/*--------------------------------------
   TYPER.C -- Typing Program
              (c) Charles Petzold, 1996
  --------------------------------------*/

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

#define BUFFER(x,y) *(pBuffer + y * cxBuffer + x)

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
     {
     static char szAppName[] = "Typer" ;
     HWND        hwnd ;
     MSG         msg ;
     WNDCLASSEX  wndclass ;

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

     RegisterClassEx (&wndclass) ;

     hwnd = CreateWindow (szAppName, "Typing Program",
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;

     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;

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

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static char *pBuffer = NULL ;
     static int  cxChar, cyChar, cxClient, cyClient, cxBuffer, cyBuffer,
                 xCaret, yCaret ;
     HDC         hdc ;
     int         x, y, i ;
     PAINTSTRUCT ps ;
     TEXTMETRIC  tm ;

     switch (iMsg)
          {
          case WM_CREATE :
               hdc = GetDC (hwnd) ;

               SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;
               GetTextMetrics (hdc, &tm) ;
               cxChar = tm.tmAveCharWidth ;
               cyChar = tm.tmHeight ;

               ReleaseDC (hwnd, hdc) ;
               return 0 ;

          case WM_SIZE :
                                   // obtain window size in pixels

               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;

                                   // calculate window size in characters

               cxBuffer = max (1, cxClient / cxChar) ;
               cyBuffer = max (1, cyClient / cyChar) ;

                                   // allocate memory for buffer and clear it

               if (pBuffer != NULL)
                    free (pBuffer) ;

               if ((pBuffer = (char *) malloc (cxBuffer * cyBuffer)) == NULL)
                    MessageBox (hwnd, "Window too large.  Cannot "
                                      "allocate enough memory.", "Typer",
                                      MB_ICONEXCLAMATION | MB_OK) ;
               else
                    for (y = 0 ; y < cyBuffer ; y++)
                         for (x = 0 ; x < cxBuffer ; x++)
                              BUFFER(x,y) = ' ' ;

                                   // set caret to upper left corner
               xCaret = 0 ;
               yCaret = 0 ;

               if (hwnd == GetFocus ())
                    SetCaretPos (xCaret * cxChar, yCaret * cyChar) ;

               return 0 ;

          case WM_SETFOCUS :
                                   // create and show the caret

               CreateCaret (hwnd, NULL, cxChar, cyChar) ;
               SetCaretPos (xCaret * cxChar, yCaret * cyChar) ;
               ShowCaret (hwnd) ;
               return 0 ;

          case WM_KILLFOCUS :
                                   // hide and destroy the caret
               HideCaret (hwnd) ;
               DestroyCaret () ;
               return 0 ;

          case WM_KEYDOWN :
               switch (wParam)
                    {
                    case VK_HOME :
                         xCaret = 0 ;
                         break ;

                    case VK_END :
                         xCaret = cxBuffer - 1 ;
                         break ;

                    case VK_PRIOR :
                         yCaret = 0 ;
                         break ;

                    case VK_NEXT :
                         yCaret = cyBuffer - 1 ;
                         break ;

                    case VK_LEFT :
                         xCaret = max (xCaret - 1, 0) ;
                         break ;

                    case VK_RIGHT :
                         xCaret = min (xCaret + 1, cxBuffer - 1) ;
                         break ;

                    case VK_UP :
                         yCaret = max (yCaret - 1, 0) ;
                         break ;

                    case VK_DOWN :
                         yCaret = min (yCaret + 1, cyBuffer - 1) ;
                         break ;

                    case VK_DELETE :
                         for (x = xCaret ; x < cxBuffer - 1 ; x++)
                              BUFFER (x, yCaret) = BUFFER (x + 1, yCaret) ;

                         BUFFER (cxBuffer - 1, yCaret) = ' ' ;

                         HideCaret (hwnd) ;
                         hdc = GetDC (hwnd) ;

                         SelectObject (hdc,
                              GetStockObject (SYSTEM_FIXED_FONT)) ;

                         TextOut (hdc, xCaret * cxChar, yCaret * cyChar,
                                  & BUFFER (xCaret, yCaret),
                                  cxBuffer - xCaret) ;

                         ShowCaret (hwnd) ;
                         ReleaseDC (hwnd, hdc) ;
                         break ;
                    }

               SetCaretPos (xCaret * cxChar, yCaret * cyChar) ;
               return 0 ;

          case WM_CHAR :
               for (i = 0 ; i < (int) LOWORD (lParam) ; i++)
                    {
                    switch (wParam)
                         {
                         case '\b' :                    // backspace
                              if (xCaret > 0)
                                   {
                                   xCaret-- ;
                                   SendMessage (hwnd, WM_KEYDOWN,
                                                VK_DELETE, 1L) ;
                                   }
                              break ;

                         case '\t' :                    // tab
                              do
                                   {
                                   SendMessage (hwnd, WM_CHAR, ' ', 1L) ;
                                   }
                              while (xCaret % 8 != 0) ;
                              break ;

                         case '\n' :                    // line feed
                              if (++yCaret == cyBuffer)
                                   yCaret = 0 ;
                              break ;

                         case '\r' :                    // carriage return
                              xCaret = 0 ;

                              if (++yCaret == cyBuffer)
                                   yCaret = 0 ;
                              break ;

                         case '\x1B' :                  // escape
                              for (y = 0 ; y < cyBuffer ; y++)
                                   for (x = 0 ; x < cxBuffer ; x++)
                                        BUFFER (x, y) = ' ' ;

                              xCaret = 0 ;
                              yCaret = 0 ;

                              InvalidateRect (hwnd, NULL, FALSE) ;
                              break ;

                         default :                       // character codes
                              BUFFER (xCaret, yCaret) = (char) wParam ;

                              HideCaret (hwnd) ;
                              hdc = GetDC (hwnd) ;

                              SelectObject (hdc,
                                   GetStockObject (SYSTEM_FIXED_FONT)) ;

                              TextOut (hdc, xCaret * cxChar, yCaret * cyChar,
                                       & BUFFER (xCaret, yCaret), 1) ;

                              ShowCaret (hwnd) ;
                              ReleaseDC (hwnd, hdc) ;

                              if (++xCaret == cxBuffer)
                                   {
                                   xCaret = 0 ;

                                   if (++yCaret == cyBuffer)
                                        yCaret = 0 ;
                                   }
                              break ;
                         }
                    }

               SetCaretPos (xCaret * cxChar, yCaret * cyChar) ;
               return 0 ;

          case WM_PAINT :
               hdc = BeginPaint (hwnd, &ps) ;
               SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ;

               for (y = 0 ; y < cyBuffer ; y++)
                    TextOut (hdc, 0, y * cyChar, & BUFFER(0,y), cxBuffer) ;

               EndPaint (hwnd, &ps) ;
               return 0 ;

          case WM_DESTROY :
               PostQuitMessage (0) ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }
