window.c

#include <windows.h>
#include <tchar.h>
#include <math.h>
#include <stdio.h>

#define PI 3.13159265358979323846

// Window Procedure: Handles messages sent to the window
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    static int rotX = 100;
    static int rotY = 100;
    static int posX = 100;
    static int posY = 100;
    static double angle = 0.0;
    RECT rcrect;

    switch (uMsg)
    {
    case WM_DESTROY:
        KillTimer(hwnd, 1);
        PostQuitMessage(0); // Signal that the application should exit
        return 0;
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        // get window's client rectangle. We need this for bitmap creation.
        // create memory DC and memory bitmap where we shall do our drawing

        HDC memDC = CreateCompatibleDC(hdc);

        // get window's client rectangle. We need this for bitmap creation.
        GetClientRect(hwnd, &rcrect);

        // now we can create bitmap where we shall do our drawing
        HBITMAP bmp = CreateCompatibleBitmap(hdc,
                                             rcrect.right - rcrect.left,
                                             rcrect.bottom - rcrect.top);

        // we need to save original bitmap, and select it back when we are done,
        // in order to avoid GDI leaks!
        HBITMAP oldBmp = (HBITMAP)SelectObject(memDC, bmp);

        HBRUSH hBrush = CreateSolidBrush(RGB(255, 0, 0));
        SelectObject(memDC, hBrush);
        //----------------

        FillRect(memDC, &rcrect, (HBRUSH)(COLOR_WINDOW + 1));

        int cx = (rcrect.right - rcrect.left) / 2;
        int cy = (rcrect.bottom - rcrect.top) / 2;

        // Use static angle, calculate rotating endpoint
        double radius = 200; // Fixed radius for visible rotation
        double offset = 100;
        double x2 = cx + radius * cos(angle);
        double y2 = cy + radius * sin(angle);
        double x3 = cx + radius * cos(angle + PI);
        double y3 = cy + radius * sin(angle + PI);
        double x4 = cx + radius * cos(angle + (PI / 2));
        double y4 = cy + radius * sin(angle + (PI / 2));
        MoveToEx(memDC, (int)x3, (int)y3, NULL); // Start at center
        LineTo(memDC, (int)x2, (int)y2);         // Draw to rotating endpoint
        MoveToEx(memDC, (int)x3, (int)y3, NULL); // Start at center
        LineTo(memDC, (int)x4, (int)y4);         // Draw to rotating endpoint
        //-----------------------------------------------------
        // OK, everything is drawn into memory DC,
        // now is the time to draw that final result into our target DC

        BitBlt(hdc, 0, 0, rcrect.right - rcrect.left,
               rcrect.bottom - rcrect.top, memDC, 0, 0, SRCCOPY);

        // all done, now we need to cleanup
        DeleteObject(hBrush);

        SelectObject(memDC, oldBmp); // select back original bitmap
        DeleteObject(bmp);           // delete bitmap since it is no longer required
        DeleteDC(memDC);             // delete memory DC since it is no longer required
        EndPaint(hwnd, &ps);
        return 0;
    }
    case WM_CREATE:
        // ID + time in ms
        SetTimer(hwnd, 1, 16, NULL);
        return 0;
    case WM_TIMER:
        angle += 0.05;
        InvalidateRect(hwnd, NULL, FALSE);
        return 0;
    default:
        // Let Windows handle any messages we don't explicitly handle
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }
}

// Entry point for a graphical Windows application
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    char appInName[] = "WindowApp";
    char appName[] = "TestGame";
    // 1. Define and register the window class
    WNDCLASSEX wc = {0}; // Initialize to zero
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.lpfnWndProc = WindowProc; // Pointer to our window procedure
    wc.hInstance = hInstance;
    wc.lpszClassName = appInName;

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

    // 2. Create the window
    HWND hwnd = CreateWindowEx(
        0,                                // Optional window styles
        appInName,                        // Window class name
        appName,                          // Window title
        WS_OVERLAPPEDWINDOW | WS_VISIBLE, // Window style
        CW_USEDEFAULT, CW_USEDEFAULT,     // Position (x, y)
        800, 600,                         // Size (width, height)
        NULL,                             // Parent window handle
        NULL,                             // Menu handle
        hInstance,                        // Instance handle
        NULL                              // Additional creation parameters
    );

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

    // 3. Show the window
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // 4. Message loop: Process messages until WM_QUIT is received
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}