ICTS_2021/Unity3/Assets/UI/UIElementTransition.cs

using UnityEngine;
using System.Collections;
using System;
using UnityEngine.UI;

/// <summary>
/// This component is responsible for animating the showing and hiding of a UI element.
/// It will also avoid the user from clicking while the element is being animated.
/// This avoids double clicking by mistake.
/// </summary>
public class UIElementTransition : MonoBehaviour
{
	/// <summary>
	/// Fired when the show transition is complete
	/// </summary>
	public Action OnShowComplete;
	/// <summary>
	/// Fired when the hide transition is complete
	/// </summary>
	public Action OnHideComplete;
	/// <summary>
	/// Fired when the hiding transition is going to start
	/// </summary>
	public Action OnHiding;
	/// <summary>
	/// The position when is transitioned out (or from where to start)
	/// </summary>
	public Vector3 hiddenPosition;

	public bool fadeInAndOut;
	Vector3 _originalPosition;
	Collider _collider;
	Image[] _widgets;

	const float TRANSITION_IN_TIME = 0.5f;
	const float TRANSITION_OUT_TIME = 0.5f;

	void Start()
	{
		_originalPosition = transform.localPosition;
		transform.localPosition = hiddenPosition;
		_collider = GetComponent<Collider>();
	}

	public void Show()
	{
		//clear any iTweens from previous Hide, just in case
		iTween.Stop(gameObject);

		gameObject.SetActive(true);
		if (_collider != null)
		{
			_collider.enabled = false; //to avoid clicking while transitioning
		}
		iTween.MoveTo(gameObject, iTween.Hash(
			"islocal", true,
			"ignoretimescale", true,
			"time", TRANSITION_IN_TIME,
			"position", _originalPosition,
			"easetype", iTween.EaseType.easeOutBack,
			"oncompletetarget", gameObject,
			"oncomplete", "OniTweenShowFinished"));
		if (fadeInAndOut)
		{
			FadeIn();
		}
	}

	public void Hide()
	{
		if (OnHiding != null)
		{
			OnHiding();
		}
		if (_collider != null)
		{
			_collider.enabled = false; //to avoid clicking while transitioning
		}
		iTween.MoveTo(gameObject, iTween.Hash(
			"islocal", true,
			"ignoretimescale", true,
			"time", TRANSITION_OUT_TIME,
			"position", hiddenPosition,
			"easetype", iTween.EaseType.easeInBack,
			"oncompletetarget", gameObject,
			"oncomplete", "OniTweenHideFinished"));
		if (fadeInAndOut)
		{
			FadeOut();
		}
	}

	#region iTween Callbacks
	void OniTweenShowFinished()
	{
		if (_collider != null)
		{
			GetComponent<Collider>().enabled = true;
		}
		if (OnShowComplete != null)
		{
			OnShowComplete();
		}
	}

	void OniTweenHideFinished()
	{
		gameObject.SetActive(false);
		if (OnHideComplete != null)
		{
			OnHideComplete();
		}
	}

	void OniTweenUpdateAlpha(float newAlpha)
	{
		UpdateWidgetsAlpha(newAlpha);
	}
	#endregion

	void UpdateWidgetsAlpha(float newAlpha)
	{
		foreach (Image w in _widgets)
		{
			w.color = new Color(w.color.r, w.color.g, w.color.b, newAlpha);
		}
	}

	void FadeIn()
	{
		if (_widgets == null)
		{
			_widgets = GetComponentsInChildren<Image>();
			UpdateWidgetsAlpha(0);
		}

		if (_widgets.Length != 0)
		{
			iTween.ValueTo(gameObject, iTween.Hash(
				"from", _widgets[0].color.a,
				"to", 1,
				"time", TRANSITION_IN_TIME,
				"onupdate", "OniTweenUpdateAlpha",
				"onupdatetarget", gameObject));
		}
	}

	void FadeOut()
	{
		if (_widgets == null ||
			_widgets.Length == 0)
		{
			return;
		}
		iTween.ValueTo(gameObject, iTween.Hash(
			"from", _widgets[0].color.a,
			"to", 0,
			"time", TRANSITION_OUT_TIME,
			"onupdate", "OniTweenUpdateAlpha",
			"onupdatetarget", gameObject));
	}
}