Synthesizing Events

Before you synthesize and send custom events, you should understand how the UI Toolkit event system allocates and sends operating system events.

The event system uses a pool of events to avoid allocating event objects repeatedly. To synthesize and send your own events, you should allocate and send events by following the same steps:

1. Get an event object from the pool of events.
2. Fill in the event properties.
3. Enclose the event in a using block to ensure it is returned to the event pool.
4. Pass the event to element.SendEvent().

If you want to send events that usually come from the operating system, such as keyboard events and some mouse events, use a UnityEngine.Event to initialize the UI Toolkit event.

The following example demonstrates how to synthesize and send events:

void SynthesizeAndSendKeyDownEvent(IPanel panel, KeyCode code,
     char character = '\0', EventModifiers modifiers = EventModifiers.None)
{
    // Create a UnityEngine.Event to hold initialization data.
    // Also, this event will be forwarded to IMGUIContainer.m_OnGUIHandler
    var evt = new Event() {
        type = EventType.KeyDownEvent,
        keyCode = code,
        character = character,
        modifiers = modifiers
    };

    using (KeyDownEvent keyDownEvent = KeyDownEvent.GetPooled(evt))
    {
        panel.SendEvent(keyDownEvent);
    }
}

• 2018–11–02 Page amended