画时钟表盘c语言

下面是一个简单的 C 语言时钟表盘的示例代码，使用了 Windows API 的 GDI 绘图功能：

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

#define WINDOW_WIDTH 400
#define WINDOW_HEIGHT 400
#define PI 3.1415926

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

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASS wc = { 0 };
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszClassName = "ClockWindowClass";
    wc.style = CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&wc);

    HWND hwnd = CreateWindow("ClockWindowClass", "时钟表盘", WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, hInstance, NULL);

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

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

    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static int cxClient, cyClient;

    switch (message) {
    case WM_SIZE:
        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);
        return 0;

    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        // 绘制表盘
        HPEN pen = CreatePen(PS_SOLID, 2, RGB(0, 0, 0));
        HPEN oldPen = (HPEN)SelectObject(hdc, pen);
        HBRUSH brush = CreateSolidBrush(RGB(255, 255, 255));
        HBRUSH oldBrush = (HBRUSH)SelectObject(hdc, brush);
        Ellipse(hdc, 50, 50, cxClient - 50, cyClient - 50);
        SelectObject(hdc, oldPen);
        DeleteObject(pen);
        SelectObject(hdc, oldBrush);
        DeleteObject(brush);

        // 绘制刻度
        double radius = (cxClient - 100) / 2.0;
        int centerX = cxClient / 2;
        int centerY = cyClient / 2;
        for (int i = 0; i < 12; i++) {
            double angle = i * PI / 6.0;
            int x1 = (int)(centerX + (radius - 20) * cos(angle));
            int y1 = (int)(centerY - (radius - 20) * sin(angle));
            int x2 = (int)(centerX + radius * cos(angle));
            int y2 = (int)(centerY - radius * sin(angle));
            MoveToEx(hdc, x1, y1, NULL);
            LineTo(hdc, x2, y2);
        }

        EndPaint(hwnd, &ps);
        return 0;
    }

    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hwnd, message, wParam, lParam);
}

这个程序使用了 Windows API 来创建一个窗口，并在窗口中绘制了一个简单的时钟表盘。程序主要的代码在 WM_PAINT 事件处理中，首先绘制了一个白色的圆形表盘，然后在表盘上绘制了 12 条刻度线，每条刻度线之间相隔 30 度，最后使用 EndPaint 函数结束绘制。