本文主要是介绍Unity UGUI Selectable部分源码浅析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
private readonly List<CanvasGroup> m_CanvasGroupCache = new List<CanvasGroup>();protected override void OnCanvasGroupChanged(){//判断父节点中是否允许交互var groupAllowInteraction = true;Transform t = transform;while (t != null){t.GetComponents(m_CanvasGroupCache);bool shouldBreak = false;for (var i = 0; i < m_CanvasGroupCache.Count; i++){//如果父节点中的canvasgroup不允许交互，那么断开循环，设置falseif (!m_CanvasGroupCache[i].interactable){groupAllowInteraction = false;shouldBreak = true;}// 如果此节点设置了“忽略父设置”，那么也直接断开if (m_CanvasGroupCache[i].ignoreParentGroups)shouldBreak = true;}if (shouldBreak)break;t = t.parent;}if (groupAllowInteraction != m_GroupsAllowInteraction){m_GroupsAllowInteraction = groupAllowInteraction;OnSetProperty();}}
在canvasGroup属性改变时调用OnCanvasGroupChanged
public virtual bool IsInteractable(){return m_GroupsAllowInteraction && m_Interactable;}
物体的可交互属性需要一起判断m_GroupsAllowInteraction 和 m_Interactable，即自身或父物体上的canvasGroup是否允许交互，以及自身是否允许交互
protected override void OnEnable(){base.OnEnable();if (s_IsDirty)RemoveInvalidSelectables(); //如果标记为脏，就从可选择物体数组中移除m_WillRemove = false;if (s_SelectableCount == s_Selectables.Length) //如果可选择物体数组满了，则扩容两倍{Selectable[] temp = new Selectable[s_Selectables.Length * 2];Array.Copy(s_Selectables, temp, s_Selectables.Length);s_Selectables = temp;}s_Selectables[s_SelectableCount++] = this;isPointerDown = false;DoStateTransition(currentSelectionState, true); //设置初始状态}
protected override void OnTransformParentChanged(){base.OnTransformParentChanged();// 如果父物体有改变，需要判断自身和父物体的canvasGroup属性是否有改变OnCanvasGroupChanged();}
private void OnSetProperty(){
#if UNITY_EDITORif (!Application.isPlaying)DoStateTransition(currentSelectionState, true);else
#endifDoStateTransition(currentSelectionState, false);}
设置状态属性，如果是Editor模式，如果正在运行，那么立即改变，没有过渡，如果非Editor模式，那么有过渡
protected override void OnDisable(){m_WillRemove = true;s_IsDirty = true;InstantClearState(); //重置各种状态base.OnDisable();}
取消激活时，将自身标记为脏
private static void RemoveInvalidSelectables(){for (int i = s_SelectableCount - 1; i >= 0; --i){// Swap last element in array with element to be removedif (s_Selectables[i] == null || s_Selectables[i].m_WillRemove)s_Selectables[i] = s_Selectables[--s_SelectableCount];}s_IsDirty = false;}
将元素从可选择物体数组列表中移除，同时标记为脏
protected SelectionState currentSelectionState{get{if (!IsInteractable())return SelectionState.Disabled;if (isPointerDown)return SelectionState.Pressed;if (hasSelection)return SelectionState.Selected;if (isPointerInside)return SelectionState.Highlighted;return SelectionState.Normal;}}
获取当前的选择状态
protected virtual void InstantClearState(){string triggerName = m_AnimationTriggers.normalTrigger;isPointerInside = false;isPointerDown = false;hasSelection = false;switch (m_Transition){case Transition.ColorTint:StartColorTween(Color.white, true);break;case Transition.SpriteSwap:DoSpriteSwap(null);break;case Transition.Animation:TriggerAnimation(triggerName);break;}}
即时清除状态，将Selectable的状态还原
protected virtual void DoStateTransition(SelectionState state, bool instant){if (!gameObject.activeInHierarchy)return;Color tintColor;Sprite transitionSprite;string triggerName;switch (state){case SelectionState.Normal:tintColor = m_Colors.normalColor;transitionSprite = null;triggerName = m_AnimationTriggers.normalTrigger;break;case SelectionState.Highlighted:tintColor = m_Colors.highlightedColor;transitionSprite = m_SpriteState.highlightedSprite;triggerName = m_AnimationTriggers.highlightedTrigger;break;case SelectionState.Pressed:tintColor = m_Colors.pressedColor;transitionSprite = m_SpriteState.pressedSprite;triggerName = m_AnimationTriggers.pressedTrigger;break;case SelectionState.Selected:tintColor = m_Colors.selectedColor;transitionSprite = m_SpriteState.selectedSprite;triggerName = m_AnimationTriggers.selectedTrigger;break;case SelectionState.Disabled:tintColor = m_Colors.disabledColor;transitionSprite = m_SpriteState.disabledSprite;triggerName = m_AnimationTriggers.disabledTrigger;break;default:tintColor = Color.black;transitionSprite = null;triggerName = string.Empty;break;}switch (m_Transition){case Transition.ColorTint:StartColorTween(tintColor * m_Colors.colorMultiplier, instant);break;case Transition.SpriteSwap:DoSpriteSwap(transitionSprite);break;case Transition.Animation:TriggerAnimation(triggerName);break;}}
状态切换方法
public Selectable FindSelectable(Vector3 dir){dir = dir.normalized;Vector3 localDir = Quaternion.Inverse(transform.rotation) * dir;Vector3 pos = transform.TransformPoint(GetPointOnRectEdge(transform as RectTransform, localDir));float maxScore = Mathf.NegativeInfinity;Selectable bestPick = null;if (s_IsDirty)RemoveInvalidSelectables();for (int i = 0; i < s_SelectableCount; ++i){Selectable sel = s_Selectables[i];if (sel == this)continue;if (!sel.IsInteractable() || sel.navigation.mode == Navigation.Mode.None)continue;#if UNITY_EDITOR除了运行时使用，FindSelectable被自定义编辑器用来在不同的可选项之间绘制箭头。对于场景视图摄像机，只考虑同一阶段的可选对象。if (Camera.current != null && !UnityEditor.SceneManagement.StageUtility.IsGameObjectRenderedByCamera(sel.gameObject, Camera.current))continue;
#endifvar selRect = sel.transform as RectTransform;Vector3 selCenter = selRect != null ? (Vector3)selRect.rect.center : Vector3.zero;Vector3 myVector = sel.transform.TransformPoint(selCenter) - pos;//值就是沿着这个方向的距离float dot = Vector3.Dot(dir, myVector);//跳过方向错误或距离为0的元素这也确保了下面的评分公式不会有除数为零的误差if (dot <= 0)continue;// This scoring function has two priorities:// - Score higher for positions that are closer.// - Score higher for positions that are located in the right direction.// This scoring function combines both of these criteria.// It can be seen as this:// Dot (dir, myVector.normalized) / myVector.magnitude// The first part equals 1 if the direction of myVector is the same as dir, and 0 if it's orthogonal.// The second part scores lower the greater the distance is by dividing by the distance.// The formula below is equivalent but more optimized.//// If a given score is chosen, the positions that evaluate to that score will form a circle// that touches pos and whose center is located along dir. A way to visualize the resulting functionality is this:// From the position pos, blow up a circular balloon so it grows in the direction of dir.// The first Selectable whose center the circular balloon touches is the one that's chosen.float score = dot / myVector.sqrMagnitude;if (score > maxScore){maxScore = score;bestPick = sel;}}return bestPick;}
此方法用来寻找临近的可选择对象
public virtual void OnMove(AxisEventData eventData){switch (eventData.moveDir){case MoveDirection.Right:Navigate(eventData, FindSelectableOnRight());break;case MoveDirection.Up:Navigate(eventData, FindSelectableOnUp());break;case MoveDirection.Left:Navigate(eventData, FindSelectableOnLeft());break;case MoveDirection.Down:Navigate(eventData, FindSelectableOnDown());break;}}
当焦点移动到另一个可选择对象时，调用此方法，确定选择的对象
protected bool IsHighlighted(){if (!IsActive() || !IsInteractable())return false;return isPointerInside && !isPointerDown && !hasSelection;}
判断是否高亮，即鼠标移上去的时候，需判断三个状态，鼠标在UI范围内，没有点下，没有选择
protected bool IsPressed(){if (!IsActive() || !IsInteractable())return false;return isPointerDown;}
是否按下
private void EvaluateAndTransitionToSelectionState(){if (!IsActive() || !IsInteractable())return;DoStateTransition(currentSelectionState, false);}
执行状态改变
public virtual void OnPointerDown(PointerEventData eventData){if (eventData.button != PointerEventData.InputButton.Left) //如果不是鼠标左键，returnreturn;//如果可以交互，导航模式不为空，且EventSystem存在，那么设置EventSystem的当前选择物体if (IsInteractable() && navigation.mode != Navigation.Mode.None && EventSystem.current != null)EventSystem.current.SetSelectedGameObject(gameObject, eventData);isPointerDown = true;EvaluateAndTransitionToSelectionState();}
鼠标按下回调
public virtual void OnPointerUp(PointerEventData eventData){if (eventData.button != PointerEventData.InputButton.Left)return;isPointerDown = false;EvaluateAndTransitionToSelectionState();}
鼠标抬起回调
public virtual void OnPointerEnter(PointerEventData eventData){isPointerInside = true;EvaluateAndTransitionToSelectionState();}
鼠标进入回调
public virtual void OnPointerExit(PointerEventData eventData){isPointerInside = false;EvaluateAndTransitionToSelectionState();}
鼠标离开回调
public virtual void OnSelect(BaseEventData eventData){hasSelection = true;EvaluateAndTransitionToSelectionState();}
选择回调
public virtual void OnDeselect(BaseEventData eventData){hasSelection = false;EvaluateAndTransitionToSelectionState();}
取消选择回调
public virtual void Select(){if (EventSystem.current == null || EventSystem.current.alreadySelecting)return;EventSystem.current.SetSelectedGameObject(gameObject);}
直接确定EventSystem的选择物体
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