以下為判斷usb設備是插入還是拔出狀態(熱插拔)的測試代碼：?在Windows下是不支持的，在Linux是支持的，下一個版本可能會支持Windows下的熱插拔：

#include <chrono>
#include <thread>
#include <iostream>
#include <libusb.h>namespace {bool running = true;int LIBUSB_CALL hotplug_callback(libusb_context* ctx, libusb_device* dev, libusb_hotplug_event event, void* user_data)
{struct libusb_device_descriptor desc;int ret = libusb_get_device_descriptor(dev, &desc);if (LIBUSB_SUCCESS != ret) {fprintf(stderr, "fail to get device descriptor: %d, %s\n", ret, libusb_error_name(ret));//return -1;}if (event == LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED)fprintf(stdout, "device attached: %04x:%04x\n", desc.idVendor, desc.idProduct);else if (event == LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT)fprintf(stdout, "device detached: %04x:%04x\n", desc.idVendor, desc.idProduct);elsefprintf(stderr, "Error: unsupported hotplug events\n");return 0;
}void run()
{for (int i = 0; i < 60; ++i)std::this_thread::sleep_for(std::chrono::seconds(1));running = false;
}} // namespaceint test_libusb_hotplug()
{// reference: examples/hotplugtest.c
#ifdef _MSC_VERconst char* platform = "Windows";
#elseconst char* platform = "Linux";
#endifint ret = libusb_init(nullptr);if (ret != 0) {fprintf(stderr, "fail to init: %d, %s\n", ret, libusb_error_name(ret));return -1;}if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {fprintf(stderr, "hotplug capabilites are not supported on this platform: %s\n", platform);libusb_exit(nullptr);return -1;}int vendor_id = 0x046d, product_id = 0x081b;libusb_hotplug_callback_handle hp[2];ret = libusb_hotplug_register_callback(nullptr, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED, LIBUSB_HOTPLUG_NO_FLAGS, vendor_id,product_id, LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, nullptr, &hp[0]);if (LIBUSB_SUCCESS != ret) {fprintf(stderr, "fail to register callback arrived: %d, %s\n", ret, libusb_error_name(ret));libusb_exit(nullptr);return -1;}ret = libusb_hotplug_register_callback(nullptr, LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT, LIBUSB_HOTPLUG_NO_FLAGS, vendor_id,product_id, LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, nullptr, &hp[1]);if (LIBUSB_SUCCESS != ret) {fprintf(stderr, "fail to register callback left: %d, %s\n", ret, libusb_error_name(ret));libusb_exit(nullptr);return -1;}std::thread th(run);while (running) {//ret = libusb_handle_events(nullptr);timeval tv = {1, 0};ret = libusb_handle_events_timeout(nullptr, &tv);if (ret < 0)fprintf(stderr, "fail to libusb_handle_events: %d, %s\n", ret, libusb_error_name(ret));}libusb_exit(nullptr);th.join();return 0;
}

在Windows下執行結果如下：

在Linux下執行結果如下：對usb視頻設備進行反復插拔

GitHub：https://github.com//fengbingchun/OpenCV_Test

總結

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