How to limit the scroll to a range [0,MAX] ?

[Rodrigue]

Hi,

How to limit the scroll to a range [0,MAX] ?

Here is a code :

Code: Select all

 if(Chart1->BottomAxis->Minimum < 0)
      Chart1->BottomAxis->SetMinMax(0, Chart1->BottomAxis->Maximum);

   if(Chart1->BottomAxis->Maximum > 500)
      Chart1->BottomAxis->SetMinMax(Chart1->BottomAxis->Minimum, 500);

it gives a cool effect but not that I've expected ! It limits the range to 0,500 but it stretch the graphic

Thank you in advance for your help !
Cordially,
Rodrigue

[Marjan]

The following code will limit axis minimum to 0 and axis maximum to 500:

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void __fastcall LimitAxisRange(TChartAxis *axis, double amin, double amax)
{
  axis->Minimum = Math::Max(axis->Minimum,amin);
  axis->Maximum = Math::Min(axis->Maximum,amax);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Chart1BeforeDrawAxes(TObject *Sender)
{
  LimitAxisRange(Chart1->BottomAxis,0.0,500);
}

In case you don't want stretched image, you'll have to define the offset and add/subtract it to/from axis minimum/maximum when amin or amax value is reached.

[Rodrigue]

Hi,

Thanks for your reply ! I use C++ Builder 6. I don't know :

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Math::Max
Math::Min

I must include a file ?

Cordially,
Rodrigue

[Marjan]

Hi.

Yes, Math.hpp

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...
#include <Math.hpp>

[Rodrigue]

Sorry,

I've included <math.h> or <Math> but not <Math.hpp>

I test your code but my data are always streched ... maybe it's because I put an offset of 5 pixels on my bottom axe ?

Cordially,
Rodrigue

[Marjan]

Hi.

Not really, axis scales are adjusted exactly as coded (following boolean evaluators I used). If you want different behavior, you'll have to define axis minimum or maximum value as Minimum = Maximum-YourManuallyDefinedOffset OR Maximum = Minimum + YourManuallyDefinedOffset. This way you can ensure chart range will not be "stretched" as it will always show [Minimum, Minimum + offset] or [maximum-offset,maximum] range.