From 5608b720efc8eaa6d3007b30ca52114e6c6ef02b Mon Sep 17 00:00:00 2001
From: Terry Truong <terry06890@gmail.com>
Date: Fri, 30 Dec 2022 11:20:46 +1100
Subject: Add timeline position label

---
 src/components/TimeLine.vue | 40 +++++++++++++++++++++++++++-
 src/lib.ts                  | 65 ++++++++++++++++++++++++---------------------
 2 files changed, 74 insertions(+), 31 deletions(-)

(limited to 'src')

diff --git a/src/components/TimeLine.vue b/src/components/TimeLine.vue
index 5f39dae..1e78a87 100644
--- a/src/components/TimeLine.vue
+++ b/src/components/TimeLine.vue
@@ -54,6 +54,10 @@
 			{{idToEvent.get(id)!.title}}
 		</div>
 	</div>
+	<!-- Timeline position label -->
+	<div class="absolute top-2 left-2 z-20 text-lg text-stone-50">
+		{{timelinePosStr}}
+	</div>
 	<!-- Buttons -->
 	<icon-button v-if="closeable" :size="30" class="absolute top-2 right-2 z-20"
 		:style="{color: store.color.text, backgroundColor: store.color.altDark2}"
@@ -70,7 +74,7 @@ import IconButton from './IconButton.vue';
 // Icons
 import CloseIcon from './icon/CloseIcon.vue';
 // Other
-import {WRITING_MODE_HORZ, MIN_DATE, MAX_DATE, MONTH_SCALE, DAY_SCALE, SCALES, MIN_CAL_DATE,
+import {WRITING_MODE_HORZ, MIN_DATE, MAX_DATE, MONTH_SCALE, DAY_SCALE, SCALES, MONTH_NAMES, MIN_CAL_DATE,
 	getDaysInMonth, HistDate, stepDate, getScaleRatio, getNumSubUnits, getUnitDiff,
 	getEventPrecision, dateToUnit,
 	moduloPositive, TimelineState, HistEvent, getImagePath} from '../lib';
@@ -387,6 +391,21 @@ const lastIdx = computed((): number => { // Index of last major tick before whic
 	return idx;
 });
 const lastDate = computed(() => lastIdx.value < 0 ? endDate.value : ticks.value[lastIdx.value]!.date);
+const startIsFirstVisible = computed(() => {
+	if (ticks.value.length == 0){
+		return true;
+	} else {
+		return ticks.value.find((tick: Tick) => tick.offset >= 0)!.date.equals(startDate.value);
+	}
+});
+const endIsLastVisible = computed(() => {
+	if (ticks.value.length == 0){
+		return true;
+	} else {
+		let numUnits = getNumDisplayUnits();
+		return ticks.value.findLast((tick: Tick) => tick.offset <= numUnits)!.date.equals(endDate.value);
+	}
+});
 
 // For displayed events
 function dateToOffset(date: HistDate){ // Assumes 'date' is >=firstDate and <=lastDate
@@ -671,6 +690,25 @@ const tickToCount = computed((): Map<number, number> => {
 	return tickToCount;
 });
 
+// For timeline position label
+const timelinePosStr = computed((): string => {
+	const date1 = startIsFirstVisible.value ? startDate.value : firstDate.value;
+	const date2 = endIsLastVisible.value ? endDate.value : lastDate.value;
+	if (minorScale.value == DAY_SCALE){
+		const multiMonth = date1.month != date2.month;
+		return `${date1.toYearString()} ${MONTH_NAMES[date1.month - 1]}${multiMonth ? ' >' : ''}`;
+	} else if (minorScale.value == MONTH_SCALE){
+		const multiYear = date1.year != date2.year;
+		return `${date1.toYearString()}${multiYear ? ' >' : ''}`;
+	} else {
+		if (date1.year > 0){
+			return `${date1.toYearString()} - ${date2.toYearString()}`;
+		} else {
+			return `${date1.toYearString()} >`;
+		}
+	}
+});
+
 // For panning/zooming
 function panTimeline(scrollRatio: number){
 	let numUnits = getNumDisplayUnits();
diff --git a/src/lib.ts b/src/lib.ts
index cd177ff..d9d5867 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -80,6 +80,7 @@ export function getDaysInMonth(year: number, month: number){
 
 // For date representation
 export const MIN_CAL_YEAR = -4713; // Earliest year where months/day scales are usable
+export const MONTH_NAMES = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
 export class HistDate {
 	gcal: boolean | null;
 	year: number;
@@ -161,40 +162,44 @@ export class HistDate {
 			return `${this.year}`;
 		}
 	}
-	toDisplayString(){
-		if (this.month == 1 && this.day == 1){
-			if (this.year > 0){
-				return String(this.year);
-			} else if (this.year > -1e3){
+	toYearString(){
+		if (this.year >= 1000){
+			return String(this.year);
+		} else if (this.year > 0){
+			return String(this.year) + ' AD';
+		} else if (this.year > -1e3){
+			return String(-this.year) + ' BC';
+		} else if (this.year > -1e6){
+			if (this.year % 1e3 == 0){
+				return String(Math.floor(-this.year / 1e3)) + 'k BC';
+			} else if (this.year % 100 == 0){
+				return String(Math.floor(-this.year / 100) / 10) + 'k BC';
+			} else {
 				return String(-this.year) + ' BC';
-			} else if (this.year > -1e6){
-				if (this.year % 1e3 == 0){
-					return String(Math.floor(-this.year / 1e3)) + 'k BC';
-				} else if (this.year % 100 == 0){
-					return String(Math.floor(-this.year / 100) / 10) + 'k BC';
-				} else {
-					return String(-this.year) + ' BC';
-				}
-			} else if (this.year > -1e9){
-				if (this.year % 1e6 == 0){
-					return String(Math.floor(-this.year / 1e6)) + ' mya';
-				} else if (this.year % 1e3 == 0){
-					return String(Math.floor(-this.year / 1e3) / 1e3) + ' mya';
-				} else {
-					return String(-this.year.toLocaleString());
-				}
+			}
+		} else if (this.year > -1e9){
+			if (this.year % 1e6 == 0){
+				return String(Math.floor(-this.year / 1e6)) + ' mya';
+			} else if (this.year % 1e3 == 0){
+				return String(Math.floor(-this.year / 1e3) / 1e3) + ' mya';
 			} else {
-				if (this.year % 1e9 == 0){
-					return String(Math.floor(-this.year / 1e9)) + ' bya';
-				} else if (this.year % 1e6 == 0){
-					return String(Math.floor(-this.year / 1e6) / 1e3) + ' bya';
-				} else {
-					return String(this.year.toLocaleString());
-				}
+				return String(this.year.toLocaleString());
+			}
+		} else {
+			if (this.year % 1e9 == 0){
+				return String(Math.floor(-this.year / 1e9)) + ' bya';
+			} else if (this.year % 1e6 == 0){
+				return String(Math.floor(-this.year / 1e6) / 1e3) + ' bya';
+			} else {
+				return String(this.year.toLocaleString());
 			}
+		}
+	}
+	toDisplayString(){
+		if (this.month == 1 && this.day == 1){
+			return this.toYearString();
 		} else if (this.day == 1){
-			const monthNames = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
-			return monthNames[this.month - 1];
+			return MONTH_NAMES[this.month - 1];
 		} else {
 			if (this.day == 1){
 				return '1st';
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