Using Chart Tools on the Fly
lazarus / 55-TAChart

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chucky · 2013-06-02 04:54

I am trying to create a form with a TChart object on the fly also with
chart tools. I am using 1.0.8 which has a builtin zoom but not a
builtin pan. The relevant code in the class

  TForm1 = class(TForm)
    Chart                      : TChart;
    Toolset                     :TChartToolset;
    PanDragTool             : TPanDragTool;
    ZoomDragTool          : TZoomDragTool;
  end;

The relevant code in the constructor:

Constructor TForm1.Create(AOwner : TComponent);
Begin
  Chart := TChart.Create(Self);

// ---------------------------- Chart Tool Set
  ToolSet := TChartToolset.Create(Self);

  Chart.ToolSet := ToolSet;    // This assignment will set activetool
count to -1
 
  ZoomDragTool := TZoomDragTool.Create(ToolSet);
  ZoomDragTool.Shift := [ssLeft];
 
  PanDragTool := TPanDragTool.Create(ChartToolSet);
  PanDragTool.Shift := [ssRight];
end;

The program builds the chart and displays data correctly but no
zooming and and no panning. The default zooming works again if I
comment out the line:

  Chart.ToolSet := ToolSet;

Apparently I am not enabling or registering something correctly.

Can anyone help????

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chucky · 2013-06-02 05:39

I solved my problem.

The zoom and pan toos need to point back to the tool set like this:

  ZoomDragTool := TZoomDragTool.Create(ToolSet);
***  ZoomDragTool.ToolSet := ToolSet; ***
  ZoomDragTool.Shift := [ssLeft];
 
  PanDragTool := TPanDragTool.Create(ChartToolSet);
***  PanDragTool.ToolSet := ToolSet ***
  PanDragTool.Shift := [ssRight];

Now both Zoomming and Panning works!!!