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Update GeoMap component to include adaptive zoom for small polygons #12

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Update GeoMap component to include adaptive zoom for small polygons #12

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2 changes: 1 addition & 1 deletion components/entity-geo-map.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ const features = computed(() => {
<template>
<Card class="h-96 overflow-hidden">
<VisualisationContainer v-slot="{ height, width }">
<GeoMap v-if="height && width" :features="features" :height="height" :width="width" />
<GeoMap v-if="height && width" :features="features" :height="height" :width="width" adaptive-zoom />
</VisualisationContainer>
</Card>
</template>
106 changes: 94 additions & 12 deletions components/geo-map.client.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import "maplibre-gl/dist/maplibre-gl.css";

import { assert } from "@acdh-oeaw/lib";
import * as turf from "@turf/turf";
import type { FeatureCollection } from "geojson";
import {
FullscreenControl,
type GeoJSONSource,
Expand All @@ -11,17 +12,31 @@ import {
NavigationControl,
ScaleControl,
} from "maplibre-gl";
import { watch } from "vue";

import { type GeoMapContext, geoMapContextKey } from "@/components/geo-map.context";
import { initialViewState } from "@/config/geo-map.config";
import { project } from "@/config/project.config";
import type { GeoJsonFeature } from "@/utils/create-geojson-feature";

const props = defineProps<{
features: Array<GeoJsonFeature>;
height: number;
width: number;
}>();
const props = defineProps({
features: {
type: Array<GeoJsonFeature>,
required: true,
},
height: {
type: Number,
required: true,
},
width: {
type: Number,
required: true,
},
adaptiveZoom: {
type: Boolean,
default: false,
},
});

const emit = defineEmits<{
(
Expand Down Expand Up @@ -59,7 +74,7 @@ async function create() {
const map = new GeoMap({
center: [initialViewState.longitude, initialViewState.latitude],
container: elementRef.value,
maxZoom: 16,
maxZoom: defaultMaxZoom,
minZoom: 1,
pitch: initialViewState.pitch,
style: mapStyle.value,
Expand All @@ -71,6 +86,7 @@ async function create() {
map.on("load", init);
}

const sourceId = "data";
function init() {
assert(context.map != null);
const map = context.map;
Expand All @@ -92,7 +108,6 @@ function init() {

//

const sourceId = "data";
map.addSource(sourceId, { type: "geojson", data: createFeatureCollection([]) });

//
Expand Down Expand Up @@ -165,24 +180,91 @@ function init() {
function dispose() {
context.map?.remove();
}
const zoomLimit = 20;
const maxArea = 1000;
const minArea = 1;
const defaultMaxZoom = 16;

let geojson: FeatureCollection | null = null;
let area = 0;
let point: FeatureCollection | null = null;
let zoomBreakPoint = defaultMaxZoom;
const showPoint = ref(false);



watch(showPoint, () => {
const source = context.map?.getSource(sourceId) as GeoJSONSource | undefined;
if (!source || !point || !geojson) return;

showPoint.value ? source.setData(point) : source.setData(geojson);
})

/**
* Gets the breakpoint for the zoom level based on the area.
* The smaller the area, the higher the zoom level.
*/
function getBreakpoint(): number {
if (!props.adaptiveZoom || !props.features.length || !geojson || !area) return defaultMaxZoom - 2;

if (area < minArea) return zoomLimit - 2;
if (area > maxArea) return zoomBreakPoint = defaultMaxZoom - 2;

return Math.round((area - minArea) / (maxArea - minArea) * (zoomLimit - defaultMaxZoom) + defaultMaxZoom) - 2;
}

function getMaxZoom() {
if (!props.adaptiveZoom || !props.features.length || !geojson || !area) return defaultMaxZoom;

if (area < minArea) return zoomLimit;
if (area > maxArea) return defaultMaxZoom;

return Math.round((area - minArea) / (maxArea - minArea) * (zoomLimit - defaultMaxZoom) + defaultMaxZoom);
}

watch(() => {
return props.features;
}, update);

function resetData(map: GeoMap, source?: GeoJSONSource) {
map.setMaxZoom(defaultMaxZoom);
source?.setData(createFeatureCollection([]));
point = null;
area = 0;
}

function update() {
assert(context.map != null);
const map = context.map;

const sourceId = "data";
const source = map.getSource(sourceId) as GeoJSONSource | undefined;
const geojson = createFeatureCollection(props.features);
geojson = createFeatureCollection(props.features);

if (!geojson.features.length) {
resetData(map, source);
return;
}

point = turf.centroid(geojson);

const bounds = turf.bbox(geojson);
area = turf.area(geojson);
map.setMaxZoom(getMaxZoom()); // Needs to be called after setting the area in order to work
zoomBreakPoint = getBreakpoint();

source?.setData(geojson);

if (geojson.features.length > 0) {
const bounds = turf.bbox(geojson);
map.fitBounds(bounds, { padding: 50 });
if (props.adaptiveZoom) {
map.on("zoom", () => {
if (map.getZoom() < zoomBreakPoint) {
showPoint.value = true;
} else {
showPoint.value = false;
}
});
}

map.fitBounds(bounds, { padding: 50 });
}

defineExpose(context);
Expand Down
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