GDI+ 中绘制圆角矩形：解决 "Gdiplus::Graphics" 类没有 "DrawRoundRect" 方法的问题

GDI+ 库中的 'Graphics' 类确实没有 'DrawRoundRect' 方法。为了实现绘制圆角矩形，我们可以使用 GDI 函数来进行绘制。以下是修改后的代码：

#include <windows.h>
#include <gdiplus.h>

using namespace Gdiplus;

void DrawCustomControl(HWND hwnd, COLORREF borderColor = RGB(0, 0, 0), COLORREF buttonColor = RGB(255, 255, 255)) {
    HDC hdc = GetDC(hwnd);
    RECT rect;
    GetClientRect(hwnd, &rect);

    // 绘制背景色
    HBRUSH hBrush = CreateSolidBrush(buttonColor);
    FillRect(hdc, &rect, hBrush);
    DeleteObject(hBrush);

    // 绘制圆角矩形边框
    HPEN hPen = CreatePen(PS_SOLID, 2, borderColor);
    SelectObject(hdc, hPen);
    RoundRect(hdc, rect.left, rect.top, rect.right, rect.bottom, 10, 10);
    DeleteObject(hPen);

    ReleaseDC(hwnd, hdc);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
        case WM_PAINT: {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hwnd, &ps);

            // 调用自定义绘制函数
            DrawCustomControl(hwnd, RGB(255, 0, 0), RGB(0, 0, 255));

            EndPaint(hwnd, &ps);
            return 0;
        }
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    // 初始化 GDI+
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

    // 创建窗口
    WNDCLASSEX wc = {0};
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszClassName = L"WindowClass";
    RegisterClassEx(&wc);

    HWND hwnd = CreateWindowEx(0, L"WindowClass", L"Window", WS_OVERLAPPEDWINDOW,
                               CW_USEDEFAULT, CW_USEDEFAULT, 500, 300,
                               NULL, NULL, hInstance, NULL);
    ShowWindow(hwnd, nCmdShow);

    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    // 释放 GDI+
    GdiplusShutdown(gdiplusToken);

    return (int)msg.wParam;
}

在示例代码中，我们使用了 GDI 函数 'RoundRect' 来绘制圆角矩形边框。在 'DrawCustomControl' 函数中，我们创建了一个 'HPEN' 对象，设置边框颜色和宽度，然后将其选入设备上下文，并调用 'RoundRect' 函数绘制圆角矩形。

再次对之前的错误表示歉意，希望新的示例代码能够满足你的需求。如果还有任何问题，请随时提问。