#include "wx/msgdlg.h"
#include "wx/intl.h"
#include "wx/dynarray.h"
-# include "wx/wxchar.h"
-# include "wx/icon.h"
+ #include "wx/wxchar.h"
+ #include "wx/icon.h"
#endif
#include "wx/log.h"
#endif
// OLE is used for drag-and-drop, clipboard, OLE Automation...
+#ifndef wxUSE_NORLANDER_HEADERS
#if defined(__GNUWIN32__) || defined(__SC__) || defined(__SALFORDC__)
#undef wxUSE_OLE
#define wxUSE_OLE 0
#endif // broken compilers
+#endif
#if wxUSE_OLE
#include <ole2.h>
#include <string.h>
#include <ctype.h>
-#if (defined(__WIN95__) && !defined(__GNUWIN32__)) || defined(__TWIN32__)
+#if (defined(__WIN95__) && !defined(__GNUWIN32__)) || defined(__TWIN32__) || defined(wxUSE_NORLANDER_HEADERS)
#include <commctrl.h>
#endif
#include "wx/msw/msvcrt.h"
+// ----------------------------------------------------------------------------
+// conditional compilation
+// ----------------------------------------------------------------------------
+
+// The macro _WIN32_IE is defined by commctrl.h (unless it had already been
+// defined before) and shows us what common control features are available
+// during the compile time (it doesn't mean that they will be available during
+// the run-time, use GetComCtl32Version() to test for them!). The possible
+// values are:
+//
+// 0x0200 for comctl32.dll 4.00 shipped with Win95/NT 4.0
+// 0x0300 4.70 IE 3.x
+// 0x0400 4.71 IE 4.0
+// 0x0401 4.72 IE 4.01 and Win98
+// 0x0500 5.00 IE 5.x and NT 5.0 (Win2000)
+
+#ifndef _WIN32_IE
+ // minimal set of features by default
+ #define _WIN32_IE 0x0200
+#endif
+
+#if _WIN32_IE >= 0x0300
+ #include <shlwapi.h>
+#endif
+
// ---------------------------------------------------------------------------
// global variables
// ---------------------------------------------------------------------------
extern wxChar *wxOsVersion;
extern wxList *wxWinHandleList;
extern wxList WXDLLEXPORT wxPendingDelete;
-#if wxUSE_THREADS
-extern wxList *wxPendingEvents;
-extern wxCriticalSection *wxPendingEventsLocker;
-#endif
extern void wxSetKeyboardHook(bool doIt);
extern wxCursor *g_globalCursor;
-HINSTANCE wxhInstance = 0;
MSG s_currentMsg;
wxApp *wxTheApp = NULL;
-// FIXME why not const? and not static?
-wxChar wxFrameClassName[] = _T("wxFrameClass");
-wxChar wxMDIFrameClassName[] = _T("wxMDIFrameClass");
-wxChar wxMDIChildFrameClassName[] = _T("wxMDIChildFrameClass");
-wxChar wxPanelClassName[] = _T("wxPanelClass");
-wxChar wxCanvasClassName[] = _T("wxCanvasClass");
+// NB: all "NoRedraw" classes must have the same names as the "normal" classes
+// with NR suffix - wxWindow::MSWCreate() supposes this
+const wxChar *wxFrameClassName = wxT("wxFrameClass");
+const wxChar *wxFrameClassNameNoRedraw = wxT("wxFrameClassNR");
+const wxChar *wxMDIFrameClassName = wxT("wxMDIFrameClass");
+const wxChar *wxMDIFrameClassNameNoRedraw = wxT("wxMDIFrameClassNR");
+const wxChar *wxMDIChildFrameClassName = wxT("wxMDIChildFrameClass");
+const wxChar *wxMDIChildFrameClassNameNoRedraw = wxT("wxMDIChildFrameClassNR");
+const wxChar *wxPanelClassName = wxT("wxPanelClass");
+const wxChar *wxCanvasClassName = wxT("wxCanvasClass");
HICON wxSTD_FRAME_ICON = (HICON) NULL;
HICON wxSTD_MDICHILDFRAME_ICON = (HICON) NULL;
HBRUSH wxDisableButtonBrush = (HBRUSH) 0;
-LRESULT APIENTRY wxWndProc(HWND, UINT, WPARAM, LPARAM);
-
-#if defined(__WIN95__) && !defined(__TWIN32__)
- #define wxUSE_RICHEDIT 1
-#else
- #define wxUSE_RICHEDIT 0
-#endif
-
-#if wxUSE_RICHEDIT
- static HINSTANCE gs_hRichEdit = (HINSTANCE) NULL;
-#endif
+LRESULT WXDLLEXPORT APIENTRY wxWndProc(HWND, UINT, WPARAM, LPARAM);
// ===========================================================================
// implementation
// wxApp
// ---------------------------------------------------------------------------
-#if !USE_SHARED_LIBRARY
IMPLEMENT_DYNAMIC_CLASS(wxApp, wxEvtHandler)
BEGIN_EVENT_TABLE(wxApp, wxEvtHandler)
EVT_END_SESSION(wxApp::OnEndSession)
EVT_QUERY_END_SESSION(wxApp::OnQueryEndSession)
END_EVENT_TABLE()
-#endif
//// Initialize
bool wxApp::Initialize()
wxClassInfo::InitializeClasses();
#if wxUSE_RESOURCES
- wxGetResource(_T("wxWindows"), _T("OsVersion"), &wxOsVersion);
+ wxGetResource(wxT("wxWindows"), wxT("OsVersion"), &wxOsVersion);
#endif
- // I'm annoyed ... I don't know where to put this and I don't want to
- // create a module for that as it's part of the core.
#if wxUSE_THREADS
- wxPendingEvents = new wxList();
- wxPendingEventsLocker = new wxCriticalSection();
+ wxPendingEventsLocker = new wxCriticalSection;
#endif
wxTheColourDatabase = new wxColourDatabase(wxKEY_STRING);
#if defined(__WIN95__)
InitCommonControls();
-#if wxUSE_RICHEDIT
- gs_hRichEdit = LoadLibrary(_T("RICHED32.DLL"));
-
- if (gs_hRichEdit == (HINSTANCE) NULL)
- {
- wxLogError(_("Could not initialise Rich Edit DLL"));
- }
-#endif // wxUSE_RICHEDIT
-
#endif // __WIN95__
+#if wxUSE_OLE
+
+#ifdef __WIN16__
// for OLE, enlarge message queue to be as large as possible
int iMsg = 96;
- while (!SetMessageQueue(iMsg) && (iMsg -= 8));
-
-#if wxUSE_OLE
+ while (!SetMessageQueue(iMsg) && (iMsg -= 8))
+ ;
+#endif // Win16
// we need to initialize OLE library
if ( FAILED(::OleInitialize(NULL)) )
wxLogError(_("Cannot initialize OLE"));
-#endif
+#endif // wxUSE_OLE
#if wxUSE_CTL3D
if (!Ctl3dRegister(wxhInstance))
- wxLogError(_T("Cannot register CTL3D"));
+ wxLogError(wxT("Cannot register CTL3D"));
Ctl3dAutoSubclass(wxhInstance);
#endif
g_globalCursor = new wxCursor;
- wxSTD_FRAME_ICON = LoadIcon(wxhInstance, _T("wxSTD_FRAME"));
- wxSTD_MDIPARENTFRAME_ICON = LoadIcon(wxhInstance, _T("wxSTD_MDIPARENTFRAME"));
- wxSTD_MDICHILDFRAME_ICON = LoadIcon(wxhInstance, _T("wxSTD_MDICHILDFRAME"));
+ // VZ: these icons are not in wx.rc anyhow (but should they?)!
+#if 0
+ wxSTD_FRAME_ICON = LoadIcon(wxhInstance, wxT("wxSTD_FRAME"));
+ wxSTD_MDIPARENTFRAME_ICON = LoadIcon(wxhInstance, wxT("wxSTD_MDIPARENTFRAME"));
+ wxSTD_MDICHILDFRAME_ICON = LoadIcon(wxhInstance, wxT("wxSTD_MDICHILDFRAME"));
- wxDEFAULT_FRAME_ICON = LoadIcon(wxhInstance, _T("wxDEFAULT_FRAME"));
- wxDEFAULT_MDIPARENTFRAME_ICON = LoadIcon(wxhInstance, _T("wxDEFAULT_MDIPARENTFRAME"));
- wxDEFAULT_MDICHILDFRAME_ICON = LoadIcon(wxhInstance, _T("wxDEFAULT_MDICHILDFRAME"));
+ wxDEFAULT_FRAME_ICON = LoadIcon(wxhInstance, wxT("wxDEFAULT_FRAME"));
+ wxDEFAULT_MDIPARENTFRAME_ICON = LoadIcon(wxhInstance, wxT("wxDEFAULT_MDIPARENTFRAME"));
+ wxDEFAULT_MDICHILDFRAME_ICON = LoadIcon(wxhInstance, wxT("wxDEFAULT_MDICHILDFRAME"));
+#endif // 0
RegisterWindowClasses();
LOGBRUSH lb;
lb.lbStyle = BS_PATTERN;
- lb.lbHatch = (int)LoadBitmap( wxhInstance, _T("wxDISABLE_BUTTON_BITMAP") );
+ lb.lbHatch = (int)LoadBitmap( wxhInstance, wxT("wxDISABLE_BUTTON_BITMAP") );
if ( lb.lbHatch )
{
wxDisableButtonBrush = ::CreateBrushIndirect( & lb );
// RegisterWindowClasses
// ---------------------------------------------------------------------------
+// TODO we should only register classes really used by the app. For this it
+// would be enough to just delay the class registration until an attempt
+// to create a window of this class is made.
bool wxApp::RegisterWindowClasses()
{
WNDCLASS wndclass;
+ // for each class we register one with CS_(V|H)REDRAW style and one
+ // without for windows created with wxNO_FULL_REDRAW_ON_REPAINT flag
+ static const long styleNormal = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS;
+ static const long styleNoRedraw = CS_DBLCLKS;
+
// the fields which are common to all classes
- wndclass.style = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS;
wndclass.lpfnWndProc = (WNDPROC)wxWndProc;
wndclass.cbClsExtra = 0;
- wndclass.cbWndExtra = sizeof( DWORD ); // what is this DWORD used for?
+ wndclass.cbWndExtra = sizeof( DWORD ); // VZ: what is this DWORD used for?
wndclass.hInstance = wxhInstance;
wndclass.hIcon = (HICON) NULL;
wndclass.hCursor = ::LoadCursor((HINSTANCE)NULL, IDC_ARROW);
// Register the frame window class.
wndclass.hbrBackground = (HBRUSH)(COLOR_APPWORKSPACE + 1);
-#ifdef _MULTIPLE_INSTANCES
- sprintf( wxFrameClassName,"wxFrameClass%d", wxhInstance );
-#endif
wndclass.lpszClassName = wxFrameClassName;
+ wndclass.style = styleNormal;
if ( !RegisterClass(&wndclass) )
{
return FALSE;
}
+ // "no redraw" frame
+ wndclass.lpszClassName = wxFrameClassNameNoRedraw;
+ wndclass.style = styleNoRedraw;
+
+ if ( !RegisterClass(&wndclass) )
+ {
+ wxLogLastError("RegisterClass(no redraw frame)");
+
+ return FALSE;
+ }
+
// Register the MDI frame window class.
wndclass.hbrBackground = (HBRUSH)NULL; // paint MDI frame ourselves
wndclass.lpszClassName = wxMDIFrameClassName;
+ wndclass.style = styleNormal;
if ( !RegisterClass(&wndclass) )
{
return FALSE;
}
+ // "no redraw" MDI frame
+ wndclass.lpszClassName = wxMDIFrameClassNameNoRedraw;
+ wndclass.style = styleNoRedraw;
+
+ if ( !RegisterClass(&wndclass) )
+ {
+ wxLogLastError("RegisterClass(no redraw MDI parent frame)");
+
+ return FALSE;
+ }
+
// Register the MDI child frame window class.
wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wndclass.lpszClassName = wxMDIChildFrameClassName;
+ wndclass.style = styleNormal;
if ( !RegisterClass(&wndclass) )
{
return FALSE;
}
+ // "no redraw" MDI child frame
+ wndclass.lpszClassName = wxMDIChildFrameClassNameNoRedraw;
+ wndclass.style = styleNoRedraw;
+
+ if ( !RegisterClass(&wndclass) )
+ {
+ wxLogLastError("RegisterClass(no redraw MDI child)");
+
+ return FALSE;
+ }
+
// Register the panel window class.
wndclass.hbrBackground = (HBRUSH) GetStockObject( LTGRAY_BRUSH );
wndclass.lpszClassName = wxPanelClassName;
+ wndclass.style = styleNormal;
if ( !RegisterClass(&wndclass) )
{
if (i < len)
{
- if (cmdLine.GetChar(i) == _T('"')) // We found the start of a string
+ if (cmdLine.GetChar(i) == wxT('"')) // We found the start of a string
{
i ++;
int first = i;
- while ((i < len) && (cmdLine.GetChar(i) != _T('"')))
+ while ((i < len) && (cmdLine.GetChar(i) != wxT('"')))
i ++;
wxString arg(cmdLine.Mid(first, (i - first)));
wxSetKeyboardHook(FALSE);
-#ifdef __WIN95__
-
-#if wxUSE_RICHEDIT
- if (gs_hRichEdit != (HINSTANCE) NULL)
- FreeLibrary(gs_hRichEdit);
-#endif
-
-#endif
-
#if wxUSE_PENWINDOWS
wxCleanUpPenWin();
#endif
if (wxWinHandleList)
delete wxWinHandleList;
- // GL: I'm annoyed ... I don't know where to put this and I don't want to
+ // GL: I'm annoyed ... I don't know where to put this and I don't want to
// create a module for that as it's part of the core.
-#if wxUSE_THREADS
delete wxPendingEvents;
+#if wxUSE_THREADS
delete wxPendingEventsLocker;
// If we don't do the following, we get an apparent memory leak.
((wxEvtHandler&) wxDefaultValidator).ClearEventLocker();
// wxDebugContext, too.
if (wxDebugContext::CountObjectsLeft(TRUE) > 0)
{
- wxLogDebug(_T("There were memory leaks."));
+ wxLogDebug(wxT("There were memory leaks."));
wxDebugContext::Dump();
wxDebugContext::PrintStatistics();
}
// (another useful flag is _CRTDBG_DELAY_FREE_MEM_DF which doesn't free
// deallocated memory which may be used to simulate low-memory condition)
wxCrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF);
-
+#ifdef __MWERKS__
+#if (defined(__WXDEBUG__) && wxUSE_MEMORY_TRACING) || wxUSE_DEBUG_CONTEXT
+ // This seems to be necessary since there are 'rogue'
+ // objects present at this point (perhaps global objects?)
+ // Setting a checkpoint will ignore them as far as the
+ // memory checking facility is concerned.
+ // Of course you may argue that memory allocated in globals should be
+ // checked, but this is a reasonable compromise.
+ wxDebugContext::SetCheckpoint();
+#endif
+#endif
// take everything into a try-except block in release build
// FIXME other compilers must support Win32 SEH (structured exception
// handling) too, just find the appropriate keyword in their docs!
#else
#undef CATCH_PROGRAM_EXCEPTIONS
#endif
-
wxhInstance = (HINSTANCE) hInstance;
if (!wxApp::Initialize())
// the IMPLEMENT_APP macro is used instead, which sets an initializer
// function for delayed, dynamic app object construction.
wxCHECK_MSG( wxApp::GetInitializerFunction(), 0,
- _T("No initializer - use IMPLEMENT_APP macro.") );
+ wxT("No initializer - use IMPLEMENT_APP macro.") );
wxTheApp = (*wxApp::GetInitializerFunction()) ();
}
- wxCHECK_MSG( wxTheApp, 0, _T("You have to define an instance of wxApp!") );
+ wxCHECK_MSG( wxTheApp, 0, wxT("You have to define an instance of wxApp!") );
// save the WinMain() parameters
wxTheApp->ConvertToStandardCommandArgs(lpCmdLine);
// but this call is provided for compatibility across platforms.
wxTheApp->OnInitGui();
+ // We really don't want timestamps by default, because it means
+ // we can't simply double-click on the error message and get to that
+ // line in the source. So VC++ at least, let's have a sensible default.
+#ifdef __VISUALC__
+ wxLog::SetTimestamp(NULL);
+#endif
+
int retValue = 0;
if ( wxTheApp->OnInit() )
{
#if wxUSE_THREADS
wxASSERT_MSG( wxThread::IsMain(),
- _T("only the main thread can process Windows messages") );
+ wxT("only the main thread can process Windows messages") );
static bool s_hadGuiLock = TRUE;
static wxMsgArray s_aSavedMessages;
return event.MoreRequested();
}
-#if wxUSE_THREADS
-void wxApp::ProcessPendingEvents()
-{
- wxNode *node = wxPendingEvents->First();
- wxCriticalSectionLocker locker(*wxPendingEventsLocker);
-
- while (node)
- {
- wxEvtHandler *handler = (wxEvtHandler *)node->Data();
-
- handler->ProcessPendingEvents();
-
- delete node;
- node = wxPendingEvents->First();
- }
-}
-#endif
-
-
void wxApp::ExitMainLoop()
{
m_keepGoing = FALSE;
while ( hWnd && !wndThis )
{
hWnd = ::GetParent(hWnd);
- wndThis = wxFindWinFromHandle((WXHWND)hWnd);
+ wndThis = wxFindWinFromHandle((WXHWND)hWnd);
}
// Try translations first; find the youngest window with
event.RequestMore(TRUE);
}
- // If they are pending events, we must process them.
-#if wxUSE_THREADS
+ // If they are pending events, we must process them: pending events are
+ // either events to the threads other than main or events posted with
+ // wxPostEvent() functions
ProcessPendingEvents();
-#endif
+
s_inOnIdle = FALSE;
}
}
}
-int wxApp::GetComCtl32Version() const
+/* static */
+int wxApp::GetComCtl32Version()
{
- // have we loaded COMCTL32 yet?
- HMODULE theModule = ::GetModuleHandle(_T("COMCTL32"));
- int version = 0;
+ // cache the result
+ static int s_verComCtl32 = -1;
- // if so, then we can check for the version
- if (theModule)
+ wxCRIT_SECT_DECLARE(csComCtl32);
+ wxCRIT_SECT_LOCKER(lock, csComCtl32);
+
+ if ( s_verComCtl32 == -1 )
{
- // InitCommonControlsEx is unique to 4.7 and later
- FARPROC theProc = ::GetProcAddress(theModule, "InitCommonControlsEx");
+ // initally assume no comctl32.dll at all
+ s_verComCtl32 = 0;
- if (! theProc)
- { // not found, must be 4.00
- version = 400;
- }
- else
+ // do we have it?
+ HMODULE hModuleComCtl32 = ::GetModuleHandle(wxT("COMCTL32"));
+
+ // if so, then we can check for the version
+ if ( hModuleComCtl32 )
{
- // The following symbol are unique to 4.71
- // DllInstall
- // FlatSB_EnableScrollBar FlatSB_GetScrollInfo FlatSB_GetScrollPos
- // FlatSB_GetScrollProp FlatSB_GetScrollRange FlatSB_SetScrollInfo
- // FlatSB_SetScrollPos FlatSB_SetScrollProp FlatSB_SetScrollRange
- // FlatSB_ShowScrollBar
- // _DrawIndirectImageList _DuplicateImageList
- // InitializeFlatSB
- // UninitializeFlatSB
- // we could check for any of these - I chose DllInstall
- FARPROC theProc = ::GetProcAddress(theModule, "DllInstall");
- if (! theProc)
- {
- // not found, must be 4.70
- version = 470;
- }
- else
- { // found, must be 4.71
- version = 471;
- }
+ // try to use DllGetVersion() if available in _headers_
+ #ifdef DLLVER_PLATFORM_WINDOWS // defined in shlwapi.h
+ DLLGETVERSIONPROC pfnDllGetVersion = (DLLGETVERSIONPROC)
+ ::GetProcAddress(hModuleComCtl32, _T("DllGetVersion"));
+ if ( pfnDllGetVersion )
+ {
+ DLLVERSIONINFO dvi;
+ dvi.cbSize = sizeof(dvi);
+
+ HRESULT hr = (*pfnDllGetVersion)(&dvi);
+ if ( FAILED(hr) )
+ {
+ wxLogApiError(_T("DllGetVersion"), hr);
+ }
+ else
+ {
+ // this is incompatible with _WIN32_IE values, but
+ // compatible with the other values returned by
+ // GetComCtl32Version()
+ s_verComCtl32 = 100*dvi.dwMajorVersion +
+ dvi.dwMinorVersion;
+ }
+ }
+ #endif
+ // DllGetVersion() unavailable either during compile or
+ // run-time, try to guess the version otherwise
+ if ( !s_verComCtl32 )
+ {
+ // InitCommonControlsEx is unique to 4.70 and later
+ FARPROC theProc = ::GetProcAddress
+ (
+ hModuleComCtl32,
+#if defined(__BORLANDC__) && (__BORLANDC__ <= 0x520)
+ "InitCommonControlsEx"
+#else
+ _T("InitCommonControlsEx")
+#endif
+ );
+
+ if ( !theProc )
+ {
+ // not found, must be 4.00
+ s_verComCtl32 = 400;
+ }
+ else
+ {
+ // many symbols appeared in comctl32 4.71, could use
+ // any of them except may be DllInstall
+ theProc = ::GetProcAddress
+ (
+ hModuleComCtl32,
+#if defined(__BORLANDC__) && (__BORLANDC__ <= 0x520)
+ "InitializeFlatSB"
+#else
+ _T("InitializeFlatSB")
+#endif
+ );
+ if ( !theProc )
+ {
+ // not found, must be 4.70
+ s_verComCtl32 = 470;
+ }
+ else
+ {
+ // found, must be 4.71
+ s_verComCtl32 = 471;
+ }
+ }
+ }
}
}
- return version;
+
+ return s_verComCtl32;
}
void wxExit()
// Yield to incoming messages
bool wxYield()
{
+ // we don't want to process WM_QUIT from here - it should be processed in
+ // the main event loop in order to stop it
+
MSG msg;
- // We want to go back to the main message loop
- // if we see a WM_QUIT. (?)
-#ifdef __WXWINE__
- while (PeekMessage(&msg, (HWND)NULL, 0, 0, PM_NOREMOVE) && msg.message != WM_QUIT)
-#else
- while (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE) && msg.message != WM_QUIT)
-#endif
+ while ( PeekMessage(&msg, (HWND)0, 0, 0, PM_NOREMOVE) &&
+ msg.message != WM_QUIT )
{
if ( !wxTheApp->DoMessage() )
break;
}
+
// If they are pending events, we must process them.
-#if wxUSE_THREADS
wxTheApp->ProcessPendingEvents();
-#endif
return TRUE;
}
+//-----------------------------------------------------------------------------
+// wxWakeUpIdle
+//-----------------------------------------------------------------------------
+
+void wxWakeUpIdle()
+{
+ // Send the top window a dummy message so idle handler processing will
+ // start up again. Doing it this way ensures that the idle handler
+ // wakes up in the right thread (see also wxWakeUpMainThread() which does
+ // the same for the main app thread only)
+ wxWindow *topWindow = wxTheApp->GetTopWindow();
+ if ( topWindow )
+ {
+ if ( !::PostMessage(GetHwndOf(topWindow), WM_NULL, 0, 0) )
+ {
+ // should never happen
+ wxLogLastError("PostMessage(WM_NULL)");
+ }
+ }
+}
+
+//-----------------------------------------------------------------------------
+
wxIcon
wxApp::GetStdIcon(int which) const
{
return wxIcon("wxICON_WARNING");
default:
- wxFAIL_MSG(_T("requested non existent standard icon"));
+ wxFAIL_MSG(wxT("requested non existent standard icon"));
// still fall through
case wxICON_HAND:
}
}
-
-HINSTANCE wxGetInstance()
-{
- return wxhInstance;
-}
-
-void wxSetInstance(HINSTANCE hInst)
-{
- wxhInstance = hInst;
-}
-
// For some reason, with MSVC++ 1.5, WinMain isn't linked in properly
// if in a separate file. So include it here to ensure it's linked.
-#if (defined(__VISUALC__) && !defined(__WIN32__)) || (defined(__GNUWIN32__) && !defined(__TWIN32__))
+#if (defined(__VISUALC__) && !defined(__WIN32__)) || (defined(__GNUWIN32__) && !defined(__TWIN32__) && !defined(WXMAKINGDLL))
#include "main.cpp"
#endif