Add LineGraph.

osu.Game/Graphics/UserInterface/LineGraph.cs

@@ -0,0 +1,62 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using OpenTK;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Lines;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    public class LineGraph : Container
+    {
+        /// <summary>
+        /// Manually set the max value, otherwise <see cref="Enumerable.Max(IEnumerable{float})"/> will be used.
+        /// </summary>
+        public float? MaxValue { get; set; }
+
+        /// <summary>
+        /// Manually set the min value, otherwise <see cref="Enumerable.Min(IEnumerable{float})"/> will be used.
+        /// </summary>
+        public float? MinValue { get; set; }
+
+        private const float transform_duration = 250;
+
+        /// <summary>
+        /// Hold an empty area if values are less.
+        /// </summary>
+        public int DefaultValueCount;
+
+        private Path path;
+
+        /// <summary>
+        /// A list of floats decides position of each line node.
+        /// </summary>
+        public IEnumerable<float> Values
+        {
+            set
+            {
+                path?.Expire();
+                Path localPath = new Path { RelativeSizeAxes = Axes.Both }; //capture a copy to avoid potential change
+                Add(path = localPath);
+
+                var values = value.ToArray();
+                int count = Math.Max(values.Length, DefaultValueCount);
+
+                float max = values.Max(), min = values.Min();
+                if (MaxValue > max) max = MaxValue.Value;
+                if (MinValue < min) min = MinValue.Value;
+
+                for (int i = 0; i < values.Length; i++)
+                {
+                    float x = (i + count - values.Length) / (float)(count - 1);
+                    float y = (max - values[i]) / (max - min);
+                    Scheduler.AddDelayed(() => localPath.AddVertex(new Vector2(x, y)), x * transform_duration);
+                }
+            }
+        }
+    }
+}