/// <summary>
/// Removes a control from the update list.
/// If no managed controls remain in the list, then the update timer is stopped.
/// </summary>
/// <param name="control">
/// The <see cref="ICadencedControl"/> to be removed from the update list.
/// </param>
/// <remarks>
/// If the control is null, or is not in the update list, no action is taken.
/// If the update list is empty after the control is removed, then the cadence timer is stopped.
/// </remarks>
public void Remove(ICadencedControl control)
{
if (control == null)
{
return;
}
try
{
// Putting all the code in the finally block makes it a CONSTRAINED REGION that executes atomically
// This prevents a timer event from happening in the middle of an add/remove operation.
}
finally
{
if (UpdateList.Contains(control))
{
UpdateList.Remove(control); // Make sure this object doesn't receive any more timer updates.
}
// Stop the update timer if there are no items left in the update list.
if (UpdateList.Count == 0)
{
CadenceTimer.Stop();
CadenceTimer.Elapsed -= TmrCadenceTick; // For symmetry, unregister the handler.
}
}
}
/// <summary>
/// Adds the specified <see cref="ICadencedControl" /> to the list of managed controls. If this is the first
/// <paramref name="control" /> being added, then the update timer is configured and started.
/// </summary>
/// <remarks>
/// Each <paramref name="control" /> can only appear in the list once (duplicate adds will be silently
/// ignored).
/// </remarks>
/// <param name="control">The control to be managed.</param>
public void Add(ICadencedControl control)
{
var hashCode = control.GetHashCode();
Trace.WriteLine($"Adding hash {hashCode}");
if (ControlList.ContainsKey(hashCode))
{
Trace.TraceWarning($"Ignoring duplicate hash code {hashCode}.");
}
else
{
ControlList.Add(hashCode, new WeakReference <ICadencedControl>(control));
}
if (updateTask == null)
{
StartUpdates();
}
}
/// <summary>
/// Removes a <paramref name="control" /> from the
/// <see cref="TA.WinFormsControls.CadencedControlUpdater.ControlList" /> . If no managed controls remain in
/// the list, then the update timer is stopped.
/// </summary>
public void Remove(ICadencedControl control)
{
try
{
var hash = control.GetHashCode();
Trace.TraceInformation($"Removing hash {hash}");
if (ControlList.ContainsKey(hash))
{
ControlList.Remove(hash);
}
}
catch (Exception e)
{
Trace.TraceError($"{e.GetType().Name} removing control: {e.Message}");
}
finally
{
if (!ControlList?.Any() ?? false)
{
StopUpdates();
}
}
}
/// <summary>
/// Adds the specified <see cref = "ICadencedControl" /> to the list of managed controls.
/// If this is the first control being added, then the update timer is configured and started.
/// </summary>
/// <param name = "control">The control to be managed.</param>
/// <remarks>
/// Each control can only appear in the list once (duplicate adds will be silently ignored).
/// </remarks>
public void Add(ICadencedControl control)
{
try
{
// Putting all the code in the finally block makes it a CONSTRAINED REGION that executes atomically
// This prevents a timer event from happening in the middle of an add/remove operation.
}
finally
{
if (!UpdateList.Contains(control))
{
UpdateList.Add(control);
// If this is the first instance, then create and start the timer.
if (UpdateList.Count == 1)
{
CadenceTimer.Interval = 125;
CadenceTimer.Elapsed += TmrCadenceTick;
CadenceTimer.Start(); // Let rip.
}
}
}
}
