#include <windows.h>
#include <dshow.h>

// 初始化 DirectShow
HRESULT InitializeDirectShow(HWND hwnd) {
    // 初始化 COM
    CoInitialize(NULL);

    // 创建 Filter Graph Manager
    IGraphBuilder *pGraph = NULL;
    CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&pGraph);

    // 创建 Capture Graph Builder
    ICaptureGraphBuilder2 *pCaptureGraphBuilder = NULL;
    CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void **)&pCaptureGraphBuilder);

    // 设置 Filter Graph Manager 到 Capture Graph Builder
    pCaptureGraphBuilder->SetFiltergraph(pGraph);

    // 创建设备过滤器，比如摄像头
    IBaseFilter *pDeviceFilter = NULL;
    CoCreateInstance(CLSID_VideoInputDeviceCategory, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void **)&pDeviceFilter);

    // 将设备过滤器添加到 Filter Graph Manager
    pGraph->AddFilter(pDeviceFilter, L"Video Capture");

    // 渲染流到窗口
    pCaptureGraphBuilder->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, pDeviceFilter, NULL, NULL);

    // 获取 IMediaEvent 接口
    IMediaEvent *pMediaEvent = NULL;
    pGraph->QueryInterface(IID_IMediaEvent, (void **)&pMediaEvent);

    // 设置窗口句柄以接收事件
    pMediaEvent->SetNotifyWindow((OAHWND)hwnd, WM_GRAPHNOTIFY, 0);

    // 释放资源
    pDeviceFilter->Release();
    pCaptureGraphBuilder->Release();

    return S_OK;
}

// 处理消息的窗口过程
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    switch (uMsg) {
        case WM_CREATE:
            // 在窗口创建时初始化 DirectShow
            InitializeDirectShow(hwnd);
            break;

        case WM_DESTROY:
            // 在窗口销毁时清理资源
            CoUninitialize();
            PostQuitMessage(0);
            break;

        case WM_GRAPHNOTIFY:
            // 处理媒体事件
            HandleMediaEvent(hwnd);
            break;

        default:
            return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }

    return 0;
}

// 处理媒体事件的函数
void HandleMediaEvent(HWND hwnd) {
    long evCode, param1, param2;
    IMediaEvent *pMediaEvent = NULL;

    // 获取 IMediaEvent 接口
    pGraph->QueryInterface(IID_IMediaEvent, (void **)&pMediaEvent);

    // 处理所有待处理的事件
    while (pMediaEvent->GetEvent(&evCode, &param1, &param2, 0) == S_OK) {
        // 在这里处理事件，可以根据事件类型执行相应的操作
        switch (evCode) {
            case EC_COMPLETE:
                // 播放完成事件
                break;

            case EC_USERABORT:
                // 用户中断事件
                break;

            // 其他事件类型可以在这里处理

            default:
                break;
        }

        // 释放事件资源
        pMediaEvent->FreeEventParams(evCode, param1, param2);
    }

    pMediaEvent->Release();
}