Chart X grid, standard timeframes

Src/Myc.Fmx.Chart.Series.pas

@@ -1,4 +1,4 @@
-unit Myc.FMX.Chart.Series;
+unit Myc.Fmx.Chart.Series;
 
 interface
 
@@ -58,14 +58,14 @@ type
     end;
 
     { TChartCustomLayer }
-    TChartCustomLayer<T> = class(TMycChart.TLayer)
+    TChartCustomLayer<T> = class abstract(TMycChart.TDataLayer)
     private
         FSeries: TChartSeriesProcessor<T>;
     protected
         function GetSeries: TMycChart.TSeries; override;
-        function GetValueRange(First, Last: Int64; out MinValue, MaxValue: Double): Boolean; override;
+        function GetValueRange(First, Last: Int64; out MinValue, MaxValue: Double): Boolean; override; abstract;
         procedure Update; override;
-        procedure Paint(const Canvas: TCanvas; First, Last: Int64; const XForm, YForm: TFunc<Double, Single>); override;
+        procedure Paint(const Canvas: TCanvas; First, Last: Int64; const XForm, YForm: TFunc<Double, Single>); override; abstract;
     public
         constructor Create(AParent: TMycChart.TPanel; const ADataProvider: IMycDataProvider<T>);
         destructor Destroy; override;
@@ -104,6 +104,30 @@ type
         );
     end;
 
+    { TChartXAxisLayer }
+    TChartXAxisLayer<T> = class(TMycChart.TXAxisLayer)
+    private
+        FSeries: TChartSeriesProcessor<T>;
+    protected
+        function GetSeries: TMycChart.TSeries; override;
+        procedure Update; override;
+        function GetCaption(Idx: Int64): String; override; abstract;
+    public
+        constructor Create(AOwner: TMycChart; const ADataProvider: IMycDataProvider<T>);
+        destructor Destroy; override;
+    end;
+
+    { TChartXAxisTimestampLayer }
+    TChartXAxisTimestampLayer = class(TChartXAxisLayer<TDateTime>)
+    private
+        FTimeframe: TTimeframe;
+    protected
+        // Provide a formatted timestamp string for a given data index.
+        function GetCaption(Idx: Int64): String; override; final;
+    public
+        constructor Create(AOwner: TMycChart; ATimeframe: TTimeframe; const ADataProvider: IMycDataProvider<TDateTime>);
+    end;
+
 implementation
 
 uses
@@ -320,19 +344,61 @@ begin
     Result := FSeries;
 end;
 
-function TChartCustomLayer<T>.GetValueRange(First, Last: Int64; out MinValue, MaxValue: Double): Boolean;
-begin
-    Result := false;
-end;
-
-procedure TChartCustomLayer<T>.Paint(const Canvas: TCanvas; First, Last: Int64; const XForm, YForm: TFunc<Double, Single>);
-begin
-    // nope
-end;
-
 procedure TChartCustomLayer<T>.Update;
 begin
     FSeries.Update;
 end;
 
+{ TChartXAxisLayer }
+
+constructor TChartXAxisLayer<T>.Create(AOwner: TMycChart; const ADataProvider: IMycDataProvider<T>);
+begin
+    inherited Create(AOwner);
+    FSeries := TChartSeriesProcessor<T>.Create(ADataProvider, AOwner.Lookback.AsMutable);
+end;
+
+destructor TChartXAxisLayer<T>.Destroy;
+begin
+    FSeries.Free;
+    inherited;
+end;
+
+function TChartXAxisLayer<T>.GetSeries: TMycChart.TSeries;
+begin
+    Result := FSeries;
+end;
+
+procedure TChartXAxisLayer<T>.Update;
+begin
+    FSeries.Update;
+end;
+
+constructor TChartXAxisTimestampLayer.Create(AOwner: TMycChart; ATimeframe: TTimeframe; const ADataProvider: IMycDataProvider<TDateTime>);
+begin
+    inherited Create(AOwner, ADataProvider);
+    FTimeframe := ATimeframe;
+end;
+
+function TChartXAxisTimestampLayer.GetCaption(Idx: Int64): String;
+var
+    dt: TDateTime;
+    formatStr: string;
+begin
+    Result := '';
+    if (Idx >= 0) and (Idx < FSeries.Count) then
+    begin
+        dt := FSeries.Data[Idx];
+
+        // Choose format based on the series timeframe.
+        if FTimeframe >= D then // Daily, Weekly, Monthly, Yearly
+            formatStr := 'dd.mm.yyyy'
+        else if FTimeframe >= M then // Hourly + Minutes
+            formatStr := 'dd.mm.yyyy hh:nn'
+        else // Seconds
+            formatStr := 'dd.mm.yyyy hh:nn:ss';
+
+        Result := FormatDateTime(formatStr, dt);
+    end;
+end;
+
 end.