Question: distance units customization

[JoanaSmit]

We have an option to select a unit system (IModelApp.quantityFormatter.setActiveUnitSystem). Is it possible to customize the distance units further?
I mean selecting km / m / cm for metric, inches / feet / yards or square feet / square yards / acres for imperial unit system

[hl662]

Hi, can I ask how you are currently using the quantity formatter? Is this for a frontend viewer that utilizes different published measure tools, or are you utilizing custom formatProps and constructing formattingSpec and parsingSpec objects for use outside of those tools?

[JoanaSmit]

• We call MeasureTools.startup() with no StartupOptions
• IModelApp.quantityFormatter.setActiveUnitSystem to switch between metric and imperial unit system
• IModelApp.quantityFormatter.formatQuantity to format display values, we pass formatSpec that we get from MeasurementSelectionSet.global.measurements

[hl662]

I see that the formatSpecs from MeasurementSelectionSet.global.measurements come from IModelApp.quantityFormatter.getFormatterSpecByQuantityType. If that's the case, you could customize within your app to utilize setOverrideFormat. This code example at the bottom of the page is one example - A user retrieves the formatProps for a QuantityType, adds a property to the props, and overrides the format inside of iModelApp's quantityFormatter. The formatter will emit a onChange event, which should tell MeasurementSelectionSet to also update things.

Problem with the above is you would need to know the QuantityType to override, which I don't think MeasurementSelectionSet.global.measurements provides. In that case, you can use the formatSpec retrieved, and create a new formatSpec, with a new format object. For example:

  const oldFormatProps = oldFormatterSpec.format.toJSON();
  const newFormatProps: FormatProps = {
    ...oldFormatProps,
    composite: {
      ...oldFormatProps.composite,
      units: [{ name: "Units.KM", label: "km" }], // perhaps the previous format used just "m" as the unit
    },
  }
  const newFormat = await Format.createFromJSON("newFormat", IModelApp.quantityFormatter.unitsProvider, newFormatProps);
  const newFormatterSpec = FormatterSpec.create("NewSpec", newFormat, quantityFormatter.unitsProvider, newFormatterSpec!.persistenceUnit);

const newQuantity = IModelApp.quantityFormatter.formatQuantity(value, newFormatterSpec);

We also have a React component that lets you configure how quantities are formattted easily, propagating these updates across the measurement tools (Also code example of introducing the component)