添加项目文件。

Live-Charts-master/UwpView/Components/DependencyObjectExtensions.cs

@@ -0,0 +1,22 @@
+using Windows.UI.Xaml;
+
+namespace LiveCharts.Uwp.Components
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public static class DependencyObjectExtensions
+    {
+        /// <summary>
+        /// Sets if not set.
+        /// </summary>
+        /// <param name="o">The o.</param>
+        /// <param name="dp">The dp.</param>
+        /// <param name="value">The value.</param>
+        public static void SetIfNotSet(this DependencyObject o, DependencyProperty dp, object value)
+        {
+            if (o.ReadLocalValue(dp) == DependencyProperty.UnsetValue)
+                o.SetValue(dp, value);
+        }
+    }
+}