Add formatting of PV values

app/components/InstrumentPage.test.ts

@@ -49,7 +49,7 @@ test("toPrecision truncates block if it has precision", () => {
     precision: precision,
   };
   expect(toPrecision(aBlock, originalValue)).toBe(
-    originalValue.toPrecision(precision),
+    originalValue.toFixed(precision),
   );
 });
 

app/components/InstrumentPage.tsx

@@ -15,7 +15,10 @@ import {
   IfcPVWSMessage,
   IfcPVWSRequest,
 } from "@/app/types";
-import { findPVByAddress } from "@/app/components/PVutils";
+import {
+  findPVByAddress,
+  ExponentialOnThresholdFormat,
+} from "@/app/components/PVutils";
 import CheckToggle from "@/app/components/CheckToggle";
 
 let lastUpdate: string = "";
@@ -91,8 +94,8 @@ export function toPrecision(
   block: IfcBlock,
   pvVal: number | string,
 ): string | number {
-  return block.precision && typeof pvVal == "number"
-    ? pvVal.toPrecision(block.precision)
+  return block.precision
+    ? ExponentialOnThresholdFormat(pvVal, block.precision)
     : pvVal;
 }
 

app/components/PVutils.test.ts

@@ -2,6 +2,7 @@ import { IfcPV } from "@/app/types";
 import {
   findPVByAddress,
   findPVByHumanReadableName,
+  ExponentialOnThresholdFormat,
 } from "@/app/components/PVutils";
 
 test("findPVByAddress finds a PV and returns it", () => {
@@ -46,3 +47,123 @@ test("findPVByHumanReadableName does not find a nonexistant PV and returns undef
 
   expect(result).toBe(undefined);
 });
+
+// Test of ExponentialOnThresholdFormat ported from ibex_gui Java code
+test("GIVEN value 0.1 which is above lower threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0.1)).toBe("0.100");
+});
+
+test("GIVEN negative value 0.1 which is above lower threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-0.1)).toBe("-0.100");
+});
+
+test("GIVEN value 0.01 which is above lower threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0.01)).toBe("0.010");
+});
+
+test("GIVEN value equal to lower threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0.001)).toBe("0.001");
+});
+
+test("GIVEN negative value equal to lower threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-0.001)).toBe("-0.001");
+});
+
+test("GIVEN value above lower threshold with extra fractioanl digits WHEN formatting with precision 3 THEN no exponential notation used and some digits are lost", () => {
+  expect(ExponentialOnThresholdFormat(0.01234)).toBe("0.012");
+});
+
+test("GIVEN value above lower threshold with integer part WHEN formatting with precision 5 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(1234.56, 5)).toBe("1234.56000");
+});
+
+test("GIVEN value above lower threshold with integer part and extra fractional digits WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(12.5678)).toBe("12.568");
+});
+
+test("GIVEN value below lower threshold WHEN formatting with precision 3 THEN exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0.0009)).toBe("9.000E-4");
+});
+
+test("GIVEN very small value WHEN formatting with precision 5 THEN exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0.000000001234567, 5)).toBe("1.23457E-9");
+});
+
+test("GIVEN very small negative value WHEN formatting with precision 5 THEN exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-0.000000001234567, 5)).toBe(
+    "-1.23457E-9",
+  );
+});
+
+test("GIVEN value just below higher threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(999999.1234)).toBe("999999.123");
+});
+
+test("GIVEN negative value just below higher threshold WHEN formatting with precision 3 THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-999999.1234)).toBe("-999999.123");
+});
+
+// TypeScript does not have separate integer/float types - for integers never use exponential so change test a bit
+test("GIVEN value equal to higher threshold WHEN formatting with precision 3 THEN exponential notation used", () => {
+  //expect(ExponentialOnThresholdFormat(1000000)).toBe("1.000E6");
+  expect(ExponentialOnThresholdFormat(1000000.1)).toBe("1.000E6");
+});
+
+test("GIVEN negative value equal to higher threshold WHEN formatting with precision 3 THEN exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-1000000.1)).toBe("-1.000E6");
+});
+
+test("GIVEN value above higher threshold WHEN formatting with precision 5 THEN exponential notation used", () => {
+  //expect(ExponentialOnThresholdFormat(123456789, 5)).toBe("1.23457E8");
+  expect(ExponentialOnThresholdFormat(123456789.1, 5)).toBe("1.23457E8");
+});
+
+test("GIVEN negative value above higher threshold WHEN formatting with precision 5 THEN exponential notation used", () => {
+  //expect(ExponentialOnThresholdFormat(-123456789, 5)).toBe("-1.23457E8");
+  expect(ExponentialOnThresholdFormat(-123456789.1, 5)).toBe("-1.23457E8");
+});
+
+// TypeScript does not have separate integer/float types - so ignore next two tests.
+//it("GIVEN value 0 WHEN formatting THEN no exponential notation used", () => {
+//  expect(ExponentialOnThresholdFormat(0)).toBe("0.000");
+//});
+//
+//it("GIVEN negative value 0 WHEN formatting THEN no exponential notation used", () => {
+//  expect(ExponentialOnThresholdFormat(-0)).toBe("0.000");
+//});
+
+test("GIVEN integer below higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(13)).toBe("13");
+});
+
+test("GIVEN negative integer below higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-13)).toBe("-13");
+});
+
+test("GIVEN integer just below higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(999999)).toBe("999999");
+});
+
+test("GIVEN integer equal to higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(1000000)).toBe("1000000");
+});
+
+test("GIVEN negative integer equal to higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-1000000)).toBe("-1000000");
+});
+
+test("GIVEN integer above higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(123456789)).toBe("123456789");
+});
+
+test("GIVEN negative integer above higher threshold WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-123456789)).toBe("-123456789");
+});
+
+test("GIVEN integer equal to 0 WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(0)).toBe("0");
+});
+
+test("GIVEN negative integer equal to 0 WHEN formatting THEN no exponential notation used", () => {
+  expect(ExponentialOnThresholdFormat(-0)).toBe("0");
+});

app/components/PVutils.ts

@@ -19,3 +19,30 @@ export function findPVByAddress(
 ): IfcPV | undefined {
   return arr.find((b: IfcPV) => b.pvaddress == address);
 }
+
+/**
+ * Formats a given PV value input such that above or below a threshold value,
+ * it uses scientific (exponential) notation, matching behaviour of ibex_gui
+ */
+export function ExponentialOnThresholdFormat(
+  value: string | number,
+  precision: number = 3,
+) {
+  var nValue: number = value == undefined ? NaN : +value;
+  if (isNaN(nValue)) {
+    return value;
+  } else {
+    if (nValue == 0) {
+      return "0";
+    } else if (Number.isInteger(nValue)) {
+      return nValue.toString();
+    } else if (Math.abs(nValue) < 0.001 || Math.abs(nValue) >= 1000000) {
+      return nValue
+        .toExponential(precision)
+        .replace("e+", "E")
+        .replace("e", "E");
+    } else {
+      return nValue.toFixed(precision);
+    }
+  }
+}