一：

.GetComponent<>()调用效率低下,尤其是在编辑器外部.避免在任何类型的Update()方法中使用它们.

二：

拖动ScrollView的每个帧都调用OnValueChanged().因此,从某种意义上讲,它等效于Update(),因此您应该避免在此方法中使用.GetComponent<>()调用.

三：

每当更改Canvas上的任何元素时,整个Canvas都必须重建其批次.此操作可能非常昂贵.因此,建议您将UI元素划分为至少两个Canvas,一个用于很少或永远不会更改的元素,而一个则是经常更改的元素.

每当ScrollView滚动整个画布时,都会弄脏它.因此,建议您将每个ScrollView放在单独的Canvas上.

四：

EventSystem.Update()处理场景中的输入检测,使用射线广播在层次结构中进行过滤,以便找到接受此输入的组件.因此,仅在与场景交互时才进行这些计算,例如在滚动ScrollView时.从图形和文本中删除不必要的RaycastTarget属性将缩短此处理时间.可能并没有太大的区别,但是如果您不注意足够的对象,则可以使输入处理时间真正加起来.

五：

使用任何种类的遮罩组件,甚至是RectMask2D,都可以批处理并渲染ScrollView中的所有对象.如果ScrollView中包含很多元素,建议您使用某种合并解决方案.在应用程序商店中有许多可用的方法.

但是,如果您的项目与此项目不兼容,需要持久性元素,则建议您隐藏屏幕外对象以减少性能开销. Transform.SetParent()和GameObject.SetActive()都是资源密集型方法,而是将CanvasGroup组件附加到每个元素并调整alpha值以实现相同的效果.

这是一个静态脚本,用于检测对象是否可见并相应地设置Alpha：

using UnityEngine;
using UnityEngine.UI;
public class ScrollHider : MonoBehaviour {
static public float contentTop;
static public float contentBottom;
static public bool HideObject(GameObject givenObject, CanvasGroup canvasGroup, float givenPosition, float givenHeight) {
if ((Mathf.Abs(givenPosition) + givenHeight > contentTop && Mathf.Abs(givenPosition) + givenHeight < contentBottom) || (Mathf.Abs(givenPosition) > contentTop && Mathf.Abs(givenPosition) < contentBottom)) {
if (canvasGroup.alpha != 1) {
canvasGroup.alpha = 1;
}
return true;
} else {
if (canvasGroup.alpha != 0) {
canvasGroup.alpha = 0;
}
return false;
}
}
static public void Setup(Scroll givenScroll) {
contentTop = (1 - givenScroll.verticalNormalizedPosition) * (givenScroll.content.rect.height - givenScroll.viewport.rect.height);
contentBottom = contentTop + givenScroll.viewport.rect.height;
}
}

六：

Unity的内置ScrollRect组件可实现广泛的模块化功能.但是,就性能而言,它可能比您自己编写的要慢得多.这是一个达到相同目的的Scroll脚本,但仅支持Unity的ScrollRect的vertical,clamped和惯性属性.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;
public class Scroll : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IDragHandler, IScrollHandler {
private Camera mainCamera;
private RectTransform canvasRect;
public RectTransform viewport;
public RectTransform content;
private Rect viewportOld;
private Rect contentOld;
private List dragCoordinates = new List();
private List offsets = new List();
private int offsetsAveraged = 4;
private float offset;
private float velocity = 0;
private bool changesMade = false;
public float decelration = 0.135f;
public float scrollSensitivity;
public OnValueChanged onValueChanged;
[System.Serializable]
public class OnValueChanged : UnityEvent { }
[HideInInspector]
public float verticalNormalizedPosition
{
get
{
float sizeDelta = CaculateDeltaSize();
if (sizeDelta == 0) {
return 0;
} else {
return 1 - content.transform.localPosition.y / sizeDelta;
}
}
set
{
float o_verticalNormalizedPosition = verticalNormalizedPosition;
float m_verticalNormalizedPosition = Mathf.Max(0, Mathf.Min(1, value));
float maxY = CaculateDeltaSize();
content.transform.localPosition = new Vector3(content.transform.localPosition.x, Mathf.Max(0, (1 - m_verticalNormalizedPosition) * maxY), content.transform.localPosition.z);
float n_verticalNormalizedPosition = verticalNormalizedPosition;
if (o_verticalNormalizedPosition != n_verticalNormalizedPosition) {
onValueChanged.Invoke();
}
}
}
private float CaculateDeltaSize() {
return Mathf.Max(0, content.rect.height - viewport.rect.height); ;
}
private void Awake() {
mainCamera = GameObject.Find("Main Camera").GetComponent();
canvasRect = transform.root.GetComponent();
}
private Vector2 ConvertEventDataDrag(PointerEventData eventData) {
return new Vector2(eventData.position.x / mainCamera.pixelWidth * canvasRect.rect.width, eventData.position.y / mainCamera.pixelHeight * canvasRect.rect.height);
}
private Vector2 ConvertEventDataScroll(PointerEventData eventData) {
return new Vector2(eventData.scrollDelta.x / mainCamera.pixelWidth * canvasRect.rect.width, eventData.scrollDelta.y / mainCamera.pixelHeight * canvasRect.rect.height) * scrollSensitivity;
}
public void OnPointerDown(PointerEventData eventData) {
velocity = 0;
dragCoordinates.Clear();
offsets.Clear();
dragCoordinates.Add(ConvertEventDataDrag(eventData));
}
public void OnScroll(PointerEventData eventData) {
UpdateOffsetsScroll(ConvertEventDataScroll(eventData));
OffsetContent(offsets[offsets.Count - 1]);
}
public void OnDrag(PointerEventData eventData) {
dragCoordinates.Add(ConvertEventDataDrag(eventData));
UpdateOffsetsDrag();
OffsetContent(offsets[offsets.Count - 1]);
}
public void OnPointerUp(PointerEventData eventData) {
dragCoordinates.Add(ConvertEventDataDrag(eventData));
UpdateOffsetsDrag();
OffsetContent(offsets[offsets.Count - 1]);
float totalOffsets = 0;
foreach (float offset in offsets) {
totalOffsets += offset;
}
velocity = totalOffsets / offsetsAveraged;
dragCoordinates.Clear();
offsets.Clear();
}
private void OffsetContent(float givenOffset) {
float newY = Mathf.Max(0, Mathf.Min(CaculateDeltaSize(), content.transform.localPosition.y + givenOffset));
if (content.transform.localPosition.y != newY) {
content.transform.localPosition = new Vector3(content.transform.localPosition.x, newY, content.transform.localPosition.z);
}
onValueChanged.Invoke();
}
private void UpdateOffsetsDrag() {
offsets.Add(dragCoordinates[dragCoordinates.Count - 1].y - dragCoordinates[dragCoordinates.Count - 2].y);
if (offsets.Count > offsetsAveraged) {
offsets.RemoveAt(0);
}
}
private void UpdateOffsetsScroll(Vector2 givenScrollDelta) {
offsets.Add(givenScrollDelta.y);
if (offsets.Count > offsetsAveraged) {
offsets.RemoveAt(0);
}
}
private void LateUpdate() {
if (viewport.rect != viewportOld) {
changesMade = true;
viewportOld = new Rect(viewport.rect);
}
if (content.rect != contentOld) {
changesMade = true;
contentOld = new Rect(content.rect);
}
if (velocity != 0) {
changesMade = true;
velocity = (velocity / Mathf.Abs(velocity)) * Mathf.FloorToInt(Mathf.Abs(velocity) * (1 - decelration));
offset = velocity;
}
if (changesMade) {
OffsetContent(offset);
changesMade = false;
offset = 0;
}
}
}