/* boxbox.c  (win32) */
#include <windows.h>

#define STEP 3

static char name[] = "BoxBox";
static int xBox1;
static int yBox1;
static int xBox2;
static int yBox2;

LRESULT CALLBACK callback(HWND,UINT,WPARAM,LPARAM);

int WINAPI WinMain(HINSTANCE instance,
        HINSTANCE prev,PSTR commandLine,int showCommand)
{
    HWND window;
    MSG message;
    WNDCLASSEX winclass;

    winclass.cbSize = sizeof (winclass);
    winclass.style = CS_HREDRAW | CS_VREDRAW;
    winclass.lpfnWndProc = callback;
    winclass.cbClsExtra = 0;
    winclass.cbWndExtra = 0;
    winclass.hInstance = instance;
    winclass.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    winclass.hCursor = LoadCursor(NULL,IDC_ARROW);
    winclass.lpszMenuName = NULL;
    winclass.lpszClassName = name;
    winclass.hIconSm = LoadIcon(NULL,IDI_APPLICATION);
    winclass.hbrBackground =
            (HBRUSH)GetStockObject(WHITE_BRUSH);

    RegisterClassEx(&winclass);
    window = CreateWindow (name,"Boxes in Boxes",
            WS_OVERLAPPEDWINDOW,
            CW_USEDEFAULT,CW_USEDEFAULT,
            CW_USEDEFAULT,CW_USEDEFAULT,
            NULL,NULL,instance,NULL);
    ShowWindow(window,showCommand);
    UpdateWindow (window);

    while(GetMessage(&message,NULL,0,0)) {
        TranslateMessage(&message);
        DispatchMessage(&message);
    }
    return(message.wParam);
}

LRESULT CALLBACK callback(HWND window,UINT messageType,
        WPARAM wParam,LPARAM lParam)
{
    int x1;
    int y1;
    int x2;
    int y2;
    HDC hdc;
    PAINTSTRUCT ps;

    switch (messageType) {
    case WM_SIZE:
        xBox1 = 10;
        yBox1 = 10;
        xBox2 = LOWORD(lParam) - 10;
        yBox2 = HIWORD(lParam) - 10;
        return(0);
    case WM_PAINT:
        hdc = BeginPaint(window,&ps);
        SetViewportOrgEx(hdc,0,0,NULL);
        x1 = xBox1;
        x2 = xBox2;
        y1 = yBox1;
        y2 = yBox2;
        while((x1 < x2) && (y1 < y2)) {
            MoveToEx(hdc,x1,y1,NULL);
            LineTo(hdc,x2,y1);
            LineTo(hdc,x2,y2);
            LineTo(hdc,x1,y2);
            LineTo(hdc,x1,y1);
            x1 += STEP;
            y1 += STEP;
            x2 -= STEP;
            y2 -= STEP;
        }
        EndPaint(window,&ps);
        return(0);
          case WM_DESTROY:
               PostQuitMessage(0);
               return(0);
    }
    return(DefWindowProc(window,messageType,
            wParam,lParam));
}