// Beginning Game Programming
// Chapter 3
// WindowTest program
//header files to include
#include <windows.h>
#include <stdlib.h>
#include <time.h>
//application title
#define APPTITLE "Hello World"
//function prototypes (forward declarations)
BOOL InitInstance(HINSTANCE,int);
ATOM MyRegisterClass(HINSTANCE);
LRESULT CALLBACK WinProc(HWND,UINT,WPARAM,LPARAM);
//the window event callback function
LRESULT CALLBACK WinProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
    PAINTSTRUCT ps;
    HDC hdc;
    char *szHello = "Hello World!";
    RECT rt;
    int x, y, n;
    COLORREF c;
    switch (message) {
        case WM_PAINT:
            //get the dimensions of the window
            GetClientRect(hWnd, &rt);
            //start drawing on device context
            hdc = BeginPaint(hWnd, &ps);
            //draw some text
            DrawText(hdc, szHello, strlen(szHello), &rt, DT_CENTER);
            //draw 1000 random pixels
            for (n=0; n<3000; n++)
            {
            x = rand() % (rt.right - rt.left);
            y = rand() % (rt.bottom - rt.top);
            c = RGB(rand()%256, rand()%256, rand()%256);
            SetPixel(hdc, x, y, c);
            }
            //stop drawing
            EndPaint(hWnd, &ps);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
    }
    return DefWindowProc(hWnd, message, wParam, lParam);
}
//helper function to set up the window properties
ATOM MyRegisterClass(HINSTANCE hInstance) {
    //create the window class structure
    WNDCLASSEX wc;
    wc.cbSize = sizeof(WNDCLASSEX);
    //fill the struct with info
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = (WNDPROC)WinProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = NULL;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = APPTITLE;
    wc.hIconSm = NULL;
    //set up the window with the class info
    return RegisterClassEx(&wc);
}
//helper function to create the window and refresh it
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow) {
    HWND hWnd;
    //create a new window
    hWnd = CreateWindow(
    APPTITLE, //window class
    APPTITLE, //title bar
    WS_OVERLAPPEDWINDOW, //window style
    CW_USEDEFAULT, //x position of window
    CW_USEDEFAULT, //y position of window
    500, //width of the window
    400, //height of the window
    NULL, //parent window
    NULL, //menu
    hInstance, //application instance
    NULL); //window parameters
    //was there an error creating the window?
    if (!hWnd)
        return FALSE;
    //display the window
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
    return TRUE;
}
//entry point for a Windows program
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    // declare variables
    MSG msg;
    // register the class
    MyRegisterClass(hInstance);
    // initialize application
    if (!InitInstance (hInstance, nCmdShow))
        return FALSE;
    //set random number seed
    srand(time(NULL));
    //main message loop
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}