/* mingwscr.c */

#include <windows.h>
#include <tchar.h>
#include <scrnsave.h>
#include <time.h>
#include <stdlib.h>
#include "resource.h"

#define FPS        60

#define ID_TIMER   101


/* screensaver main processing */
LRESULT WINAPI ScreenSaverProc(HWND hWnd, UINT msg,
                               WPARAM wParam, LPARAM lParam)
{
  static HBITMAP hBitmap;
  static HBITMAP hBitmap_mask;
  static HBITMAP hBitmap_bg;
  static HBITMAP hBitmap_preview;
  static HBITMAP offScrnBitmap;

  static int wdw_w, wdw_h;
  static int imgw, imgh;
  static int bgw, bgh;
  static int pvw, pvh;
  static float x, y, dx, dy, bgx, bgy;
  int bx, by;

  switch (msg)
    {
    case WM_CREATE:
      /* initialize */

      // get window size
      {
        RECT rc;

        GetClientRect(hWnd, &rc);
        wdw_w = rc.right - rc.left;
        wdw_h = rc.bottom - rc.top;
      }

      // create off-screen bitmap
      {
        HDC hdc;

        hdc = GetDC(hWnd);
        offScrnBitmap = CreateCompatibleBitmap(hdc, wdw_w, wdw_h);
        ReleaseDC(hWnd, hdc);
      }

      // load bitmaps
      hBitmap = LoadBitmap(((LPCREATESTRUCT)lParam)->hInstance, TEXT("IDI_BALL"));
      hBitmap_mask = LoadBitmap(((LPCREATESTRUCT)lParam)->hInstance, TEXT("IDI_BALL_MSK"));
      hBitmap_bg = LoadBitmap(((LPCREATESTRUCT)lParam)->hInstance, TEXT("IDI_BG"));
      hBitmap_preview = LoadBitmap(((LPCREATESTRUCT)lParam)->hInstance, TEXT("IDI_PREVIEW"));

      // get images size
      {
        BITMAP bp;

        // get ball image size
        GetObject(hBitmap, sizeof(BITMAP), &bp);
        imgw = bp.bmWidth;
        imgh = bp.bmHeight;

        // get bg image size
        GetObject(hBitmap_bg, sizeof(BITMAP), &bp);
        bgw = bp.bmWidth;
        bgh = bp.bmHeight;

        // get preview image size
        GetObject(hBitmap_preview, sizeof(BITMAP), &bp);
        pvw = bp.bmWidth;
        pvh = bp.bmHeight;
      }

      // init work
      x = wdw_w / 2;
      y = wdw_h / 2;
      dx = (float)wdw_w / (float)FPS;
      dy = dx * 0.5;
      bgx = 0;
      bgy = 0;

      // create timer
      SetTimer(hWnd, ID_TIMER, (int)(1000 / FPS), NULL);
      break;

    case WM_TIMER:
      /* main loop */

      // update ball position
      x += dx;
      y += dy;

      if (x <= 0 || x + imgw >= wdw_w) dx *= -1;

      if (y <= 0 || y + imgh >= wdw_h) dy *= -1;

      // update bg position
      bgx -= 2;
      bgy -= 2;

      if (bgx <= -bgw) bgx += bgw;

      if (bgy <= -bgh) bgy += bgh;

      // draw bitmap

      if (wdw_w >= 160)
        {
          // draw fullscreen

          HDC hdc, hBmpDC, hMemDC;

          hdc = GetDC(hWnd);

          // set off-screen bitmap
          hMemDC = CreateCompatibleDC(hdc);
          SelectObject(hMemDC, offScrnBitmap);

          // draw bg to off-screen
          hBmpDC = CreateCompatibleDC(hdc);
          SelectObject(hBmpDC, hBitmap_bg);
          {
            int by = bgy;

            while (by <= wdw_h)
              {
                int bx = bgx;

                while (bx <= wdw_w)
                  {
                    BitBlt(hMemDC, bx, by, bgw, bgh, hBmpDC, 0, 0, SRCCOPY);
                    bx += bgw;
                  }

                by += bgh;
              }
          }
          DeleteDC(hBmpDC);

          // draw ball mask to off-screen
          hBmpDC = CreateCompatibleDC(hdc);
          SelectObject(hBmpDC, hBitmap_mask);
          BitBlt(hMemDC, (int)x, (int)y, imgw, imgh, hBmpDC, 0, 0, SRCAND);
          DeleteDC(hBmpDC);

          // draw ball source to off-screen
          hBmpDC = CreateCompatibleDC(hdc);
          SelectObject(hBmpDC, hBitmap);
          BitBlt(hMemDC, (int)x, (int)y, imgw, imgh, hBmpDC, 0, 0, SRCPAINT);
          DeleteDC(hBmpDC);

          // drawing to off-screen is finished

          // draw off-screen bitmap to window
          BitBlt(hdc, 0, 0, wdw_w, wdw_h, hMemDC, 0, 0, SRCCOPY);

          DeleteDC(hMemDC);      // Create*() -> DeleteDC()
          ReleaseDC(hWnd, hdc);  // GetDC() -> ReleaseDC()
        }
      else
        {
          // draw preview
          HDC hdc, hBmpDC;
          hdc = GetDC(hWnd);
          hBmpDC = CreateCompatibleDC(hdc);
          SelectObject(hBmpDC, hBitmap_preview);
          BitBlt(hdc, 0, 0, pvw, pvh, hBmpDC, 0, 0, SRCCOPY);
          DeleteDC(hBmpDC);      // Create*() -> DeleteDC()
          ReleaseDC(hWnd, hdc);  // GetDC() -> ReleaseDC()
        }

      break;

    case WM_DESTROY:
      KillTimer(hWnd, ID_TIMER);  // kill timer

      // delete bitmap
      DeleteObject(offScrnBitmap);
      DeleteObject(hBitmap);
      DeleteObject(hBitmap_mask);
      DeleteObject(hBitmap_bg);
      DeleteObject(hBitmap_preview);

      PostQuitMessage(0);
      break;

    default:
      break;
    }

  return DefScreenSaverProc(hWnd, msg, wParam, lParam);
}

/* Processing of dialog boxes for configuration */
BOOL WINAPI ScreenSaverConfigureDialog(HWND hDlg, UINT msg,
                                       WPARAM wParam, LPARAM lParam)
{
  switch (msg)
    {
    case WM_COMMAND:
      switch (LOWORD(wParam))
        {
        case IDOK:
          EndDialog(hDlg, 0);
          return TRUE;

        case IDCANCEL:
          EndDialog(hDlg, 1);
          return TRUE;
        }

      return FALSE;
    }

  return FALSE;
}

/* Register non-standard window classes required by dialog boxes for configuration */
BOOL WINAPI RegisterDialogClasses(HANDLE hInst)
{
  return TRUE;
}