在windows cpp 动态库读取test.mp4视频流到Windows窗口的离屏表面,且不卡UI，在Qt调用该动态库。完整源码

以下是一个简单的示例代码，可以将test.mp4视频流读取到Windows窗口的离屏表面，并在Qt中调用该动态库：

1. 创建动态链接库项目，并添加以下代码：

#include <windows.h>
#include <d3d9.h>
#include <d3dx9.h>
#include <string>
#include <iostream>
#include <fstream>

#pragma comment(lib, "d3d9.lib")
#pragma comment(lib, "d3dx9.lib")

// 视频宽度和高度
#define VIDEO_WIDTH 640
#define VIDEO_HEIGHT 480

// 全局变量
LPDIRECT3D9 g_pD3D = NULL;
LPDIRECT3DDEVICE9 g_pd3dDevice = NULL;
LPDIRECT3DSURFACE9 g_pSurface = NULL;
LPD3DXSPRITE g_pSprite = NULL;

// 初始化Direct3D
bool InitD3D(HWND hWnd)
{
    // 创建Direct3D对象
    g_pD3D = Direct3DCreate9(D3D_SDK_VERSION);
    if (g_pD3D == NULL)
        return false;

    // 配置显示模式
    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;

    // 创建Direct3D设备
    if (FAILED(g_pD3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
        D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &g_pd3dDevice)))
    {
        return false;
    }

    // 创建表面
    if (FAILED(g_pd3dDevice->CreateOffscreenPlainSurface(
        VIDEO_WIDTH, VIDEO_HEIGHT, D3DFMT_X8R8G8B8,
        D3DPOOL_SYSTEMMEM, &g_pSurface, NULL)))
    {
        return false;
    }

    // 创建Sprite
    if (FAILED(D3DXCreateSprite(g_pd3dDevice, &g_pSprite)))
    {
        return false;
    }

    return true;
}

// 从视频文件中读取数据到表面
bool ReadSurfaceFromFile(std::string filePath)
{
    // 打开文件
    std::ifstream file(filePath, std::ios::binary);
    if (!file.is_open())
    {
        return false;
    }

    // 读取数据
    char* pBuffer = new char[VIDEO_WIDTH * VIDEO_HEIGHT * 4];
    file.read(pBuffer, VIDEO_WIDTH * VIDEO_HEIGHT * 4);

    // 创建Surface
    IDirect3DSurface9* pDestSurface = NULL;
    if (FAILED(g_pd3dDevice->CreateOffscreenPlainSurface(
        VIDEO_WIDTH, VIDEO_HEIGHT, D3DFMT_X8R8G8B8,
        D3DPOOL_DEFAULT, &pDestSurface, NULL)))
    {
        delete[] pBuffer;
        return false;
    }

    // 锁定表面
    D3DLOCKED_RECT lockedRect;
    if (FAILED(g_pSurface->LockRect(&lockedRect, NULL, D3DLOCK_DISCARD)))
    {
        pDestSurface->Release();
        delete[] pBuffer;
        return false;
    }

    // 将数据复制到表面
    char* pSrc = pBuffer;
    char* pDest = (char*)lockedRect.pBits;
    for (int i = 0; i < VIDEO_HEIGHT; i++)
    {
        memcpy(pDest, pSrc, VIDEO_WIDTH * 4);
        pSrc += VIDEO_WIDTH * 4;
        pDest += lockedRect.Pitch;
    }

    // 解锁表面
    g_pSurface->UnlockRect();

    // 绘制表面
    if (SUCCEEDED(g_pd3dDevice->GetRenderTarget(0, &pDestSurface)))
    {
        g_pd3dDevice->StretchRect(g_pSurface, NULL, pDestSurface, NULL, D3DTEXF_NONE);
        pDestSurface->Release();
    }

    // 释放资源
    delete[] pBuffer;
    pDestSurface->Release();

    return true;
}

// 渲染函数
void Render()
{
    // 清空屏幕
    g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    // 开始渲染
    if (SUCCEEDED(g_pd3dDevice->BeginScene()))
    {
        // 设置Sprite
        g_pSprite->Begin(D3DXSPRITE_ALPHABLEND);

        // 绘制表面
        g_pSprite->Draw(g_pSurface, NULL, NULL, NULL, D3DCOLOR_XRGB(255, 255, 255));

        // 结束渲染
        g_pSprite->End();
        g_pd3dDevice->EndScene();
    }

    // 显示画面
    g_pd3dDevice->Present(NULL, NULL, NULL, NULL);
}

// 释放资源
void Cleanup()
{
    if (g_pSprite != NULL)
        g_pSprite->Release();

    if (g_pSurface != NULL)
        g_pSurface->Release();

    if (g_pd3dDevice != NULL)
        g_pd3dDevice->Release();

    if (g_pD3D != NULL)
        g_pD3D->Release();
}

// DLL入口函数
extern "C" __declspec(dllexport) bool PlayVideo(HWND hWnd, std::string filePath)
{
    // 初始化Direct3D
    if (!InitD3D(hWnd))
        return false;

    // 读取数据到表面
    if (!ReadSurfaceFromFile(filePath))
        return false;

    // 渲染画面
    Render();

    // 释放资源
    Cleanup();

    return true;
}

2. 在Qt中调用该动态库：

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <Windows.h>

typedef bool(*PlayVideoFunc)(HWND hWnd, std::string filePath);

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    // 加载动态库
    HINSTANCE hDll = LoadLibrary(TEXT("MyVideoPlayer.dll"));
    if (hDll == NULL)
    {
        QMessageBox::warning(this, "Error", "Failed to load DLL.");
        return;
    }

    // 获取函数指针
    PlayVideoFunc PlayVideo = (PlayVideoFunc)GetProcAddress(hDll, "PlayVideo");
    if (PlayVideo == NULL)
    {
        QMessageBox::warning(this, "Error", "Failed to get function.");
        return;
    }

    // 调用函数
    if (!PlayVideo((HWND)ui->widget->winId(), "test.mp4"))
    {
        QMessageBox::warning(this, "Error", "Failed to play video.");
        return;
    }
}

注意：上述代码仅为示例代码，具体实现可能需要根据实际情况进行调整。同时，还需要在项目中添加相关的头文件和库文件，并将test.mp4放置在程序运行目录下。