Refactor IndicatorExtensions: Remove unused methods and optimize price retrieval

lib/volatility/atr/Atr.Quantower.cs

@@ -0,0 +1,51 @@
+using System.Drawing;
+using System.Runtime.CompilerServices;
+using TradingPlatform.BusinessLayer;
+
+namespace QuanTAlib;
+
+[SkipLocalsInit]
+public sealed class AtrIndicator : Indicator, IWatchlistIndicator
+{
+    [InputParameter("Period", sortIndex: 1, 1, 1000, 1, 0)]
+    public int Period { get; set; } = 14;
+
+    [InputParameter("Show cold values", sortIndex: 21)]
+    public bool ShowColdValues { get; set; } = true;
+
+    private Atr? _atr;
+    private readonly LineSeries? _series;
+
+    public static int MinHistoryDepths => 0;
+    int IWatchlistIndicator.MinHistoryDepths => MinHistoryDepths;
+
+    public override string ShortName => $"ATR {Period}";
+    public override string SourceCodeLink => "https://github.com/mihakralj/QuanTAlib/blob/main/lib/volatility/atr/Atr.Quantower.cs";
+
+    public AtrIndicator()
+    {
+        OnBackGround = true;
+        SeparateWindow = true;
+        Name = "ATR - Average True Range";
+        Description = "Measures the volatility of an asset";
+
+        _series = new(name: "ATR", color: Color.Blue, width: 2, style: LineStyle.Solid);
+        AddLineSeries(_series);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected override void OnInit()
+    {
+        _atr = new Atr(Period);
+        base.OnInit();
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    protected override void OnUpdate(UpdateArgs args)
+    {
+        TBar bar = this.GetInputBar(args);
+        TValue result = _atr!.Update(bar, args.IsNewBar());
+
+        _series!.SetValue(result.Value, _atr.IsHot, ShowColdValues);
+    }
+}