Drill-down help and examples

[RichardAnderson]

Environment - Delphi 7 and TChart 7.07 working against an Oracle database (using DOA components).

I have a fairly standard bar chart and my user wants to double-click on a bar and then navigate to a new screen that displays the detail data. What I need to be able to do on the Double-click event is determine the text of the X-Axis (the bars go up the Y-Axis and the points go along the X-Axis) under the bar they double-clicked on. I can use that value to then get the detail data and show this data (thats easy). I can't quite figure out is how to get the value of the X-Axis label. Is there an easy way to do this? Also, is there any built in "Drill-down" capability in this version.

Thanks
Richard Anderson

[Narcís]

Hi Richard,

Yes, labels can be retrieved like this:

Code: Select all

procedure TForm1.Series1DblClick(Sender: TChartSeries; ValueIndex: Integer;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  Chart1.Title.Text[0]:=Sender.Labels[ValueIndex];
end;

Regarding built in drill-down, there's MarkTips tool, another option is interpolating series like shown here or using hints over the line like this:

Code: Select all

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, TeEngine, Series, ExtCtrls, TeeProcs, Chart;

type
  TForm1 = class(TForm)
    Chart1: TChart;
    Series1: TLineSeries;
    procedure FormCreate(Sender: TObject);
    procedure Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
  private
    { Private declarations }
   OnSeriesPoint : Boolean;
   OnLegendPoint : Boolean;
   tmpL2 : Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Series1.FillSampleValues(10);
  Chart1.View3D := False;
end;

procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var tmp, tmpL : Integer;
begin
  With Chart1 do
  begin
    If (Series1.Clicked(X, Y) <> -1) And (OnSeriesPoint = False) Then
    begin
     Canvas.Brush.Style := bsSolid;
     Canvas.Pen.Color := clBlack;
     Canvas.Brush.Color := clWhite;
     canvas.TextOut(x+10,y,FormatFloat('#.00',Series1.XScreenToValue(x))+','+FormatFloat('#.00',Series1.YScreenToValue(y)));
     OnSeriesPoint := True;
    End;
    //Repaint Chart to clear Textoutputted Mark
    If (Series1.Clicked(X, Y) = -1) And (OnSeriesPoint = True) Then
    begin
      OnSeriesPoint := False;
      Repaint;
    End;

    tmpL := Chart1.Legend.Clicked(X, Y);
    If (tmpL <> -1) And ((tmpL <> tmpL2) Or (OnLegendPoint = False)) Then
    begin
       Repaint;
       Canvas.Brush.Color := Series1.LegendItemColor(tmpL);
       Canvas.Rectangle( X, Y, X + 20, Y + 20);
       Canvas.Brush.Color := clWhite;
       canvas.TextOut(x+7,y+7,FormatFloat('#.00',Series1.XValues.Items[Series1.LegendToValueIndex(tmpl)]));
       tmpL2 := tmpL;
       OnLegendPoint := True;
    End;

    If (Legend.Clicked(X, Y) = -1) And (OnLegendPoint = True) Then
    begin
       OnLegendPoint := False;
       Repaint;
    End;
  End;
end;

end.