+init

1 files changed, 307 insertions, 0 deletions

diff --git a/Assets/uGUI-2017.1/UnityEngine.UI/UI/Core/CanvasUpdateRegistry.cs b/Assets/uGUI-2017.1/UnityEngine.UI/UI/Core/CanvasUpdateRegistry.cs
new file mode 100644
index 0000000..200b4e5
--- /dev/null
+++ b/Assets/uGUI-2017.1/UnityEngine.UI/UI/Core/CanvasUpdateRegistry.cs
@@ -0,0 +1,307 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine.UI.Collections;
+
+namespace UnityEngine.UI
+{
+    // canvas的不同阶段，用来设置layout、graphic做不同的事情，具体看CanvasUpdateRegistry
+    // prelayout  ->  layout  ->  postlayout  -> prerender  ->  laterender  =>=>=>  render  
+    public enum CanvasUpdate
+    {
+        Prelayout = 0,
+        Layout = 1,
+        PostLayout = 2,
+        PreRender = 3,
+        LatePreRender = 4,
+
+        MaxUpdateValue = 5
+    }
+
+    public interface ICanvasElement
+    {
+        Transform transform { get; }
+        void Rebuild(CanvasUpdate executing);
+        void LayoutComplete();
+        void GraphicUpdateComplete();
+        // due to unity overriding null check
+        // we need this as something may not be null
+        // but may be destroyed
+        bool IsDestroyed();
+    }
+
+    // 需要注意整个游戏只有一个单例
+    public class CanvasUpdateRegistry
+    {
+        private static CanvasUpdateRegistry s_Instance;
+
+        private bool m_PerformingLayoutUpdate;
+        private bool m_PerformingGraphicUpdate;
+
+        private readonly IndexedSet<ICanvasElement> m_LayoutRebuildQueue = new IndexedSet<ICanvasElement>();
+        private readonly IndexedSet<ICanvasElement> m_GraphicRebuildQueue = new IndexedSet<ICanvasElement>();
+
+        protected CanvasUpdateRegistry()
+        {
+            // willRenderCanvases在渲染canvas之前调用，执行PerformUpdate来Rebuild处理m_LayoutRebuildQueue和m_GraphicRebuildQueue
+            Canvas.willRenderCanvases += PerformUpdate;
+        }
+
+        // 简单单例 
+        public static CanvasUpdateRegistry instance
+        {
+            get
+            {
+                if (s_Instance == null)
+                    s_Instance = new CanvasUpdateRegistry();
+                return s_Instance;
+            }
+        }
+
+        // 检查一下实现了ICanvasElement的对象合法性，实现了ICanvasElement接口的对象必须是Unity Object，
+        private bool ObjectValidForUpdate(ICanvasElement element)
+        {
+            var valid = element != null;
+
+            var isUnityObject = element is Object;
+            if (isUnityObject)
+                valid = (element as Object) != null; //Here we make use of the overloaded UnityEngine.Object == null, that checks if the native object is alive.
+
+            return valid;
+        }
+
+        private void CleanInvalidItems()
+        {
+            // So MB's override the == operator for null equality, which checks
+            // if they are destroyed. This is fine if you are looking at a concrete
+            // mb, but in this case we are looking at a list of ICanvasElement
+            // this won't forward the == operator to the MB, but just check if the
+            // interface is null. IsDestroyed will return if the backend is destroyed.
+
+            for (int i = m_LayoutRebuildQueue.Count - 1; i >= 0; --i)
+            {
+                var item = m_LayoutRebuildQueue[i];
+                if (item == null)
+                {
+                    m_LayoutRebuildQueue.RemoveAt(i);
+                    continue;
+                }
+
+                if (item.IsDestroyed())
+                {
+                    m_LayoutRebuildQueue.RemoveAt(i);
+                    item.LayoutComplete();
+                }
+            }
+
+            for (int i = m_GraphicRebuildQueue.Count - 1; i >= 0; --i)
+            {
+                var item = m_GraphicRebuildQueue[i];
+                if (item == null)
+                {
+                    m_GraphicRebuildQueue.RemoveAt(i);
+                    continue;
+                }
+
+                if (item.IsDestroyed())
+                {
+                    m_GraphicRebuildQueue.RemoveAt(i);
+                    item.GraphicUpdateComplete();
+                }
+            }
+        }
+
+        private static readonly Comparison<ICanvasElement> s_SortLayoutFunction = SortLayoutList;
+        // 在渲染canvas之前对canvas下的元素进行rebuild
+        // 进行 prelayout -> layout -> postlayout -> prerender -> LatePreRender 流程
+        private void PerformUpdate()
+        {
+            UISystemProfilerApi.BeginSample(UISystemProfilerApi.SampleType.Layout);
+            CleanInvalidItems();
+
+            m_PerformingLayoutUpdate = true;
+
+            // 重建layout
+
+            // 根据父节点从少到多排序，先布局父节点少的，由少到多，由内到外
+            m_LayoutRebuildQueue.Sort(s_SortLayoutFunction);
+            // prelayout -> layout -> postlayout
+            for (int i = 0; i <= (int)CanvasUpdate.PostLayout; i++) // 不同的阶段
+            {
+                for (int j = 0; j < m_LayoutRebuildQueue.Count; j++)
+                {
+                    var rebuild = instance.m_LayoutRebuildQueue[j];
+                    try
+                    {
+                        if (ObjectValidForUpdate(rebuild))
+                            rebuild.Rebuild((CanvasUpdate)i);
+                    }
+                    catch (Exception e)
+                    {
+                        Debug.LogException(e, rebuild.transform);
+                    }
+                }
+            }
+
+            // 布局完成
+            for (int i = 0; i < m_LayoutRebuildQueue.Count; ++i)
+                m_LayoutRebuildQueue[i].LayoutComplete();
+
+            // 清空队列，重置状态
+            instance.m_LayoutRebuildQueue.Clear();
+            m_PerformingLayoutUpdate = false;
+
+            // 做剔除+裁剪
+            // now layout is complete do culling...
+            ClipperRegistry.instance.Cull();
+
+            // 重建graphic
+
+            m_PerformingGraphicUpdate = true;
+            // prerender -> lateprerender
+            for (var i = (int)CanvasUpdate.PreRender; i < (int)CanvasUpdate.MaxUpdateValue; i++)
+            {
+                for (var k = 0; k < instance.m_GraphicRebuildQueue.Count; k++)
+                {
+                    try
+                    {
+                        var element = instance.m_GraphicRebuildQueue[k];
+                        if (ObjectValidForUpdate(element))
+                            element.Rebuild((CanvasUpdate)i);
+                    }
+                    catch (Exception e)
+                    {
+                        Debug.LogException(e, instance.m_GraphicRebuildQueue[k].transform);
+                    }
+                }
+            }
+
+            // graphic设置mesh和材质完成
+            for (int i = 0; i < m_GraphicRebuildQueue.Count; ++i)
+                m_GraphicRebuildQueue[i].GraphicUpdateComplete();
+
+            // 清空队列，重置状态
+            instance.m_GraphicRebuildQueue.Clear();
+            m_PerformingGraphicUpdate = false;
+
+            // 到了这里布局和网格、材质都设置完毕，后面canvas会渲染
+
+            // profiler不用管
+            UISystemProfilerApi.EndSample(UISystemProfilerApi.SampleType.Layout);
+        }
+
+        // 统计父节点个数
+        private static int ParentCount(Transform child)
+        {
+            if (child == null)
+                return 0;
+
+            var parent = child.parent;
+            int count = 0;
+            while (parent != null)
+            {
+                count++;
+                parent = parent.parent;
+            }
+            return count;
+        }
+
+        // 根据父节点由少到多排序
+        private static int SortLayoutList(ICanvasElement x, ICanvasElement y)
+        {
+            Transform t1 = x.transform;
+            Transform t2 = y.transform;
+
+            return ParentCount(t1) - ParentCount(t2);
+        }

+

+        public static bool IsRebuildingLayout()
+        {
+            return instance.m_PerformingLayoutUpdate;
+        }
+
+        public static bool IsRebuildingGraphics()
+        {
+            return instance.m_PerformingGraphicUpdate;
+        }

+

+#region 将canvas elements注册到队列里的方法
+

+        public static void RegisterCanvasElementForLayoutRebuild(ICanvasElement element)
+        {
+            instance.InternalRegisterCanvasElementForLayoutRebuild(element);
+        }
+
+        public static bool TryRegisterCanvasElementForLayoutRebuild(ICanvasElement element)
+        {
+            return instance.InternalRegisterCanvasElementForLayoutRebuild(element);
+        }
+
+        private bool InternalRegisterCanvasElementForLayoutRebuild(ICanvasElement element)
+        {
+            if (m_LayoutRebuildQueue.Contains(element))
+                return false;
+
+            /* TODO: this likely should be here but causes the error to show just resizing the game view (case 739376)
+            if (m_PerformingLayoutUpdate)
+            {
+                Debug.LogError(string.Format("Trying to add {0} for layout rebuild while we are already inside a layout rebuild loop. This is not supported.", element));
+                return false;
+            }*/
+
+            return m_LayoutRebuildQueue.AddUnique(element);
+        }
+
+        public static void RegisterCanvasElementForGraphicRebuild(ICanvasElement element)
+        {
+            instance.InternalRegisterCanvasElementForGraphicRebuild(element);
+        }
+
+        public static bool TryRegisterCanvasElementForGraphicRebuild(ICanvasElement element)
+        {
+            return instance.InternalRegisterCanvasElementForGraphicRebuild(element);
+        }
+
+        private bool InternalRegisterCanvasElementForGraphicRebuild(ICanvasElement element)
+        {
+            if (m_PerformingGraphicUpdate)
+            {
+                Debug.LogError(string.Format("Trying to add {0} for graphic rebuild while we are already inside a graphic rebuild loop. This is not supported.", element));
+                return false;
+            }
+
+            return m_GraphicRebuildQueue.AddUnique(element);
+        }
+
+        public static void UnRegisterCanvasElementForRebuild(ICanvasElement element)
+        {
+            instance.InternalUnRegisterCanvasElementForLayoutRebuild(element);
+            instance.InternalUnRegisterCanvasElementForGraphicRebuild(element);
+        }
+
+        private void InternalUnRegisterCanvasElementForLayoutRebuild(ICanvasElement element)
+        {
+            if (m_PerformingLayoutUpdate)
+            {
+                Debug.LogError(string.Format("Trying to remove {0} from rebuild list while we are already inside a rebuild loop. This is not supported.", element));
+                return;
+            }
+
+            element.LayoutComplete();
+            instance.m_LayoutRebuildQueue.Remove(element);
+        }
+
+        private void InternalUnRegisterCanvasElementForGraphicRebuild(ICanvasElement element)
+        {
+            if (m_PerformingGraphicUpdate)
+            {
+                Debug.LogError(string.Format("Trying to remove {0} from rebuild list while we are already inside a rebuild loop. This is not supported.", element));
+                return;
+            }
+            element.GraphicUpdateComplete();
+            instance.m_GraphicRebuildQueue.Remove(element);
+        }

+

+#endregion 
+
+    }
+}