public static bool Begin(string name, ref bool open, Point position, Size size, double bg_alpha = 1, WindowFlags flags = WindowFlags.VerticalScrollbar)
{
Form form = Form.current;
GUIContext g = form.uiContext;
WindowManager w = g.WindowManager;
Debug.Assert(name != null); // Window name required
Debug.Assert(g.Initialized); // Forgot to call NewFrame()
Debug.Assert(g.FrameCountEnded != g.FrameCount); // Called Render() or EndFrame() and haven't called NewFrame() again yet
if (flags.HaveFlag(WindowFlags.NoInputs))
{
flags |= WindowFlags.NoMove | WindowFlags.NoResize;
}
// Find or create
Window window = w.FindWindowByName(name) ?? w.CreateWindow(name, position, size, flags);
// Check if this is the first call of Begin
long current_frame = g.FrameCount;
bool first_begin_of_the_frame = (window.LastActiveFrame != current_frame);
if (first_begin_of_the_frame)
{
window.Flags = flags;
}
else
{
flags = window.Flags;
}
// Add to stack
Window parent_window = w.WindowStack.Count != 0 ? w.WindowStack[w.WindowStack.Count - 1] : null;
w.WindowStack.Add(window);
w.CurrentWindow = window;
Debug.Assert(parent_window != null || !flags.HaveFlag(WindowFlags.ChildWindow));
// Update known root window (if we are a child window, otherwise window == window->RootWindow)
int root_idx;
for (root_idx = w.WindowStack.Count - 1; root_idx > 0; root_idx--)
{
if (!(w.WindowStack[root_idx].Flags.HaveFlag(WindowFlags.ChildWindow)))
{
break;
}
}
window.RootWindow = w.WindowStack[root_idx];
// When reusing window again multiple times a frame, just append content (don't need to setup again)
if (first_begin_of_the_frame)
{
window.Setup(name, position, size, ref open, bg_alpha, flags, current_frame, parent_window);
}
// Inner clipping rectangle
{
// We set this up after processing the resize grip so that our clip rectangle doesn't lag by a frame
// Note that if our window is collapsed we will end up with a null clipping rectangle which is the correct behavior.
Rect title_bar_rect = window.TitleBarRect;
const float border_size = 0;
var paddingHorizontal = window.Style.PaddingHorizontal;
// Force round to ensure that e.g. (int)(max.x-min.x) in user's render code produce correct result.
Rect clip_rect = new Rect(
new Point(Math.Floor(0.5f + title_bar_rect.Min.X + Math.Max(border_size, Math.Floor(paddingHorizontal * 0.5f))),
Math.Floor(0.5f + title_bar_rect.Max.Y + border_size)),
new Point(Math.Floor(0.5f + window.Position.X + window.Size.Width - Math.Max(border_size, Math.Floor(paddingHorizontal * 0.5f))),
Math.Floor(0.5f + window.Position.Y + window.Size.Height - border_size)));
window.DrawList.PushClipRect(clip_rect, true);
window.ClipRect = clip_rect;
//window.DrawList.AddRect(window.ClipRect.TopLeft, window.ClipRect.BottomRight, Color.Red);//test only
}
// Clear 'accessed' flag last thing
if (first_begin_of_the_frame)
{
window.Accessed = false;
}
window.BeginCount++;
// Child window can be out of sight and have "negative" clip windows.
// Mark them as collapsed so commands are skipped earlier (we can't manually collapse because they have no title bar).
if (flags.HaveFlag(WindowFlags.ChildWindow))
{
Debug.Assert(flags.HaveFlag(WindowFlags.NoTitleBar));
window.Collapsed = parent_window != null && parent_window.Collapsed;
}
window.StackLayout.Begin();
// Return false if we don't intend to display anything to allow user to perform an early out optimization
window.SkipItems = window.Collapsed || !window.Active;
return(!window.SkipItems);
}