diff options
Diffstat (limited to 'src/lib.ts')
| -rw-r--r-- | src/lib.ts | 30 |
1 files changed, 29 insertions, 1 deletions
@@ -628,7 +628,7 @@ export function getUnitDiff(date: HistDate, date2: HistDate, scale: number): num } } -// Returns smallest scale at which 'event's start-startUpper range is within one unit, or infinity +// Returns smallest scale at which 'event's start-startUpper range is within one unit, or infinity if there is none export function getEventPrecision(event: HistEvent): number { // Note: Intentionally not adding an exception for century and millenia ranges like // 101 to 200 (as opposed to 100 to 199) being interpreted as 'within' one 100/1000-year scale unit @@ -649,6 +649,34 @@ export function getEventPrecision(event: HistEvent): number { return Number.POSITIVE_INFINITY; } +// Returns an 'appropriate' scale to use when jumping to a target date +export function getScaleForJump(event: HistEvent): number { + const start = event.start; + const startUpper = event.startUpper; + if (start.gcal != null){ + if (start.day > 1){ + return MONTH_SCALE; // Intentionally not using DAY_SCALE + } else if (start.month > 1 + || startUpper != null // Account for month-precision events + && gregorianToJdn(start.year, start.month+1, 0) + == gregorianToJdn(startUpper.year, startUpper.month, startUpper.day)){ + return MONTH_SCALE; + } + } + for (let scaleIdx = 0; scaleIdx < SCALES.length - 2; scaleIdx++){ + const scale = SCALES[scaleIdx]; + if ((scale == 100 || scale == 1e3) // Account for century/millenium-precision events + && moduloPositive(start.year - 1, scale) == 0 && startUpper != null + && startUpper.year == start.year + scale - 1 || start.year + scale - 1 == 0){ // Account for no 0 BC + return scale; + } + if (moduloPositive(start.year, scale) == 0){ + return scale; + } + } + throw new Error('Invalid state'); +} + export function dateToUnit(date: HistDate, scale: number): number { // For a YearDate and sub-yearly scale, uses the first day of the YearDate's year if (scale >= 1){ |