WinAPI_2_2_Sinus_v2

#pragma warning(disable:4996)
#undef UNICODE
#include <windows.h>
#include "KWnd.h"

#define _USE_MATH_DEFINES
#include <cmath>
const int WIDTH = 314;
const int HEIGHT = 200;

void updateRegion(HRGN& hRgn, int left, int top, int right, int bottom);

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

const int INTERVAL = 50;

//bool isOdd(int i);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    MSG msg;
    KWnd mainWnd("MyWin", hInstance, nCmdShow, WndProc);
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (msg.wParam);
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hDC;
    //coordinates
    static int sx, sy;
    static int x_scr, y_scr;
    double x;
    //ball coord
    //timer t
    static bool paused = false;
    static int t = 0;
    //pens
    static HPEN hPenAxis, hPenGraphic;
    //brush
    static HBRUSH hBrushYellow;
    //regions
    static HRGN ellipse;
    //angle for ball
    static double ballAngle = -M_PI;
    //direction
    static bool forward = true;

    switch (message) {
    case WM_CREATE:
        //create pens
        hPenAxis = CreatePen(PS_SOLID, 2, RGB(0, 0, 255));
        hPenGraphic = CreatePen(PS_SOLID, 2, RGB(255, 0, 0));
        //create brush
        hBrushYellow = CreateSolidBrush(RGB(255, 165, 0));
        //create timer
        SetTimer(hWnd, 1, INTERVAL, NULL);
        //create rgn
        ellipse = CreateEllipticRgn(sx, sy, sx, sy);
        break;
    case WM_SIZE:
        sx = LOWORD(lParam);
        sy = HIWORD(lParam);
        break;
    case WM_PAINT:
        //begin paint
        hDC = BeginPaint(hWnd, &ps);
        //set modes
        SetMapMode(hDC, MM_ANISOTROPIC);
        SetWindowExtEx(hDC, 2 * WIDTH, -2 * HEIGHT, NULL);
        SetViewportExtEx(hDC, 3 * sx / 4, 3 * sy / 4, NULL);
        SetViewportOrgEx(hDC, sx / 2, sy / 2, NULL);
        //draw axis
        SelectObject(hDC, hPenAxis);
        MoveToEx(hDC, -WIDTH, 0, NULL);
        LineTo(hDC, WIDTH, 0);
        MoveToEx(hDC, 0, HEIGHT, NULL);
        LineTo(hDC, 0, -HEIGHT);
        //draw graphic
        SelectObject(hDC, hPenGraphic);
        MoveToEx(hDC, -WIDTH, 0, NULL);
        for (x = -M_PI, x_scr = -WIDTH; x < M_PI; x += 0.02, x_scr += 2)
        {
            y_scr = HEIGHT * sin(x);
            LineTo(hDC, x_scr, y_scr);
        }
        //draw ball
        SelectObject(hDC, hBrushYellow);
        x_scr = t - WIDTH;
        y_scr = HEIGHT * sin(ballAngle);
        updateRegion(ellipse, x_scr - 15, y_scr - 15, x_scr + 15, y_scr + 15);
        FillRgn(hDC, ellipse, hBrushYellow);
        EndPaint(hWnd, &ps);
        break;
    case WM_RBUTTONDOWN:
        paused = !paused;
        break;
    case WM_TIMER:
        if (!paused)
        {
            if (forward)
            {
                t += 3;
                ballAngle += 0.03;
            }
            else if (!forward)
            {
                t -= 3;
                ballAngle -= 0.03;
            }
            if (t >= 2 * WIDTH) {
                forward = false;
            }
            else if (t <= 0) {
                forward = true;
            }
            InvalidateRgn(hWnd, NULL, true);
        }
            break;
        case WM_DESTROY:
            //delete pens
            DeleteObject(hPenAxis);
            DeleteObject(hPenGraphic);
            //delete brush
            DeleteObject(hBrushYellow);
            //delete timer
            KillTimer(hWnd, 1);
            //delete rgn
            DeleteObject(ellipse);
            PostQuitMessage(0);
            break;
        default: return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

void updateRegion(HRGN& hRgn, int left, int top, int right, int bottom) {
    DeleteObject(hRgn);
    hRgn = CreateEllipticRgn(left, top, right, bottom);
}