Add UsbCameraList

Author: PeterJohnson

glass/src/libcs/native/cpp/UsbCameraList.cpp

@@ -0,0 +1,82 @@
+// 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 "glass/camera/UsbCameraList.h"
+
+#include <cscore_cpp.h>
+#include <fmt/format.h>
+#include <imgui.h>
+
+using namespace glass;
+
+struct UsbCameraList::UsbInfoThread : public wpi::SafeThread {
+  void Main() override;
+
+  std::vector<cs::UsbCameraInfo> m_usbInfo;
+};
+
+void UsbCameraList::UsbInfoThread::Main() {
+  std::unique_lock lock{m_mutex};
+  while (m_active) {
+    // enumerate without lock held
+    lock.unlock();
+    CS_Status status = 0;
+    auto usbInfo = cs::EnumerateUsbCameras(&status);
+
+    lock.lock();
+    m_usbInfo = std::move(usbInfo);
+
+    // wait for change
+    m_cond.wait(lock);
+  }
+}
+
+UsbCameraList::UsbCameraList() : m_poller{cs::CreateListenerPoller()} {
+  CS_Status status = 0;
+  cs::AddPolledListener(m_poller, CS_USB_CAMERAS_CHANGED, false, &status);
+
+  m_usbInfoThread.Start();
+}
+
+UsbCameraList::~UsbCameraList() {
+  cs::DestroyListenerPoller(m_poller);
+}
+
+std::string UsbCameraList::DisplayMenu() {
+  std::string rv;
+  bool any = false;
+  if (auto thr = m_usbInfoThread.GetThread()) {
+    // TODO: hide cameras that already exist as sources
+    for (auto&& info : thr->m_usbInfo) {
+      ImGui::SeparatorText(fmt::format("{} ({:04x}:{:04x})", info.name,
+                                       info.vendorId, info.productId)
+                               .c_str());
+      if (ImGui::MenuItem(info.path.c_str())) {
+        rv = info.path;
+      }
+      for (auto&& path : info.otherPaths) {
+        if (ImGui::MenuItem(path.c_str())) {
+          rv = info.path;
+        }
+      }
+    }
+    any = !thr->m_usbInfo.empty();
+  }
+  if (!any) {
+    ImGui::MenuItem("(None)", nullptr, false, false);
+  }
+  return rv;
+}
+
+void UsbCameraList::Update() {
+  bool timedOut = false;
+  for (auto&& event : cs::PollListener(m_poller, 0, &timedOut)) {
+    if (event.kind == cs::RawEvent::kUsbCamerasChanged) {
+      // enumerate on separate thread
+      if (auto thr = m_usbInfoThread.GetThread()) {
+        thr->m_cond.notify_all();
+      }
+    }
+  }
+}

glass/src/libcs/native/include/glass/camera/UsbCameraList.h

@@ -0,0 +1,43 @@
+// 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.
+
+#pragma once
+
+#include <string>
+
+#include <cscore_cpp.h>
+#include <wpi/SafeThread.h>
+
+namespace glass {
+
+class Storage;
+
+/**
+ * Provider for CameraServer models and views for USB cameras.
+ */
+class UsbCameraList {
+ public:
+  explicit UsbCameraList();
+  ~UsbCameraList();
+
+  UsbCameraList(const UsbCameraList&) = delete;
+  UsbCameraList& operator=(const UsbCameraList&) = delete;
+
+  void Update();
+
+  /**
+   * Displays menu contents.
+   *
+   * @return camera path to add, if not empty
+   */
+  std::string DisplayMenu();
+
+ private:
+  struct UsbInfoThread;
+  wpi::SafeThreadOwner<UsbInfoThread> m_usbInfoThread;
+
+  CS_ListenerPoller m_poller;
+};
+
+}  // namespace glass