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Refine fraction formatting behavior

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This commit is contained in:
Sam Becker 2024-04-12 12:20:24 -05:00
parent 4e3d1dec08
commit ae3770ae30
2 changed files with 46 additions and 10 deletions
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12
__tests__/exif.test.ts
View File

@ -12,23 +12,35 @@ describe('EXIF', () => {
expect(formatExposureTime(1.5)).toBe('1.5s');
});
it('exposure compensation', () => {
expect(formatExposureCompensation(1)).toBe('+1ev');
expect(formatExposureCompensation(-1)).toBe('-1ev');
expect(formatExposureCompensation(0)).toBe(undefined);
expect(formatExposureCompensation(0.25)).toBe('+1/4ev');
expect(formatExposureCompensation(0.33)).toBe('+1/3ev');
expect(formatExposureCompensation(0.333)).toBe('+1/3ev');
expect(formatExposureCompensation(-0.25)).toBe('-1/4ev');
expect(formatExposureCompensation(-0.33)).toBe('-1/3ev');
expect(formatExposureCompensation(-0.333)).toBe('-1/3ev');
expect(formatExposureCompensation(0.5)).toBe('+1/2ev');
expect(formatExposureCompensation(0.4998458896569944)).toBe('+1/2ev');
expect(formatExposureCompensation(0.66)).toBe('+2/3ev');
expect(formatExposureCompensation(0.67)).toBe('+2/3ev');
expect(formatExposureCompensation(0.015625)).toBe('+1/64ev');
expect(formatExposureCompensation(-0.015625)).toBe('-1/64ev');
expect(formatExposureCompensation(1)).toBe('+1ev');
expect(formatExposureCompensation(1.1)).toBe('+1 1/10ev');
expect(formatExposureCompensation(-1.1)).toBe('-1 1/10ev');
expect(formatExposureCompensation(1.7)).toBe('+1 7/10ev');
expect(formatExposureCompensation(-1.7)).toBe('-1 7/10ev');
expect(formatExposureCompensation(-1.33)).toBe('-1 1/3ev');
expect(formatExposureCompensation(1.33)).toBe('+1 1/3ev');
expect(formatExposureCompensation(1.333)).toBe('+1 1/3ev');
expect(formatExposureCompensation(1.3333)).toBe('+1 1/3ev');
expect(formatExposureCompensation(1.5)).toBe('+1 1/2ev');
expect(formatExposureCompensation(2.5)).toBe('+2 1/2ev');
expect(formatExposureCompensation(-2.5)).toBe('-2 1/2ev');
expect(formatExposureCompensation(1.9960938)).toBe('+2ev');
expect(formatExposureCompensation(-1.9960938)).toBe('-2ev');
// Ignore long fractions
expect(formatExposureCompensation(-0.119)).toBe('-0.12ev');
expect(formatExposureCompensation(-0.112340989)).toBe('-0.11ev');

44
src/utility/number.ts
View File

@ -14,10 +14,13 @@ const gcd = (a: number, b: number): number => {
}
};
const formatDecimalToFraction = (decimal: number) => {
if (Math.abs(decimal - 0.33) < 0.011) {
const formatDecimalToFraction = (_decimal: number) => {
// Prevent imprecision which causes numbers such as,
// 0.1 to equal 0.10000000000000009
const decimal = parseFloat(_decimal.toPrecision(8));
if (Math.abs(Math.abs(decimal) - 0.33) < 0.011) {
return '1/3';
} else if (Math.abs(decimal - 0.66) <= 0.011) {
} else if (Math.abs(Math.abs(decimal) - 0.66) <= 0.011) {
return '2/3';
} else {
const length = decimal.toString().length - 2;
@ -34,22 +37,43 @@ const formatDecimalToFraction = (decimal: number) => {
}
};
const STICKY_THRESHOLD = 0.011;
const STICKY_DECIMALS = [0.25, 0.33, 0.5, 0.66, 0.75];
const MAX_FRACTION_LENGTH = 4; // 1/64 not 1/100
export const formatNumberToFraction = (number: number) => {
const decimal = (1 - number % 1) > 0.01
const sign = number >= 0 ? '+' : '-';
let decimal = (1 - Math.abs(number % 1)) > STICKY_THRESHOLD
? number % 1
: 0;
const integer = Math.round(Math.abs(number - decimal));
if (decimal !== 0) {
for (const stickyDecimal of STICKY_DECIMALS) {
if (Math.abs(Math.abs(decimal) - stickyDecimal) < STICKY_THRESHOLD) {
decimal = decimal < 0 ? -stickyDecimal : stickyDecimal;
break;
}
}
}
let integer = Math.round(Math.abs(number - decimal));
if (Math.abs(decimal) === 1) {
decimal = 0;
integer += 1;
}
const fraction = decimal !== 0
? formatDecimalToFraction(Math.abs(decimal))
: '';
const sign = number >= 0 ? '+' : '-';
// Ensure fractions are not too long
if (!fraction || fraction.length <= 4) {
const whole = integer > 0
// Ensure fractions aren't too long
if (!fraction || fraction.length <= MAX_FRACTION_LENGTH) {
const integerString = integer > 0
? fraction ? `${integer} ` : integer
: fraction ? '' : '0';
return `${sign}${whole}${fraction}`;
return `${sign}${integerString}${fraction}`;
} else {
// console.log({ fraction });
const decimalFormatted = decimal.toPrecision(2).replace(/^-*0+/, '');
return `${sign}${integer}${decimalFormatted}`;
}