Merge pull request oxyplot#1282 from danpaul88/trackercontrol-recyclecontentcontrol

Change TrackerControl to reuse existing ContentControls

Author: Oystein Bjorke

CHANGELOG.md

@@ -28,6 +28,7 @@ All notable changes to this project will be documented in this file.
 - Place label below negative ColumnSeries (#1119)
 - Use PackageReference instead of packages.config
 - Migrated NUnit v2 to v3 and added test adapter
+- TrackerControl reuses existing ContentControl when a new hit tracker result uses the same template as the currently shown tracker (#1281)
 
 ### Deprecated
 - OxyPlot.WP8 package. Use OxyPlot.Windows instead (#996)

CONTRIBUTORS

@@ -29,6 +29,7 @@ csabar <rumancsabi@gmail.com>
 Curt Mullin <curt.mullin@gmail.com>
 Cyril Martin <cyril.martin.cm@gmail.com>
 Dan Aizenstros
+danpaul88 <danpaul88@users.noreply.github.com>
 darrelbrown
 David Laundav <davelaundav@gmail.com>
 David Wong <dvkwong0@gmail.com>

Source/OxyPlot.Wpf/PlotBase.cs

@@ -51,6 +51,11 @@ public abstract partial class PlotBase : Control, IPlotView
         /// </summary>
         private FrameworkElement currentTracker;
 
+        /// <summary>
+        /// The current tracker template.
+        /// </summary>
+        private ControlTemplate currentTrackerTemplate;
+
         /// <summary>
         /// The grid.
         /// </summary>
@@ -181,6 +186,7 @@ public void HideTracker()
             {
                 this.overlays.Children.Remove(this.currentTracker);
                 this.currentTracker = null;
+                this.currentTrackerTemplate = null;
             }
         }
 
@@ -341,14 +347,15 @@ public void ShowTracker(TrackerHitResult trackerHitResult)
                 return;
             }
 
-            var tracker = new ContentControl { Template = trackerTemplate };
-
             // ReSharper disable once RedundantNameQualifier
-            if (!object.ReferenceEquals(tracker, this.currentTracker))
+            if (!object.ReferenceEquals(trackerTemplate, this.currentTrackerTemplate))
             {
                 this.HideTracker();
+
+                var tracker = new ContentControl { Template = trackerTemplate };
                 this.overlays.Children.Add(tracker);
                 this.currentTracker = tracker;
+                this.currentTrackerTemplate = trackerTemplate;
             }
 
             if (this.currentTracker != null)