Parameter Display: rounded / truncated for precision

Developer VSTGUI
1

I want to add a Parameter Display view and let it show the control tag value but truncated or rounded to a specific number of decimal points. I was thinking value-precision would set just that but it doesn’t seem to have any effect. What’s the proper way to do that?

2

The value-precision is overwritten when you use the VST3Editor class. In that case you need to make sure that the Parameter in your VST3 plug-in does this truncation for its string representation.

3

Which class should I use instead of the VST3Editor class for this to work?

4

You need to change your parameter class, not the UI. Make sure that the string display of your parameter the generic editor is as you want.

1 Like
5

@clwe found it:

parameter->setPrecision(0);
	parameter->toString (valueNormalized, string);
6

yes, for those having the same question – you need to override the getParamStringByValue() method in your VST3Editor-derived controller class, e.g. like so:

tresult PLUGIN_API getParamStringByValue (ParamID tag, ParamValue valueNormalized, String128 string) SMTG_OVERRIDE {
    if (Parameter* parameter = getParameterObject (tag))
	{
        parameter->setPrecision(0); //  <-- set precision here
		parameter->toString (valueNormalized, string);
		return kResultTrue;
	}
	return kResultFalse;
  }

Thanks!

7

Actually you do this at the time when you create the Parameter, not when you change the value of it. That’s at least more efficient.

1 Like
8

The precision is commonly set in
Controller::initialize(FUnknown* context)
{
//…
Parameter* param = new RangeParameter(USTRING(Attack), kAttack, USTRING( %), 0, 1, 0);
param->setPrecision(4); // fractional sig digits|
parameters.addParameter(param);|
// …
}
However there is another precision setting in ui-description i.e.:
value-precision=“2”
which makes nary any discernible change in the displayed digits.

9

Yes, this threw us off too, a bit confusing that is.

10

Yes. I would like my internal calculations to be high precision and the displayed values adjustable in the ui-description file.

1 Like