TMS Software FAQ: TMS VCL Chart

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TMS VCL Chart
Programmatically scrolling and zooming in the chart

Scrolling and zooming via code in the chart is simple. This is just a matter of programmatically changing the properties Pane.Range.RangeFrom and Pane.Range.RangeTo. To illustrate this, we create a single sinus serie in a chart and add 4 buttons to control the scrolling & zooming:

Initialization of the chart:

procedure TForm1.FormCreate(Sender: TObject);
var
  i: integer;
begin
  advchartview1.BeginUpdate;
  advchartview1.Panes.Clear;
  advchartview1.Panes.Add;
  advchartview1.Panes[0].Options := advchartview1.Panes[0].Options + [poMoving, poHorzScroll, poHorzScale];
  advchartview1.Panes[0].Series.Add;

  with advchartview1.Panes[0].Series[0] do
  begin
    for i := 1 to 200 do
      AddSinglePoint(50 * sin(i/20*PI));
  end;
  advchartview1.Panes[0].Series[0].AutoRange := arCommon;
  advchartview1.Panes[0].Range.RangeFrom := 0;
  advchartview1.Panes[0].Range.RangeTo := 200;

  advchartview1.EndUpdate;
end;

Code to perform zoom and scroll:

procedure TForm1.Scroll(delta: integer);
begin
  advchartview1.BeginUpdate;
  advchartview1.Panes[0].Range.RangeFrom :=   advchartview1.Panes[0].Range.RangeFrom + delta;
  advchartview1.Panes[0].Range.RangeTo :=   advchartview1.Panes[0].Range.RangeTo + delta;
  advchartview1.EndUpdate;
end;

procedure TForm1.Zoom(delta: integer);
begin
  advchartview1.BeginUpdate;
  advchartview1.Panes[0].Range.RangeFrom :=   advchartview1.Panes[0].Range.RangeFrom + delta;
  advchartview1.Panes[0].Range.RangeTo :=   advchartview1.Panes[0].Range.RangeTo - delta;
  advchartview1.EndUpdate;
end;

The code to zoom and scroll can then simply be attached to buttons:

procedure TForm1.ScrollLeftClick(Sender: TObject);
begin
  Scroll(-10);
end;

procedure TForm1.ScrollRightClick(Sender: TObject);
begin
  Scroll(+10);
end;

procedure TForm1.ZoomOutClick(Sender: TObject);
begin
  Zoom(+10);
end;

procedure TForm1.ZoomInClick(Sender: TObject);
begin
  Zoom(-10);
end;

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