自学教程：C++ IsDefined函数代码示例

    HINTERNET OpenRequest(LPCSTR lpszVerb, LPCSTR lpszObjectName,                          LPCSTR lpszVersion, LPCSTR lpszReferer,                          LPCSTR *lplpszAcceptTypes,                          DWORD dwFlags,                          DWORD_PTR dwContext) const {      assert(IsDefined());      return ::HttpOpenRequestA(Get(),                                lpszVersion, lpszObjectName,                                lpszVersion, lpszReferer,                                lplpszAcceptTypes,                                dwFlags,                                dwContext);    }

  /**   * Returns the position on the screen.   */  gcc_pure  const PixelRect GetScreenPosition() const  {    assert(IsDefined());    PixelRect rc;#ifndef USE_WINUSER    rc = GetPosition();    ToScreen(rc);#else    ::GetWindowRect(hWnd, &rc);#endif    return rc;  }

//------------------------------------------------------------------------------voidCanvas::Stretch(int dest_x, int dest_y,                unsigned dest_width, unsigned dest_height,                const Bitmap &_src)  {#if 0  assert(IsDefined());  assert(_src.IsDefined());  ConstImageBuffer src = _src.GetNative();  Stretch(dest_x, dest_y, dest_width, dest_height,          src, 0, 0, src.width, src.height);#endif  }

voidCanvas::Stretch(int dest_x, int dest_y,                unsigned dest_width, unsigned dest_height,                const Bitmap &src,                int src_x, int src_y,                unsigned src_width, unsigned src_height){  assert(IsDefined());  assert(src.IsDefined());  Stretch(dest_x, dest_y, dest_width, dest_height,          src.GetNative(),          src_x, src_y, src_width, src_height);}

boolFileDescriptor::CreateEventFD(unsigned initval){  assert(!IsDefined());#ifdef __BIONIC__  /* Bionic provides the eventfd() function only since Android 2.3,     therefore we must roll our own system call here */  fd = syscall(__NR_eventfd2, initval, O_NONBLOCK|O_CLOEXEC);#else  fd = ::eventfd(initval, EFD_NONBLOCK|EFD_CLOEXEC);#endif  return fd >= 0;}

voidCanvas::Stretch(PixelScalar dest_x, PixelScalar dest_y,                UPixelScalar dest_width, UPixelScalar dest_height,                const Bitmap &src,                PixelScalar src_x, PixelScalar src_y,                UPixelScalar src_width, UPixelScalar src_height,                DWORD dwRop){  assert(IsDefined());  assert(src.IsDefined());  Stretch(dest_x, dest_y, dest_width, dest_height,          src.GetNative(), src_x, src_y, src_width, src_height,          dwRop);}

voidPen::Reset(){  assert(!IsDefined() || IsScreenInitialized());  if (pen != NULL) {#ifndef NDEBUG    bool success =#endif      ::DeleteObject(pen);    assert(success);    pen = NULL;  }}

boolIOThread::Start(){  assert(!IsDefined());  assert(loop.IsEmpty());  quit = false;  if (!pipe.Create())    return false;  loop.Add(pipe.GetReadFD(), READ, *this);  return Thread::Start();}

boolIOThread::Start(){  assert(!IsDefined());  assert(files.empty());  modified = quit = running = false;  if (!pipe.Create())    return false;  poll.SetMask(pipe.GetReadFD(), Poll::READ);  return Thread::Start();}

voidDockWindow::SetWidget(Widget *_widget){  assert(IsDefined());  assert(widget == nullptr);  widget = _widget;  if (widget != nullptr) {    const PixelRect rc = GetClientRect();    widget->Initialise(*this, rc);    widget->Prepare(*this, rc);    widget->Show(rc);  }}

voidThread::Join(){  assert(IsDefined());  assert(!IsInside());#ifdef HAVE_POSIX  pthread_join(handle, NULL);  defined = false;#else  ::WaitForSingleObject(handle, INFINITE);  ::CloseHandle(handle);  handle = NULL;#endif}

  gcc_pure  const PixelSize GetSize() const  {    assert(IsDefined());#ifdef USE_GDI    PixelRect rc = GetClientRect();    PixelSize s;    s.cx = rc.right;    s.cy = rc.bottom;    return s;#else    return size;#endif  }

voidBrush::Reset(){  assert(!IsDefined() || IsScreenInitialized());  if (brush != nullptr) {#ifndef NDEBUG    bool success =#endif      ::DeleteObject(brush);    assert(success);    brush = nullptr;  }}

voidStandbyThread::WaitStopped(){  assert(!IsInside());  assert(mutex.IsLockedByCurrent());  assert(stop);  if (!IsDefined())    /* was never started */    return;  /* mutex must be unlocked because Thread::Join() blocks */  const ScopeUnlock unlock(mutex);  Thread::Join();}

voidCanvas::Copy(int dest_x, int dest_y,             unsigned dest_width, unsigned dest_height,             HBITMAP src, int src_x, int src_y,             DWORD dwRop){  assert(IsDefined());  assert(src != nullptr);  HDC virtual_dc = GetCompatibleDC();  HBITMAP old = (HBITMAP)::SelectObject(virtual_dc, src);  Copy(dest_x, dest_y, dest_width, dest_height,       virtual_dc, src_x, src_y,       dwRop);  ::SelectObject(virtual_dc, old);}

voidBufferCanvas::CopyTo(Canvas &other){  assert(IsDefined());  assert(!active || frame_buffer != nullptr);#ifdef USE_GLSL  OpenGL::texture_shader->Use();#else  const GLEnable<GL_TEXTURE_2D> scope;  OpenGL::glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);#endif  texture->Bind();  texture->DrawFlipped(other.GetRect(), GetRect());}

bool RegionOfRows::IsInRegion(unsigned int Column,unsigned int Row)const{    if (!IsDefined()) return false;			// Can't process an empty region    // In range of rows ?    if (!Rows.IsInRange(Row)) return false;	// Row is out of range    // Row is in range, investigate the columns    unsigned int RowOffset = Row - Rows.GetStart();    // Column is in range ?    return Columns[RowOffset].IsInRange(Column);}

WndProperty *RowFormWidget::AddSpacer(){  assert(IsDefined());  const PixelRect edit_rc = InitialControlRect(Layout::Scale(6));  WindowStyle style;  EditWindowStyle edit_style;  edit_style.SetVerticalCenter();  edit_style.SetReadOnly();  PanelControl &panel = *(PanelControl *)GetWindow();  WndProperty *edit = new WndProperty(panel, look, _T(""), edit_rc, 0, style, edit_style, NULL);  Add(edit);  return edit;}

unsigned int RegionOfRows::GetNumberOfColumnsOnLargestRow() const{    if (!IsDefined()) return 0;    unsigned int MaximumNumberofColumns = 0;    const ClosedInterval<unsigned int>* MyColumns = GetColumns();    unsigned int NumberOfRows = Rows.GetSpan() + 1;    for (unsigned int i=0; i < NumberOfRows;++i)    {        unsigned int ColumnsOnRow = MyColumns->GetSpan() + 1;        if (ColumnsOnRow > MaximumNumberofColumns)  MaximumNumberofColumns = ColumnsOnRow;        MyColumns++;    }    return MaximumNumberofColumns;}

voidTabMenuDisplay::SetCursor(unsigned i){  if (i == cursor)    return;  if (IsDefined()) {    if (SupportsPartialRedraw() &&        GetPageMainIndex(cursor) == GetPageMainIndex(i)) {      Invalidate(GetSubMenuButtonSize(cursor));      Invalidate(GetSubMenuButtonSize(i));    } else      Invalidate();  }  cursor = i;}

void UnitSymbol::Draw(Canvas &canvas, PixelScalar x, PixelScalar y,                 Color bg_color, Color text_color) const{  assert(IsDefined());  const PixelSize size = GetSize();  const PixelSize screen_size = GetScreenSize();  canvas.StretchMono(x, y, screen_size.cx, screen_size.cy,#if defined(USE_GDI) || defined(ENABLE_OPENGL)                     bitmap,#else                     buffer,#endif                     0, 0, size.cx, size.cy,                     text_color, bg_color);}

boolEventPipe::Create(){  assert(!IsDefined());#ifdef HAVE_EVENTFD  return r.CreateEventFD();#else  if (!UniqueFileDescriptor::CreatePipe(r, w))    return false;  r.SetNonBlocking();  w.SetNonBlocking();  return true;#endif}

intSocketDescriptor::WaitWritable(int timeout_ms) const{  assert(IsDefined());  fd_set wfds;  FD_ZERO(&wfds);  FD_SET(Get(), &wfds);  struct timeval timeout, *timeout_p = nullptr;  if (timeout_ms >= 0) {    timeout.tv_sec = unsigned(timeout_ms) / 1000;    timeout.tv_usec = (unsigned(timeout_ms) % 1000) * 1000;    timeout_p = &timeout;  }  return select(Get() + 1, nullptr, &wfds, nullptr, timeout_p);}

voidRowFormWidget::AddButton(const TCHAR *label, ActionListener &listener, int id){  assert(IsDefined());  const PixelRect button_rc =    InitialControlRect(Layout::GetMinimumControlHeight());  ButtonWindowStyle button_style;  button_style.TabStop();  button_style.multiline();  ContainerWindow &panel = *(ContainerWindow *)GetWindow();  WndButton *button = new WndButton(panel, look, label, button_rc, button_style, listener, id);  Add(Row::Type::BUTTON, button);}

voidCanvas::StretchAnd(int dest_x, int dest_y,               unsigned dest_width, unsigned dest_height,               const Bitmap &src,                int src_x, int src_y, unsigned src_width, unsigned src_height){  assert(IsDefined());  assert(src.IsDefined());    ConstImageBuffer srcImg = src.GetNative();      SDLRasterCanvas canvas(buffer);  BitAndPixelOperations<ActivePixelTraits> operations;  canvas.ScaleRectangle(dest_x, dest_y, dest_width, dest_height,                       srcImg.At(src_x, src_y), srcImg.pitch, src_width, src_height,                       operations);}

voidWindow::Destroy(){  if (!IsDefined())    return;  assert(IsScreenInitialized());  AssertThread();#ifndef USE_WINUSER  OnDestroy();  size = {0, 0};#else /* USE_WINUSER */  ::DestroyWindow(hWnd);  hWnd = nullptr;#endif /* USE_WINUSER */}