public void Register(IImageSourceServiceListener listener)
{
if (listener == null)
{
throw new ArgumentNullException(nameof(listener));
}
if (listeners.Contains(listener))
{
throw new InvalidOperationException();
}
if (listeners.Count == 0)
{
Debug.Assert(imageIterator == null);
imageIterator = new ImageIterator(backgroundImageSettings.IsRandom);
backgroundImageSettings.SettingsChanged += BackgroundImageSettings_SettingsChanged;
themeService.ThemeChangedLowPriority += ThemeService_ThemeChangedLowPriority;
OnSettingsChanged();
}
listeners.Add(listener);
if (enabled)
{
listener.OnEnabled();
listener.OnSettingsChanged();
}
}
public void Unregister(IImageSourceServiceListener listener)
{
if (listener == null)
{
throw new ArgumentNullException(nameof(listener));
}
int index = listeners.IndexOf(listener);
if (index < 0)
{
throw new ArgumentException();
}
listeners.RemoveAt(index);
if (listeners.Count == 0)
{
DisposeTimer();
backgroundImageSettings.SettingsChanged -= BackgroundImageSettings_SettingsChanged;
themeService.ThemeChangedLowPriority -= ThemeService_ThemeChangedLowPriority;
Debug.Assert(imageIterator != null);
imageIterator.Dispose();
imageIterator = null;
}
}
