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RikdeBoer/4b-Leaflet-marker-rotated-with-indicator.html

Created December 21, 2019 06:29
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Leaflet marker rotated, with indicator
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4b-Leaflet-marker-rotated-with-indicator.html
<!DOCTYPE html>
<html lang="en">
<head>
<title>Leaflet - Rotated marker with inidicator</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link href="https://unpkg.com/[email protected]/dist/leaflet.css" rel="stylesheet" integrity="sha512-xwE/Az9zrjBIphAcBb3F6JVqxf46+CDLwfLMHloNu6KEQCAWi6HcDUbeOfBIptF7tcCzusKFjFw2yuvEpDL9wQ==" crossorigin=""/>
<script src="https://unpkg.com/[email protected]/dist/leaflet.js" integrity="sha512-gZwIG9x3wUXg2hdXF6+rVkLF/0Vi9U8D2Ntg4Ga5I5BZpVkVxlJWbSQtXPSiUTtC0TjtGOmxa1AJPuV0CPthew==" crossorigin=""></script>
<style>
.mymarker svg path { fill: dodgerblue; }
.mymarker {
transition: transform 0.5s linear;
}
.indicator {
background-color: white;
border: 1px solid dodgerblue;
border-radius: 6px;
color: dodgerblue;
font-size: 14px;
font-weight: 600;
padding: 2px 4px;
position: relative;
bottom: 35px;
left: 20px;
white-space: nowrap;
transition: transform 0.5s linear;
}
.leaflet-popup {
margin-bottom: 47px;
}
</style>
</head>
<body>
<div id="map-placeholder" style="height:400px"></div>
<script>
(function() {
// Save original method before overwriting it below.
const _setPosOriginal = L.Marker.prototype._setPos
L.Marker.addInitHook(function() {
const anchor = this.options.icon.options.iconAnchor
this.options.rotationOrigin = anchor ? `${anchor[0]}px ${anchor[1]}px` : 'center center'
// Ensure marker remains rotated during dragging.
this.on('drag', data => { this._rotate() })
})
L.Marker.include({
// _setPos is alled when update() is called, e.g. on setLatLng()
_setPos: function(pos) {
_setPosOriginal.call(this, pos)
if (this.options.rotation) this._rotate()
},
_rotate: function() {
this._icon.style[`${L.DomUtil.TRANSFORM}Origin`] = this.options.rotationOrigin
this._icon.style[L.DomUtil.TRANSFORM] += ` rotate(${this.options.rotation}deg)`
}
})
})()
Math.radians = (degrees) => degrees * Math.PI / 180
function calcHeading(point1, point2) {
const pnt1lat = Math.radians(point1.lat)
const pnt2lat = Math.radians(point2.lat)
const lngDiff = Math.radians(point2.lng - point1.lng)
const y = Math.sin(lngDiff) * Math.cos(pnt2lat)
const x = Math.cos(pnt1lat) * Math.sin(pnt2lat) - Math.sin(pnt1lat) * Math.cos(pnt2lat) * Math.cos(lngDiff)
let heading = Math.atan2(y, x) * 180.0 / Math.PI
// Convert to compass heading, 0..360, rather than -180..+180
if (heading < 0) heading += 360
return heading;
}
function markerOptions(size, heading) {
const iconOptions = {
iconSize : [size, size],
iconAnchor: [size/2, size/2],
className : 'mymarker',
html : '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><path d="M 16 3 C 8.832031 3 3 8.832031 3 16 C 3 23.167969 8.832031 29 16 29 C 23.167969 29 29 23.167969 29 16 C 29 8.832031 23.167969 3 16 3 Z M 16 5 C 22.085938 5 27 9.914063 27 16 C 27 22.085938 22.085938 27 16 27 C 9.914063 27 5 22.085938 5 16 C 5 9.914063 9.914063 5 16 5 Z M 16 8.875 L 9.59375 15.28125 L 11 16.71875 L 15 12.71875 L 15 23 L 17 23 L 17 12.71875 L 21 16.71875 L 22.40625 15.28125 Z"/></svg>'
}
return {
draggable: true,
icon: L.divIcon(iconOptions),
rotation: heading
}
}
const center = [-37.8179, 144.936]
const heading = 253;
const myMap = L.map('map-placeholder').setView(center, 16)
const myMarker = L.marker(center, markerOptions(50, heading)).addTo(myMap)
myMarker
.bindPopup('Click on the map<br/>to point me there.<br/><br/>You can drag me too.')
.openPopup()
myMap.addLayer(L.tileLayer(
'https://maps.wikimedia.org/osm-intl/{z}/{x}/{y}@2x.png',
{ attribution: '© <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contr.' }
))
function updateIndicatorPos(marker, heading) {
const pos = marker._icon._leaflet_pos
const indicator = marker._icon.nextElementSibling
if (heading) indicator.innerHTML = `🧭 ${heading}°`
indicator.style.transform = `translate3d(${pos.x}px, ${pos.y}px, 0)`
}
myMap.whenReady( _ => {
L.DomUtil.create('div', 'indicator', myMarker._icon.parentNode)
updateIndicatorPos(myMarker, heading)
})
myMarker.on('move', data => { updateIndicatorPos(myMarker) })
myMap.on('zoom', data => { updateIndicatorPos(myMarker) })
myMap.on('click', data => {
myMarker.options.rotation = Math.round(calcHeading(myMarker.getLatLng(), data.latlng))
myMarker.update()
updateIndicatorPos(myMarker, myMarker.options.rotation)
})
</script>
</body>
</html>
@RikdeBoer
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RikdeBoer commented Mar 24, 2022 via email

@hehazelhorst
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hehazelhorst commented Mar 25, 2022 via email

@hehazelhorst
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hehazelhorst commented May 19, 2022 via email

@RikdeBoer
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RikdeBoer commented May 22, 2022 via email

@nathanh2011
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Hi Rik,

The code you have for rotation and SVG markers is great and really helped me.

I did however find problems with the indicator when there is more than 1 marker. It seems the first marker will have the indicator set correctly but then the others seem to be out of position. What is odd is that the results of the transform on the indicators match the markers but they are not in the right position.

Attached are some screenshots to illustrate.

image
image

@RikdeBoer
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Hi Nathan,
Glad to hear my code got you started at least. Thanks for sharing!
I'm not much involved with this project any more, so I can't tell you off the top of my head what might be going wrong when there's multiple markers.
I'm sure you'll work it out. You're so close!

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