/// <summary>Shows a context menu.</summary>
/// <param name='menu'>The menu.</param>
/// <param name='parent'>The parent widget.</param>
/// <param name='evt'>The mouse event. May be null if triggered by keyboard.</param>
/// <param name='caret'>The caret/selection position within the parent, if the EventButton is null.</param>
public static void ShowContextMenu(Gtk.Menu menu, Gtk.Widget parent, Gdk.EventButton evt, Gdk.Rectangle caret)
{
Gtk.MenuPositionFunc posFunc = null;
if (parent != null)
{
menu.AttachToWidget(parent, null);
menu.Hidden += (sender, e) => {
menu.Detach();
};
posFunc = delegate(Gtk.Menu m, out int x, out int y, out bool pushIn) {
Gdk.Window window = evt != null? evt.Window : parent.GdkWindow;
window.GetOrigin(out x, out y);
var alloc = parent.Allocation;
if (evt != null)
{
x += (int)evt.X;
y += (int)evt.Y;
}
else if (caret.X >= alloc.X && caret.Y >= alloc.Y)
{
x += caret.X;
y += caret.Y + caret.Height;
}
else
{
x += alloc.X;
y += alloc.Y;
}
Gtk.Requisition request = m.SizeRequest();
var screen = parent.Screen;
Gdk.Rectangle geometry = GetUsableMonitorGeometry(screen, screen.GetMonitorAtPoint(x, y));
//whether to push or flip menus that would extend offscreen
//FIXME: this is the correct behaviour for mac, check other platforms
bool flip_left = true;
bool flip_up = false;
if (x + request.Width > geometry.X + geometry.Width)
{
if (flip_left)
{
x -= request.Width;
}
else
{
x = geometry.X + geometry.Width - request.Width;
}
if (x < geometry.Left)
{
x = geometry.Left;
}
}
if (y + request.Height > geometry.Y + geometry.Height)
{
if (flip_up)
{
y -= request.Height;
}
else
{
y = geometry.Y + geometry.Height - request.Height;
}
if (y < geometry.Top)
{
y = geometry.Top;
}
}
pushIn = false;
};
}
uint time;
uint button;
if (evt == null)
{
time = Gtk.Global.CurrentEventTime;
button = 0;
}
else
{
time = evt.Time;
button = evt.Button;
}
//HACK: work around GTK menu issues on mac when passing button to menu.Popup
//some menus appear and immediately hide, and submenus don't activate
if (Platform.IsMac)
{
button = 0;
}
menu.Popup(null, null, posFunc, button, time);
}
