Windows API - Double Buffer

/* animation_shell.c
** -- Bare bones windows animation program.
** cs230 2/07
*/

#include <stdlib.h>
#include <time.h>
#include <windows.h>

#define SCREEN_SIZE_X 320
#define SCREEN_SIZE_Y 240

#define BOARD_SIZE_X 200
#define BOARD_SIZE_Y 220

#define BLOCK1_SIZE_X 20
#define BLOCK1_SIZE_Y 20

void draw(HWND win);

char *block1     = "block1.bmp";
char *board1      = "board1.bmp";
char *background = "background.bmp";

COORD block1Coord = {20, 20};

;

LRESULT CALLBACK WinProc(HWND win, UINT msg, WPARAM wp, LPARAM lp) {

  HDC dc;
  PAINTSTRUCT ps;
  static HBITMAP g_hbmBackground = NULL;
  static HBITMAP g_hbmBoard1 = NULL;
  static HBITMAP g_hbmBlock1 = NULL;

  static BITMAP bmp_Board1;
  static BITMAP bmp_Background;
  static BITMAP bmp_Block1;

  static HDC hdcMem;

  static HDC tempDC;

  RECT redrawRect;

  switch (msg) {

    case WM_CREATE:

      dc = GetDC(win);
      // Create the HANDLES for all my bitmaps
		  g_hbmBoard1      = (HBITMAP) LoadImage(NULL, board1,     IMAGE_BITMAP, BOARD_SIZE_X,  BOARD_SIZE_Y,  LR_VGACOLOR | LR_LOADFROMFILE | LR_LOADTRANSPARENT);

      g_hbmBackground  = (HBITMAP) LoadImage(NULL, background, IMAGE_BITMAP, SCREEN_SIZE_X, SCREEN_SIZE_Y, LR_LOADFROMFILE | LR_VGACOLOR );

      g_hbmBlock1      = (HBITMAP) LoadImage(NULL, block1,     IMAGE_BITMAP, block1Coord.X, block1Coord.Y, LR_LOADFROMFILE);

      // Make sure the Handles were created
      if(g_hbmBackground  == NULL || g_hbmBoard1 == NULL || g_hbmBlock1 == NULL)
        MessageBox(win, "Image Loaded Incorrectly", "Error", MB_OK | MB_ICONEXCLAMATION);

      // Place the bitmaps into there proper place
      GetObject(g_hbmBackground , sizeof(bmp_Background), &bmp_Background);
      GetObject(g_hbmBlock1     , sizeof(bmp_Block1)    , &bmp_Block1);
      GetObject(g_hbmBoard1     , sizeof(bmp_Board1)    , &bmp_Board1);



      ReleaseDC(win, dc);
      srand((unsigned int)time(NULL));
      break;

    case WM_PAINT:
      {

      dc = BeginPaint(win, &ps);
      
      // Setup 2 Temp DC for writting

      HDC tempDC_1 = CreateCompatibleDC(dc);  // This one will hold the final screen to be BitBlt'ed

      HDC tempDC_2 = CreateCompatibleDC(dc);  // This one will temporarily hold the bitmaps

      // These should not be monocrome bitmaps since there loaded with the same DC as the windows

      HBITMAP hTempBmp1 = CreateCompatibleBitmap(dc, SCREEN_SIZE_X, SCREEN_SIZE_Y);

      HBITMAP hTempBmp2 = CreateCompatibleBitmap(dc, SCREEN_SIZE_X, SCREEN_SIZE_Y);

      // Load these compatible BMP's into each tempDC
      HBITMAP hOldBmp1 = (HBITMAP) SelectObject(tempDC_1, hTempBmp1);
      HBITMAP hOldBmp2 = (HBITMAP) SelectObject(tempDC_2, hTempBmp2);

      // Color in the tempDC's before I load anything in
      // I will use the Default White Brush
      Rectangle(tempDC_1, 0, 0, SCREEN_SIZE_X, SCREEN_SIZE_Y);
      Rectangle(tempDC_2, 0, 0, SCREEN_SIZE_X, SCREEN_SIZE_Y);
      
      // Select a bitmap and write it to the temporary DC
      SelectObject(tempDC_1, g_hbmBackground );

      // Write to the Temp Screen
      BitBlt(tempDC_2, 0, 0, 320, 240, tempDC_1, 0, 0, SRCCOPY);

      // Do the same as above
      SelectObject(tempDC_1, g_hbmBoard1);

      BitBlt(tempDC_2, 0, 0, BOARD_SIZE_X, BOARD_SIZE_Y, tempDC_1, 0, 0, SRCCOPY);
      

      //SelectObject(tempDC_1, g_hbmBlock1);

      //BitBlt(tempDC_2, block1Coord.X, block1Coord.Y, 
                 //   BLOCK1_SIZE_X, 
                   // BLOCK1_SIZE_Y,
                   // tempDC_1, 0, 0, SRCCOPY);

      BitBlt(dc, 0, 0, 320, 240, tempDC_2, 0, 0, SRCCOPY);

      // Always select the old bitmap back into the device context
      SelectObject(tempDC_1, hOldBmp1);
      SelectObject(tempDC_2, hOldBmp2);
      DeleteObject(hTempBmp1);
      DeleteObject(hTempBmp2);
      DeleteDC(tempDC_1);
      DeleteDC(tempDC_2);

      EndPaint(win, &ps);

      break;
      }
    case WM_CHAR:
      if (wp == 0x1b)
        DestroyWindow(win);
      break;
    case WM_KEYDOWN:

      switch (wp)
      {
      case VK_RIGHT:

        block1Coord.X += 3;
        InvalidateRect(win, NULL, true);
        break;

      case VK_LEFT:

        block1Coord.X -= 3;
        InvalidateRect(win, NULL, true);
        break;

      case VK_UP:

        block1Coord.Y -= 3;
        InvalidateRect(win, NULL, true);
        break;

      case VK_DOWN:
        
        block1Coord.Y += 3;
        InvalidateRect(win, NULL, true);
        break;

      default:
        break;
      }

    case WM_DESTROY:

      DeleteObject(g_hbmBackground);
      DeleteObject(g_hbmBoard1);
      DeleteObject(g_hbmBlock1);

      PostQuitMessage(0);
      break;

    default:
      return DefWindowProc(win,msg,wp,lp);
  }
  return 0;
}


int WINAPI WinMain(HINSTANCE instance, HINSTANCE ignore,
                   LPSTR command_line, int show) {
  char *window_title = "Tetris Initial Development",
       *class_name = "Tetris";
  WNDCLASS wc;
  HWND win;
  MSG msg;

  wc.style = 0;//CS_HREDRAW | CS_VREDRAW;
  wc.lpfnWndProc = WinProc;
  wc.cbClsExtra = 0;
  wc.cbWndExtra = 0;
  wc.hInstance = instance;
  wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
  wc.hCursor = LoadCursor(NULL,IDC_ARROW);
  wc.hbrBackground = NULL;
  wc.lpszMenuName = NULL;
  wc.lpszClassName = class_name;
  RegisterClass(&wc);

  win = CreateWindow(class_name,window_title,
          WS_VISIBLE | WS_CAPTION | WS_SYSMENU ,0 ,0,
          320, 240,NULL,NULL,instance,NULL);
  ShowWindow(win,show);

  // Animation Styple "greedy" event loop
  while (IsWindow(win)) {
    if (PeekMessage(&msg,win,0,0,PM_REMOVE)) {
      //^^^^^^^^^^^ Non-Blocking - looks at event queue, returns nonzero
      // if there is no message; zero otherwise
      // Note: it is possible to look for a specific message
      // or messages; however,   
      // 
      TranslateMessage(&msg);
      DispatchMessage(&msg); }
    //else
      // draw stuff if there is no messages on the queue:
      //draw(win);
      // give some cycles back to the CPU
      //Sleep(10);
  }
  
  UnregisterClass(class_name,instance);

  return msg.wParam;
}