wip: layout.

src/Ursa/Controls/Timeline/TimelinePanel.cs

@@ -0,0 +1,43 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Layout;
+
+namespace Ursa.Controls;
+
+public class TimelinePanel: Panel
+{
+    public static readonly StyledProperty<TimelineDisplayMode> ModeProperty =
+        Timeline.ModeProperty.AddOwner<TimelinePanel>();
+
+    public TimelineDisplayMode Mode
+    {
+        get => GetValue(ModeProperty);
+        set => SetValue(ModeProperty, value);
+    }
+
+    static TimelinePanel()
+    {
+        AffectsMeasure<TimelinePanel>(ModeProperty);
+    }
+    
+    protected override Size MeasureOverride(Size availableSize)
+    {
+        double left = 0;
+        double right = 0;
+        double icon = 0;
+        foreach (var child in Children)
+        {
+            if (child is TimelineItem t)
+            {
+                
+            }
+        }
+        return base.MeasureOverride(availableSize);
+    }
+
+    protected override Size ArrangeOverride(Size finalSize)
+    {
+        return base.ArrangeOverride(finalSize);
+        
+    }
+}