1 files changed, 134 insertions, 0 deletions
diff --git a/Library/PackageCache/com.unity.timeline@1.2.13/Editor/treeview/Drawers/Layers/ItemsLayer.cs b/Library/PackageCache/com.unity.timeline@1.2.13/Editor/treeview/Drawers/Layers/ItemsLayer.cs
new file mode 100644
index 0000000..7446d59
--- /dev/null
+++ b/Library/PackageCache/com.unity.timeline@1.2.13/Editor/treeview/Drawers/Layers/ItemsLayer.cs
@@ -0,0 +1,134 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+using UnityEngine.Timeline;
+
+namespace UnityEditor.Timeline
+{
+    enum Layer : byte
+    {
+        Clips,
+        ClipHandles,
+        Markers,
+        MarkerHeaderTrack,
+        MarkersOnHeader
+    }
+
+    struct LayerZOrder : IComparable<LayerZOrder>
+    {
+        Layer m_Layer;
+        int m_ZOrder;
+
+        public LayerZOrder(Layer layer, int zOrder)
+        {
+            m_Layer = layer;
+            m_ZOrder = zOrder;
+        }
+
+        public int CompareTo(LayerZOrder other)
+        {
+            if (m_Layer == other.m_Layer)
+                return m_ZOrder.CompareTo(other.m_ZOrder);
+            return m_Layer.CompareTo(other.m_Layer);
+        }
+
+        public static LayerZOrder operator++(LayerZOrder x)
+        {
+            return new LayerZOrder(x.m_Layer, x.m_ZOrder + 1);
+        }
+
+        public LayerZOrder ChangeLayer(Layer layer)
+        {
+            return new LayerZOrder(layer, m_ZOrder);
+        }
+    }
+
+    interface ILayerable
+    {
+        LayerZOrder zOrder { get; }
+    }
+
+    interface IZOrderProvider
+    {
+        LayerZOrder Next();
+    }
+
+    abstract class ItemsLayer : IZOrderProvider
+    {
+        // provide a buffer for time-based culling to allow for UI that extends slightly beyong the time (e.g. markers)
+        // prevents popping of marker visibility.
+        private const int kVisibilityBufferInPixels = 10;
+
+        int m_PreviousLayerStateHash = -1;
+        LayerZOrder m_LastZOrder;
+
+        public LayerZOrder Next()
+        {
+            return m_LastZOrder++;
+        }
+
+        readonly List<TimelineItemGUI> m_Items = new List<TimelineItemGUI>();
+        bool m_NeedSort = true;
+
+        public virtual void Draw(Rect rect, WindowState state)
+        {
+            if (!m_Items.Any()) return;
+
+            Sort();
+
+            // buffer to prevent flickering of markers at boundaries
+            var onePixelTime = state.PixelDeltaToDeltaTime(kVisibilityBufferInPixels);
+            var visibleTime = state.timeAreaShownRange + new Vector2(-onePixelTime, onePixelTime);
+            var layerViewStateHasChanged = GetLayerViewStateChanged(rect, state);
+
+            foreach (var item in m_Items)
+            {
+                item.visible = item.end > visibleTime.x && item.start < visibleTime.y;
+                if (!item.visible)
+                    continue;
+
+                item.Draw(rect, layerViewStateHasChanged, state);
+            }
+        }
+
+        public IEnumerable<TimelineItemGUI> items
+        {
+            get
+            {
+                return m_Items;
+            }
+        }
+
+        protected void AddItem(TimelineItemGUI item)
+        {
+            m_Items.Add(item);
+            m_NeedSort = true;
+        }
+
+        protected ItemsLayer(Layer layerOrder)
+        {
+            m_LastZOrder = new LayerZOrder(layerOrder, 0);
+        }
+
+        void Sort()
+        {
+            if (!m_NeedSort)
+                return;
+
+            m_Items.Sort((a, b) => a.zOrder.CompareTo(b.zOrder));
+            m_NeedSort = false;
+        }
+
+        bool GetLayerViewStateChanged(Rect rect, WindowState state)
+        {
+            var layerStateHash = rect.GetHashCode().CombineHash(state.viewStateHash);
+            var layerViewStateHasChanged = layerStateHash != m_PreviousLayerStateHash;
+
+            if (Event.current.type == EventType.Layout && layerViewStateHasChanged)
+                m_PreviousLayerStateHash = layerStateHash;
+
+            return layerViewStateHasChanged;
+        }
+    }
+}