr<cs::WindowsMessagePump> m_messagePump;
+};
+
+UsbCameraListener::UsbCameraListener(wpi::Logger& logger, Notifier& notifier)
+    : m_impl{std::make_unique<Impl>(notifier)} {}
+
+UsbCameraListener::~UsbCameraListener() {
+  Stop();
+}
+
+void UsbCameraListener::Start() {
+  m_impl->Start();
+}
+
+void UsbCameraListener::Stop() {
+  m_impl->Stop();
+}