randrect.c

图形基础 GDI 的例子

/*------------------------------------------
   RANDRECT.C -- Displays Random Rectangles
                 (c) Charles Petzold, 1996
  ------------------------------------------*/

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

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

int cxClient, cyClient ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
     {
     static char szAppName[] = "RandRect" ;
     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, "Random Rectangles",
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;

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

     while (TRUE)
          {
          if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
               {
               if (msg.message == WM_QUIT)
                    break ;

               TranslateMessage (&msg) ;
               DispatchMessage (&msg) ;
               }
          else
               DrawRectangle (hwnd) ;
          }

     return msg.wParam ;
     }

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     switch (iMsg)
          {
          case WM_SIZE:
               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;
               return 0 ;

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

void DrawRectangle (HWND hwnd)
     {
     HBRUSH hBrush ;
     HDC    hdc ;
     RECT   rect ;

     if (cxClient == 0 || cyClient == 0)
          return ;

     SetRect (&rect, rand () % cxClient, rand () % cyClient,
                     rand () % cxClient, rand () % cyClient) ;


     hBrush = CreateSolidBrush (RGB (rand () % 256, rand () % 256,
                                                    rand () % 256)) ;
     hdc = GetDC (hwnd) ;

     FillRect (hdc, &rect, hBrush) ;

     ReleaseDC (hwnd, hdc) ;

     DeleteObject (hBrush) ;
     }