blokout2.c

Programming Windows 程序开发设计指南

/*---------------------------------------------------
   BLOKOUT2.C -- Mouse Button & Capture Demo Program
                 (c) Charles Petzold, 1996
  ---------------------------------------------------*/

#include <windows.h>

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
     {
     static char szAppName[] = "BlokOut2" ;
     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, "Mouse Button & Capture Demo",
                          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 ;
     }

void DrawBoxOutline (HWND hwnd, POINT ptBeg, POINT ptEnd)
     {
     HDC hdc ;

     hdc = GetDC (hwnd) ;

     SetROP2 (hdc, R2_NOT) ;
     SelectObject (hdc, GetStockObject (NULL_BRUSH)) ;
     Rectangle (hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y) ;

     ReleaseDC (hwnd, hdc) ;
     }

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static BOOL  fBlocking, fValidBox ;
     static POINT ptBeg, ptEnd, ptBoxBeg, ptBoxEnd ;
     HDC          hdc ;
     PAINTSTRUCT  ps ;

     switch (iMsg)
          {
          case WM_LBUTTONDOWN :
               ptBeg.x = ptEnd.x = LOWORD (lParam) ;
               ptBeg.y = ptEnd.y = HIWORD (lParam) ;

               DrawBoxOutline (hwnd, ptBeg, ptEnd) ;

               SetCapture (hwnd) ;
               SetCursor (LoadCursor (NULL, IDC_CROSS)) ;

               fBlocking = TRUE ;
               return 0 ;

          case WM_MOUSEMOVE :
               if (fBlocking)
                    {
                    SetCursor (LoadCursor (NULL, IDC_CROSS)) ;

                    DrawBoxOutline (hwnd, ptBeg, ptEnd) ;

                    ptEnd.x = LOWORD (lParam) ;
                    ptEnd.y = HIWORD (lParam) ;

                    DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
                    }
               return 0 ;

          case WM_LBUTTONUP :
               if (fBlocking)
                    {
                    DrawBoxOutline (hwnd, ptBeg, ptEnd) ;

                    ptBoxBeg   = ptBeg ;
                    ptBoxEnd.x = LOWORD (lParam) ;
                    ptBoxEnd.y = HIWORD (lParam) ;

                    ReleaseCapture () ;
                    SetCursor (LoadCursor (NULL, IDC_ARROW)) ;

                    fBlocking = FALSE ;
                    fValidBox  = TRUE ;

                    InvalidateRect (hwnd, NULL, TRUE) ;
                    }
               return 0 ;

          case WM_CHAR :
               if (fBlocking & wParam == '\x1B')       // i.e., Escape
                    {
                    DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
                    ReleaseCapture () ;
                    SetCursor (LoadCursor (NULL, IDC_ARROW)) ;

                    fBlocking = FALSE ;
                    }
               return 0 ;

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

               if (fValidBox)
                    {
                    SelectObject (hdc, GetStockObject (BLACK_BRUSH)) ;
                    Rectangle (hdc, ptBoxBeg.x, ptBoxBeg.y,
                                    ptBoxEnd.x, ptBoxEnd.y) ;
                    }

               if (fBlocking)
                    {
                    SetROP2 (hdc, R2_NOT) ;
                    SelectObject (hdc, GetStockObject (NULL_BRUSH)) ;
                    Rectangle (hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y) ;
                    }

               EndPaint (hwnd, &ps) ;
               return 0 ;

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