Steema Central

Posted: **Thu Mar 19, 2009 12:51 am**

Hi,

I have a chart with a cursor tool (followmouse is true).
I use the double click chart event to zoom sections of the chart depending where the cursor is (in my case the chart is zoomed when the cursor/mouse is in a colorband). The problem is that the cursor is in 'selection' mode after the double click event, but only if the chart was zoomed during the double click handler.

Posted: **Thu Mar 19, 2009 10:07 am**

Hi strobbekoen,

I think that you should use a custom zoom. Something as follows:

Code: Select all

var
  Form1: TForm1;
  DrawRect: Boolean;
  XStart, XEnd, YStart, YEnd: Integer;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  XStart := -1;
  XEnd := -1;
  YStart := -1;
  YEnd := -1;

  DrawRect := false;

  Chart1.Zoom.Allow := false;
end;

procedure TForm1.Chart1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var ZoomRect: TRect;
begin
  If DrawRect then
  begin
    DrawRect := false;
    ZoomRect.Left := XStart;
    ZoomRect.Top := YStart;
    ZoomRect.Right := XEnd;
    ZoomRect.Bottom := YEnd;
    Chart1.ZoomRect(ZoomRect);
  end;
end;

procedure TForm1.Chart1AfterDraw(Sender: TObject);
begin
  if DrawRect then
  begin
    Chart1.Canvas.Pen.Color := clWhite;
    Chart1.Canvas.Brush.Style := bsClear;
    Chart1.Canvas.Rectangle(XStart,YStart,XEnd,YEnd);
  end;
end;

procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if DrawRect then
  begin
    XEnd := X;
    YEnd := Y;
    Chart1.Draw;
  end
  else
  begin
    XStart := X;
    YStart := Y;
  end;
end;

procedure TForm1.Chart1DblClick(Sender: TObject);
begin
  DrawRect := True;
end;

Also, let me suggest you to consider another possibility. You could use mousewheel to zoom the chart as described here.

Posted: **Thu Mar 19, 2009 2:33 pm**

Thanks for the tip

Steema Central

Double Click bug

Double Click bug