examples: add events example (listen for events & health report)

examples/events/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.10.2)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+project(events)
+
+add_executable(events
+    events.cpp
+)
+
+find_package(MAVSDK REQUIRED)
+
+target_link_libraries(events
+    MAVSDK::mavsdk
+)
+
+if(NOT MSVC)
+    add_compile_options(events PRIVATE -Wall -Wextra)
+else()
+    add_compile_options(events PRIVATE -WX -W2)
+endif()

examples/events/events.cpp

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+//
+// Simple example to demonstrate how to use the events plugin.
+//
+
+#include <mavsdk/mavsdk.h>
+#include <mavsdk/plugins/events/events.h>
+#include <mavsdk/plugins/telemetry/telemetry.h>
+#include <iostream>
+#include <thread>
+#include <future>
+
+using namespace mavsdk;
+
+void usage(const std::string& bin_name)
+{
+    std::cerr << "Usage : " << bin_name << " <connection_url> [-v] [monitor]\n"
+              << "Connection URL format should be:\n"
+              << " For TCP : tcp://[server_host][:server_port]\n"
+              << " For UDP : udp://[bind_host][:bind_port]\n"
+              << " For Serial : serial:///path/to/serial/dev[:baudrate]\n"
+              << "For example, to connect to the simulator use URL: udp://:14540\n\n"
+              << " -v: enable verbose output\n"
+              << " monitor: listen for events (instead of printing the arming report)\n";
+}
+
+int main(int argc, char** argv)
+{
+    if (argc < 2) {
+        usage(argv[0]);
+        return 1;
+    }
+
+    // Parse CLI arguments
+    bool monitor = false;
+    bool verbose = false;
+    for (int i = 2; i < argc; ++i) {
+        if (strcmp(argv[i], "-v") == 0) {
+            verbose = true;
+        } else if (strcmp(argv[i], "monitor") == 0) {
+            monitor = true;
+        }
+    }
+
+    Mavsdk mavsdk{Mavsdk::Configuration{Mavsdk::ComponentType::GroundStation}};
+    ConnectionResult connection_result = mavsdk.add_any_connection(argv[1]);
+
+    if (connection_result != ConnectionResult::Success) {
+        std::cerr << "Connection failed: " << connection_result << '\n';
+        return 1;
+    }
+
+    auto system = mavsdk.first_autopilot(3.0);
+    if (!system) {
+        std::cerr << "Timed out waiting for system\n";
+        return 1;
+    }
+
+    auto events = Events{*system};
+
+    if (monitor) {
+        // Listen for events
+        events.subscribe_events([verbose](const Events::Event& event) {
+            std::cout << "[" << event.log_level << "] " << event.message << std::endl;
+            if (verbose) {
+                if (!event.description.empty()) {
+                    std::cout << "    Description: " << event.description << std::endl;
+                }
+                std::cout << "    Event name: " << event.event_namespace << "/" << event.event_name
+                          << std::endl;
+            }
+        });
+        while (true) {
+            std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        }
+    } else {
+        // Listen for arming checks report
+        const auto telemetry = Telemetry{*system};
+        std::promise<bool> promise;
+        auto future = promise.get_future();
+        bool reported = false;
+        events.subscribe_health_and_arming_checks(
+            [&telemetry, &promise, &verbose, &reported](
+                const Events::HealthAndArmingCheckReport& report) {
+                if (reported) { // Report only once
+                    return;
+                }
+                reported = true;
+                std::cout << "Current Mode (intention): " << report.current_mode_intention.mode_name
+                          << std::endl;
+                const std::string can_arm_or_run = telemetry.armed() ? "Can Run: " : "Can Arm: ";
+                std::cout << can_arm_or_run
+                          << (report.current_mode_intention.can_arm_or_run ? "yes" : "No")
+                          << std::endl;
+                if (!report.current_mode_intention.problems.empty()) {
+                    std::cout << "Reports:" << std::endl;
+                    for (const auto& problem : report.current_mode_intention.problems) {
+                        std::cout << "  [" << problem.log_level << "] [" << problem.health_component
+                                  << "]: " << problem.message << std::endl;
+                    }
+                }
+
+                if (verbose && !report.all_problems.empty()) {
+                    std::cout << "All Reports:" << std::endl;
+                    for (const auto& problem : report.all_problems) {
+                        std::cout << "  [" << problem.log_level << "] [" << problem.health_component
+                                  << "]: " << problem.message << std::endl;
+                    }
+                }
+                promise.set_value(true);
+            });
+        future.get();
+    }
+
+    return 0;
+}