bezier

最新推荐文章于 2025-12-17 21:08:13 发布

原创最新推荐文章于 2025-12-17 21:08:13 发布 · 570 阅读

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#null #callback #winapi #application #windows

本文介绍了一个使用Windows API实现Bezier曲线绘制的简单示例。该示例通过动态调整控制点来实时更新Bezier曲线的形状，并演示了如何在窗口中响应鼠标事件以改变控制点位置。

/*----------------------------------------------------------------------- BEZIER.C -- Bezier Splines Demo ------------------------------------------------------------------------*/ #include <windows.h> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("Bezier") ; HWND hwnd ; MSG msg ; WNDCLASS 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 ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("Program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("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 message, WPARAM wParam, LPARAM lParam) { static POINT apt[4] ; HDC hdc ; int cxClient, cyClient ; PAINTSTRUCT ps ; switch (message) { 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_LBUTTONDOWN: case WM_RBUTTONDOWN: 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) ; } DeleteObject(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, message, wParam, lParam) ; }