Steema Central

Posted: **Tue Jul 17, 2007 8:06 am**

Hi !

I have some customaxis in my chart which need to bee zoomed.
In the OnZoom Event I use this code:

procedure TForm1.Chart1Zoom(Sender: TObject);
var Achse   : TChartAxis;
    i       : Byte;
begin
 if Chart1.Zoom.Direction in [tzdBoth, tzdVertical] then

  for i := 0 to Chart1.SeriesCount - 1 do begin
    Achse := Chart1.Series[i].GetVertAxis;
    if Achse.Visible then
      Achse.SetMinMax(Achse.CalcPosPoint(Chart1.Zoom.Y1),Achse.CalcPosPoint(Chart1.Zoom.Y0));
  end;  
end;

If I try to zoom in / Zoom out with the ZoomRect function the chart alsways zoom out.

I use the sample from your helpfile:
Zoom in example:

Code: Select all

Chart1.ZoomRect( Rect( 5,5,Chart1.Width-5,Chart1.Height-5 ) );

Zoom out example:

Code: Select all

Chart1.ZoomRect( Rect( -5,-5,Chart1.Width+5,Chart1.Height+5 ) );

What must I do in order to zoom in and zoom out correctly the axis using ZoomRect ?

Posted: **Tue Jul 17, 2007 9:21 am**

Hi Dominik,

have you tried using similar code to the following ?

Code: Select all

  procedure TForm1.FormCreate(Sender: TObject);
    var tmp: TChartAxis;
  begin
      Series1.FillSampleValues(20);
      tmp := (Chart1.CustomAxes.Add as TChartAxis);
      tmp.OtherSide:=true;
      tmp.Horizontal:=false;
      tmp.PositionPercent:=20;
      Series1.CustomVertAxis:=tmp;
  end;

  procedure TForm1.Chart1Zoom(Sender: TObject);
  begin
    With Series1.GetVertAxis 
      SetMinMax(CalcPosPoint(Chart1.IZoom.Y1),CalcPosPoint(Chart1.IZoom.Y0));
  end;

  procedure TForm1.Chart1UndoZoom(Sender: TObject);
  begin
    Series1.GetVertAxis.Automatic:=true;
  end;

Posted: **Tue Jul 17, 2007 9:56 am**

Hi Pep !

This won´t work for me.

I´ve uploaded a small demo appilcation to your server:

Received ZoomRect Test.zip Content Type application/x-zip-compressed Length 13796

Zoomin and Zoomout always does the same.

Posted: **Fri Jul 20, 2007 9:27 am**

Hi Pep,

did you checked my demo application ?

Posted: **Sun Jul 22, 2007 11:42 am**

On request of Dominik I post here a piece of my code using ZoomRect

Code: Select all

      
..
//From OnMouseWheel hanlder
if WheelDelta>0 then
        ZoomPercentage:=ZoomInRate*WheelDelta
      else
        ZoomPercentage:=ZoomOutRate*WheelDelta;
      with ChartRect do
        InflateRect(ChartRect,Round((Right-Left)*ZoomPercentage/100),Round((Bottom-Top)*ZoomPercentage/100));
      ZoomRect(ChartRect);

//From UndoZoomHandler
 with ParentChart, CustomAxes do
 for iX:=0 to Count-1 do
 with Items[iX] do
   Automatic:=True;

Posted: **Mon Jul 23, 2007 6:31 am**

Hi xxxxxx,

could you please add some information for the variables?

ZoomInRate, ZoomOutRate What value do you use for this?
ChartRect How if it defined and how to set the values?

Posted: **Mon Jul 23, 2007 7:02 am**

Hi !

I tried this:

Code: Select all

procedure TForm1.Chart1MouseWheel(Sender: TObject; Shift: TShiftState;
  WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
var 
  ZoomInRate, ZoomOutRate     : double;
  ChartRect : TRect;
begin
if ([ssShift,ssCtrl] <= Shift) then begin
  ZoomInRate  := 2;
  ZoomOutRate := 2;
  ChartRect := Rect( 0,0,Chart1.Width,Chart1.Height);
  if WheelDelta>0 then
    ZoomPercentage:=ZoomInRate*WheelDelta
  else
    ZoomPercentage:=ZoomOutRate*WheelDelta;
  with ChartRect do
    InflateRect(ChartRect,Round((Right-Left)*ZoomPercentage/100),Round((Bottom-Top)*ZoomPercentage/100));
  Chart1.ZoomRect(ChartRect);
end;
end;

This won´t work for me. Could you please post an example of your whole Chart1MouseWheel procedure?

Steema Central

How to use ZoomRect with CustomAxis?

How to use ZoomRect with CustomAxis?