用vc画图当把图复制到剪贴板时怎么通过GetTextExtent得到正确的字符长度完整的示例代码

以下是一个完整的示例代码，它演示了如何使用VC ++来绘制一个简单的图形，并通过GetTextExtent函数获取文本的正确宽度：

#include <windows.h>

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wcex;
    HWND hWnd;
    MSG msg;

    // 注册窗口类
    ZeroMemory(&wcex, sizeof(wcex));
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.hInstance = hInstance;
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszClassName = L"WindowClass";
    RegisterClassEx(&wcex);

    // 创建窗口
    hWnd = CreateWindow(L"WindowClass", L"VC++ Draw Text Demo", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 640, 480, NULL, NULL, hInstance, NULL);
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    // 消息循环
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    RECT rect;
    SIZE size;
    wchar_t text[] = L"Hello, World!";

    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);

        // 绘制文本
        SetTextColor(hdc, RGB(0, 0, 255));
        SetBkMode(hdc, TRANSPARENT);
        TextOut(hdc, 10, 10, text, wcslen(text));

        // 获取文本宽度
        GetClientRect(hWnd, &rect);
        GetTextExtentPoint32(hdc, text, wcslen(text), &size);
        DrawText(hdc, L"Text Width: " + std::to_wstring(size.cx).c_str(), -1, &rect, DT_SINGLELINE | DT_BOTTOM | DT_RIGHT);

        EndPaint(hWnd, &ps);
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

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

    return 0;
}

在这个示例中，我们使用TextOut函数来绘制文本，并使用GetTextExtentPoint32函数获取文本的宽度。我们还使用DrawText函数在窗口的右下角显示文本的宽度。注意，我们使用std :: to_wstring函数将整数转换为宽字符字符串