c++如何显示时轮滑滚动

在 C++ 中，实现滚动条可以使用 WinAPI 中的 ScrollBar 控件。具体实现步骤如下：

1. 在窗口中添加一个 ScrollBar 控件，可以使用 CreateWindow 函数创建。

2. 在窗口的消息处理函数中处理 WM_VSCROLL 和 WM_HSCROLL 消息，根据消息的参数来更新滚动条的位置。

3. 在绘制窗口内容时，根据滚动条的位置来绘制对应的内容。

下面是一个简单的示例代码：

#include <Windows.h>

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static int nVScrollPos = 0;
    static int nHScrollPos = 0;

    switch (message)
    {
    case WM_CREATE:
        // 创建纵向滚动条
        CreateWindowW(L"SCROLLBAR", NULL, WS_CHILD | WS_VISIBLE | SBS_VERT,
            0, 0, 20, 200, hWnd, (HMENU)1, GetModuleHandle(NULL), NULL);
        // 创建横向滚动条
        CreateWindowW(L"SCROLLBAR", NULL, WS_CHILD | WS_VISIBLE | SBS_HORZ,
            0, 200, 200, 20, hWnd, (HMENU)2, GetModuleHandle(NULL), NULL);
        break;

    case WM_VSCROLL:
        switch (LOWORD(wParam))
        {
        case SB_LINEUP:
            nVScrollPos--;
            break;
        case SB_LINEDOWN:
            nVScrollPos++;
            break;
        case SB_PAGEUP:
            nVScrollPos -= 10;
            break;
        case SB_PAGEDOWN:
            nVScrollPos += 10;
            break;
        case SB_THUMBPOSITION:
            nVScrollPos = HIWORD(wParam);
            break;
        }
        nVScrollPos = max(0, nVScrollPos);
        nVScrollPos = min(180, nVScrollPos);
        SetScrollPos((HWND)lParam, SB_CTL, nVScrollPos, TRUE);
        InvalidateRect(hWnd, NULL, TRUE);
        break;

    case WM_HSCROLL:
        switch (LOWORD(wParam))
        {
        case SB_LINELEFT:
            nHScrollPos--;
            break;
        case SB_LINERIGHT:
            nHScrollPos++;
            break;
        case SB_PAGELEFT:
            nHScrollPos -= 10;
            break;
        case SB_PAGERIGHT:
            nHScrollPos += 10;
            break;
        case SB_THUMBPOSITION:
            nHScrollPos = HIWORD(wParam);
            break;
        }
        nHScrollPos = max(0, nHScrollPos);
        nHScrollPos = min(180, nHScrollPos);
        SetScrollPos((HWND)lParam, SB_CTL, nHScrollPos, TRUE);
        InvalidateRect(hWnd, NULL, TRUE);
        break;

    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // 根据滚动条的位置绘制对应的内容
            int x = -nHScrollPos;
            int y = -nVScrollPos;
            for (int i = 0; i < 10; i++)
            {
                TextOut(hdc, x, y + i * 20, L"Hello, world!", 13);
            }
            EndPaint(hWnd, &ps);
        }
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wcex = { sizeof(WNDCLASSEX) };
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.hInstance = hInstance;
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.lpszClassName = L"MyWindowClass";
    RegisterClassEx(&wcex);

    HWND hWnd = CreateWindow(L"MyWindowClass", L"Scroll Bar Demo", WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 400, 400, NULL, NULL, hInstance, NULL);
    ShowWindow(hWnd, nCmdShow);

    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;
}

这个示例程序创建了一个带有纵向和横向滚动条的窗口，可以通过拖动滚动条或者使用键盘上下左右键来滚动窗口内容。