At each scale, always display a unit that includes MAX_DATEunit-after-max

Without this, with a MAX_DATE of, say 2000/1/1, zooming out to
scale 1e9 won't show events after 1 AD.

3 files changed, 36 insertions, 13 deletions

diff --git a/src/components/TimeLine.vue b/src/components/TimeLine.vue
index 3172e80..823fe86 100644
--- a/src/components/TimeLine.vue
+++ b/src/components/TimeLine.vue
@@ -26,7 +26,7 @@
 		<line :stroke="store.color.alt" stroke-width="2px" x1="-1" y1="0" x2="2" y2="0" :style="mainlineStyles"/>
 		<!-- Tick markers -->
 		<template v-for="tick in ticks" :key="tick.date.toInt()">
-			<line v-if="tick.major && (tick.date.equals(MIN_DATE, scale) || tick.date.equals(MAX_DATE, scale))"
+			<line v-if="tick.major && (tick.date.equals(MIN_DATE, scale) || tick.date.equals(maxDateOnScale, scale))"
 				:x1="vert ? -store.endTickSz / 2 : 0" :y1="vert ? 0 : -store.endTickSz / 2"
 				:x2="vert ?  store.endTickSz / 2 : 0" :y2="vert ? 0 :  store.endTickSz / 2"
 				:stroke="store.color.alt" :stroke-width="`${store.endTickSz}px`"
@@ -235,6 +235,7 @@ function initScale(){ // Initialises to smallest usable scale
 // Tick data
 const tickLabelMargin = computed(() => props.vert ? 20 : 30); // Distance from label to mainline
 const tickLabelWidth = computed(() => store.mainlineBreadth - store.largeTickLen / 2 - tickLabelMargin.value);
+const maxDateOnScale = computed(() => dateToScaleDate(MAX_DATE, scale.value, true));
 class Tick {
 	date: HistDate;
 	major: boolean; // False if tick is on the minor scale
@@ -314,7 +315,7 @@ const ticks = computed((): Tick[] => {
 	// Get after-endDate ticks (including end-offset ticks and hidden ticks)
 	let endDateOffset = ticks[ticks.length - 1].offset;
 	for (let i = 0; i < panUnits + Math.ceil(endOffset.value); i++){
-		if (MAX_DATE.equals(date, scale.value)){
+		if (maxDateOnScale.value.equals(date, scale.value)){
 			break;
 		}
 		// Add minor ticks
@@ -349,7 +350,7 @@ const ticks = computed((): Tick[] => {
 			offset = ticks[ticks.length - 1].offset;
 			for (let i = 0; i < (zoomUnits - panUnits) / unitsPerZoomedUnit; i++){
 				date = stepDate(date, zoomedScale);
-				if (MAX_DATE.isEarlier(date, scale.value)){
+				if (maxDateOnScale.value.isEarlier(date, scale.value)){
 					break;
 				}
 				ticksAfter.push(new Tick(date, true, offset + (i + 1) * unitsPerZoomedUnit));
@@ -731,7 +732,7 @@ function panTimeline(scrollRatio: number){
 		getMovedBounds(startOffset.value, endOffset.value, chgUnits, chgUnits);
 	if (scrollRatio > 0){
 		while (true){
-			if (newEnd.equals(MAX_DATE, scale.value)){
+			if (newEnd.equals(maxDateOnScale.value, scale.value)){
 				// Pan up to an offset of store.defaultEndTickOffset
 				if (store.defaultEndTickOffset == endOffset.value){
 					console.log('Reached maximum date limit');
@@ -824,7 +825,7 @@ function panTimeline(scrollRatio: number){
 function zoomTimeline(zoomRatio: number, ignorePointer=false){
 	if (zoomRatio > 1
 			&& startDate.value.equals(MIN_DATE, scale.value)
-			&& endDate.value.equals(MAX_DATE, scale.value)){
+			&& endDate.value.equals(maxDateOnScale.value, scale.value)){
 		console.log('Reached upper scale limit');
 		return;
 	}
@@ -875,7 +876,7 @@ function zoomTimeline(zoomRatio: number, ignorePointer=false){
 			newNumUnits += 1;
 		}
 		while (numEndSteps > 0){
-			if (MAX_DATE.equals(newEnd, scale.value)){
+			if (maxDateOnScale.value.equals(newEnd, scale.value)){
 				newEndOffset = store.defaultEndTickOffset;
 				break;
 			}
@@ -975,7 +976,7 @@ function zoomTimeline(zoomRatio: number, ignorePointer=false){
 					console.log('Unable to zoom into range where month/day scale is invalid');
 					return;
 				}
-				if (newStart.isEarlier(MIN_DATE, newScale) || MAX_DATE.isEarlier(newEnd, newScale)){
+				if (newStart.isEarlier(MIN_DATE, newScale) || maxDateOnScale.value.isEarlier(newEnd, newScale)){
 					console.log('Disallowing zooming in beyond min/max dates');
 					return;
 				}
@@ -1146,15 +1147,15 @@ watch(() => props.searchTarget, () => {
 			targetStart = MIN_DATE;
 		}
 		let targetEnd = stepDate(targetStart, tempScale, {count: startEndDiff});
-		if (MAX_DATE.isEarlier(targetEnd)){
+		if (maxDateOnScale.value.isEarlier(targetEnd)){
 			if (targetStart != MIN_DATE){
 				targetStart = stepDate(targetStart, tempScale,
-					{forward: false, count: getUnitDiff(targetEnd, MAX_DATE, tempScale)});
+					{forward: false, count: getUnitDiff(targetEnd, maxDateOnScale.value, tempScale)});
 				if (targetStart.isEarlier(MIN_DATE)){
 					targetStart = MIN_DATE;
 				}
 			}
-			targetEnd = MAX_DATE;
+			targetEnd = maxDateOnScale.value;
 		}
 		// Jump to range
 		startDate.value = targetStart;
diff --git a/src/lib.ts b/src/lib.ts
index 3b0bc68..03b443d 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -582,14 +582,31 @@ export function dateToUnit(date: HistDate, scale: number): number {
 		}
 	}
 }
-export function dateToScaleDate(date: HistDate, scale: number): HistDate {
+export function dateToScaleDate(date: HistDate, scale: number, upward=false): HistDate {
 	// Returns a date representing the unit on 'scale' that 'date' is within
 	if (scale == DAY_SCALE){
 		return new CalDate(date.year, date.month, date.day);
 	} else if (scale == MONTH_SCALE){
-		return new CalDate(date.year, date.month, 1);
+		if (upward && date.day > 1){
+			return stepDate(new CalDate(date.year, date.month, 1), MONTH_SCALE);
+		} else {
+			return new CalDate(date.year, date.month, 1);
+		}
+	} else if (scale == 1){
+		if (upward && date.month > 1){
+			return stepDate(new CalDate(date.year, 1, 1), 1);
+		} else {
+			if (date.year < MIN_CAL_YEAR){
+				return new YearDate(date.year);
+			} else {
+				return new CalDate(date.year == 0 ? 1 : date.year, 1, 1);
+			}
+		}
 	} else {
-		const year = Math.floor(date.year / scale) * scale;
+		let year = Math.floor(date.year / scale) * scale;
+		if (upward && moduloPositive(date.year, scale) > 0){
+			year += scale;
+		}
 		if (year < MIN_CAL_YEAR){
 			return new YearDate(year);
 		} else {
diff --git a/tests/lib.test.ts b/tests/lib.test.ts
index c87627c..6bf3d89 100644
--- a/tests/lib.test.ts
+++ b/tests/lib.test.ts
@@ -156,11 +156,16 @@ test('dateToUnit', () => {
 })
 test('dateToScaleDate', () => {
 	expect(dateToScaleDate(new CalDate(2013, 10, 3), DAY_SCALE)).toEqual(new CalDate(2013, 10, 3))
+	expect(dateToScaleDate(new CalDate(2013, 10, 3), DAY_SCALE, true)).toEqual(new CalDate(2013, 10, 3))
 	expect(dateToScaleDate(new CalDate(2013, 10, 3, false), MONTH_SCALE)).toEqual(new CalDate(2013, 10, 1))
+	expect(dateToScaleDate(new CalDate(2013, 10, 3), MONTH_SCALE, true)).toEqual(new CalDate(2013, 11, 1))
 	expect(dateToScaleDate(new CalDate(2013, 10, 3), 1)).toEqual(new CalDate(2013, 1, 1))
+	expect(dateToScaleDate(new CalDate(2013, 10, 3), 1, true)).toEqual(new CalDate(2014, 1, 1))
 	expect(dateToScaleDate(new CalDate(2013, 10, 3), 1e3)).toEqual(new CalDate(2000, 1, 1))
+	expect(dateToScaleDate(new CalDate(2013, 10, 3), 1e3, true)).toEqual(new CalDate(3000, 1, 1))
 	expect(dateToScaleDate(new CalDate(2013, 10, 3), 1e4)).toEqual(new CalDate(1, 1, 1))
 	expect(dateToScaleDate(new YearDate(-1222333), 1e6)).toEqual(new YearDate(-2000000))
+	expect(dateToScaleDate(new YearDate(-1222333), 1e6, true)).toEqual(new YearDate(-1000000))
 })
 
 test('DateRangeTree', () => {