Drawing on Chart

[McMClark]

I would like to enable a user too highlight a part of a graph by draw a box or circle around a section of the chart. I have tried to use the rectangle tool but at runtime the only effect I get is to in act the zoom feature. If the rectangle is the right tool then how do I enable it? I have also tried the annotation tool but I can not enact it.

[Narcís]

Hi McMClark,

I've just replied to the thread you posted in the ActiveX forum:

http://www.teechart.net/support/viewtop ... 1566#31566

Same idea applies to the VCL version.

[McMClark]

Thank you for your reply. The code does draw the on the canvas but the drawing does not persist. How do I get it to stay after the user finishes drawing?

[Yeray]

Hi McMClark,

One solution could be drawing a Shape series instead of a canvas rectangle in OnMouseUp event:

Code: Select all

var
  Form1: TForm1;
  X0, X1, Y0, Y1: Integer;
implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
    X0 := -1;
    Y0 := -1;

    Chart1.Zoom.Allow := false;
    Chart1.View3D := false;
end;

procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  X1 := X;
  Y1 := Y;

  If (X0 <> -1) And (Y0 <> -1) Then
  begin
    Chart1.Canvas.Brush.Style := bsClear;
    Chart1.Canvas.Pen.Color := clBlack;
    Chart1.Canvas.Rectangle(X0, Y0, X1, Y1);
    Chart1.Draw;
  End;
end;

procedure TForm1.Chart1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  X0 := X;
  Y0 := Y;
end;

procedure TForm1.Chart1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var RectSeries: TChartShape;
begin
  If (X0 <> -1) And (Y0 <> -1) Then
  begin
    RectSeries := TChartShape.Create(Self);
    Chart1.AddSeries(RectSeries);

    with (Chart1.Axes) do
    begin
      RectSeries.Style := chasRectangle;
      RectSeries.X0 := Bottom.CalcPosPoint(X0);
      RectSeries.Y0 := Left.CalcPosPoint(Y0);
      RectSeries.X1 := Bottom.CalcPosPoint(X1);
      RectSeries.Y1 := Left.CalcPosPoint(Y1);
    end;
  End;

  X0 := -1;
  Y0 := -1;
end;

[xxxxxx]

Since using TeeChart Standard I used to utilize TChart.OnAfterDraw for such persistent drawings. Isn't it not bad?

[Narcís]

Hi Alexander,

No, using OnAfterDraw event is a good option for custom drawing on the chart.