c++ 根据qrcode生成图片流并创建一个子窗口显示在窗口上 不使用qt

可以使用第三方库来生成图片流，并使用操作系统提供的API来创建子窗口并显示图片。

生成图片流可以使用OpenCV库中的QRCode生成功能。具体实现步骤如下：

1. 安装OpenCV库。

2. 使用以下代码生成QRCode图片流：

#include <opencv2/opencv.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>

using namespace cv;

int main(int argc, char** argv)
{
    std::string text = "Hello, world!";
    Mat qr = QRCodeDetector::decode(text);

    if (!qr.empty())
    {
        imshow("QR Code", qr);
        waitKey(0);
    }

    return 0;
}

3. 将生成的图片流传递给子窗口并显示。

可以使用Windows提供的API函数来创建子窗口并显示图片。具体实现步骤如下：

1. 在窗口创建完成后，使用以下代码创建子窗口：

HWND hChildWnd = CreateWindowEx(
    0,                      // Optional window styles.
    TEXT("STATIC"),         // Window class
    NULL,                   // Window text
    WS_CHILD | WS_VISIBLE,  // Window style
    0,                      // Position x
    0,                      // Position y
    width,                  // Width
    height,                 // Height
    hWndParent,             // Parent window
    NULL,                   // Menu
    hInst,                  // Instance handle
    NULL                    // Additional application data
);

其中，hWndParent为父窗口句柄，width和height为图片流的宽度和高度。

2. 将图片流传递给子窗口：

HBITMAP hBitmap = CreateBitmap(width, height, 1, 32, pData);
SendMessage(hChildWnd, STM_SETIMAGE, IMAGE_BITMAP, (LPARAM)hBitmap);

其中，pData为图片流数据。

3. 显示子窗口：

ShowWindow(hChildWnd, SW_SHOW);

完整代码示例：

#include <opencv2/opencv.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui.hpp>
#include <Windows.h>

using namespace cv;

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    // Step 1: Registering the Window Class
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = "WindowClass";
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    if (!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // Step 2: Creating the Window
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        "WindowClass",
        "The title of my window",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
        NULL, NULL, hInstance, NULL);

    if (hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // Step 3: Showing the Window
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // Step 4: The Message Loop
    while (GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    return Msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    static HWND hChildWnd = NULL;

    switch (msg)
    {
    case WM_CREATE:
    {
        std::string text = "Hello, world!";
        Mat qr = QRCodeDetector::decode(text);

        if (!qr.empty())
        {
            int width = qr.cols;
            int height = qr.rows;

            hChildWnd = CreateWindowEx(
                0,                      // Optional window styles.
                TEXT("STATIC"),         // Window class
                NULL,                   // Window text
                WS_CHILD | WS_VISIBLE,  // Window style
                0,                      // Position x
                0,                      // Position y
                width,                  // Width
                height,                 // Height
                hwnd,                   // Parent window
                NULL,                   // Menu
                (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), // Instance handle
                NULL                    // Additional application data
            );

            if (hChildWnd != NULL)
            {
                int bpp = qr.elemSize() * 8;
                int stride = qr.step;
                uchar* pData = qr.data;

                HBITMAP hBitmap = CreateBitmap(width, height, 1, bpp, pData);
                SendMessage(hChildWnd, STM_SETIMAGE, IMAGE_BITMAP, (LPARAM)hBitmap);

                ShowWindow(hChildWnd, SW_SHOW);
            }
        }

        break;
    }
    case WM_CLOSE:
    {
        DestroyWindow(hwnd);
        break;
    }
    case WM_DESTROY:
    {
        PostQuitMessage(0);
        break;
    }
    default:
        return DefWindowProc(hwnd, msg, wParam, lParam);
    }

    return 0;
}