unit Interactive.Main;

// One TAtlasPlot that switches between four charts. Drag to zoom, right-drag
// to pan, use the wheel, double-click to reset; click to report the nearest
// point; move the mouse to see values and exact hits in the status line.

interface

uses
  System.Classes, System.SysUtils, System.Types, Vcl.Controls, Vcl.Forms, Vcl.StdCtrls,
  Vcl.ExtCtrls, Vcl.Graphics, Atlas.Plot, Atlas.PlotSeries;

type
  TInteractiveForm = class(TForm)
  private
    FPlot: TAtlasPlot;
    FStatus: TLabel;
    FBar: TPanel;
    procedure AddButton(const Caption: string; Tag: Integer; OnClick: TNotifyEvent);
    procedure Reset;
    function Describe(Series: TAtlasPlotSeries; Index: Integer): string;
    procedure ShowChart(Sender: TObject);
    procedure BuildStackedAreas;
    procedure BuildDateLine;
    procedure BuildLogPoints;
    procedure BuildDonut;
    procedure PlotClicked(Sender: TObject);
    procedure PointClicked(Sender: TObject; Series: TAtlasPlotSeries; PointIndex: Integer);
    procedure PlotMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure ZoomChanged(Sender: TObject);
  public
    constructor Create(AOwner: TComponent); override;
  end;

implementation

constructor TInteractiveForm.Create(AOwner: TComponent);
begin
  inherited CreateNew(AOwner);
  Caption := 'Atlas Plot: interactive';
  SetBounds(0, 0, 900, 620);
  Position := poScreenCenter;
  FBar := TPanel.Create(Self);
  FBar.Parent := Self;
  FBar.Align := alTop;
  FBar.Height := 34;
  FBar.BevelOuter := bvNone;
  FStatus := TLabel.Create(Self);
  FStatus.Parent := Self;
  FStatus.Align := alBottom;
  FStatus.AlignWithMargins := True;
  FStatus.Caption := 'Drag to zoom, right-drag to pan, wheel to zoom, double-click to reset. Click to find the nearest point.';
  FPlot := TAtlasPlot.Create(Self);
  FPlot.Parent := Self;
  FPlot.Align := alClient;
  // With TabStop a click focuses the chart, so it also receives wheel messages.
  FPlot.TabStop := True;
  FPlot.OnPointClick := PointClicked;
  FPlot.OnClick := PlotClicked;
  FPlot.OnMouseMove := PlotMouseMove;
  FPlot.OnZoom := ZoomChanged;
  AddButton('Stacked areas', 0, ShowChart);
  AddButton('Dates + average', 1, ShowChart);
  AddButton('Log-log points', 2, ShowChart);
  AddButton('Donut', 3, ShowChart);
  ShowChart(Self); // the form's Tag is 0: stacked areas
end;

procedure TInteractiveForm.AddButton(const Caption: string; Tag: Integer; OnClick: TNotifyEvent);
var Button: TButton;
begin
  Button := TButton.Create(Self);
  Button.Parent := FBar;
  Button.Caption := Caption;
  Button.Tag := Tag;
  Button.Width := 130;
  // ControlCount already includes this button.
  Button.Left := 4 + (FBar.ControlCount - 1) * 134;
  Button.Top := 4;
  Button.OnClick := OnClick;
end;

procedure TInteractiveForm.Reset;
begin
  // Every chart starts from the same settings; Clear also ends any zoom.
  // Logarithmic is cleared before DateTime: a date/time axis cannot be logarithmic.
  FPlot.Clear;
  FPlot.ArgumentAxis.Logarithmic := False;
  FPlot.ArgumentAxis.DateTime := False;
  FPlot.ArgumentAxis.Title := '';
  FPlot.ValueAxis.Logarithmic := False;
  FPlot.ValueAxis.Title := '';
  FPlot.Stacking := psNone;
  FPlot.DonutPercent := 0;
  FPlot.LegendPosition := lpRight;
  FPlot.Footnote := '';
end;

procedure TInteractiveForm.ShowChart(Sender: TObject);
begin
  // One batch: the chart repaints once, after the new chart is complete.
  FPlot.BeginUpdate;
  try
    Reset;
    case TComponent(Sender).Tag of
      0: BuildStackedAreas;
      1: BuildDateLine;
      2: BuildLogPoints;
    else
      BuildDonut;
    end;
  finally
    FPlot.EndUpdate;
  end;
end;

procedure TInteractiveForm.BuildStackedAreas;
const Names: array[0..2] of string = ('Desktop', 'Mobile', 'Tablet');
var I, Month: Integer; S: TAtlasPlotSeries;
begin
  FPlot.Title := 'Sessions by device (stacked areas)';
  FPlot.Stacking := psStacked;
  FPlot.LegendPosition := lpTop;
  FPlot.ArgumentAxis.Title := 'Month';
  FPlot.ValueAxis.Title := 'Sessions';
  for I := 0 to High(Names) do
  begin
    S := FPlot.AddSeries(Names[I], pkArea);
    for Month := 1 to 12 do
      S.Add(Month, 30 + 10 * I + Month * (3 - I) + 8 * Sin(Month / 2 + I));
  end;
end;

procedure TInteractiveForm.BuildDateLine;
var Daily: TAtlasPlotSeries; I: Integer; Start: TDateTime;
begin
  FPlot.Title := 'Daily orders with a 7-day average and trend';
  FPlot.ArgumentAxis.DateTime := True;
  FPlot.ValueAxis.Title := 'Orders';
  FPlot.LegendPosition := lpBottom;
  Start := EncodeDate(2026, 3, 1);
  Daily := FPlot.AddSeries('Orders');
  Daily.LineWidth := 1;
  for I := 0 to 89 do
    if (I >= 40) and (I < 44) then Daily.AddNull(Start + I) // a gap: the line breaks here
    else Daily.Add(Start + I, 120 + I * 0.9 + 25 * Sin(I / 3.1) + 12 * Cos(I * 1.7));
  FPlot.AddMovingAverage(Daily, 7).LineWidth := 3;
  FPlot.AddTrendLine(Daily);
end;

procedure TInteractiveForm.BuildLogPoints;
var Measured, Limit: TAtlasPlotSeries; I: Integer;
begin
  FPlot.Title := 'Response time by payload (log-log)';
  FPlot.ArgumentAxis.Logarithmic := True;
  FPlot.ArgumentAxis.Title := 'Payload, KB';
  FPlot.ValueAxis.Logarithmic := True;
  FPlot.ValueAxis.Title := 'Milliseconds';
  Measured := FPlot.AddSeries('Measured', pkPoint);
  for I := 0 to 24 do
    Measured.Add(Exp(Ln(10) * I / 6), 2 * Exp(Ln(10) * I / 8) * (1 + 0.3 * Sin(I * 2.3)));
  Limit := FPlot.AddSeries('Tier limit', pkStep);
  Limit.Add(1, 10); Limit.Add(100, 100); Limit.Add(10000, 1000);
end;

procedure TInteractiveForm.BuildDonut;
var S: TAtlasPlotSeries;
begin
  FPlot.Title := 'Support tickets by channel';
  FPlot.Footnote := 'Click a slice';
  FPlot.DonutPercent := 45;
  S := FPlot.AddSeries('Tickets', pkPie);
  S.Marks := pmPercent;
  S.AddY(412, 'Email'); S.AddY(268, 'Chat'); S.AddY(131, 'Phone'); S.AddY(54, 'Forum');
  S.AddY(19, 'Post', clSilver); // a per-point colour
end;

function TInteractiveForm.Describe(Series: TAtlasPlotSeries; Index: Integer): string;
var P: TAtlasPlotPoint; Arg: string;
begin
  P := Series[Index];
  if FPlot.ArgumentAxis.DateTime then Arg := FormatDateTime('yyyy-mm-dd', P.X)
  else Arg := FormatFloat('0.###', P.X);
  Result := Format('%s [%d]: x = %s, y = %s', [Series.Title, Index, Arg, FormatFloat('0.###', P.Y)]);
  if P.Text <> '' then Result := Result + ' (' + P.Text + ')';
end;

procedure TInteractiveForm.PlotClicked(Sender: TObject);
var
  At, Pixel: TPoint;
  I, J, BestSeries, BestPoint, Distance, Best: Integer;
  S: TAtlasPlotSeries;
begin
  // ValuesToPixel describes the latest render, so the nearest point can be
  // found along the argument axis in screen space, whatever the stacking.
  At := FPlot.ScreenToClient(Mouse.CursorPos);
  Best := 0; BestSeries := -1; BestPoint := -1;
  for I := 0 to FPlot.Series.Count - 1 do
  begin
    S := FPlot.Series[I];
    if S.Visible then
      for J := 0 to S.Count - 1 do
        if not S[J].IsNull and FPlot.ValuesToPixel(S[J].X, S[J].Y, Pixel) then
        begin
          if FPlot.Rotated then Distance := Abs(Pixel.Y - At.Y) else Distance := Abs(Pixel.X - At.X);
          if (BestSeries < 0) or (Distance < Best) then
          begin
            Best := Distance; BestSeries := I; BestPoint := J;
          end;
        end;
  end;
  if BestSeries >= 0 then
    FStatus.Caption := Format('Nearest along the argument axis (%d px): %s',
      [Best, Describe(FPlot.Series[BestSeries], BestPoint)]);
end;

procedure TInteractiveForm.PointClicked(Sender: TObject; Series: TAtlasPlotSeries; PointIndex: Integer);
begin
  // Fires after OnClick, only when the click lands on a bar, dot, vertex or slice.
  FStatus.Caption := 'Clicked ' + Describe(Series, PointIndex);
end;

procedure TInteractiveForm.PlotMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
var Arg, Val: Double; SeriesIndex, PointIndex: Integer; Text: string;
begin
  if ssLeft in Shift then Exit; // keep the click or zoom message while dragging
  Text := '';
  if FPlot.PixelToValues(X, Y, Arg, Val) then
    if FPlot.ArgumentAxis.DateTime then
      Text := Format('Cursor: %s, %s', [FormatDateTime('yyyy-mm-dd', Arg), FormatFloat('0.###', Val)])
    else
      Text := Format('Cursor: x = %s, y = %s', [FormatFloat('0.###', Arg), FormatFloat('0.###', Val)]);
  if FPlot.HitTest(X, Y, SeriesIndex, PointIndex) then
    Text := Text + '  |  over ' + Describe(FPlot.Series[SeriesIndex], PointIndex);
  if FPlot.Zoomed then Text := Text + '  |  zoomed (double-click to reset)';
  if Text <> '' then FStatus.Caption := Text;
end;

procedure TInteractiveForm.ZoomChanged(Sender: TObject);
begin
  if FPlot.Zoomed then FStatus.Caption := 'Zoomed in. Right-drag to pan, wheel to zoom further, double-click to reset.'
  else FStatus.Caption := 'Back to the full data range.';
end;

end.