Linguagem C - SetCapture

/** Mouse Button & Capture Demo Program (c) Charles Petzold, 1998 - 273p - Com pequenas modificações */ #include <windows.h> LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); int WINAPI WinMain(HINSTANCE hI, HINSTANCE hPI, PSTR szCL, int iCS) { static TCHAR szAppName[] = TEXT("SetCapture"); HWND hwnd; MSG msg; WNDCLASS wndclass; wndclass.style = CS_HREDRAW | CS_VREDRAW; wndclass.lpfnWndProc = WndProc; wndclass.cbClsExtra = 0; wndclass.cbWndExtra = 0; wndclass.hInstance = hI; wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION); wndclass.hCursor = LoadCursor(NULL, IDC_ARROW); wndclass.hbrBackground = GetSysColorBrush(COLOR_INFOBK); wndclass.lpszMenuName = NULL; wndclass.lpszClassName = szAppName; if(!RegisterClass(&wndclass)) { MessageBox(NULL, TEXT("W. NT!"), szAppName, MB_ICONERROR); return 0; } hwnd = CreateWindow(szAppName, TEXT("DrawBoxOutline"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hI, NULL); ShowWindow(hwnd, iCS); 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 msg, WPARAM wParam, LPARAM lParam) { static BOOL fBloking, fValidBox; static POINT ptBeg, ptEnd, ptBoxBeg, ptBoxEnd; HDC hdc; PAINTSTRUCT ps; switch(msg) { 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)); fBloking = TRUE; return 0; case WM_MOUSEMOVE: if(fBloking) { 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(fBloking) { DrawBoxOutline(hwnd, ptBeg, ptEnd); ptBoxBeg = ptBeg; ptBoxEnd.x = LOWORD(lParam); ptBoxEnd.y = HIWORD(lParam); ReleaseCapture(); SetCursor(LoadCursor(NULL, IDC_ARROW)); fBloking = FALSE; fValidBox = TRUE; InvalidateRect(hwnd, NULL, TRUE); } return 0; case WM_CHAR: if(fBloking & wParam == '\x1B') { DrawBoxOutline(hwnd, ptBeg, ptEnd); ReleaseCapture(); SetCursor(LoadCursor(NULL, IDC_ARROW)); fBloking = 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(fValidBox) { 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, msg, wParam, lParam); }