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Currency rate: always display minimum 4 significant decimals or 2 trailing zeros if the number is integer (#256)

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* Currency rate: Compute how many decimals we need to display two meaningful digits at minimum

* formatting

* nit

* Increase the number of meaningfull digits (2->4)

* Revert "Increase the number of meaningfull digits (2->4)"

This reverts commit 9ad93e0d59.

* Rename constants

* modify FORMATTER_RATE_* values

* format CurrencyConverterUnitTests.cpp
This commit is contained in:
Rudy Huyn 2019-08-01 15:07:27 -07:00 • committed by Stephanie Anderl
parent 796d171960
commit cc8491a3d7
3 changed files with 56 additions and 9 deletions
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30
src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
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@ -39,7 +39,9 @@ static constexpr auto CURRENCY_UNIT_TO_KEY = L"CURRENCY_UNIT_TO_KEY";
static constexpr long long DAY_DURATION = 1LL * 60 * 60 * 24 * 10000000;
static constexpr long long WEEK_DURATION = DAY_DURATION * 7;
static constexpr int FORMATTER_DIGIT_COUNT = 4;
static constexpr int FORMATTER_RATE_FRACTION_PADDING = 2;
static constexpr int FORMATTER_RATE_MIN_DECIMALS = 4;
static constexpr int FORMATTER_RATE_MIN_SIGNIFICANT_DECIMALS = 4;
static constexpr auto CACHE_TIMESTAMP_KEY = L"CURRENCY_CONVERTER_TIMESTAMP";
static constexpr auto CACHE_LANGCODE_KEY = L"CURRENCY_CONVERTER_LANGCODE";
@ -128,7 +130,7 @@ CurrencyDataLoader::CurrencyDataLoader(_In_ unique_ptr<ICurrencyHttpClient> clie
m_ratioFormatter = localizationService->GetRegionalSettingsAwareDecimalFormatter();
m_ratioFormatter->IsGrouped = true;
m_ratioFormatter->IsDecimalPointAlwaysDisplayed = true;
m_ratioFormatter->FractionDigits = FORMATTER_DIGIT_COUNT;
m_ratioFormatter->FractionDigits = FORMATTER_RATE_FRACTION_PADDING;
m_ratioFormat = AppResourceProvider::GetInstance().GetResourceString(L"CurrencyFromToRatioFormat")->Data();
m_timestampFormat = AppResourceProvider::GetInstance().GetResourceString(L"CurrencyTimestampFormat")->Data();
@ -267,6 +269,23 @@ pair<wstring, wstring> CurrencyDataLoader::GetCurrencySymbols(const UCM::Unit& u
return make_pair(symbol1, symbol2);
}
double CurrencyDataLoader::RoundCurrencyRatio(double ratio)
{
// Compute how many decimals we need to display two meaningful digits at minimum
// For example: 0.00000000342334 -> 0.000000003423, 0.000212 -> 0.000212
int numberDecimals = FORMATTER_RATE_MIN_DECIMALS;
if (ratio < 1)
{
numberDecimals = max(
FORMATTER_RATE_MIN_DECIMALS,
(int)(-log10(ratio)) + FORMATTER_RATE_MIN_SIGNIFICANT_DECIMALS);
}
unsigned long long scale = (unsigned long long)powl(10l, numberDecimals);
return (double)(round(ratio * scale) / scale);
}
pair<wstring, wstring> CurrencyDataLoader::GetCurrencyRatioEquality(_In_ const UCM::Unit& unit1, _In_ const UCM::Unit& unit2)
{
try
@ -279,12 +298,7 @@ pair<wstring, wstring> CurrencyDataLoader::GetCurrencyRatioEquality(_In_ const U
if (iter2 != ratioMap.end())
{
double ratio = (iter2->second).ratio;
// Round the ratio to FORMATTER_DIGIT_COUNT digits using int math.
// Ex: to round 1.23456 to three digits, use
// ((int) 1.23456 * (10^3)) / (10^3)
double scale = pow(10, FORMATTER_DIGIT_COUNT);
double rounded = static_cast<int>(ratio * static_cast<int>(scale)) / scale;
double rounded = RoundCurrencyRatio(ratio);
wstring digitSymbol = wstring{ LocalizationSettings::GetInstance().GetDigitSymbolFromEnUsDigit(L'1') };
wstring roundedFormat = m_ratioFormatter->Format(rounded)->Data();