Storing reference to object in TeeChart - delphi

Question

I'm using TeeChart with Delphi XE5 and utilizing the BubbleSeries component to show X/Y/Radius bubbles in a chart.
I'm building the chart using an list of objects that I have, calculating X/Y/Radius values for these objects on the fly and inserting them using the TBubbleSeries.AddBubble method.
The problem is when I want to perform some action on the objects when the corresponding bubble is hovered/clicked/etc. I use the TChartSeries.Clicked method to find out which bubble is clicked, but the index I get returned is only usable for finding out the xy/radius values of the bubble, not which object originated it.
Maybe I'm missing something simple, because this seems to be something that any charting library should handle easily. I tried using the returned index from AddBubble method, but this index is only valid until another call to AddBubble is performed, at which point, the internal list seems to be re-ordered.
Edit: Was asked for some code, here it is!
procedure TBubbleReportForm.ChartMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
var
Index: Integer;
Device: TDevice;
begin
Index := BubbleSeries.Clicked(X,Y);
if Index = -1 then
begin
BubbleChart.ShowHint := False;
Exit;
end;
// This does not work as indexing does seems to correspond to the order which the bubbles was added.
Device := FDevices[Index];
BubbleChart.Hint := Device.Name;
BubbleChart.ShowHint := True;
end;
procedure TBubbleReportForm.FormCreate(Sender: TObject);
var
Device: TDevice;
begin
BubbleChart.OnMouseMove := ChartMouseMove;
// FDevices is of TObjectList type.
for Device in FDevices do
begin
BubbleSeries.AddBubble(Device.CalculateXVal,Device.CalculateYVal,Device.CalculateRadius);
end;
end;

Answer 1

I would use a a Generic TObjectList. Or an descendant og a TObjectList.
First Iimpelment your BoubleObject, and a list of them. In the following example I've just used a dummy implementation:
unit BubbleU;
interface
uses
System.Generics.Collections, System.SysUtils, Vcl.Graphics;
{$M+}
type
TBubble = class
private
FX: Double;
FRadius: Double;
FY: Double;
FLabelText: String;
FColor: TColor;
FIndex: Integer;
FChartIndex: Integer;
procedure SetChartIndex(const Value: Integer);
protected
procedure DoCalculation;
public
constructor Create(aIndex: Integer); reintroduce;
published
property X: Double read FX;
property Y: Double read FY;
property Radius: Double read FRadius;
property LabelText: String read FLabelText;
property Color: TColor read FColor;
property ChartIndex: Integer read FChartIndex write SetChartIndex;
end;
TBubbleList = class(TObjectList<TBubble>)
public
function ElementFormChartIndex(ChartIndex: Integer): TBubble; overload;
end;
implementation
{ TBubble }
constructor TBubble.Create(aIndex: Integer);
begin
inherited Create;
FIndex := aIndex;
DoCalculation;
end;
procedure TBubble.DoCalculation;
begin
FX := FIndex;
FY := FIndex;
FRadius := 1;
FColor := clRed;
FLabelText := 'Index: ' + FIndex.ToString;
end;
procedure TBubble.SetChartIndex(const Value: Integer);
begin
FChartIndex := Value;
end;
{ TBubbleList }
function TBubbleList.ElementFormChartIndex(ChartIndex: Integer): TBubble;
var
Element : TBubble;
begin
for Element in Self do
if Element.FChartIndex = ChartIndex then
Exit(element);
Exit(nil);
end;
end.
Next Extend your TBubbleSeries
unit BubbleSeriesExtention;
interface
uses
System.Classes, System.SysUtils,
VclTee.BubbleCh,
BubbleU;
type
TBubbleSeries = class(VclTee.BubbleCh.TBubbleSeries)
strict private
FBoubleList: TBubbleList;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
function AddBubble(aBubble: TBubble): Integer; reintroduce;
published
property BoubleList : TBubbleList read FBoubleList;
end;
implementation
{ TBubbleSeries }
function TBubbleSeries.AddBubble(aBubble: TBubble): Integer;
begin
aBubble.ChartIndex := Inherited AddBubble(aBubble.X, aBubble.Y, aBubble.Radius, aBubble.LabelText, aBubble.Color);
FBoubleList.Add(aBubble);
Result := aBubble.ChartIndex;
end;
constructor TBubbleSeries.Create(AOwner: TComponent);
begin
inherited;
FBoubleList := TBubbleList.Create(True);
end;
destructor TBubbleSeries.Destroy;
begin
FreeAndNil(FBoubleList);
inherited;
end;
end.
Finally Use it in your from:
Add BubbleSeriesExtention toh the uses list AFTER VclTee.BubbleCh
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, VclTee.TeeGDIPlus, VclTee.TeEngine,
VclTee.Series, VclTee.BubbleCh, Vcl.ExtCtrls, VclTee.TeeProcs, VclTee.Chart,
BubbleU, BubbleSeriesExtention;
And use it:
type
TForm4 = class(TForm)
Chart1: TChart;
BubbleSeries: TBubbleSeries;
procedure FormCreate(Sender: TObject);
procedure Chart1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form4: TForm4;
implementation
{$R *.dfm}
procedure TForm4.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
var
Index: Integer;
Bouble: TBubble;
begin
Index := BubbleSeries.Clicked(X, Y);
if index < 0 then
exit;
Bouble := BubbleSeries.BoubleList.ElementFormChartIndex(Index);
Caption := Bouble.LabelText;
end;
procedure TForm4.FormCreate(Sender: TObject);
var
i: Integer;
begin
//Add dummy data
for i := 0 to 9 do
BubbleSeries.AddBubble(TBubble.Create(i));
end;
end.
this solution has this advantage that you have acces to your Object all the time and when your BubbleSeries are destroyes so is your objects for calculating elements in it. and gives you a kind of garbage collection

Answer 2

You can exploit unused AXLabel argument like this:
for DevIndex := 0 to DeviceCount - 1 do begin
Device := FDevices[DevIndex];
BubbleSeries.AddBubble(Device.CalculateXVal,Device.CalculateYVal, Device.CalculateRadius, IntToStr(DevIndex));
end;
// to avoid labels' text ox X-Axis:
Chart1.BottomAxis.LabelStyle := talValue;
//in Clicked:
DeviceIndex := StrToInt(BubbleSeries.Labels[Index]);