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Resizable Split Map Panes

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Page Summary

This example demonstrates how to compare two Google Maps layers side-by-side using resizable panes.
It utilizes the Split.js library to create and manage the resizable panes for a seamless user experience.
The code synchronizes the two map instances, ensuring that they maintain the same center and zoom level as the user interacts with either pane.
Both TypeScript and JavaScript code snippets are provided, along with HTML and CSS for styling and structure.
Users can clone and run the sample locally using Git and Node.js or try it directly in Google Cloud Shell.

Comparing layers

This example allows comparison of two layers with resizable map panes using the Split.js library.

[フレーム]

TypeScript

functioninitMap():void{
constmapOptions={
center:{lat:44.5250489,lng:-110.83819},
zoom:18,
scaleControl:false,
streetViewControl:false,
};
// instantiate the map on the left with control positioning
mapLeft=newgoogle.maps.Map(
document.getElementById("map-left")asHTMLElement,
{
...mapOptions,
mapTypeId:"satellite",
tilt:0,// at high zoom levels we need to maintain the same projection
fullscreenControlOptions:{
position:google.maps.ControlPosition.LEFT_BOTTOM,
},
mapTypeControlOptions:{
position:google.maps.ControlPosition.LEFT_TOP,
},
zoomControlOptions:{
position:google.maps.ControlPosition.LEFT_BOTTOM,
},
}
);
// instantiate the map on the right with control positioning
mapRight=newgoogle.maps.Map(
document.getElementById("map-right")asHTMLElement,
{
...mapOptions,
fullscreenControlOptions:{
position:google.maps.ControlPosition.RIGHT_BOTTOM,
},
mapTypeControlOptions:{
position:google.maps.ControlPosition.RIGHT_TOP,
},
zoomControlOptions:{
position:google.maps.ControlPosition.RIGHT_BOTTOM,
},
}
);
// helper function to keep maps in sync
functionsync(...maps:google.maps.Map[]){
letcenter:google.maps.LatLng,zoom:number;
functionupdate(changedMap){
maps.forEach((m)=>{
if(m===changedMap){
return;
}
m.setCenter(center);
m.setZoom(zoom);
});
}
maps.forEach((m)=>{
m.addListener("bounds_changed",()=>{
constchangedCenter=m.getCenter()!;
constchangedZoom=m.getZoom()!;
if(changedCenter!==center||changedZoom!==zoom){
center=changedCenter;
zoom=changedZoom;
update(m);
}
});
});
}
sync(mapLeft,mapRight);
functionhandleContainerResize(){
constwidth=(document.getElementById("container")asHTMLElement)
.offsetWidth;
(
document.getElementById("map-left")asHTMLElement
).style.width=`${width}px`;
(
document.getElementById("map-right")asHTMLElement
).style.width=`${width}px`;
}
// trigger to set map container size since using absolute
handleContainerResize();
// add event listener
window.addEventListener("resize",handleContainerResize);
//@ts-ignore
Split(["#left","#right"],{
sizes:[50,50],
});
}
declareglobal{
interfaceWindow{
initMap:()=>void;
}
}
window.initMap=initMap;index.ts

JavaScript

functioninitMap(){
constmapOptions={
center:{lat:44.5250489,lng:-110.83819},
zoom:18,
scaleControl:false,
streetViewControl:false,
};
// instantiate the map on the left with control positioning
mapLeft=newgoogle.maps.Map(document.getElementById("map-left"),{
...mapOptions,
mapTypeId:"satellite",
tilt:0,// at high zoom levels we need to maintain the same projection
fullscreenControlOptions:{
position:google.maps.ControlPosition.LEFT_BOTTOM,
},
mapTypeControlOptions:{
position:google.maps.ControlPosition.LEFT_TOP,
},
zoomControlOptions:{
position:google.maps.ControlPosition.LEFT_BOTTOM,
},
});
// instantiate the map on the right with control positioning
mapRight=newgoogle.maps.Map(document.getElementById("map-right"),{
...mapOptions,
fullscreenControlOptions:{
position:google.maps.ControlPosition.RIGHT_BOTTOM,
},
mapTypeControlOptions:{
position:google.maps.ControlPosition.RIGHT_TOP,
},
zoomControlOptions:{
position:google.maps.ControlPosition.RIGHT_BOTTOM,
},
});
// helper function to keep maps in sync
functionsync(...maps){
letcenter,zoom;
functionupdate(changedMap){
maps.forEach((m)=>{
if(m===changedMap){
return;
}
m.setCenter(center);
m.setZoom(zoom);
});
}
maps.forEach((m)=>{
m.addListener("bounds_changed",()=>{
constchangedCenter=m.getCenter();
constchangedZoom=m.getZoom();
if(changedCenter!==center||changedZoom!==zoom){
center=changedCenter;
zoom=changedZoom;
update(m);
}
});
});
}
sync(mapLeft,mapRight);
functionhandleContainerResize(){
constwidth=document.getElementById("container").offsetWidth;
document.getElementById("map-left").style.width=`${width}px`;
document.getElementById("map-right").style.width=`${width}px`;
}
// trigger to set map container size since using absolute
handleContainerResize();
// add event listener
window.addEventListener("resize",handleContainerResize);
//@ts-ignore
Split(["#left","#right"],{
sizes:[50,50],
});
}
window.initMap=initMap;index.js

CSS

/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
#map{
height:100%;
}
/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body{
height:100%;
margin:0;
padding:0;
}
#container,
#left,
#right,
.map,
.gutter{
height:100%;
}
#left,
#right,
.gutter{
float:left;
position:relative;
overflow:hidden;
}
#map-left{
position:absolute;
left:0;
top:0;
}
#map-right{
position:absolute;
right:0;
top:0;
}
.gutter{
background-color:#eee;
background-repeat:no-repeat;
background-position:50%;
}
.gutter.gutter-horizontal{
cursor:col-resize;
background-image:url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg==");
}
style.css

HTML

<html>
 <head>
 <title>Split Map Panes</title>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js"></script>
 <link rel="stylesheet" type="text/css" href="./style.css" />
 <script type="module" src="./index.js"></script>
 </head>
 <body>
 <div id="container">
 <div id="left">
 <div id="map-left" class="map"></div>
 </div>
 <div id="right">
 <div id="map-right" class="map"></div>
 </div>
 </div>
 <!-- 
 The `defer` attribute causes the script to execute after the full HTML
 document has been parsed. For non-blocking uses, avoiding race conditions,
 and consistent behavior across browsers, consider loading using Promises. See
 https://developers.google.com/maps/documentation/javascript/load-maps-js-api
 for more information.
 -->
 <script
 src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
 defer
 ></script>
 </body>
</html>index.html

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.

gitclone-bsample-split-map-paneshttps://github.com/googlemaps/js-samples.git
cdjs-samples
npmi
npmstart

Other samples can be tried by switching to any branch beginning with sample-SAMPLE_NAME.

gitcheckoutsample-SAMPLE_NAME
npmi
npmstart