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Showing Pixel and Tile Coordinates

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Page Summary

This example demonstrates how to display a map centered on Chicago, IL.
An info window shows the latitude, longitude, zoom level, world, pixel, and tile coordinates for the specified location.
The info window content dynamically updates as the user changes the map's zoom level.
The sample code utilizes the Web Mercator projection to calculate pixel and tile coordinates from latitude and longitude.

This example creates a map that displays a window with the latitude, longitude, and world, pixel, and tile coordinates for Chicago, IL. It also shows how these values change as the zoom level is adjusted.

Read the documentation.

[フレーム]

TypeScript

functioninitMap():void{
constchicago=newgoogle.maps.LatLng(41.85,-87.65);
constmap=newgoogle.maps.Map(
document.getElementById("map")asHTMLElement,
{
center:chicago,
zoom:3,
}
);
constcoordInfoWindow=newgoogle.maps.InfoWindow();
coordInfoWindow.setContent(createInfoWindowContent(chicago,map.getZoom()!));
coordInfoWindow.setPosition(chicago);
coordInfoWindow.open(map);
map.addListener("zoom_changed",()=>{
coordInfoWindow.setContent(
createInfoWindowContent(chicago,map.getZoom()!)
);
coordInfoWindow.open(map);
});
}
constTILE_SIZE=256;
functioncreateInfoWindowContent(latLng:google.maps.LatLng,zoom:number){
constscale=1 << zoom;
constworldCoordinate=project(latLng);
constpixelCoordinate=newgoogle.maps.Point(
Math.floor(worldCoordinate.x*scale),
Math.floor(worldCoordinate.y*scale)
);
consttileCoordinate=newgoogle.maps.Point(
Math.floor((worldCoordinate.x*scale)/TILE_SIZE),
Math.floor((worldCoordinate.y*scale)/TILE_SIZE)
);
return[
"Chicago, IL",
"LatLng: "+latLng,
"Zoom level: "+zoom,
"World Coordinate: "+worldCoordinate,
"Pixel Coordinate: "+pixelCoordinate,
"Tile Coordinate: "+tileCoordinate,
].join("<br>");
}
// The mapping between latitude, longitude and pixels is defined by the web
// mercator projection.
functionproject(latLng:google.maps.LatLng){
letsiny=Math.sin((latLng.lat()*Math.PI)/180);
// Truncating to 0.9999 effectively limits latitude to 89.189. This is
// about a third of a tile past the edge of the world tile.
siny=Math.min(Math.max(siny,-0.9999),0.9999);
returnnewgoogle.maps.Point(
TILE_SIZE*(0.5+latLng.lng()/360),
TILE_SIZE*(0.5-Math.log((1+siny)/(1-siny))/(4*Math.PI))
);
}
declareglobal{
interfaceWindow{
initMap:()=>void;
}
}
window.initMap=initMap;index.ts

JavaScript

functioninitMap(){
constchicago=newgoogle.maps.LatLng(41.85,-87.65);
constmap=newgoogle.maps.Map(document.getElementById("map"),{
center:chicago,
zoom:3,
});
constcoordInfoWindow=newgoogle.maps.InfoWindow();
coordInfoWindow.setContent(createInfoWindowContent(chicago,map.getZoom()));
coordInfoWindow.setPosition(chicago);
coordInfoWindow.open(map);
map.addListener("zoom_changed",()=>{
coordInfoWindow.setContent(createInfoWindowContent(chicago,map.getZoom()));
coordInfoWindow.open(map);
});
}
constTILE_SIZE=256;
functioncreateInfoWindowContent(latLng,zoom){
constscale=1 << zoom;
constworldCoordinate=project(latLng);
constpixelCoordinate=newgoogle.maps.Point(
Math.floor(worldCoordinate.x*scale),
Math.floor(worldCoordinate.y*scale),
);
consttileCoordinate=newgoogle.maps.Point(
Math.floor((worldCoordinate.x*scale)/TILE_SIZE),
Math.floor((worldCoordinate.y*scale)/TILE_SIZE),
);
return[
"Chicago, IL",
"LatLng: "+latLng,
"Zoom level: "+zoom,
"World Coordinate: "+worldCoordinate,
"Pixel Coordinate: "+pixelCoordinate,
"Tile Coordinate: "+tileCoordinate,
].join("<br>");
}
// The mapping between latitude, longitude and pixels is defined by the web
// mercator projection.
functionproject(latLng){
letsiny=Math.sin((latLng.lat()*Math.PI)/180);
// Truncating to 0.9999 effectively limits latitude to 89.189. This is
// about a third of a tile past the edge of the world tile.
siny=Math.min(Math.max(siny,-0.9999),0.9999);
returnnewgoogle.maps.Point(
TILE_SIZE*(0.5+latLng.lng()/360),
TILE_SIZE*(0.5-Math.log((1+siny)/(1-siny))/(4*Math.PI)),
);
}
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;
}
style.css

HTML

<html>
 <head>
 <title>Showing Pixel and Tile Coordinates</title>
 <link rel="stylesheet" type="text/css" href="./style.css" />
 <script type="module" src="./index.js"></script>
 </head>
 <body>
 <div id="map"></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-map-coordinateshttps://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