bezier.c

图形基础 GDI 的例子

/*---------------------------------------
   BEIZER.C -- Bezier Splines Demo
               (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[] = "Bezier" ;
     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, "Bezier Splines",
                          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 DrawBezier (HDC hdc, POINT apt[])
     {
     PolyBezier (hdc, apt, 4) ;

     MoveToEx (hdc, apt[0].x, apt[0].y, NULL) ;
     LineTo   (hdc, apt[1].x, apt[1].y) ;

     MoveToEx (hdc, apt[2].x, apt[2].y, NULL) ;
     LineTo   (hdc, apt[3].x, apt[3].y) ;
     }

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static POINT apt[4] ;
     HDC          hdc ;
     int          cxClient, cyClient ;
     PAINTSTRUCT  ps ;

     switch (iMsg)
          {
          case WM_SIZE:
               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;

               apt[0].x = cxClient / 4 ;
               apt[0].y = cyClient / 2 ;

               apt[1].x = cxClient / 2 ;
               apt[1].y = cyClient / 4 ;

               apt[2].x =     cxClient / 2 ;
               apt[2].y = 3 * cyClient / 4 ;

               apt[3].x = 3 * cxClient / 4 ;
               apt[3].y =     cyClient / 2 ;

               return 0 ;

          case WM_MOUSEMOVE:
               if (wParam & MK_LBUTTON || wParam & MK_RBUTTON)
                    {
                    hdc = GetDC (hwnd) ;

                    SelectObject (hdc, GetStockObject (WHITE_PEN)) ;
                    DrawBezier (hdc, apt) ;

                    if (wParam & MK_LBUTTON)
                         {
                         apt[1].x = LOWORD (lParam) ;
                         apt[1].y = HIWORD (lParam) ;
                         }

                    if (wParam & MK_RBUTTON)
                         {
                         apt[2].x = LOWORD (lParam) ;
                         apt[2].y = HIWORD (lParam) ;
                         }

                    SelectObject (hdc, GetStockObject (BLACK_PEN)) ;
                    DrawBezier (hdc, apt) ;
                    ReleaseDC (hwnd, hdc) ;
                    }

               return 0 ;

          case WM_PAINT:
               InvalidateRect (hwnd, NULL, TRUE) ;

	           hdc = BeginPaint (hwnd, &ps) ;

               DrawBezier (hdc, apt) ;

	           EndPaint (hwnd, &ps) ;
               return 0 ;

          case WM_DESTROY:
               PostQuitMessage (0) ;
               return 0 ;
          }

     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }