Steema Central

Posted: **Tue Dec 18, 2007 1:26 pm**

Hi,

Is there a way to zoom starting from out side of the plot rectangle? I've been trying to zoom with mouse down at the outside of plot rectangle (within the Chart), but as soon as mouse is down out side of the plot rectangle, the zoom function disables. I'd like to zoom in (zoom rectangle covers both in and out of the plot) at the edge of the plot rectangle without have to move the plot first.

Thanks

-Bill

Posted: **Tue Dec 18, 2007 2:21 pm**

Hi Bill,

In that case you can zoom doing something like this:

Code: Select all

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

procedure TForm1.Chart1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var R: TRect;
begin
  if ((X0<>-1) and (Y0<>-1)) then
  begin
    R.Left:=X0;
    R.Top:=Y0;
    R.Right:=X;
    R.Bottom:=Y;
    Chart1.ZoomRect(R);
  end;

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

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

function TForm1.MouseOutOfChartRect(X, Y: Integer): boolean;
begin
  result:=((X<Chart1.ChartRect.Left) or (Y<Chart1.ChartRect.Top));
end;

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

  Chart1.Repaint;
end;

procedure TForm1.Chart1AfterDraw(Sender: TObject);
begin
  if ((X0<>-1) and (Y0<>-1)) then
  begin
    Chart1.Canvas.Brush.Style:=bsClear;
    Chart1.Canvas.Pen.Color:=Chart1.Zoom.Pen.Color;
    Chart1.Canvas.Pen.Style:=Chart1.Zoom.Pen.Style;
    Chart1.Canvas.Rectangle(X0,Y0,X1,Y1);
  end;
end;

Steema Central

Zoom outside of Plot rectangle

Zoom outside of Plot rectangle